29th graduate research symposiumsymposium.chbe.gatech.edu/sites/default/files/abstract...31st annual...

29
31 st Annual Graduate Research Symposium Tuesday, February 12 Wednesday, February 13 2019

Upload: others

Post on 07-Aug-2020

3 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

2018 31st Annual Graduate Research Symposium

Tuesday, February 12 –

Wednesday, February 13

2019

Page 2: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

1

Tuesday, Feb 12

Time Location

Check-in and Breakfast 8:00am – 8:30 EBB CHOA Room

Welcome Talks from Faculty 8:30 – 8:55 EBB CHOA Room

Oral Presentation Session I 9:00 – 10:00 EBB CHOA Room

Keynote Speaker 10:00 – 10:45 EBB CHOA Room

Student/Industry Networking 11:00 – 12:00 MoSE 1st Floor Atrium

Lunch 12:00pm – 1:00 MoSE 2nd Floor Atrium

Poster Session 1:00 – 2:30 MoSE 3rd & 4th Floor

Atrium

Oral Presentation Session II 2:45 – 5:00 EBB CHOA Room

Reception & Student

Networking

5:00 – 6:00 MoSE 3rd Floor Atrium

Dinner 6:00 – 7:30 MoSE 2nd Floor Atrium

Wednesday, Feb 13

Breakfast 8:00am – 8:30 EBB CHOA Room

Oral Presentation Session III 8:30 – 9:30 EBB CHOA Room

Industry Panel 09:40 – 10:20 EBB CHOA Room

Oral Presentation Session IV 10:30-11:30 EBB CHOA Room

Interviews / Lab Tours / Break 11:30 – 12:30 EBB CHOA Room

Lunch & Closing Ceremony 12:30 - MoSE 2nd Floor Atrium

IBB

Marcus

Nanotech

Page 3: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

2

Contents

Keynote Address ................................................................. 3

3M ................................................................................... 3

Poster Session ..................................................................... 3

Materials and Nanotechnology........................................ 3

Energy and Sustainability.............................................. 11

Biotechnology ............................................................... 14

Oral Presentation Session I ............................................... 16

Materials and Nanotechnology...................................... 16

Oral Presentation Session II .............................................. 18

Materials and Nanotechnology...................................... 18

Oral Presentation Session III ............................................ 22

Energy and Sustainability.............................................. 22

Oral Presentation Session IV ............................................ 24

Energy and Sustainability.............................................. 24

Complex Systems .......................................................... 24

Biotechnology ............................................................... 25

Acknowledgements ........................................................... 27

2019 Graduate Symposium Executive Boards .............. 27

Special Thanks to: ......................................................... 27

Sponsors ............................................................................ 28

Page 4: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

3

Keynote Address

3M New Materials for the Simplification of Biopharmaceutical Purification Dr. Jonathan Hester / Senior Technical Specialist / 3M Dr. Jonathan Hester has a B.S. in Materials Science and Engineering from Purdue

University and a Ph.D. in Polymer Science from M.I.T. Since 2000, he has had multiple

technical roles at 3M, ranging from basic technology development in 3M’s Corporate Research Laboratory to, most recently, product development in the 3M Separation and

Purification Sciences Division, where he works on the development of liquid separation

solutions for biopharmaceutical processing. Jon is a co-inventor on 22 patent publications related to liquid separations materials, devices, and processes. With specific examples and

discussion of key learnings, Jon’s talk will illustrate how new functional porous materials

can be used to simplify the multi-step process used to purify the therapeutic proteins that are the basis for some of today’s most promising treatments for cancers and other important

indications.

Poster Session

Materials and Nanotechnology

1. A Database of 2D Zeolite Nanosheets: Development and Applications

Omar Knio / Prof. David S. Sholl

Zeolites are nanoporous aluminosilicates widely used in catalysis and separations

applications. Though generally formed as 3D crystals, new synthesis techniques have given

access to 2D zeolite nanosheets with small diffusion path lengths and accelerated molecular

diffusion. Since most previous research has focused on bulk zeolite crystals, there is little

understanding of the surface adsorption and diffusion mechanisms likely involved at such

length scales and their contributions to the permeability and selectivity of different species.

To enable the systematic examination of such surface properties, we constructed a database

of more than 800,000 computation-ready 2D zeolite nanosheets from the full range of

known zeolite structures in the IZA database of zeolite structure types. The nanosheet

surfaces cover a wide range of orientations and were created via the principle of minimizing

the number of bonds broken during the termination of a unit cell. The database consists of

two sets of nanosheets: one set with known heights and unrelaxed surfaces, and another set

with arbitrary heights and relaxed surfaces.

As an initial example of the utility of this database, we generated equilibrium Wulff shapes

for 203 3D zeolite structure types in the International Zeolite Association (IZA) database.

Since our database is pure silica, our predicted crystal shapes resembled experimentally

synthesized crystals with high Si:Al ratios. Finally, we used Molecular Dynamics to

identify zeolite nanosheet properties ideal for the industrially relevant separation of H2

from CO2. To that end, we examined the surface contribution to diffusion as a function of

slab height in MFI, a widely used zeolite. By incorporating surface effects, the current

study lays the groundwork for high throughput screening of zeolite nanomaterials in their

thinnest and most promising form.

Page 5: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

4

2. Selective CoAxial Lithography via Etching of Semiconductors

(SCALES): A Bottom-up Nanoscale Patterning Process for Very Large-

Scale Electronic Device Manufacturing

Amar Mohabir / Prof. Michael Filler

Nanoscale electronic devices, such as field effect transistors, contain one or more features

with nanoscale dimensions. When such devices are to be produced at very large

manufacturing rates (e.g., for large-area integrated circuitry), a bottom-up alternative to

top-down patterning is necessary to define these features. Here, we show how surfaces with

regions of differing composition can be selectively masked using surface-initiated growth

of polymer films. Our approach is particularly useful for patterning semiconductor

nanowires where composition is modulated along the nanowire length. Surface masking is

accomplished in a two-step procedure. (1) Atom transfer radical polymerization (ATRP)

of polymethylmethacrylate (PMMA) first occurs from a surface-tethered initiator in a

blanket fashion, covering all surfaces regardless of composition. (2) A subsequent selective

etch removes the polymer only from regions whose underlying surface is susceptible to the

etchant. We apply this technique, dubbed Selective CoAxial Lithography via Etching of

Semiconductors (SCALES), to nanowires containing axially-modulated doped/undoped Si

and Si/Ge regions. For the case of doped/undoped Si nanowires, KOH removes PMMA

from the undoped regions but does not attack the doped regions. For the case of Si/Ge

nanowires, PMMA is removed from the Ge regions by etching with H2O2 but remains on

the Si regions. We investigate the role of surface pre-treatment, PMMA polymerization

parameters, and post-polymerization etching on the SCALES process with a suite of

spectroscopy and microscopy techniques. The ability to mask nanoscale objects in a

bottom-up fashion opens up the possibility of nanoscale patterning in a truly scalable

manner.

3. Synthesis and Properties of Degradable Polyaldehyde Copolymers

Anthony Engler / Prof. Paul Kohl

Polyaldehydes are metastable materials at ambient conditions due to their typically low

thermodynamic ceiling temperature (TC), or the equilibrium temperature between

monomer and polymer. Breaking one backbone bond in the polymer above the TC will

initiate total depolymerization down the polymer chain, converting back to aldehyde

monomer. Polyaldehydes have yet to find a robust application in materials, because of their

instabilities at ambient temperatures. Rather than a drawback, the low TC phenomenon

offers a unique advantage in the degradation of polymers due to the minimum activation

energy required to degrade an entire polymer chain. This ability to rapidly convert to small

molecules makes polyaldehydes well suited for applications in stimuli-responsive

materials, transient technology, and sacrificial materials. Novel copolymers were

synthesized using a variety of aliphatic and functional aldehydes with o-phthalaldehyde,

which provides high molecular weight and stability. Reactivity behavior of aliphatic

aldehydes correlates positively with the aldehyde’s hydration equilibrium constant (KH),

with electron-deficient aldehydes incorporating into copolymers at higher percentages.

Higher incorporations of aliphatic aldehydes bring about lower molecular weight

polymers. The polymerization is tolerant to chain length, branching, non-conjugated

unsaturation, halogens, and sulfonate esters. Post-polymerization modifications are

performed to introduce inaccessible functional groups like epoxy, thioethers and azides.

Applications towards transient technology are discussed.

Page 6: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

5

4. Commercialization Strategies for Renewable Multilayer Chitin

Nanofiber and Cellulose Nanocrystal Barrier Films

Chinmay Satam / Prof. Carson Meredith

Petroleum derived plastics are a huge environmental concern today due to their low

biodegradability combined with the increased environmental impact associated with the

use of petroleum. Of particular concern is the accumulation of waste plastics in oceans and

landfills, which causes environmental, land management and logistical problems. In 2018,

we developed a 100% bio-based composite barrier material by spray coating chitin

nanofibers (ChNFs) and cellulose nanocrystals (CNCs) onto poly(lactic acid) (PLA). The

resulting flexible film had similar barrier properties to poly(ethylene terephthalate), but

with the added benefit of renewability and compostability. In addition to this work, we

investigated blended ChNF and CNC films using chitin with different degrees of

acetylation. We found that films produced by using deacetylated ChNFs not only had better

barrier properties but also, when blended with CNCs, required less ChNFs to achieve

comparable barrier properties. In addition, we developed a process to manufacture ChNFs

that reduces the cost of production by 40 % but at the same time improves the mechanical

properties of the resultant neat solution cast films. These developments bring the spray

coated ChNF-CNC multilayer films closer to commercialization and towards replacing part

of the plastics in food packaging with more renewable materials that are compostable and

can be produced in a circular manner.

