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Nanostructured Organic Nanostructured Organic Polymer and Hybrid Materials : Polymer and Hybrid Materials :

From Ultrathin Films to NanoparticlesFrom Ultrathin Films to Nanoparticles

Rigoberto C. AdvinculaRigoberto C. Advincula

Department of ChemistryDepartment of Chemical Engineering

University of HoustonUniversity of HoustonHouston, TX 77204

E-mail: [email protected] www.nanostructure.uh.edu

www.chem.uh.edu

University of Houston

www.nsm.uh.edu, www.chem.uh.edu, www.egr.uh.edu

Nanotechnology, Biotechnology, Materials Research, Molecular Design, Polymers, Superconductivity

Advincula Research Groupwww.nanostructure.uh.edu

Ph.D. Students: Derek Patton, Tim Fulghum, Suxiang Deng, Prasad Taranekar, Yu Shin Park, Jin Young Park, ChengyuHuang, Ted Limpoco, Guoqian Jiang, Imee Martinez, Rebecca Tsai. Chaitanya DandaPast; Chuanjun Xia, Mi-kyoung Park, Xiaowu Fan,Jason LocklinUndergraduates: Mansour Abdulbaki, Jamie Chen, Gabriel Clyde, Past: Risheng Xu, Rusty Rogers, Pemieson DiepPost-Docs and Research Staff: Dr. Akira Baba, Dr. Miko MillanPast: Dr. Seiji Inaoka, Dr. Ji Ho Youk, Dr. Shuangxi Wang, Dr. Qing-Ye Zhou, Dr. Kenji Onishi, Dr. Miko MillanVisiting: Paralee, Hiyoshi, Kawamura,Xinheng Past: Dr.Shinbo, Others: REU, Undergraduates, SEED, Foreign

•• Outline:Outline:• Introduction• Projects• Recent Studies

and Results• Conclusions

AcknowledgmentAcknowledgment

Advincula Research Group

Collaborations:- Zhenan Bao (Stanford)- Wolfgang Knoll (MPI-P)- Futao Kaneko ( Niigata University)- Hiroaki Usui (TUAT)- Jimmy Mays (UT/ORNL)- Norio Tsubokawa (Niigata University)

Funding: - NSF-CAREER- Welch Foundation - NSF Collaborative Research in Chemistry- NSF Chemical Sensors Program- Lintec Corp.- Dow Corning Corp.- Agilent Technologies

Introduction

Nanotechnology

- self-assembly- quantum effects- molecular building

blocks- surface science

Nanostructured Materials

Molecular and Macromolecular Design and Engineering at the nanoscale

-Design, synthesis, characterization-application

Organic and PolymerMaterials

- Surfactants, polymers, dendrimers, molecular organic crystals, films,

micelles, nanoparticles-Functional materials (optical,

electrical, spectroscopic)-Isotropic and “soft”

Inorganic Materials- crystals, quantum dots,films,

nanotubes, nanoparticles- Functional materials (optical,

electrical, spectroscopic)-Anisotropic or long

range order and “hard”

Hybrid materials/Nanocomposites

- Interfacial Phenomena

- Ultrathin Films

- Crystal Eng. - Solid state- High Vacuum

-FundamentalScience

-Technology

Inorganic• Nanoparticles : quantum dots,

nanocrystals, shape anisotropic nanoparticles

• Glasses and Ceramic particles• Ultrathin Films: solid state, high

vacuum, STM, doping, vacuum deposited.

• Superlattice structures: multilayer films, supramolecular structures, patterning

Nanostructured Materials : Inorganic/Metals

Nanostructured Materials : Carbon

Carbon• Carbon-Based

Nanomaterials nanotubes (SWNT and MWNT), fullerenes, polyacene structures

• Electrical and magnetic effects• Nanomechanical properties

Nanostructured Materials: Organic

Organic• Organic Polymers : homopolymers,

block-copolymers, polyelectrolytes

• Dendrimers and hyperbranched molecules – functional macromolecules with controlled shape and dimension

• Small Molecules: organic crystals, dyes, oligomers, amphiphiles

• Supramolecular Assemblies: mesophases, supramolecular structures

• Ultrathin Films: Langmuir-Blodgett films, Self-assembled Monolayers (SAM), Layer-by-layer, epitaxy

Outline of Projects

• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.

• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.

• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles

• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes

• Project 5. Functional Dendrimers as Organic Nanoparticles

• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena

• Conclusions

Project 1

Electrodeposition and Patterning of Conjugated Polymers Using the Precursor Polymer Approach.

NSF-CAREER: DMR 99-82010

Agilent Technologies

Introduction … Conjugated Polymers

• Electro-optically active• Non-linear Optical Materials• Electrically-conducting Polymers• Luminescent Polymers• Lasing Polymers

• Electro-optically active• Non-linear Optical Materials• Electrically-conducting Polymers• Luminescent Polymers• Lasing Polymers

• intractable and insoluble• defects and impurities• mobility and band-gap conditions• processability• patterning

• intractable and insoluble• defects and impurities• mobility and band-gap conditions• processability• patterning

Introduction … Display Devices

Organic Light Emitting Diode (OLED) devices

Organic Light Emitting Diode (OLED) devices

IP (eV)

ITO (-4.8)

Ca (-2.7)

Thickness (ca. 100nm)

e-

h+

e-

e-

Bias V

hν

LUMOs

HOMOs

- Asymmetric structure (diode)

- Electrons are injected in LUMOs

- Holes are injected in HOMOs

- Charge hopping leads to recombination:

e- + h+ --> hν

- Maximum estimated external efficiency < 5%

Print the image with a conducting (PEDOT) and insulating (N) polymers. Coat with continuous layer of EL polymer.

a

acathode (continuous)

EL polymer (continuous)

ITO

PEDOT

Print the image with emitting (EL) and insulating (N) polymers.

cathode (continuous)

plastic substrateITO

PEDOT

plastic substrate

N-polymer R-G-B EL polymers

N-polymer

Print the image with dyes which difuse inside a wide-band emitting polymer film.

cathode (continuous)

plastic substrateITO

PEDOT

N-polymer R-G-B dyeswide-bandEL polymer

Challenges in PLED Patterning

Full color active matrix display CDT-Seiko Epson 1999

Efficiency Green ~20 lm/W @ 100 cd/m2 (2.6V) (>5% external efficiency)

Excellent red, and good blue

Half-life approximated at room temperature: red ~30,000 hr, green>10,000, blue~2,000 h.

Colors Excellent saturation, very close to standard PAL limits.

A- Shadow Masking.

B- Filters

C- Printing (inkjet)

D- Microlithography

E- Electropatterning

F- Self-Assembly

G- Nano-patterning ??