5. Vapor Phase Infiltration of Metal Oxides into Microporous Polymers for

Solvent Stable Nanofiltration Membranes

Fengyi Zhang / Prof. Ryan P. Lively / Mark D. Losego

Owing to their high surface area and hierarchical porosity, microporous polymers, such as

polymers of intrinsic microporosity (PIMs), have shown great potential in heterogeneous

catalysis, adsorption, and membrane separations, among other applications. Linear

microporous polymers (e.g., solution-processable PIM-1), can be easily manufactured into

form factors consistent with large-scale separations (e.g., hollow fibers). However, the

limited organic solvent resistance of linear microporous polymers restrict their application

in aggressive operating environments. Two of the most prominent post-fabrication

methods for improving the stability of polymers are pyrolytic carbonization and

crosslinking. These are both promising approaches to rigidifying polymeric materials, but

require a near-complete transformation of the precursor in the former case and

chemical/thermal treatments in the latter case.

Here, we develop a novel post-fabrication modification technique for improving the

stability of microporous polymers without damaging the microstructure and macroscale

form factors. Cyclic vapor phase infiltration of metal-organic precursors and water into the

structure of PIM-1 creates monolayers or bilayers of sub-nanometer metal oxide structures

on the surfaces of the interconnected PIM-1 micropores. The resulting interpenetrating

atomic-scale networks of metal oxide and PIM-1 retain the microporosity and exhibit

excellent solvent resistance to strong solvents for PIM-1 (chloroform, dichloromethane,

and tetrahydrofuran). While PIM-1 membranes cannot effectively reject polystyrene

oligomers below 1200 g/mol from ethanol, the hybrid PIM-1 membranes reject polystyrene

oligomers larger than 400 g/mol. Besides, the interpenetrating aluminum oxide networks

inhibit the interaction between membranes and solutes, increasing the Rose Bengal

rejection from 45% to 86%. Since the vapor phase infiltration process can be directly

applied to state-of-art membrane modules, this treatment has the potential to be adopted

into the large-scale manufacturing of advanced membranes.

Page 7: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

6

6. High swing capacity MIL-101(Cr) fiber sorbents for sub-ambient CO2

capture via RCPSA

Stephen J.A. DeWitt / Prof. Ryan P. Lively

A challenge facing CO2 capture from flue gas via adsorption is the high cost of adsorbent

materials, a phenomenon partially driven by low operating capacities leading to massive

sorbent requirements. Increasing operating capacity can be accomplished by advances in

sorbent materials, cycle design, and process design, giving the sorbent more capacity or

making it operate more efficiently. This talk focuses on designing new structured sorbents

using metal organic framework (MOF) materials to enable high capacity via a sub-ambient

rapidly cycled pressure swing adsorption (RCPSA). We have found flue gas compression

and cooling is counterintuitively energy efficient when extensive heat integration and

energy recovery is utilized, and this concept enables high operating capacity for a variety

of MOF sorbents. Current technoeconomic estimates reveal parasitic loads as low as 19%

and total costs of CO2 as low as 37$/tonne.

In this talk, after a brief review of the sub-ambient RCPSA process flow sheet, we will

discuss methods of incorporating MIL-101(Cr) into fiber sorbent contactors via direct

spinning. Sub-ambient CO2 isotherms show MIL-101(Cr) may be capable of swing

capacities as large as 10 mmol/g, making it an ideal material for sub-ambient RCPSA.

Incorporating this material into a fiber sorbent contactors make possible order of magnitude

lower pressure drops as well as enabling thermal management, which increases sorbent

utilization. The talk will focus on the application of these fibers to capturing CO2 from

simulated flue gas, and will include analysis of breakthrough curves and cyclic stability of

the sorbent. These fiber sorbents containing high operating capacity sorbent materials help

to support the case for applicability of the novel process design.

7. Evidence for entropic diffusion selection of xylene isomers in polymer

derived carbon molecular sieve membranes

Yao Ma / Prof. Ryan P. Lively

The purification of benzene derivatives, particularly xylene isomers, is one of the most

important organic mixture separations practiced in industry. The separation of xylene

isomers is especially challenging due to the similarity of their physical properties. Carbon

molecular sieve (CMS) membranes are promising materials for such challenging solvent

separations due to their thermal and chemical stability, but these materials have not been

studied in detail in the case of large organic molecules. Xylene isomer transport and

sorption properties in a CMS membrane derived from a prototypical polymer of intrinsic

microporosity (PIM-1) reveal that diffusion selectivity is the dominant factor in

contributing to the preferential permeation of p-xylene over o-xylene. Moreover, the

contributions of “enthalpic” and “entropic” selectivity to the diffusion selectivity are

studied in detail and reveal that entropic factors dominate the xylene selection mechanism.

Overall, this study provides fundamental insight and guidance into the separation of large

organic molecules in amorphous microporous materials.

8. Effects of acid gases in chemically stable metal-organic frameworks

Eli Carter / Prof. Krista S. Walton

Metal-organic frameworks (MOFs) are promising materials for a variety of applications,

including adsorption separation processes. Some of these potential gas separation

applications involve exposure to acid gases (e.g. sulfur dioxide and nitrogen oxides), which

may cause framework degradation or poisoning of adsorption sites, limiting the

applicability of MOFs in adsorption processes or making their repeated use more difficult.

Page 8: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

7

In this work, MIL-101(Cr)—a chemically stable MOF predicted in literature to experience

poisoning by acid gases and derivatives—is exposed to SO2 and NO2 at varying

concentrations under both dry and humid conditions. Post-exposure nitrogen physisorption

measurements demonstrate a loss of adsorption capacity—as measured by BET surface

area—caused by exposure to SO2 and NO2, but without structural degradation (as

indicated by powder x-ray diffraction). Repeated single-component breakthrough

experiments (with sample regeneration conducted in situ) done with both SO2 and NO2 on

MIL-101(Cr) show that this loss in adsorption capacity applies to multiple adsorbates and

cannot be completely reversed by normal activation conditions. X-ray photoelectron and

infrared spectroscopy conducted post-exposure and after regeneration conditions show

retention of acid gas species and their derivatives in the MIL-101(Cr) samples, suggesting

that the cause of the reduced post-exposure capacity includes acid gas species strongly

bound to the framework structure. These results experimentally confirm a difficulty that

acid gases may present in MOF adsorbents in addition to well-known issues of chemical

stability. Hence, the results draw attention to a detrimental effect of acid gases to be

accounted for in future work on chemically stable MOFs.

9. Porous MOF-Polymer Composite Fibers by Solution Blow Spinning

Jacob Deneff / Prof. Krista S. Walton

Nonwoven polymer composites containing metal organic frameworks (MOFs) as active

materials have shown promise as protective textiles and adsorbents. Solution blow spinning

(SBS) is a recently developed technique for nanofiber production that represents an

alternative to electrospinning. SBS uses high velocity gas to draw polymer solutions

through a nozzle, forming fibers upon solvent evaporation. It is capable of producing fibers

with the same diameter range as electrospinning, but with higher throughput and requiring

no specialized solvent or electrical field, making it attractive for scaled-up and in-situ

applications. By suspending MOF in the polymer solution before spraying we can produce

MOF-polymer composites combining the structure and mechanical stability of nonwoven

textiles with the adsorbent and catalytic properties of MOFs. Additionally, by incorporating

non-solvent into the spray we can create porosity through phase separation, ensuring that

the active material is accessible within the polymer matrix. These composites can be

applied in-situ for personal protection and detoxification of industrial chemicals and

chemical warfare agents.

10. Facile Integration of Porous Nanomaterials on and from Support Media

Jayraj N. Joshi / Prof. Krista S. Walton

Unconventional strategies for synthesizing advanced separation materials can reduce

manufacturing complexity while affording economic and environmental benefits.

Accordingly, we present a novel method for producing supported porous nanomaterials

both from and on aluminum-based support structures. Supported MOF composites are

created in one-step from inexpensive aluminum oxides, alloys, meshes, foil, and even

recycled beverage cans. Microscopy reveals uniform monolayer epitaxial MOF growth.

The same strategy is adapted to different framework systems, as well as non-supported

adsorbent production with unique textural properties. Scaffolded microneedle MIL-53(Al)

MOFs produced from this study are additionally ideal precursors for creating supported

aluminum oxide nanotubes. Through MOF pyrolysis, micro/mesoporous alumina

structures emerge 1-5µm perpendicular from the underlying support. In addition to the

conventional uses of alumina as catalyst and adsorbent supports, newly-generated oxides

investigated here afford unique MOF regrowth and acid gas remediation applications.

Page 9: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

8

Presented findings establish a simple and accessible gateway for building nanoscale-

controlled devices, hierarchical separation media, and high performance membranes.