Patterning

Patterning by Electrodeposition

Cyclic

voltammeterReference electrode (Ag/Ag+)

Working electrode (ITO, Pt)

Counter-electrode (Pt)

n M M-(M)n-M

-2(n-1)e-

-2(n-1)H+

Monomers

S S

SS

S

SS

S

H

H

-e

-2H+

n

- Thin Films, R. Advincula, C. Xia, S. Inaoka, D. Roitman “Ultrathin Films of Conjugated Polymers on Conducting Surfaces” M. Soriaga, Editor.

Possibilities for site- directednanopatterning?

Problems with film morphology using traditional monomers

• ill-defined mechanism of film growth• chemical defects• rapid precipitation from solution

• ill-defined mechanism of film growth• chemical defects• rapid precipitation from solution

J. Phys. Chem. B, Vol. 103, No. 40, p.8456, 1999

Precursor Polymers: Electropolymerization approaches to Functional Ultrathin Films and Patterning of Conjugated Polymers

Electrochemistry

Electrochemistry

Electropolymerizable units

Conjugated Polymer systemConjugated Polymer system

Conjugated backboneConjugated backbone

Scheme I

Scheme II

- Baba, A.; Onishi, K.; Knoll, W.; Advincula, R.* J. Phys. Chem. B. 2004, 108, 18949-18955.- Xia, C.; Advincula, R.*; Baba, A.; Knoll, W.* Chem. Mater. 2004, 16, 2852-2856.- Deng, S.; Advincula, R.* Chem. Mater. 2002, 14, 4073-4080.- Taranekar, P.; Fan, X.; Advincula, R.* Langmuir 2002, 18, 7943-7952.

Intermolecular Intramolecular

Polyfluorenes

RR

n

Project 1a.Project 1a. Surface Grafting of Polyfluorenes onto SAM Modified Surface Grafting of Polyfluorenes onto SAM Modified Conducting Substrates by ElectrochemistryConducting Substrates by Electrochemistry

- Blue emitter- PLED Devices- Color-tuning via copolymerization- Synthesis by Suzuki or Yamamoto Coupling- Aggregation behavior as films- Polarized Emission in oriented films

Chuanjun Xia and R. C. Advincula;, Chemistry of Materials 2001, 13(5); p. 1682-1691.

Electropolymerization from Films or Solutions

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Electropolymerization of P73 from solution

0.44V

10μA

Potential (V vs Ag/Ag+(0.01M))

350 400 450 500 550 600 650

0.0

0.2

0.4

0.6

0.8

1.0

P82 in THF solution

P82 spin-coated film

P82 electropolymerized

spin-coated film

P82 electropolymerized

from solution

INT

(nor

mal

ized

)

Wavelength(nm)

Photoluminescence of P82

Electropolymerization

SAM modified ITOSAM modified ITO

P73 spin-coated film after

electropolymerizationP73 spin-coated film after

electropolymerization

-0.2 0.0 0.2 0.4 0.6 0.8 1.0

0.58V

0.53V

0.78V

Eletrochemistry of the first 5 cycles

of the carbazole monolayer in ACN

0.5μA

Potential (V vs Ag/Ag+(0.01M))

Siloxane polymers• low surface tension• high gas permeability • thermal stability• water repellence

• high dielectric constant

SiO

R

R n

S

R

n• Important conducting polymer• Color tunable light-emitting polymer• Superconducting at low temperature• High mobilities • Non-linear optical polymer

Polythiophene

S

R

Oxidative polymerization by FeCl3

Grignard Coupling

Stille coupling

Electropolymerzation

S

R

BrBrMg

S

R

BrBu3Sn

S

R

n

Project 1 b.Project 1 b. Polysiloxane Modified Polythiophene Precursors

Xia, C.; Fan, X.; Park, M-K.; Advincula, R. “Ultrathin Film Electrodeposition of Polythiophene Conjugated Networks through a Polymer Precursor Route”, Langmuir 2001 17(25), 7893-7898.

Polysiloxane modified polythiophene - crosslinking

S

Br(CH2)9Br

Mg, NidpppCl2 S

(H2C)9Si

O HSi

OSin Si

OSi

OSin

CH2)11

S

SiO

SiO

SinCH2)11

S

Electrochemistry

or FeCl3

m

H2PtCl6

S

I

II

S S

SS

S

SS

S

H

H

-e

-2H+

n

250 300 350 400 450 500 550 600

0.0

0.2

0.4

0.6

0.8

1.0

INT

(nor

mal

ized

)

Wavelength(nm)

-0 .5 0 .0 0 .5 1 .0 1 .5

5 0 0 μ A

P o ten tia l (V vs A g /A g +(0 .01M ))-0 .5 0 .0 0 .5 1 .0 1 .5

2 0 0 μA

P o te n tia l(V vs A g /A g + (0 .0 1 M in A C N ))

-0 .5 0 .0 0 .5 1 .0 1 .5

2 0 0 μA

P o te n tia l(V vs A g /A g + (0 .0 1 M in A C N ))

(a)

(b) (c)

Xia, C.; Fan, X.; Park, M-K.; Advincula, R. Langmuir 2001 17(25), 7893-7898.

Nanostructured electrodeposited layer-by-layer films observed by Surface Plasmon Spectroscopy (SPS)

30 40 50 60

0.0

0.2

0.4

0.6

0.8

1.0

Bare gold Film after 3 cycles

Ref

lect

ivity

Incident Angle [deg]0 2 4 6 8 10 12

0

10

20

30

40

50

60

70

80

thic

knes

s (n

m)

Cycles

θ

prism

glass substrategold layer

organic thin film

HeNe Laser633 nm

photodiodedetector

computer interface

lock-in amplifier

chopper

Knoll, W. Annu. Rev. Phys. Chem. 1998, 49, 569-638.

- Attenuated total reflection (ATR) setup in a Kretschmann configuration, optics is away from the sample and subphase

- Evanescent wave optical technique- Quantitative treatment by the Fresnel theory- PSP excitation observed in reflectivity-angular

scan

Morphology Control from Copolymerization of Monomers and Precursor polymers

AFM image of the Indium-tin oxide (ITO) substrate

Deposited from a solution containing 0.09M thiophene and 0.01M precursor polymer.

0.08M thiophene and 0.02M precursor polymer.

0.07M thiophene and 0.03M precursor polymer.

Morphology dependent on Monomer/Precursor polymer ratio.

Combined SPS-Electrochemical Set-up

- Combined SPS and Electrochemical Cell Set-up- Calculated reflectivity

- Au(50nm)/electrolyte(ε = ε’ + iε” = 1.75 + i0) interface

- Au (50nm)/deposited film (10nm, ε = 2.25 + i0)/electrolyte.

- Kinetic information on the layer formation - monitoring the reflected intensity at a fixed angle, θobs

- Calculated reflectivity change at a fixed angle θobs - function of thickness of deposited film on the Au substrate.

Cyclic redox Stability of Cross-linked Films

• Potential Ramp, SPS and SPFELS kinetic curves during electro-deposition of different ratios of monomers and precursor polymers in the methylene chloride containing 0.1 M TBAH up to 5 cycles.

• Reversibility of cycle different with composition

• Changes in internal morphology with doping and dedoping – also composition dependent

Synthesis of Polysiloxane modified polypyrroles

BrNK N

H

Si

CH3

O

H2PtCl6

Si O

CH3

Si O

N N

CH3

Si

N

CH3

O Si

N

CH3

O


n

n

m

n

Si

N

CH3

O Si

N

CH3

O n

NH NH

NH

NH

NHHH - 2H+

NH

NH

NH

NH

NH

. . . . . .

+Electrode Surface

+ + + + + + ++300 400 500 600 700 800 900 1000 1100

0.1

0.2

0.3

0.4

0.5

0.6

Abso

rban

ce

Wavelength(nm)

Py100%Py50%Py25%Py10%Py05%PP100%

Taranekar, P.; Fan, X.; Advincula, R.* Langmuir 2002, 18, 7943-7952.

PrecursorPolypyrrole


SAM modified ITOSAM modified ITO

Project 1c. Polypyrrole Precursors: “Nanodots” on Polypyrrole fiProject 1c. Polypyrrole Precursors: “Nanodots” on Polypyrrole filmslms

Electropolymerization ofPrecursor Polypyrrole

Electropolymerization ofPrecursor Polypyrrole

Nano-dots on Polypyrrole FilmNano-dots on Polypyrrole Film

• Designed synthesis • Morphology studies.• Electrochemistry• Spectroscopy • size of dots dependent on monomer: precursor polymer ratio.

OCH3SI O

CH3SI

CH3SI

N N N

OCH3SI O

CH3SI

CH3SI

N N N


nn

m

Synthesis of Poly (6-pyrrol-1-yl-hexyl methacrylates)


CH2Cl2/ TBAHN

(CH2)6

OH

CH3

C

O

CH2O

(CH2)6

N

Cl

O OO

(CH2)6

N

CH3

C

O

CH2O

(CH2)6

N

CH3

C

O

CH2O

(CH2)6

N

CH3

C

O

CH2O

(CH2)6

N

THF/ AIBN

1 2 3

CH2CCH3

+Electropolymerization

CH2Cl2/ TBAHNH

NH

NHa b

OO

N

n CH2CCH3

OO

N

n p: mole% of pyrrole in the solution p=1% Py 1% p=5% Py 5% p=10%Py 10% p=20% Py 20% p=50% Py 50% p=80% Py 80%

Non-conjugated Precursor Polymer

Conjugated Polymer

300 350 400 450 500 550 600 650

b)

a)

Py 5% Py 10% Py 20% Py 50% Py 80%

Abso

rban

ce

Wavelength (nm)

Intermolecular Intramolecular

- Deng, S.; Advincula, R.* Chem. Mater. 2002, 14, 4073-4080.



ElectropolymerizationElectropolymerization

Project 1d. PMMAProject 1d. PMMA--Polypyrrole Precursor Ultrathin FilmsPolypyrrole Precursor Ultrathin Films

Comparison of Morphology ofPolypyrrole and Precursor

Comparison of Morphology ofPolypyrrole and Precursor

Higher optical qualityHigher optical quality

• Optical studies• Electro-optical studies • Applications

-1.0 -0.5 0.0 0.5 1.0 1.5

0.0001

0.0000

-0.0001

-0.0002

-0.0003

Conjugated Polymer 1-2 1 2 3 4~33 34 35

I [A]

E[V] (vs. Ag/AgCl)

NO

O

NO

O

NO

O

NO

O

NO

O

NO

O

NO

O

NO

O

NO

O

HH

NO

O

NO

O

NO

O

NO

O

NO

O

NO

O

- 2H+

. . . . . .

+Electrode Surface

+ + + + + + ++

+Electrode Surface

+ + + + + + ++

dedopeddedopeddopeddoped

Project 1e. Polyvinylcarbazole (PVK) to polycarbazole

n

N

Film formation and cross-linking was found above 0.8 V by CV.

Two peaks of 0.6 - 1.2 V and above 1.2 V.

Potentiostatic or CV method

DC conductivity: Dielectric properties

PVKPVK

N

N

N

N

ClO4

ClO4ClO4

ClO4

-2 H+

N

N

m

inter-molecular- highly cross-linked

-10

-5

0

5

10

15

0 0.5 1 1.5

Voltage E/(V vs.Ag/AgCl)

Cur

rent

I [m

A]

1 510

20

15Low cross-link

PVK and Polyfluorenes: Work-Function Tunable PLED Devices

Si

N

Si

N

N

Si

N

N NN

NN

N N

Si Si

N

SiGlass

PVK / CzPFO

Al

ITO

X

PFO

PLED Performance changes withDoping of PVK Films: hole-transport

Baba, A.; Onishi, K.; Knoll, W.; Advincula, R. J. Phys. Chem. B 2004, 108, 18949-18955

Micro-contact Printing of SAMs

ODT

Gold

Stamp

Schematic representation of microcontact printing

PDMS Stamp

ODTsolution

Ink

ODT

Driedunder niotrogen

Micropatterned ODT SAM

ODT SAM

Patterning strategies: Micro-contact Printed Electrodeposition

0 100 200 300 400 500

4.0x10-5

6.0x10-5

8.0x10-5

1.0x10-4

1.2x10-4

1.4x10-4

1.6x10-4

1.8x10-4

2.0x10-4

2.2x10-4

0.75V 0.77V 0.79V

Cur

rent

(A/c

m2 )

Time (s)

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

-0.0004

-0.0002

0.0000

0.0002

0.0004

0.0006

on SAM

Cur

rent

(A/c

m2 )

Potential (V vs Ag/Ag+)

-0.0004

-0.0002

0.0000

0.0002

0.0004

0.0006

on Bare gold

Cur

rent

(A/c

m2 )

Micro-contact printing of SAM monolayer

-selective deposition of precursor polymer both by potentiostatic and CV methods

Micro-contact printing of SAM monolayer

-selective deposition of precursor polymer both by potentiostatic and CV methods

N

N

N

0.4 0.4

0.2

- Xia, C.; Advincula, R.*; Baba, A.; Knoll, W.* Chem. Mater. 2004, 16, 2852-2856.

Electrochemical Nanolithography of PVK? Yes• Electropolymerization and crosslinking of PVK• Substrate patterning independent of template• Robust patterns with height profile

Valiyaveetil, S.; Advincula, R.; Subbiah Advanced Materials 2005 in press.