11. Comprehensive Study of SO2 Adsorption in a Series of Metal-organic

Frameworks

Julian Hungerford / Prof. Krista S. Walton

A series of Metal-organic Frameworks (MOFs) were synthesized and SO2 adsorption

isotherms were collected on a lab build pressure decay apparatus to develop structure-

property relationships. The MOFs tested included: DMOF-TM, DMOF-ADC, MIL-

53(Al), Cu-BTC, UiO-66, MIL-101(Cr), ZIF-7, ZIF-8, ZIF-11, and ZIF-65. All MOFs

used in this study were found to be stable upon exposure to SO2 for the duration of the

isotherm collection. We established that MOFs with larger pore volumes correlated with

higher SO2 adsorption capacity at high SO2 pressure. MIL-101(Cr) had the highest SO2

adsorption capacity of 21 mmol/g while also having the largest pore volume of 1.3 cm3/g.

MIL-53(Al), Cu-BTC, and ZIF-65 displayed similar SO2 adsorption capacities of roughly

12 mmol/g while having similar pore volumes. ZIF-7 and ZIF-11 adsorbed very little SO2

at all adsorption points, these materials have pore diameters smaller than the kinetic

diameter of SO2 and we hypothesize that any SO2 adsorption is likely due to structure

defects or linker flexibility. When analyzing the low pressure region of the SO2 adsorption

isotherms for these MOFs a different relationship is observed. Cu-BTC, a MOF containing

open metal sites (OMS), displayed strong SO2 adsorption at the lowest adsorption points.

DMOF-TM does not contain OMS, however it displayed greater low pressure adsorption

than Cu-BTC. The pore diameter of DMOF-TM is nearly identical to the kinetic diameter

of SO2 such that molecular sieving may contribute to a large SO2 adsorption at low

pressure. Our overall findings show that MOFs with the large pore volumes will have large

SO2 adsorption capacities at high pressures, while OMS or molecular sieving dominate the

low pressure region.

12. Rheological Characterization of Nanocellulose Materials for Quality

Control

Jianshan Liao / Prof. Victor Breedveld

Nanocellulose material is a renewable and sustainable nanomaterial produced from

abundant cellulose sources. Its high strength and biodegradability make it attractive to

many applications such as composites, coatings and rheological modifiers. To ensure

consistent production of high quality nanocellulose materials, one of the most urgent issues

to be addressed is the lack of standardized, rapid and reliable characterization methods.

Current techniques, such as electron microscopy and light scattering, are expensive and

time-consuming. Moreover, they only probe a small portion of the nanocellulose sample,

which may misrepresent the sample’s bulk properties. Rheology provides a fast and cost-

effective way to characterize nanocelluloses in large volume. In this work, we will show

the influence of concentration and salt content on rheological properties of cellulose

nanocrystal and TEMPO oxidized cellulose nanofiber. A rheological model was

formulated to capture the viscosity across shear rates and concentrations. We will also

demonstrate the change of fiber length and carboxylic content of cellulose nanofiber

reflected on the change of their rheological properties, which can be captured by the

rheological model.

13. The Geode Process: A Route to the Large-Scale Manufacturing of

Functionally-Encoded

Maritza Mujica / Prof. Victor Breedveld / Prof. Michael Filler

Page 10: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

9

Future large-area electronic and photonic technologies will require the manufacturing of

materials and devices at very high rates without sacrificing nanoscale control of structure

and composition. Semiconductor nanowires can be produced with exquisite spatial control

of composition and morphology using the vapor-liquid-solid (VLS) mechanism that,

unfortunately, remains limited to very small manufacturing rates. Here, we introduce the

Geode process to synthesize functionally-encoded semiconductor nanowires at

throughputs orders of magnitude beyond the state-of-the art. Central to the Geode process

are sacrificial, porous-walled, seed particle-lined silica microcapsules, whose interior

surface serves as a high-surface area growth substrate. Microcapsules protect the growing

nanostructures, are produced with a scalable emulsion templating technique, and are

compatible with large-scale chemical reactors. We will show how microcapsule structure

and drying is influenced by silica nanoparticle type and concentration, emulsification

parameters, and nanoparticle cross-linking agent. We will also demonstrate the synthesis

of Si nanowires with programmable dopant profiles on the microcapsule interior, which

not only shows the versatility of the process, but also allows the impact of precursor gas

transport limitations to be characterized.

14. Control of Nucleation Density in Conjugated Polymers via Seed

Crystallization

Michael McBride / Prof. Martha Grover

Desired semiconducting electronic properties of conjugated polymer systems are highly

dependent on the thin film morphology. The requirement of interconnected assemblies has

been deemed most influential for long range percolative charge transport. However,

entanglement effects in conjugated polymers severely limits the π stacking of polymer

chains into interconnected crystalline domains. The entanglement of individual chains can

be reduced through solution processing methods that promote the nucleation and growth

of tightly packed, ordered structures.

Herein, we demonstrate facile solution processing methods to target the formation of

interconnected assemblies. Poly(3-hexylthiophene) (P3HT), the canonical semicrystalline

conjugated polymer to investigate the mechanism of self-assembly in solution, was utilized

as a representative model polymer. Manipulation of the polymer molecular weight

distribution, solute-solvent interactions via solution environment, and quantity of seed

nuclei are shown to be tunable parameters impacting the degree of interconnectivity during

self-assembly. Both the generality and limitations of these approaches were investigated

using a wide array of nucleation events including exposure to low dose UV, microfluidic

flow processing, and poor solvent addition. A particularly promising approach involves the

selective mixing of a nucleated polymer solution with a non-nucleated sample.

Mechanistically, highly crystalline and order domains can be formed during primary

nucleation and then interconnected via secondary nucleation. These processing approaches

have improved the charge carrier mobility from a base of ~10-3 to exceeding 0.200 cm2/V-

s.

General process-structure-property relationships were developed to quantitatively describe

the tradeoffs between polymer network formation and grain boundaries on charge

transport. All examined cases suggest an optimal processing window for long range

interconnectivity.

Page 11: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

10

15. Enhanced electrical conductivity of polyacrylonitrile (PAN) fiber with

reduced amount of carbon

Mingxuan Lu / Prof. Satish Kumar

Carbon nanotubes (CNT) have gained much attention and interest to be used as

reinforcement material because of their extraordinary mechanical, electrical, and thermal

properties. Previous literature reported that introduction of high loading (15 to 20 wt %)

CNT into polyacrylonitrile (PAN) fiber enhanced electrical conductivity of polymer matrix

and enabled multifunctionality such as Joule heating effect. Joule heating can potentially

reduce energy cost of producing carbon fibers from PAN precursors compared to

traditional heating by convection oven. Recent research work is aimed to reduce CNT

amount in fibers while maintaining good electrical conductivity of PAN/CNT fibers. Core-

sheath structure was used, and highly percolated CNT (10 wt %) was put into a thin sheath

only for enhancement of electrical conductivity. PAN/PAN-CNT core/sheath fibers were

successfully made with different core-sheath area ratios. The overall CNT content in fibers

was in the range of 3.7 – 6.6 wt %. Electrical conductivity of as-spun fibers with low crystal

size and crystallinity was improved with short-time annealing or slight drawing, when

CNTs had more chance to rearrange themselves to form increased number of percolation

pathways. Slightly drawn fiber (3x draw ratio) of 4.4 wt % CNT possessed electrical

conductivity of 0.38 S/m before annealing and up to 5 S/m after annealing. The tensile

strength and modulus of corresponding fibers were as high as 299 MPa and 12.7 GPa,

respectively. These fibers will be used to verify Joule heating effect in the future. Also, we

believe these fibers can enable new applications with the combination of electrical and

mechanical properties.

16. Engineering cellulose nanomaterials as alternative supports for

heterogeneous cooperative

Nathan Ellebracht / Prof. Christopher W. Jones

Cellulose nanomaterials (CNMs) are a class of advanced bioproducts being investigated

for a range of applications. The hydroxyl-rich surfaces of these cellulosic biomass-derived

crystalline nanomaterials are excellent substrates for chemical functionalization, and their

fibril-like structures allow them to assemble as foams, films, hydrogels, and aerogels. The

unique properties of these adaptable materials have led to investigations for an array of

specialty applications including sensing, separations, and catalysis. Studies of CNMs as

catalyst supports have focused on supported metal nanoparticles in homogeneous

suspensions. Poor thermal and chemical stability pose significant limitations to the range

of catalytic applications possible for CNMs, but their ability to form structured porous

materials like aerogels offers unique opportunities in catalysis.

Co-located organic acid and base surface species, typically studied in silane-modified

silicas, can function as enzyme-inspired cooperatively catalytic active sites. Cellulose

nanomaterials as demonstrated herein as an alternative to these well-studied porous

inorganic supports for heterogeneous organocatalysis. Dual acid and base character was

imparted to CNM surfaces through controlled chemical functionalization, and these

multifunctional materials were demonstrated as viable acid-base catalysts for aldol

condensation reactions. Aspects of surface chemistry determining catalytic were probed

and optimized through quantitative control of various surface species. As cooperative

catalysts, the relative abundance and spacing of acid (COOH) and base (NH2) species were

demonstrated to be key determinants of catalytic activity. The crystalline nature of CNMs

allowed for precise understanding of the order and proximity of catalytic species, resulting

in catalysts which outperformed state of the art aminosilica catalysts in both activity and

Page 12: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

11

selectivity. Effective catalysis toward desired products in upgrading reactions of biomass-

derived furfural was demonstrated with optimized CNM catalysts. Finally, porous solid

aerogel CNM catalysts were developed for biomass upgrading catalysis in batch and flow.