NCHCH2

NCH CH2

HH

HH

n

+

n

+

NCHCH2

NCH CH2

HHHH

n

+

n

+

NCHCH2

NCH CH2

HH

n

n

-2H+

Further oxidationpolymerizationcross-linking

- 2eN

CHCH2 n

(c)

2

H2C CH

Nn

(b)

3,6ReactivityAu

PVK

Water meniscus

AFM tip

(a)

Au

PVK

AFM tip

(a)H2C CH

Nn

(b)

3,6Reactivity

Control of Nanopatterning Features

0.5μ

m/s

1 μm

/s

1.5μ

m/s

2 μm

/s

2.5μ

m/s

3 μm

/s

0.5μ

m/s

1 μm

/s

1.5μ

m/s

2 μm

/s

2.5μ

m/s

3 μm

/s

The nanopatterning of PVK film by writing lines with varying speed at constant voltage of -7v.

The polymer nanopatterns of line drawn at varying voltage of -3v to -10v at constant tip speed of 1 µm/s. Varying feature size ranging from 35 nm to 250 nm was observed.

Applied bias Vs Pattern Height

01234567

4 6 8 10 12

Applied Bias (-V)

Patt

ern

Hei

ght (

nm) PVK

Carbazole

Applied Bias Vs Pattern Width

0100200300400500600

4 6 8 10 12

Applied Bias (-V)

Patt

ern

wid

th (n

m)

PVK

Carbazole

(a) (b)AFM tip speed Vs Line Width

050

100150200250300

0 2 4 6 8 10 12

AFM tip speed (μm/s)

Line

Wid

th (n

m)

carbazolePVK

(c)

Applied bias Vs Pattern Height

01234567

4 6 8 10 12

Applied Bias (-V)

Patt

ern

Hei

ght (

nm) PVK

Carbazole

Applied Bias Vs Pattern Width

0100200300400500600

4 6 8 10 12

Applied Bias (-V)

Patt

ern

wid

th (n

m)

PVK

Carbazole

(a) (b)AFM tip speed Vs Line Width

050

100150200250300

0 2 4 6 8 10 12

AFM tip speed (μm/s)

Line

Wid

th (n

m)

carbazolePVK

(c)

Geometric Patterns based on Voltage Bias and Speed

(d)(d)(b)(b) (d)(d)(b)(b)(b)

(c)(c)

1 μm/s

-5V -5V-7V

-9V5 μm/s

10 μm/s20 μm/s

84nm

(a)

-9V

μm/s20 μm/s

-9V

μm/s20 μm/s

Valiyaveetil, S.; Advincula, R.; Subbiah JACS 2005 submitted.

SPM Monitoring of PatternedSPM Monitoring of Patterned--Electrodeposition of PolypyrroleElectrodeposition of Polypyrrole

θ0

He-Ne Laser (632.8 nm)

Polarizer

Lenses

CCD cameraElectrochemicalinstrumentation

Electrochemical cell

Microcontact Printed SAM (ODT) Polypyrrole

Au


45 50 55 60

0

1

Incident angle /deg

Ref

lect

ivity

Au Au/Polymerθ c

θobs

Reflectivity(at observation angle)

High (Au/Polymer)

Low (Au)

CCD screen

Experimental set-up for Electrochemical-surface plasmon microscopy (EC-SPM)

Experimental set-up for Electrochemical-surface plasmon microscopy (EC-SPM)

EC-SPMEC-SPM

Baba, A.; Advincula, R.; Knoll, W. " Evaluation of Electropolymerization Process of Pyrrole on Micropatterned Self-Assembled Monolayers" Polym Mat. Sci.Eng. Prep.(Am.Chem.Soc.,Div. PMSE), 2002 86, 48.

Microcontact-printing of Octadecylthiol on Au

ODT

Gold

Stamp

Schematic representation of microcontact printing

PDMS Stamp

ODTsolution

Ink

ODT

Driedunder niotrogen

Micropatterned ODT SAM

ODT SAM

0.86 V 50 60

0.4

0.6

0.8

Incident angle /deg

Ref

lect

ivity

Au Au/ODT

μCP Printing of ODT on Au, probed by SPS, SPM, and AFM: Resolution and patterning limits

μCP Printing of ODT on Au, probed by SPS, SPM, and AFM: Resolution and patterning limits

Electropolymerization process of pyrrole on Micropatterned Self-assembled Monolayers: EC-SPM

50 60 70

0.2

0.4

0.6

0.8

Incident angle /degree

Ref

lect

ivity

Au/MCP ODT

after 1 cycle

Exp.Calc.

ODT

Polypyrrole film

ODT

PDMS stamp

Gold

Stamp

Electropolymerization on MCP SAM

Change in reflectivity with polymer growth on pattern vs. Time- Different potential

Change in reflectivity with polymer growth on pattern vs. Time- Different potential

Polym Mat. Sci.Eng. Prep.(Am.Chem.Soc.,Div. PMSE), 2002 86, 48.

anodic

cathodic

EC-SPM: Different Angles and potentials

D=14nm

50 60 70

0.2

0.4

0.6

0.8

Incident angle /degree

Ref

lect

ivity

Au/MCP ODT

after 1 cycle

Exp.Calc.

60.0 °

61.0 ° 62.0 °

59.0°

80μm

0

100

Inte

nsity

[a.u

.]

0

100In

tens

ity [a

.u.]

0 100 2000

100

distance/μm

Inte

nsity

[a.u

.] 0.4 V

0 100 200distance/μm

OCP

0.0 V

0.9 V

0.4 V

0.0 V

-reflectivity changes with angle-Sensitivity to thickness and dielectric constant - reflectivity changes with potential

-reflectivity changes with angle-Sensitivity to thickness and dielectric constant - reflectivity changes with potential

Outline of Projects







• Conclusions

Project 2

Nanostructured Ultrathin Films of Oligothiophenes and Functional Dyes.

NSF-CAREER: DMR 99-82010

Field Effect Transistor (FET) Devices

SiliconSubstrateGate

molecularlyassembledoligothiophenesemiconductor

source drain

source drain

BOTTOM CONTACT

TOP CONTACT

SiO2

- Semiconductor layer supports a channel of holes (p-type) or electrons (n-type) between the source and drain electrodes.

- Density of charge carriers in the channel is modulated by voltage applied through the gate electrode.

- The most important criteria for a FET semi-conductor are: high charge carrier mobility, high current modulation (on/off current ratio), stability, and processability.