17. Silica Supported Sterically Hindered Amines for CO2 Capture

Jason J. Lee / Prof. Christopher W. Jones / Prof. Carsten Sievers

Most studies exploring CO2 adsorption on solid supported amines have focused on simple,

sterically unhindered amines or alkylimine polymers. It has been observed in extensive

solution studies that another class of amines, namely sterically hindered amines, can give

enhanced CO2 capacity when compared to their unhindered counterparts. While sterically

hindered amines have been well studied in solution, there has been limited research

conducted on this amine type on solid supports.

In this work, the CO2 adsorption performance of mesoporous silica materials

functionalized with hindered amines are investigated using fixed bed breakthrough

analysis. Furthermore, chemisorbed CO2 species formed on the sorbents are elucidated

using in situ FTIR and NMR spectroscopy. Enhancement of CO2 adsorption capacity is

observed for all supported hindered amines under humid conditions and this increase in

capacity is in part due to the formation of ammonium bicarbonates. Our experiments also

suggest that chemisorbed CO2 species formed on supported hindered amines are weakly

bound, which may lead to reduced energy costs associated with regeneration.

Energy and Sustainability

18. Selective Removal of Hydrogen Sulfide from Biogas Streams Using

Sterically Hindered Amine Adsorbents

Claudia N. Okonkwo / Prof. Christopher W. Jones

Sterically hindered amines in solution have been explored for H2S capture and they have

been found to be selective for removing H2S over CO2 compared to the conventional

methyl diethanolamine (MDEA) or unhindered amines. A disadvantage with these amine

solutions is the high regeneration energies required while operating practical, aqueous

systems. As a result, the use of solid supported materials with lower heat capacities and

improved energy costs has been proposed. This work uses sterically hindered amines on

solid supported materials to determine their H2S selectivity in the presence of CO2 and

CH4. Using a breakthrough apparatus, in-situ infrared spectroscopy and thermogravimetric

analysis we have investigated (i) the H2S selectivity in a multicomponent gas mixtures, (ii)

the nature of the chemisorbed species formed during H2S adsorption and (iii) the effect of

concentration and temperature on H2S adsorption performance on these sterically hindered

amine adsorbents under dry conditions.

19. Fabrication of AEL zeolite nanosheet membrane on alumina hollow

fibers for molecular-sieving applications

Akshay Korde / Prof. Sankar Nair / Prof. Christopher W. Jones

Two-dimensional zeolites are promising materials for the fabrication of ultra-thin zeolite

membranes that show high flux and separation efficiency as demonstrated for MFI zeolite.

Several other zeolite frameworks have been crystallized as a multi-lamellar stack of two-

dimensional nanosheets but their fabrication into membranes for separation applications

still remains unexplored. In this work, two-dimensional AEL nanosheets are used to

fabricate thin AEL zeolite membranes on the shell side of alumina hollow fibers to

demonstrate a proof of concept for scalable zeolite membranes that can display molecular-

sieving abilities. The multi-lamellar AEL nanosheets are exfoliated through polymer melt

Page 13: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

12

compounding with polystyrene. Exfoliated AEL zeolite nanosheets are then vacuum coated

on the shell side of alumina hollow fibers followed by a secondary growth step to form a

continuous membrane layer that is ~2 µm thick. These membranes are then activated

through exposure to a high intensity UV lamp and their molecular-sieving ability is

demonstrated through single-component vapor permeation of several organic molecules

that cover a wide range of kinetic diameters.

20. Kinetics of CO2 adsorption in amine-functionalized materials with

stepped isotherms

Trisha Sen / Prof. Yoshiaki Kawajiri / Prof. Matthew J. Realff

CO2 uptake in amine-functionalized MOFs, such as Mg2(dobpdc), follows a tunable

stepped isotherm behavior, which enables unprecedented high equilibrium and pressure-

swing capacities for CO2 capture under DAC (Direct Air Capture) conditions (< 0.4 mbar).

This study attempts to move beyond the equilibrium understanding of these materials, by

analyzing their kinetics associated with DAC and to determine whether this limits their

practical application.

An adsorption breakthrough setup with ultra-dilute (0.4 mbar) and dilute (1 mbar, 5 mbar

and 10 mbar) feed was used as a proxy to simulate practical systems. Local equilibrium

theory for stepped isotherms predicts a simple single shock breakthrough for CO2

concentrations above 1% (or 10 mbar). Below 10 mbar, we expect two shocks separated

by a plateau corresponding to the isotherm step pressure. The predicted shapes of the

breakthrough profiles matched the experimentally observed results only qualitatively.

Attempts to fit a traditional LDF mass transfer model to match the observed data were

unsuccessful. While CO2 is simply physisorbed below the isotherm step, a cooperative

mechanism kicks in once this critical loading has been achieved. To capture these kinetics,

a simple LDF model before the isotherm step change and a model for co-operative uptake

(Avrami / Michaelis-Menten) above the step were implemented. Further, quantifying the

CO2 capture fraction of the bed at saturation showed that the bed utilization efficiency is

severely reduced at low feed concentration especially with increasing flowrates.

The aim of this work is therefore two-fold. Firstly, to understand and quantify the system

kinetics of amine functionalized adsorbents with stepped isotherms. Secondly, this study

indicates that moving beyond equilibrium or swing capacity of these adsorbents, and

looking at their kinetics is crucial to assess their efficiency in practical DAC applications.

21. Ethylene/Ethane Separation in Metal-Organic Frameworks by

Computational Modeling

Wenqin You / Prof. David S. Sholl

Metal-organic frameworks (MOFs) with open metal sites (OMS) are known to be selective

for ethylene relative to ethane. In practical applications of this separation, the presence of

other small molecules such as H2O, CO, and C2H2 may affect the suitability of sorbents.

We used density functional theory (DFT) calculations to compute the binding energies of

H2O, CO, C2H2, C2H4, and C2H6 in M-BTC (BTC = 1,3,5-benzenetricarboxylic acid)

with 12 different metals forming OMS (M = Mg, Ti, V, Cr, Mo, Mn, Fe, Ru, Co, Ni, Cu,

and Zn). To probe the generality of these results for MOFs containing other ligands, we

performed similar calculations for metal-substituted MOFs based on four more materials

with dimeric Cu sites. Our results provide useful insights into the variations in binding

energies that are achievable by metal substitution in this broad class of MOFs, as well as

Page 14: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

13

pointing towards feasible adsorption-based separation strategies for complex molecular

mixtures. Zn OMS MOFs were predicted to have the highest C2H4/C2H6 selectivity, but

the strong binding energy of solvents and other small molecules in these materials may

create practical challenges. We used DFT calculations to examine whether functionalizing

linkers in these materials with electron withdrawing (-fluorine) and donating (-methyl)

groups offer a useful way to tune molecular binding energies on OMS in these materials.

22. SEPARATION AND PURIFICATION OF BIODERIVED FURANIC

MOLECULES WITH METAL-ORGANIC FRAMEWORKS

Yadong Chiang / Prof. Ryan P. Lively / Prof. Sankar Nair

This work investigates the use of microporous adsorbent materials to purify furanic

products from liquid mixtures generated during processing of lignocellulosic feedstocks.

Furanics are high-value added chemicals since they can be used as biofuels and as

important “platform chemical” precursors to polymers, pharmaceuticals, and fine

chemicals. Conversion of sugars or other feedstocks to furanics often leads to complex

product mixtures in which the components are typically heat sensitive, have similar

physicochemical properties, and form azeotropes, thus making conventional separation

processes such as distillation unfavorable. Such “high-resolution” separations (wherein the

molecules possess very similar characteristics) require approaches based upon precisely

tailored materials as separating agents. MOFs are a group of newly explored microporous

materials consisting of metal ions/clusters coordinated to organic linker molecules. Two

classes of MOFs (i.e., UiO and ZIF) are identified as potential adsorbents for their high

selectivity, capacity, and reusability to develop two new separation processes for the

purification of furfural and 2,5-dimethylfuran (DMF). A suite of characterization and

modeling techniques including single-component adsorption, ideal adsorbed solution

theory (IAST) calculations, multicomponent vapor/liquid mixture breakthrough

experiments, and pulsed-field-gradient nuclear magnetic resonance (PFG-NMR) are used

to build the key structure-property (i.e., adsorption/diffusion) relations. One recent advance

(Chiang et al, ACS Sus Chem Eng, 6, 7931-7939, 2018) is the purification of (DMF) from

n-butanol (BuOH) wherein the separation is limited by an azeotrope formation at 90%

DMF at 1 bar and elevated temperature. Our investigation shows that ZIF-8 (DMF/BuOH

selectivity~5 using 10% DMF feed) and defect-engineered UiO-66 (BuOH/DMF

selectivity= ~8 using 10% n-BuOH feed) adsorbents, when used in series, can upgrade

dilute DMF feeds from 10 wt% to purified (99%+) DMF and also generate a high-purity

(>95%) n-BuOH recycle. A detailed discussion on the re-design of separation using MOF

adsorbents in simulated-moving bed processes with multi-component mixtures will be

presented.

23. In operando optical visualization of Br5- electrochemistry with a planar

glass battery for Zn/Br flow batteries

Yutong Wu / Prof. Nian Liu

Rechargeable Zn-based batteries are a safe alternative to Li-ion for compatibility with

aqueous electrolyte. Also, theoretical volumetric energy density of Zn-based batteries (e.g.

Zn-air) is ~85% of lithium-sulfur battery. However, the performance of Zn anode is limited

by passivation and dissolution. Here we report a ZnO@TiN core/shell nanorod structure

for rechargeable Zn anode. The small diameter (<500 nm) of ZnO prevents passivation and

allows full utilization of active materials, while the thin and conformal titanium nitride

(TiN) coating mitigates Zn dissolution in alkaline electrolyte, mechanically maintains the

nanostructure, and delivers electron to nanorods. As a result, the ZnO@TiN core/shell

nanorod anode achieves superior battery performance compared with bulk Zn foil or

Page 15: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

14

uncoated ZnO nanorod anode. It delivers excellent long-term electrochemical performance

(more than 7,500 cycles) as cycled under start-stop conditions. The nanoscale design

principles reported here can potentially be applied to overcome other intrinsic limitations

of Zn anodes and other battery materials.

Biotechnology

24. Engineering Zika Antigens to Enhance Neutralizing Antibody

Responses

Ana Stringari de Castro / Prof. Ravi Kane

Infections with Zika virus (ZIKV) have been linked to the development of serious

neurological conditions like microcephaly and Guillain-Barré syndrome. However, a Zika

vaccine is not commercially available yet. The ZIKV Envelope (E) protein is the main

target of neutralizing antibodies and it can be divided into three domains: DI, DII, and DIII.

Recently, three distinct antigenic epitopes have been identified on DIII of the E protein.

One of them, the lateral ridge epitope, is targeted by antibodies that have demonstrated

protective efficacy in vivo, while the other two epitopes elicit poorly- or non-neutralizing

antibodies. Our goal is to engineer antigens that elicit ZIKV-neutralizing antibodies and

minimize the generation of antibodies that don’t confer protection against the virus. Our

approach involves the design of recombinant antigenic proteins incorporating unnatural

amino acids and site-specific protein functionalization with polyethylene glycol (PEG)

groups. This will allow us to shield with PEG the two epitopes that do not elicit neutralizing

Zika antibodies, leaving exposed only the lateral ridge epitope. This will be followed by

multivalent attachment of these modified proteins to scaffolds in order to enhance B cell

activation. Immunization with this engineered antigen should result in a higher generation

of neutralizing antibodies towards the lateral ridge epitope. Preliminary ELISA results

demonstrate our ability to focus antibody binding on targeted DIII epitopes while shielding

non-neutralizing epitopes. We are currently finalizing in vivo studies and will next confirm

the ability to focus the immune response on ZIKV-neutralizing epitopes and to protect mice

from a ZIKV challenge.

25. Structural Characterization of a Drug Carrier for Intracellular

Antibody Delivery

Anshul Dhankher / Prof. Julie A. Champion

In recent years, antibodies have shown great promise as therapies in multiple disease areas.

However, the application of antibodies is restricted to a small number of extracellular therapeutic targets since they can’t cross the cell membrane. To target intracellular

proteins, we developed a self-assembling protein carrier that binds the constant region (Fc)

of antibodies and delivers them intracellularly. The carrier is comprised of a self-assembling hexamer barrel (Hex) with an Fc binding domain fused to each monomer of

the barrel. Further application of the drug carrier requires characterization of the Hex

antibody complexes. In order to understand the maximum antibody loading capacity of Hex carriers, mixtures of Hex-IgG (Immunoglobulin G, a non-specific antibody) at various

Hex to IgG ratios were analyzed by size exclusion chromatography in tandem with multi

angle light scattering. We found that a 1 to 3 molar ratio saturated Hex carriers but yielded two separate populations, one at the expected molecular weight of 1 Hex to 3 IgG, and

another much larger. In addition, stability studies of the Hex-IgG complexes with dynamic

light scattering showed a decrease in particle size over time, which was accelerated by incubation at higher temperatures. Further characterization demonstrated that the larger

molecular weight species had largely disappeared into the expected 1:3 molecular weight, indicating rearrangement of the Hex-IgG complexes into a 1:3 ratio. Preliminary results

Page 16: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

15

demonstrated that aging of the Hex-IgG complexes can improve the intracellular delivery

of antibodies, relating the structural rearrangement to a functional improvement. 26. Non-enzymatic nucleic acid ligation: Rules for using carbodiimides

Chiamaka Obianyor / Prof. Martha Grover

RNA is often considered a major precursor to cellular life. However, a prebiotic mechanism

that permits multiple rounds of RNA replication has not been discovered. The discovery of

a pathway to non-enzymatic replication is often hindered by the inability to ligate

mono/oligo-nucleotides without the use of enzymes. Several pathways have been proposed

previously to solve this problem, including the use of activated primers to enable ligation

of mononucleotides, and the formation of new RNA strands from transesterification

reactions. Nevertheless, the lack of a simple pathway for the prebiotic production of these

activated primers, and low yield from transesterification reactions have prevented the

advancement of these ideas. The goal of this research is to elucidate common principles

that could explain the low yields often encountered in non-enzymatic ligation and guide

the development of future ligating systems. Using carbodiimides as the activating agent for

the formation of a phosphodiester bond, we demonstrate the feasibility of RNA as a

potential prebiotic biopolymer. We observe that the hybridization of the oligonucleotides

to the template is the rate limiting step of non-enzymatic template directed ligation

reactions. Additionally, we found that the pre-alignment of the cyclic phosphate

intermediate for RNA ligation determines the formation of products, thus explaining why

transesterification reactions only occur efficiently in naturally evolved systems.

Altogether, our results demonstrate how different factors could have played a role in the

earliest RNA ligation systems and the relevance of these factors in determining the first

prebiotic biopolymer.

27. Novel Supply Chain and Process Modeling for Cell Therapy

Manufacturing

Yi Liu / Prof. Chip White

Cell therapy is a rapidly growing industry with its unique production and supply chain

complications. We present a two-level hierarchical supply chain model of autologous

CAR-T cell therapy that serves as the basis for the development of strategies to: 1) deliver

cell therapy products that are safe and have a high level of efficacy, 2) minimize fulfillment

time and variability, and 3) reduce total manufacturing and logistics costs while reducing

the risk of patient morbidity and mortality. The model consists of two integral components:

(1) an agent-based program for a “single manufacturing facility” that simulates the

manufacturing and quality control process of cell therapy; and (2) a supply chain network

program that evaluates different supply chain configurations and sourcing strategies. The

two-level hierarchical supply chain model can be used as a decision support system to

explore manufacturing, quality assurance, and supply chain and logistics ‘what if’

questions. Using the model, we explored the impact of reagent supply chain disruptions to

manufacturing and evaluated the effectiveness of different tools that can mitigate

unexpected supply disruptions. We intend to use this model to support the design and

operation of supply chains for end-to-end manufacturing and logistics of large-scale, low-

cost, reproducible and high-quality cell therapy products.

Page 17: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

16

Oral Presentation Session I

Materials and Nanotechnology

Ion-sieving carbon nanoshells for deeply rechargeable Zn-based aqueous

batteries

Yutong Wu /Prof. Nian Liu

As an alternative to lithium-ion batteries, Zn-based aqueous batteries feature non-

flammable electrolyte, high theoretical energy density, and abundant materials. However,

a deeply rechargeable Zn anode in lean electrolyte configuration is still lacking. Different

from the solid-to-solid reaction mechanism in lithium-ion batteries, Zn anodes in alkaline

electrolyte go through a solid-solute-solid mechanism (Zn-Zn(OH)42--ZnO), which

introduces two problems. First, discharge product ZnO on the surface prevents further

reaction of Zn underneath, which leads to low utilization of active material and poor

rechargeability. Second, soluble intermediate changes Zn anode morphology over cycling.

In this work, we report an ion-sieving carbon nanoshell coated ZnO nanoparticle anode,

synthesized in a scalable way with controllable shell thickness, to solve the problems of

passivation and dissolution simultaneously. The nano-sized ZnO prevents passivation,

while microporous carbon shell slows down Zn species dissolution. Under extremely harsh

testing conditions (closed cell, lean electrolyte, no ZnO saturation), this Zn anode shows

significantly improved performance than Zn foil and bare ZnO nanoparticles. The deeply

rechargeable Zn anode reported is an important step towards practical high-energy

rechargeable aqueous batteries (e.g. Zn-air batteries). And the ion-sieving nanoshell

concept demonstrated is potentially beneficial to other electrodes such as sulfur cathode

for Li-S batteries.

The Geode Process: A Route to the Large-Scale Manufacturing of

Functionally-Encoded Semiconductor Nanowires Maritza Mujica / Prof. Michael Filler

Future large-area electronic and photonic technologies will require the manufacturing of

materials and devices at very high rates without sacrificing nanoscale control of structure

and composition. Semiconductor nanowires can be produced with exquisite spatial control

of composition and morphology using the vapor-liquid-solid (VLS) mechanism that,

unfortunately, remains limited to very small manufacturing rates. Here, we introduce the

Geode process to synthesize functionally-encoded semiconductor nanowires at

throughputs orders of magnitude beyond the state-of-the art. Central to the Geode process

are sacrificial, porous-walled, seed particle-lined silica microcapsules, whose interior

surface serves as a high-surface area growth substrate. Microcapsules protect the growing

nanostructures, are produced with a scalable emulsion templating technique, and are

compatible with large-scale chemical reactors. We will show how microcapsule structure

and drying is influenced by silica nanoparticle type and concentration, emulsification

parameters, and nanoparticle cross-linking agent. We will also demonstrate the synthesis

of Si nanowires with programmable dopant profiles on the microcapsule interior, which

not only shows the versatility of the process, but also allows the impact of precursor gas

transport limitations to be characterized.