Application … FET Devices

Bao, Z.; Lovinger, A.. Chem. Mater. 1999, 11, 2607-2612

Ultrathin Films: nanometers to μm

spin-coating

self-assembled monolayer (SAM) Langmuir-Blodgett-Kuhn (LBK)

vacuum depositionand OMBEalternate polyelectrolyte

deposition (APD)

-

- - -

------

----- ++

+

+++

++

----

----

+ ++++̀ +

++

++++

+

+++

++

--

--+ ++++̀ +

++

++

+

+++

++

---

------

-----

• Thickness of a few nm to μm• Solution, interface, vacuum methods• Substrate support or free-solution

entities (micelles, lipids)• Multilayer films• Superlattice structures• Epitaxy

• Thickness of a few nm to μm• Solution, interface, vacuum methods• Substrate support or free-solution

entities (micelles, lipids)• Multilayer films• Superlattice structures• Epitaxy

Nanostructured Layer-by-layer Self-assembly

• Electrostatic (coulombic forces)• Interfacial phenomena and colloids• Solution properties: concentration,pH

salts,temperature• Surface sensitive techniques

-

- - -

------

----- ++

+

+++

++

----

----

+ ++++`

++

+

++

++

+

+++

++

--

--+ ++++`

++

+

++

+

+++

++

---

------

-----

Colloid particles

Polyelectrolytes coated-particlesHollow sphere shells

polyelectrolyte polyelectrolyte

Layer-by-Layer in the Advincula Research Groupwww.nanostructure.uh.edu

Nanostructured Layer-by-layer Organic and Polymer Materials

- Photoalignment films with dyes

- PLED and FET devices

- Biofunctional Films for Microarrays and Sensors

- ph-Sensitive Ion-Permselective Membranes

- Functional Colloidal Particles

• Advincula, R. et.al. J. Am. Chem. Soc. 2004, 126, 13723-13731.• Advincula, R. et.al. Chem. Mater. 2004, 16, 5063-5070.• Advincula, R. et.al. Langmuir 2003, 19, 8550-8554.• Advincula, R. et.al. Langmuir 2003, 19, 654-665.• Advincula, R. et.al. Langmuir 2003, 19, 916-923.• Advincula, R. et.al. Chem. Mater. 2003, 15, 1404-1412.• Advincula, R. et.al. Colloids Surf. A 2002, 198-200, 917-922.• Advincula, R. et.al. Langmuir 2002, 18, 4532-4535.• Advincula, R. et.al. Langmuir 2002, 18, 4648-4652.• Advincula, R. et.al. Chem. Mater. 2002, 14, 2184-2191.

Project 2a. Cross-Linked, Luminescent Spherical Colloidal and Hollow-Shell Particles

BrBr

N NBr- Br-

BuLi, dibromohexaneTHF, -78C

TMEDA

DMF/MeOH(1:1), 50Cn

Ionene 1

CH2

(CH2)5 (CH2)5

H2C N (CH2)2 N

Br- Br-

n

(a) PI

CH2 CH

SO3-Na+

m

(b) PSS

500 nm

1 μm

0 1 2 3 4 5 6 7 8 9 10-60

-40

-20

0

20

40

ζ-Po

tent

ial (

mV

)

Number of Layers

0 1 2 3 4 5 6

0

5

10

15

20

25

30

35

Laye

r Thi

ckne

ss [n

m]

Number of Layers

300 350 400 450 500 5500.0

0.2

0.4

0.6

0.8

1.0

Before Cross-linking of Fluorene After Cross-linking of Fluorene

Inte

nsity

[nor

mal

ized

]

Wavelength [nm]

n

CH3CNFeCl3

Park, M-K.; Xia, C.; Schütz, P.; Caruso, F. Advincula, R.“Cross-Linked, Luminescent Spherical Colloidal and Hollow-Shell Particles” Langmuir, 2001, 17 (24),7670 -7674.

Project 2b. Nanostructured Films of Oligothiophenes using the Layer-by-layer Approach

SBr SBr S

S

1. Mg, Ether

2.1. LDA

2. Br BrS

S Br

SS

SnBu3Bu3Sn+

SS

SS

SSBr

Br

Stille Coupling

SS

SS

SSN

N

Trimethylamine/THF

SS Br NBS/DMF

SS Br

Br

0 100 200 300 400-100

0

100

200

300

400

500

600

700

800

900

10-5M in H2O 10% THF 20% THF 90% THF 92% THF 94% THF 96% THF

Inte

nsity

Wavelength(nm)Xia, C.; Locklin, J.; Youk, J.; Fulghum, T.; Advincula, R. “Distinct Aggregation and Fluorescence Properties of a Water-Soluble Oligothiophene (6TN) Bolaform Amphiphile, Langmuir 2001; 18(3); 955-957. .

- water soluble- bolaform amphiphile- Distinct aggregation- fluorescence and absorption

SYNTHESIS

Spectroscopic, Ellipsometric, and SPS Characterization

300 400 500 6000.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

1st Layer 2nd Layer 3rd Layer 4th Layer 5th Layer 6th Layer 7th Layer 8th Layer 9th Layer 10th Layer

Inte

nsity

Wavelength (nm)

0 2 4 6 8 10 12 14 16 18 20

0

50

100

150

200

250

Pure H2O 30% THF

Thic

knes

s in

Å

Number of Layers

30 35 40 45 50 55 60

0.0

0.2

0.4

0.6

0.8

1.0

Ref

lect

ivity

Incidence Angle (θ)

Average Layer ThicknessPure H2O+6T+= 13.01 ÅPSS = 9.25 Å

30% THF+6T+= 6.88 ÅPSS= 4.30 Å

R. Advincula, J. Locklin, J. Youk, C. Xia, M.K. Park, X. Fan “Nanostructured Ultrathin Films of Water-soluble Sexithiophene Bolaform Amphiphiles Prepared Using Layer-by-Layer Self-Assembly”-Langmuir 2001; 18(3); 877-883.

AFM and XPS Characterization

1400 1200 1000 800 600 400 200 0

0

1000

2000

3000

4000

5000

6000

Na 1s

C KLL

O KLL

C 1s

Na KLL

O1s

Inte

nsity

(cou

nts

per s

econ

d)

Binding Energy (eV)

S

S

S

S

S

S

N+

N+

o

40o

36.5 A

Average aggregate size from AFM = 31.7 Å

Calculated tilt angle of aggregate from substrate = 58º

Tilt angle of 6T component = 18-22º

Langmuir 2001; 18(3); 877-883.

Fan, X.; Locklin, J.; Youk, J. H.; Blanton, W.; Xia, C.; Advincula, R.; “Nanostructured Sexithiophene/Clay Hybrid Mutilayers: A Comparative Structural and Morphological Characterization”, Chem. Mater. 2002; 14(5); 2184-2191.