Page 18: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

17

Control of Nucleation Density in Conjugated Polymers via Seed

Crystallization

Michael McBride/ Prof. Martha A. Grover

Desired semiconducting electronic properties of conjugated polymer systems are highly

dependent on the thin film morphology. The requirement of interconnected assemblies has

been deemed most influential for long range percolative charge transport. However, entanglement effects in conjugated polymers severely limits the π stacking of polymer

chains into interconnected crystalline domains. The entanglement of individual chains can

be reduced through solution processing methods that promote the nucleation and growth of tightly packed, ordered structures.

Herein, we demonstrate facile solution processing methods to target the formation of

interconnected assemblies. Poly(3-hexylthiophene) (P3HT), the canonical semicrystalline

conjugated polymer to investigate the mechanism of self-assembly in solution, was utilized

as a representative model polymer. Manipulation of the polymer molecular weight

distribution, solute-solvent interactions via solution environment, and quantity of seed

nuclei are shown to be tunable parameters impacting the degree of interconnectivity during

self-assembly. Both the generality and limitations of these approaches were investigated

using a wide array of nucleation events including exposure to low dose UV, microfluidic

flow processing, and poor solvent addition. A particularly promising approach involves the

selective mixing of a nucleated polymer solution with a non-nucleated sample.

Mechanistically, highly crystalline and order domains can be formed during primary

nucleation and then interconnected via secondary nucleation. These processing approaches

have improved the charge carrier mobility from a base of ~10-3 to exceeding 0.200 cm2/V-

s. General process-structure-property relationships were developed to quantitatively

describe the tradeoffs between polymer network formation and grain boundaries on charge

transport. All examined cases suggest an optimal processing window for long range

interconnectivity.

Rheological Characterization of Nanocellulose Materials for Quality

Control

Jianshan Liao/ Prof. Victor Breedveld

Nanocellulose material is a renewable and sustainable nanomaterial produced from

abundant cellulose sources. Its high strength and biodegradability make it attractive to

many applications such as composites, coatings and rheological modifiers. To ensure

consistent production of high quality nanocellulose materials, one of the most urgent issues

to be addressed is the lack of standardized, rapid and reliable characterization methods.

Current techniques, such as electron microscopy and light scattering, are expensive and

time-consuming. Moreover, they only probe a small portion of the nanocellulose sample,

which may misrepresent the sample’s bulk properties. Rheology provides a fast and cost-

effective way to characterize nanocelluloses in large volume. In this work, we will show

the influence of concentration and salt content on rheological properties of cellulose

nanocrystal and TEMPO oxidized cellulose nanofiber. A rheological model was

formulated to capture the viscosity across shear rates and concentrations. We will also

demonstrate the change of fiber length and carboxylic content of cellulose nanofiber

reflected on the change of their rheological properties, which can be captured by the

rheological model.

Page 19: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

18

Oral Presentation Session II

Materials and Nanotechnology

Vapor Phase Infiltration of Metal Oxides into Microporous Polymers for

Solvent Stable Nanofiltration Membranes

Fengyi Zhang / Prof. Ryan P. Lively

Owing to their high surface area and hierarchical porosity, microporous polymers, such as

polymers of intrinsic microporosity (PIMs), have shown great potential in heterogeneous

catalysis, adsorption, and membrane separations, among other applications. Linear

microporous polymers (e.g., solution-processable PIM-1), can be easily manufactured into

form factors consistent with large-scale separations (e.g., hollow fibers). However, the

limited organic solvent resistance of linear microporous polymers restrict their application

in aggressive operating environments. Two of the most prominent post-fabrication

methods for improving the stability of polymers are pyrolytic carbonization and

crosslinking. These are both promising approaches to rigidifying polymeric materials, but

require a near-complete transformation of the precursor in the former case and

chemical/thermal treatments in the latter case.

Here, we develop a novel post-fabrication modification technique for improving the

stability of microporous polymers without damaging the microstructure and macroscale

form factors. Cyclic vapor phase infiltration of metal-organic precursors and water into the

structure of PIM-1 creates monolayers or bilayers of sub-nanometer metal oxide structures

on the surfaces of the interconnected PIM-1 micropores. The resulting interpenetrating

atomic-scale networks of metal oxide and PIM-1 retain the microporosity and exhibit

excellent solvent resistance to strong solvents for PIM-1 (chloroform, dichloromethane,

and tetrahydrofuran). While PIM-1 membranes cannot effectively reject polystyrene

oligomers below 1200 g/mol from ethanol, the hybrid PIM-1 membranes reject polystyrene

oligomers larger than 400 g/mol. Besides, the interpenetrating aluminum oxide networks

inhibit the interaction between membranes and solutes, increasing the Rose Bengal

rejection from 45% to 86%. Since the vapor phase infiltration process can be directly

applied to state-of-art membrane modules, this treatment has the potential to be adopted

into the large-scale manufacturing of advanced membranes.

Evidence for entropic diffusion selection of xylene isomers in polymer

derived carbon molecular sieve membranes

Yao Ma / Prof. Ryan P. Lively

The purification of benzene derivatives, particularly xylene isomers, is one of the most

important organic mixture separations practiced in industry. The separation of xylene

isomers is especially challenging due to the similarity of their physical properties. Carbon

molecular sieve (CMS) membranes are promising materials for such challenging solvent

separations due to their thermal and chemical stability, but these materials have not been

studied in detail in the case of large organic molecules. Xylene isomer transport and

sorption properties in a CMS membrane derived from a prototypical polymer of intrinsic

microporosity (PIM-1) reveal that diffusion selectivity is the dominant factor in

contributing to the preferential permeation of p-xylene over o-xylene. Moreover, the

contributions of “enthalpic” and “entropic” selectivity to the diffusion selectivity are

studied in detail and reveal that entropic factors dominate the xylene selection mechanism.

Overall, this study provides fundamental insight and guidance into the separation of large

organic molecules in amorphous microporous materials.

Page 20: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

19

Synthesis and Properties of Degradable Polyaldehyde Copolymers

Anthony Engler / Prof. Paul Kohl

Polyaldehydes are metastable materials at ambient conditions due to their typically low

thermodynamic ceiling temperature (TC), or the equilibrium temperature between

monomer and polymer. Breaking one backbone bond in the polymer above the TC will

initiate total depolymerization down the polymer chain, converting back to aldehyde

monomer. Polyaldehydes have yet to find a robust application in materials, because of their

instabilities at ambient temperatures. Rather than a drawback, the low TC phenomenon

offers a unique advantage in the degradation of polymers due to the minimum activation

energy required to degrade an entire polymer chain. This ability to rapidly convert to small

molecules makes polyaldehydes well suited for applications in stimuli-responsive

materials, transient technology, and sacrificial materials. Novel copolymers were

synthesized using a variety of aliphatic and functional aldehydes with o-phthalaldehyde,

which provides high molecular weight and stability. Reactivity behavior of aliphatic

aldehydes correlates positively with the aldehyde’s hydration equilibrium constant (KH),

with electron-deficient aldehydes incorporating into copolymers at higher percentages.

Higher incorporations of aliphatic aldehydes bring about lower molecular weight

polymers. The polymerization is tolerant to chain length, branching, non-conjugated

unsaturation, halogens, and sulfonate esters. Post-polymerization modifications are

performed to introduce inaccessible functional groups like epoxy, thioethers and azides.

Applications towards transient technology are discussed.

Facile Integration of Porous Nanomaterials on and from Support Media

Jayraj N. Joshi / Prof. Krista Walton

Unconventional strategies for synthesizing advanced separation materials can reduce

manufacturing complexity while affording economic and environmental benefits.

Accordingly, we present a novel method for producing supported porous nanomaterials

both from and on aluminum-based support structures. Supported MOF composites are

created in one-step from inexpensive aluminum oxides, alloys, meshes, foil, and even

recycled beverage cans. Microscopy reveals uniform monolayer epitaxial MOF growth.

The same strategy is adapted to different framework systems, as well as non-supported

adsorbent production with unique textural properties. Scaffolded microneedle MIL-53(Al)

MOFs produced from this study are additionally ideal precursors for creating supported

aluminum oxide nanotubes. Through MOF pyrolysis, micro/mesoporous alumina

structures emerge 1-5µm perpendicular from the underlying support. In addition to the

conventional uses of alumina as catalyst and adsorbent supports, newly-generated oxides

investigated here afford unique MOF regrowth and acid gas remediation applications.

Presented findings establish a simple and accessible gateway for building nanoscale-

controlled devices, hierarchical separation media, and high performance membranes.

Page 21: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

20

Comprehensive Study of SO2 Adsorption in a Series of Metal-organic

Frameworks

Julian Hungerford / Prof. Krista Walton

A series of Metal-organic Frameworks (MOFs) were synthesized and SO2 adsorption

isotherms were collected on a lab build pressure decay apparatus to develop structure-

property relationships. The MOFs tested included: DMOF-TM, DMOF-ADC, MIL-

53(Al), Cu-BTC, UiO-66, MIL-101(Cr), ZIF-7, ZIF-8, ZIF-11, and ZIF-65. All MOFs

used in this study were found to be stable upon exposure to SO2 for the duration of the

isotherm collection. We established that MOFs with larger pore volumes correlated with

higher SO2 adsorption capacity at high SO2 pressure. MIL-101(Cr) had the highest SO2

adsorption capacity of 21 mmol/g while also having the largest pore volume of 1.3 cm3/g.

MIL-53(Al), Cu-BTC, and ZIF-65 displayed similar SO2 adsorption capacities of roughly

12 mmol/g while having similar pore volumes. ZIF-7 and ZIF-11 adsorbed very little SO2

at all adsorption points, these materials have pore diameters smaller than the kinetic

diameter of SO2 and we hypothesize that any SO2 adsorption is likely due to structure

defects or linker flexibility. When analyzing the low pressure region of the SO2 adsorption

isotherms for these MOFs a different relationship is observed. Cu-BTC, a MOF containing

open metal sites (OMS), displayed strong SO2 adsorption at the lowest adsorption points.

DMOF-TM does not contain OMS, however it displayed greater low pressure adsorption

than Cu-BTC. The pore diameter of DMOF-TM is nearly identical to the kinetic diameter

of SO2 such that molecular sieving may contribute to a large SO2 adsorption at low

pressure. Our overall findings show that MOFs with the large pore volumes will have large

SO2 adsorption capacities at high pressures, while OMS or molecular sieving dominate the

low pressure region.

Page 22: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

21

Selective CoAxial Lithography via Etching of Semiconductors (SCALES):

A Bottom-up Nanoscale Patterning Process for Very Large-Scale Electronic

Device Manufacturing

Amar Mohabir / Prof. Michael Filler

Nanoscale electronic devices, such as field effect transistors, contain one or more features

with nanoscale dimensions. When such devices are to be produced at very large

manufacturing rates (e.g., for large-area integrated circuitry), a bottom-up alternative to

top-down patterning is necessary to define these features. Here, we show how surfaces with

regions of differing composition can be selectively masked using surface-initiated growth

of polymer films. Our approach is particularly useful for patterning semiconductor

nanowires where composition is modulated along the nanowire length. Surface masking is

accomplished in a two-step procedure. (1) Atom transfer radical polymerization (ATRP)

of polymethylmethacrylate (PMMA) first occurs from a surface-tethered initiator in a

blanket fashion, covering all surfaces regardless of composition. (2) A subsequent selective

etch removes the polymer only from regions whose underlying surface is susceptible to the

etchant. We apply this technique, dubbed Selective CoAxial Lithography via Etching of

Semiconductors (SCALES), to nanowires containing axially-modulated doped/undoped Si

and Si/Ge regions. For the case of doped/undoped Si nanowires, KOH removes PMMA

from the undoped regions but does not attack the doped regions. For the case of Si/Ge

nanowires, PMMA is removed from the Ge regions by etching with H2O2 but remains on

the Si regions. We investigate the role of surface pre-treatment, PMMA polymerization

parameters, and post-polymerization etching on the SCALES process with a suite of

spectroscopy and microscopy techniques. The ability to mask nanoscale objects in a

bottom-up fashion opens up the possibility of nanoscale patterning in a truly scalable

manner.

A Database of 2D Zeolite Nanosheets: Development and Applications

Omar Knio / Prof. David S. Sholl

Zeolites are nanoporous aluminosilicates widely used in catalysis and separations

applications. Though generally formed as 3D crystals, new synthesis techniques have given

access to 2D zeolite nanosheets with small diffusion path lengths and accelerated molecular

diffusion. Since most previous research has focused on bulk zeolite crystals, there is little

understanding of the surface adsorption and diffusion mechanisms likely involved at such

length scales and their contributions to the permeability and selectivity of different species.

To enable the systematic examination of such surface properties, we constructed a database

of more than 800,000 computation-ready 2D zeolite nanosheets from the full range of

known zeolite structures in the IZA database of zeolite structure types. The nanosheet

surfaces cover a wide range of orientations and were created via the principle of minimizing

the number of bonds broken during the termination of a unit cell. The database consists of

two sets of nanosheets: one set with known heights and unrelaxed surfaces, and another set

with arbitrary heights and relaxed surfaces.

Page 23: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

22

As an initial example of the utility of this database, we generated equilibrium Wulff shapes

for 203 3D zeolite structure types in the International Zeolite Association (IZA) database.

Since our database is pure silica, our predicted crystal shapes resembled experimentally

synthesized crystals with high Si:Al ratios. Finally, we used Molecular Dynamics to

identify zeolite nanosheet properties ideal for the industrially relevant separation of H2

from CO2. To that end, we examined the surface contribution to diffusion as a function of

slab height in MFI, a widely used zeolite. By incorporating surface effects, the current

study lays the groundwork for high throughput screening of zeolite nanomaterials in their

thinnest and most promising form.

Oral Presentation Session III

Energy and Sustainability Ethylene/Ethane Separation in Metal-Organic Frameworks by

Computational Modeling

Wenqin You / Prof. David S. Sholl

Metal-organic frameworks (MOFs) with open metal sites (OMS) are known to be selective

for ethylene relative to ethane. In practical applications of this separation, the presence of

other small molecules such as H2O, CO, and C2H2 may affect the suitability of sorbents.

We used density functional theory (DFT) calculations to compute the binding energies of

H2O, CO, C2H2, C2H4, and C2H6 in M-BTC (BTC = 1,3,5-benzenetricarboxylic acid) with

12 different metals forming OMS (M = Mg, Ti, V, Cr, Mo, Mn, Fe, Ru, Co, Ni, Cu, and

Zn). To probe the generality of these results for MOFs containing other ligands, we

performed similar calculations for metal-substituted MOFs based on four more materials

with dimeric Cu sites. Our results provide useful insights into the variations in binding

energies that are achievable by metal substitution in this broad class of MOFs, as well as

pointing towards feasible adsorption-based separation strategies for complex molecular

mixtures. Zn OMS MOFs were predicted to have the highest C2H4/C2H6 selectivity, but the

strong binding energy of solvents and other small molecules in these materials may create

practical challenges. We used DFT calculations to examine whether functionalizing linkers

in these materials with electron withdrawing (-fluorine) and donating (-methyl) groups

offer a useful way to tune molecular binding energies on OMS in these materials.

Zinc anode design for rechargeable aqueous high-energy Zn-air batteries

Yamin Zhang / Prof. Nian Liu

As an energy storage system, Li-ion batteries are not safe because they use flammable

organic electrolytes. A safer alternative is rechargeable Zn-based batteries with aqueous

electrolytes. Among them, Zn-air batteries have high theoretical volumetric energy density

(4400 Wh/L), which can even compete with lithium-sulfur batteries. Alkaline electrolyte

is preferable for Zn-air batteries. However, the performance of Zn anodes in alkaline

electrolyte is limited by passivation, dissolution and hydrogen evolution. Through SEM

investigation, critical passivation size was found to be ~ 2 µm. Sub-micron-sized Zn anodes

won’t have passivation problem. As a result, we focus our research on nanoscale. However,

Zn dissolution of nanosized anodes will be accelerated because of large electrode-

electrolyte surface area.

Thus, anode modification and protection are needed to alleviate the dissolution. We

designed a (1) Zn mesh@GO anode: GO layers on the Zn mesh surface deliver electrons

across insulating ZnO and can slow down the Zn dissolution; (2) lasagna-inspired

Page 24: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

23

ZnO@GO anode: ZnO nanoparticles encapsulated by GO can solve simultaneously the

passivation and dissolution problems; (3) core-shell ZnO@TiN nanorod anode: thin and

conformal TiN coating mitigates Zn dissolution, mechanically maintains the nanostructure,

and delivers electron to nanorods.

Hydrogen evolution is a competitive side reaction on the zinc anodes, which causes low

efficiency of Zn based batteries. Our approach is to suppress hydrogen evolution by

modifying the anode with a hydrogen suppressive material: core-shell ZnO@TiO2 nanorod

anode was made with hydrogen suppressive TiO2 coating, which solves hydrogen

evolution, passivation and dissolution problems at the same time.

All of these anodes show superior performance compared with unmodified anodes. These

anodes can be paired with air cathodes to make high energy Zn-air batteries. The nanoscale

design principles here can potentially be applied to overcome intrinsic limitations of other battery materials.

Continuous Zeolite MFI Membranes Fabricated from 2D MFI Nanosheets

on Ceramic Hollow Fibers Byunghyun Min / Prof. Sankar Nair

This work addresses the challenge of fabrication of 2D MFI hollow fiber membranes.

Defect-free 2D MFI nanosheets coating is prepared on the α-alumina hollow fiber support

by simple vacuum filtration method. Then, it is intergrown into a continuous film after

TPA-F hydrothermal treatment by sealing the gaps and increase the adhesion of the

membrane on the support without need of any support modification. Sequential TEAOH

hydrothermal treatment improves the intergrowth by selectively reducing small defect area

further. Sequential steps are optimized to selectively seal the gaps while minimizing the

overgrowth and twinning to preserve the preferred b-out-of-plane orientation and thin

thickness. This microstructurally optimized 2D MFI membrane supported on hollow fiber

exhibits high-performance for separation of n-butane from i-butane. These findings will

provide the implications for scale-up of the 2D MFI membrane with enhanced separation

performances for industrially important molecules.