0 -20 -40 -60 -80 -100

0

-1

-2

-3

-4

-5

-6

0 V

-20 V

-40 V

-60 V

-80 V

-100 V

Dra

in C

urre

nt (μ

A)

Drain-Source Voltage (VDS)

Transistor Activity: p- and n- channel

6TN (in 0.03 M NaCl) was solution cast onto polyelectrolyte covered Si wafer and solvent was evaporated under precise conditions

0 20 40 60 80 100-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

100 V

80 V

60 V

40 V

20 V

0 V

Dra

in C

urre

nt (μ

A)

Drain-Source Voltage (VDS)

Mobility: 0.008 cm2/V.sOn/Off ratio: 10

VDS from 0 to -100 V in 5 V incrementsVG from 0 to -100 V in 20 V increments

Mobility: 0.006 cm2/V.sOn/Off ratio: 9

VDS from 0 to 100 V in 5 V incrementsVG from 0 to 100 V in 20 V increments

Vg

VdId

Source Drain

Layer-by-layer Phthalocyanine Ambipolar FETs

Project 2c.Project 2c. Nanoparticle formation from Poleylectrolyte Nanoparticle formation from Poleylectrolyte Complexes of Complexes of SexithiophenesSexithiophenes

HAuCl4

Fast

Slow

PSS+ATTComplex

Wavelength (nm)

250 350 450 550 650

Abs

orba

nce

0

1

2

3

0.19/10.38/10.95/11.91/13.82/15.73/1TT+PSSSolution

250 350 450 550 6500.0

0.1

0.2

0.3

0.4

0.50.19/10.38/10.95/1

TT/HAuCl4

• Suggestion of Mayer and Mark (Eur. Polym. J., 1998, 34, 103)

1. Polymer containing sulfur would have the high affinity to gold surfaces

2. Polymer possessing reducing groups could be very suitable

• PSS increased the solubility of terthiophene amphiphile

S S

S

N+

CH - CH2m

Na+SO3-

CH - CH2m

SO3-

S SS

N+PolyelectrolyteComplex (PEC)

Poly(sodium styrenesulfonate) (PSS)

Amidatedterthiophene

(ATT)

+

Youk, J, H.; Locklin, J.; Xia, C.; Park, M.K. and Advincula, R.”Langmuir 2001 17(15); 4681-4683.

Coupling of Terthiophenes to form Sexithiophenes simultaneous with nanoparticle formation

-

--

-

-

-

--

-

- -

CH - CH2

CH - CH2

N+

(CH 2)6

S

S

CH - CH2

N+

(CH 2)6

S

S

S S

S

S

S

N+

(CH 2)6

l m

n

+.

SO 3- SO 3

-

SO 3-

• Sexithiophene bolaform amphiphile formation

• Mechanism (electrochemical or oxidative) needs to be determined

• Stabilization of gold particles is very important

• Characterization of complexes is very important

• New materials combining metallic, semi-conductor and organic materials: interesting electrical and optical properties.

Wavelength (nm)

250 300 350 400 450 500 550 600 650

Abs

orba

nce

0.0

0.5

1.0

1.5

PSS + ATT + HAuCl4PSS+ ATT + FeCl3PSS + AST

AST

SS

SN

SS

SS

SS

NN

SS

SN +

TEM Characterization

0.38/1 0.95/1 5.73/1

300 nm

- As the terthiophene concentration increases, the size of nanoparticles increases

- Nanoparticle partially stabilized: inhomogeneous growth and aggregation

- Increase in size, loss of spectroscopic properties associated with nanoparticle

Youk, J, H.; Locklin, J.; Xia, C.; Park, M.K. and Advincula, R.” Preparation of Gold Nanoparticles from a Polyelectrolyte Complex Solution ofTerthiophene Amphiphiles” Langmuir 2001 17(15); 4681-4683.

LBL Films as Nanoreactor Hosts for Nanoparticle Synthesis

Preparation of Gold Nanoparticles with PSS: Preparation of Gold Nanoparticles with PSS: WaterWater--soluble Terthiophene Complexsoluble Terthiophene Complex

(Youk et al. Langmuir 2001, 17, 4681.)(Youk et al. Langmuir 2001, 17, 4681.)

• REDOX reaction occurs between the terthiophenemoeity and the Au precursor with formation of AuNanoparticles and sexithiophene• Au nanoparticle partially stabilized by the PE complexresulting in irregular growth and aggregation

Gold Nanoparticle Formation in LBL Multilayer Films

• Red-shift in absorbance of the 3T moiety from 368 to 396 nm attributed to coupling of the terthiophene units to form sexithiophene with simultaneous formation of Au nanoparticles (surface plasmon peak = 580 nm)

• Position of the Au SP band and presence of broad absorption tail around 700 nm indicate aggregation and/or particles that deviate from a spherical geometry

Before After

J. Phys. Chem. B 1999, 103, 7441.Adv. Mater. 1998, 10, 133.

TEM Imaging

TEM image of a 3 bilayer PVP3T/PAA film containing Au nanoparticles after ~ 50 hrs at

60 ˚C/95% humidity. Scale bar = 200 nm.

TEM image depicting dendritic nanostructures formed with the PVP3T/PAA thin film.

Outline of Projects







• Conclusions

Project 3

Living Anionic Surface Initiated Polymerization (LASIP) on Surfaces and Nanoparticles:

Preparation of Nanocomposites

Army (ARO): DAAD19-99-1-0106

Grafting Methods for Polymer Brushes

Why Surface Initiated Polymerization (SIP)?- High brush density: ave. distance b/w grafting points < radius of gyration (Rg).- Functionalized surfaces, controlled surface energies, controlled surface chemistry- different methods of initiation: free-radical, ATRP, cationic, anionic,etc.- Model polymerization studies in confined environments- Novel and advanced materials, colloidal particle stabilizers, polymeric surfactants,

nanotechnology

“grafting to” surface bound monomer “grafting from” or SIP

Project 3a.Project 3a. Living Anionic Surface Initiated Polymerization on Living Anionic Surface Initiated Polymerization on Surfaces: Nanostructured SurfacesSurfaces: Nanostructured Surfaces

Grafting to Grafting From

OH

CH2

Cl-SiMe2-(CH2)11

-HCl

O

CH2

SiMe2-(CH2)11

sec-BuLi

O

Bu

SiMe2-(CH2)11 Li

O

Bu

SiMe2-(CH2)11

Li

toluene

growing polymer chain

toluene

toluene

• Polymer Brushes• Why Surface Initiated

Polymerization (SIP)?• Living Anionic SIP

Zhou, Q.; Nakamura, Y.; Inaoka, S.; Park, M.; Wang, Y.; Mays, J.; Advincula, R. in Polymer Nanocomposites, ACS Symposium Series 804, Edited by. Krishnamoorti, R. and Vaia, R.Oxford University Press, North Carolina, 2002.

SIP of Block Copolymers at Si and Au surfaces/substratesSIP of Block Copolymers at Si and Au surfaces/substrates

CH2

HS-(CH2)11OCH2

-S -(CH2)11O

sec-BuLi

Bu

-S-(CH2)11O Li

Bu

-S-(CH2)11O

toluene

Li

Au

toluene

Bu

-S-(CH2)11O

Li

Terminationstep

n

mn

PS

PIThickness = 6 nm ±2 nmΔm = 4.3 × 10-5 g/cm2

Grafting from

35 40 45 50 550.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

gold DPE PI-b-PSR

efle

ctiv

ity

Incident Angle [deg]

4000 3500 3000 2500 2000 1500 1000 500

0.000

0.001

0.002

0.003

C C stretch

C C ring stretch

methylene C-H aromatic C-H

Abs

orba

nce

Wavenumber [cm-1]

Advincula, R. et. al. Polymer Brushes by Living Anionic Surface initiated polymerization (LASIP) on surfaces, Langmuir, ASAP article.

Zhou, Q.; Wang, S.; Fan, X.; Pispas, S.; Sakellariou, G.; Hadjichristides, N.; Mays, J.; Advincula, R. Polymer Preprints (Am. Chem. Soc.), 2001, 42, 59.

Project 3b.Project 3b. Nanocomposite Materials Prepared by Surface Initiated Nanocomposite Materials Prepared by Surface Initiated Anionic Polymerization from NanoparticlesAnionic Polymerization from Nanoparticles

OH

CH2

Cl-SiMe2-(CH2)11

-HCl

O

CH2

SiMe2-(CH2)11

sec-BuLi

O

Bu

SiMe2-(CH2)11 Li

O

Bu

SiMe2-(CH2)11

Li

toluene

growing polymer chain

toluene

toluene

12-20 nm diameter

ClSi(CH3)2(CH2)8-DPE

Tolune O

OO

DPE

Si

SiSi

Si

+excess DPE

O

OO

DPE

Si

SiSi

Si

Stirring 3 days

centrifuge

redissolving

centrifuge

Si-gel- grafting from Si-nanoparticle surface by silane coupling

- Immobilization of the DPE derivative on silica surface

• Polymer Brushes- physisorption “grafting to”,

chemisorption “grafting from”• Why Surface Initiated

Polymerization (SIP)?- Novel, advance materials, colloidal

particle stabilizer, polymeric surfactants

- Model studies in confined environments

• Living Anionic SIP- Polymer conformation control, Higher

brush density- Block and graft copolymers

Zhou, Q.; Wang, S.; Fan, X.; Advincula, R.; Mays, J.; “Living Anionic Surface-Initiated Polymerization (LASIP) of a Polymer on Silica Nanoparticles”, Langmuir 2002; 18(8); 3324-3331.

LASIP on Si Nanoparticle Results

20 25

M=1.3x105

Free polymer

polymer cleaved

from si-gel

Ve, mL

0 100 200 300 400 500 600 700 800 9000.5

0.6

0.7

0.8

0.9

1.0

Initiator bound si-gel

Polymer bound si-gelWei

ght l

oss

(mg)

Temperature (0C)

- Broader Polydispersity on grafted polymer

-Living anionic polymerization mechanism demonstrated

- TGA results suggests stable grafted polymers

LASIP on Clay nanoparticles also reportedFan, X.; Zhou, Q.; Xia, C.; Cristofoli, W.; Mays, J.; Advincula, R.; “Living Anionic Surface-Initiated Polymerization (LASIP) of Styrene from Clay Nanoparticles Using Surface Bound 1,1-Diphenylethylene (DPE) Initiators”,Langmuir 2002; 18(11); 4511-4518.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

12 14 16 18 20 22 24

Monomer content (g styrene/g Si-nanoparticle)

Poly

mer

con

tent

(g

pol

ystr

yene

/g S

i-nan

opar

ticl e

A B CCollection Flask

Vacuum

Clay ParticleStirrer

Filter

Break Seal

Breaker

Other SIP Projects of the Advincula Research Group.

- Advincula, R. et.al. J. Phys. Chem. B. 2004, 108, 11672-11679. - Advincula, R. et.al. Macro. Rapid Comm. 2004, 25, 498-503.- Advincula, R. et.al. Langmuir 2003, 19, 916-923.- Advincula, R. et.al. Langmuir 2003, 19, 4381-4389.- Advincula, R. et.al. Colloids Surf. A 2003, 219, 75-86.- Advincula, R. et.al. Langmuir 2002, 18, 8672-8684.- Advincula, R. et.al. Langmuir 2002, 18, 3324-3331.- Advincula, R. et.al. Langmuir 2002, 18, 4511-4518.- Advincula, R. et.al. Chem. Mater. 2001, 13, 2465-2467.

Outline of Projects







• Conclusions

Project 4

Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte

Complexes

NASA (Microgavity): MSFC-NAG8-1678

Project 4a. Nanoparticles Using Star Block Copolymer and Polyelectrolyte Complex with Terthiophene Amphiphile

1. Silver: catalysis, photographic processes

2. CdS: optoelectronics,photoluminescence

3. Gold: optoelectronics, electronics, biosensors

4. Silica: insulator, catalyst support, membrane, filling material

5. Palladium: catalysis6. TiO2: photoelectrochemistry7. Metal oxide: Mg, Ca, Mn, Fe, Co, Ni,

Cu8. Polymer: conducting composite,

drug delivery

Nanoparticles and nanostructured Films; Fendler, J. H., Ed.; Wiley-VCH; Weinheim, 1998.

Iblock copolymers

(Stable and well-defined nanoreactor)

Iblock copolymers

(Stable and well-defined nanoreactor)

Nanoparticles with1. Size and shape uniformity2. Stability

1. Unique properties2. Ordered deposition3. Selective decoration

Nanoparticles with1. Size and shape uniformity2. Stability

1. Unique properties2. Ordered deposition3. Selective decoration

The Concept of Block Copolymers as Nanoreactors

Cationicpolyelectrolytes

Amphiphilicblock copolymers

(PS-b-P2VP)Dendrimers(PAMAM)

Self-assembledmonolayers

(n-Alkanethiols)

• “Stable Nanoreactor” for the control of size and shape of nanoparticles

• Strategies for the gold nanoparticle preparation

Nanoparticles as colloidal systems of a solid-state material -dimensions in between molecules and a bulk solid-state material.

Strategies for the synthesis of nanoparticles: surfactant or polymeric amphiphiles (block copolymers) micelles as a “nanoreactor” for nanoparticle synthesis.

Mechanism - Metal ions trapped inside the particles exposed to precipitating or reducing agents to start nanoparticle growth: the number of metal ions initially trapped inside the particle determine growth.

Key step: Control over the diffusion of reagents into the micelle.

Design: The possibility of attaching coordinating ligands to the polymer in order to stabilize both precursors and nanoparticles within.

Synthesis of Nanoparticles in General

a cb

Schematic representation of the concurrent process during reduction reaction inside block copolymer micelles.

a) Reduction is initiated by the entry of the reducing agent into the core of the micelles loaded by precursor salt.

b) Destabilized micelles exchange block copolymer and may coagulate.

C) “Empty” micelles are formed besides block copolymer stabilized gold particles.

H: reduction agent; O: precursor salt; crystal.