Selective Removal of Hydrogen Sulfide from Biogas Streams Using

Sterically Hindered Amine Adsorbents

Claudia N. Okonkwo / Prof. Christopher W. Jones

Sterically hindered amines in solution have been explored for H2S capture and they have

been found to be selective for removing H2S over CO2 compared to the conventional

methyl diethanolamine (MDEA) or unhindered amines. A disadvantage with these amine

solutions is the high regeneration energies required while operating practical, aqueous

systems. As a result, the use of solid supported materials with lower heat capacities and

improved energy costs has been proposed. This work uses sterically hindered amines on

solid supported materials to determine their H2S selectivity in the presence of CO2 and

CH4. Using a breakthrough apparatus, in-situ infrared spectroscopy and thermogravimetric

analysis we have investigated (i) the H2S selectivity in a multicomponent gas mixtures, (ii)

the nature of the chemisorbed species formed during H2S adsorption and (iii) the effect of

concentration and temperature on H2S adsorption performance on these sterically hindered

amine adsorbents under dry conditions.

Page 25: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

24

Oral Presentation Session IV

Energy and Sustainability Kinetics of CO2 adsorption in amine-functionalized materials with stepped

isotherms Trisha Sen / Prof. Matthew J. Realff

CO2 uptake in amine-functionalized MOFs, such as Mg2(dobpdc), follows a tunable

stepped isotherm behavior, which enables unprecedented high equilibrium and pressure-

swing capacities for CO2 capture under DAC (Direct Air Capture) conditions (< 0.4 mbar).

This study attempts to move beyond the equilibrium understanding of these materials, by

analyzing their kinetics associated with DAC and to determine whether this limits their

practical application.

An adsorption breakthrough setup with ultra-dilute (0.4 mbar) and dilute (1 mbar, 5 mbar

and 10 mbar) feed was used as a proxy to simulate practical systems. Local equilibrium

theory for stepped isotherms predicts a simple single shock breakthrough for CO2

concentrations above 1% (or 10 mbar). Below 10 mbar, we expect two shocks separated

by a plateau corresponding to the isotherm step pressure. The predicted shapes of the

breakthrough profiles matched the experimentally observed results only qualitatively.

Attempts to fit a traditional LDF mass transfer model to match the observed data were

unsuccessful. While CO2 is simply physisorbed below the isotherm step, a cooperative

mechanism kicks in once this critical loading has been achieved. To capture these kinetics,

a simple LDF model before the isotherm step change and a model for co-operative uptake

(Avrami / Michaelis-Menten) above the step were implemented. Further, quantifying the

CO2 capture fraction of the bed at saturation showed that the bed utilization efficiency is

severely reduced at low feed concentration especially with increasing flowrates.

The aim of this work is therefore two-fold. Firstly, to understand and quantify the system

kinetics of amine functionalized adsorbents with stepped isotherms. Secondly, this study

indicates that moving beyond equilibrium or swing capacity of these adsorbents, and

looking at their kinetics is crucial to assess their efficiency in practical DAC applications.

Complex Systems Impurity control in the continuous reactive crystallization of beta-lactam

antibiotics Matthew A. McDonald / Prof. Martha A. Grover Beta-lactam antibiotics such as cephalexin and ampicillin can be synthesized and

crystallized simultaneously with the use of penicillin G acylase (PGA) as a catalyst.

However, PGA also catalyzes the degradation of the antibiotic to form a slightly soluble by-product—phenylglycine in the case of cephalexin or ampicillin—that can contaminate

the solid product [1]. It is important that by-product concentration remain below the

solubility limit so that pure antibiotic can be filtered immediately without the need for recrystallization or other further purification. In a continuous process, online detection of

phenylglycine crystals is necessary to ensure product quality. Focused beam reflectance

measurement (FBRM) has been used to observe the nucleation of the byproduct in real

time. However, it is desirable to take preemptive action to avoid nucleation of the by-

product at all. The combination of several process analytical technologies such as ATR-

FTIR and inline polarimetry enable the detection of phenylglycine before the solubility limit is reached. Purity can then be enforced by changing the crystallizer conditions to

increase enzyme selectivity or decrease enzyme activity, both at a cost to productivity and

conversion, but without the need to stop the continuous process due to solid phase impurity. A model of the reactive crystallization system is used to inform controller actions.

Page 26: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

25

Experiments conducted in a fed-batch crystallizer, where phenylglycine accumulation is

easier to control, are used to evaluate phenylglycine crystal detection by FBRM as well as

model accuracy. A mixed-suspension mixed-product removal (MSMPR) crystallizer is

used to evaluate different control actions, such as decreasing pH (which simultaneously decreases antibiotic solubility and increases PGA selectivity), changing temperature

(increasing temperature decreases solubility of phenylglycine but increases PGA activity

while decreasing temperature has the opposite effect), and changing feed reactant concentrations (changing the reactant ratio affects both selectivity and activity).

[1] McDonald, M.A., Bommarius, A.S., and Rousseau, R.W. (2017) Chem. Eng. Sci. 165,

81-88.

Biotechnology Serum effects on nanoparticle-mediated photoporation for enhanced

macromolecular delivery

Simple Kumar / Prof. Mark R. Prausnitz

Intracellular delivery of therapeutic and diagnostic molecules is restricted by plasma

membrane. Often, endocytic route is used to transport molecules inside cells, which can

render these molecules inactive due to pH changes. Nanoparticle-mediated photoporation

offers a physical route to create transient pores allowing uptake of foreign molecules by

cells. Through near-infrared laser irradiation, nanoparticles absorb and dissipate energy to

the surroundings, vaporizing water to create steam bubble. The subsequent thermal and

acoustic outputs are believed to be responsible for membrane poration. This process has

been optimized for >90% cellular uptake of low-molecular weight molecules without

significant cell viability loss.[1] Comprehending how changes in cellular micro-

environment affect delivery efficiency is important for clinical translation of this platform

technology. Therefore, this study is focused on understanding the role of serum during

photoporation.

Experimental results reveal 75% less loss of cell viability during laser irradiation at high

fluence when cells are suspended in media containing 10 (v/v)% serum. Similar effects are

observed in media containing denatured serum. Further experiments show that some

polymer additives also help preserve cell viability and thus viability protection by serum

appears to be attributed to physical property changes in suspension media and not to

biological activity introduced by serum proteins. Thus far, nanoparticle-mediated

photoporation has been used to efficiently deliver molecules below 15 kDa range. Larger

size molecules may require high fluence which often leads to cell viability loss. However,

using serum’s viability preservation at high fluence, we were able to deliver 40 kDa, 150

kDa and 500 kDa dextran to >50% cells in presence of serum. Further optimization can

allow us to deliver these macromolecules with higher efficiencies.

[1] Sengupta et al. Efficient Intracellular Delivery of Molecules with High Cell Viability

Using Nanosecond-Pulsed Laser- Activated Carbon Nanoparticles. ACS Nano 2889–2899

(2014)

Novel Supply Chain and Process Modeling for Cell Therapy Manufacturing

Yi Liu / Prof. Chip White

Cell therapy is a rapidly growing industry with its unique production and supply chain

complications. We present a two-level hierarchical supply chain model of autologous

CAR-T cell therapy that serves as the basis for the development of strategies to: 1) deliver

cell therapy products that are safe and have a high level of efficacy, 2) minimize fulfillment

time and variability, and 3) reduce total manufacturing and logistics costs while reducing

Page 27: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

26

the risk of patient morbidity and mortality. The model consists of two integral components:

(1) an agent-based program for a “single manufacturing facility” that simulates the

manufacturing and quality control process of cell therapy; and (2) a supply chain network

program that evaluates different supply chain configurations and sourcing strategies. The

two-level hierarchical supply chain model can be used as a decision support system to

explore manufacturing, quality assurance, and supply chain and logistics ‘what if’

questions. Using the model, we explored the impact of reagent supply chain disruptions to

manufacturing and evaluated the effectiveness of different tools that can mitigate

unexpected supply disruptions. We intend to use this model to support the design and

operation of supply chains for end-to-end manufacturing and logistics of large-scale, low-

cost, reproducible and high-quality cell therapy products.

Page 28: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

27

Acknowledgements

2019 Graduate Symposium Executive Boards

Chairs

Juan Luis Mena Lapaix Samantha Pustulka Vice Chairs

William Bradley Rohan Murty Hospitality

Maggie Manspeaker Maritza Mujica Zhenzi Yu Media

Youn Ji Min Geetanjali Pendyala Young Hee Yoon Abstract

Qandeel Almas Hye Youn Jang Rebecca Schneider Food

Chunyi (Alexis) Li Sang Jae Park Brianna Thornton Logistics

Jane Agwaro Andrew Kristoff Matthew Warner

Special Thanks to:

Faculty Speakers

Dr. Christopher Jones Dr. David Sholl

Event Coordinators

Ms. Donna Peyton Dr. Sankar Nair

Poster Session Judges

All ChBE Faculty Volunteers

Page 29: 29th Graduate Research Symposiumsymposium.chbe.gatech.edu/sites/default/files/Abstract...31st Annual Graduate Research Symposium Tuesday, February 12 – Wednesday, February 13 2019

28

Sponsors