Wavelength (nm)

400 450 500 550 600 650 700

Abs

orba

nce

0.0

0.1

0.2

0.3

0.4

0.5

P4VP (NaBH4)PAMAM Dendrimer (UV)PS-b-P2VP (Hydrazine)

__200 nm

Star block copolymer

(PS-b-P2VP)N:Au=10:1

Reduction of Au in Star Copolymers

N

n m

PS P2VP

1. Synthesis of PS-b-P2VP

2. Synthesis of Star Block Copolymer

PS-b-P2VP + Coupling Agent(EGDMA)

(Ethylene glycol dimethacrylate)H2C=C(CH3)CO-OCH2CH2O-COC(CH3)=CH2

N + HAuCl4NH+ AuCl4

-4HAuCl4 + 3N2H4 --> 4Au + 3N2 + 16 HCl

1. Polyionic block 2. Reduction with Hydrazine

Polyionic star block copolymer Reduction, Nucleation and Growth

Youk, J, H.; Yang, J.; Locklin, J.; Park, M.K.; Mays, J.; Advincula, R.” Controlled Preparation of Gold Nanoparticles using Well-defined Star Block Copolymers” ACS-Polymer Preprints, 2001 42, 2, 358.

- Synthesis by anionic polymerization, complete characterization necessary

-Stability in solution compared to micelles

- Control of diffusion of salts and reducing agent in organic solvents

Youk, J. H.; Park, M.-K.; Locklin, J.; Advincula, R.; Yang, J.; Mays, J.; “Preparation of Aggregation Stable Gold Nanoparticles Using Star-Block Copolymers”, Langmuir 2002; 18(7); 2455-2458.

TEM Characterization of Nanoparticles formed from Star Copolymers

Wavelength (nm)

400 450 500 550 600 650 700

Abs

orba

nce

0.0

0.5

1.0

1.5

2.0

2.5

N:Au=10:1N:Au=10:3N:Au=10:5

__150 nm

• Controlled size of nanoparticles by controlling ratio of salt and reducing agents

• Very stable compared to micelles even after 1 month

• Control of diffusion of salts and reducing agent in organic solvents

• Good polydispersity

• Very stable!

Langmuir 2002; 18(7); 2455-2458.

Outline of Projects







• Conclusions

Project 5

Nanostructured Ultrathin Films and Functional Dendrimers

ACS-PRF: 35036-G7

Project 5a.Project 5a. Photoalignment and Synthesis of Photoalignment and Synthesis of AllAll--Azobenzene Azobenzene Functionalized DendrimersFunctionalized Dendrimers

ElectricField

PolarizationDirection

90 0

- Dendrimers as optical Nanoparticles - Anisotropic changes by photoisomerization on globular shape of dendrimer- changes in the refractive index, dielectric constants

N NC

C

C

C

OO

OO

O O

OO

CC

NN

OO

OO

C

C

O

O

NN

OEt

EtO

CC

OO

N

OEt

EtO

N

C

C

NN

O

OO

O C

C

NN

O

OO

O

C

C

O

ONN

EtO

EtO

C

C

O

O

N OEt

EtO

N

C

CN N

O

O O

O

C

C

O

ON N

OEt

EtO

C

C

O

O

N

OEt

OEt

N

C

CN N

O

OO

O

CC

N N

OO

OO

CC OO

NN

OEtEtO

C

C

O

ON

OEt

EtON

CC

NN

OO

OO

C

C

O

O

NN

EtO

OEt

CC

OO

N

EtO

OEt

N

C

C

NN

O

OO

OC

C

NN

O

O O

O

C

C

O

ON N

OEt

OEt

C

C

O

O

NEtO

OEt

N

C

CNN

O

OO

O

C

C

O

ONN

EtO

OEt

C

C

O

O

N

OEt

EtO

N

C

CNN

O

OO

O

CC

NN

OO

OO

CCO

O

NN

EtOOEt

C

C

O

ON

EtO

OEtN

SynthesisMatrix studiesPhotoisomerization

Organic Letters. S. Wang, R. Advincula, “Design and Synthesis of Photo-responsive Poly(benzyl ester) Dendrimers with All-azobenzene repeating units”- ASAP

Synthesis of Azobenzene-functionalized PAMAM Dendrimers

C6H13 NH2

OH

1) NaNO2/HCl0-5 oC

2)

C6H13 NN OH +

BrCH2COOCH2CH3

K2CO3acetone

refluxC6H13 N

N OCH2COOCH2CH3

1) NaOH/ethanlo-waterreflux C6H13 N

N OCH2COOH +

F F

OH

FF

F

DCC/DMAP

CH2CL2

C6H13 NN OCH2COO

FF

F F

F +

n NH2DMF

C6H13NNO

n NH

O

2) HCl (aq)

PAMAM Dendrimer

O(CH2)6NMe3BrNNOOC

F F

FF

F +

Reactive Dye - A

Alternative, Reactive Dye - B

Wang, S.; Park, M..; Advincula, R. Synthesis strategies and photoalignment of azobenzene functionalized dendrimers: Nanostructured ultrathin films and application Strategies, PMSE Preprints, 84, 236, 2001.

PAMAMPAMAM--PP--32A32A

Photoisomerization and Photoalignment Studies on LB-Monolayer

• Studies on Perimeter-Functionalized Dendrimers

• Monolayer prepared by LB Deposition on quartz

300 350 400 450 500 5500.00

0.02

0.04

0.06

0.08

0.10

0.12

Cis

Trans

Abso

rban

ce

Wavelength [nm]

- Deposition at 50 mN/m (high S.P.), molecular area of 620 Å2

- UV-vis spectra under UV light irradiation. - As trans-to-cis photoisomerization proceeds, π−π* band peak about 338 nm decreases, and n-π* absorption band at 440 nm increases.

PAMAMPAMAM--PP--32A32A

350 400 450 5000.00

0.02

0.04

0.06

0.08

0.10

Before Irradiation A⊥ A//

Abso

rban

ce

Wavelength [nm]

Photoalignment

Polarized UV light (>340 nm). A high dichroism - at various irradiation times (up to A(90)/A(0) = 1.45)

E-form, major component -visible light for the n-π* transition.

Photoisomerization

Wang, S.; Park, M..; Advincula, R. PMSE Preprints, 84, 236, 2001.

Bulk Photoisomerization and Photoalignment of PAMAM Dendrimers

300 350 400 450 500 5500.0

0.2

0.4

0.6

0.8

λ m ax = 349nm10-7 M PAMAM-azo in THF Irradiated at 350 nm

Before 5 sec 15 sec 30 sec 60 sec 120 sec 180 sec

Abs

orba

nce

wavelength [nm ]

300 350 400 450 500 5500.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14λmax = 342 nm

PAMAM-azoPhotoisomerization with 350 nm

Before 5 min 15 min 30 min 1 hr

Abs

orba

nce

Wavelength [nm]

Z

X

μtr

Yα

ϕ

e

300 350 400 450 500 5500.00

0.02

0.04

0.06

0.08

0.10

PAMAM-azo 100 % before

2 min 0o

2 min 90o

5 min 0o

5 min 90o

30 min 0o

30 min 90o Ab

sorb

ance

Wavelength [nm]

Advincula, R.*; Patton, D.; Park, M.-K.; Wang, S. “Evanescent Waveguide and Photochemical Characterization of Azobenzene Functionalized Dendrimer Ultrathin Films” Langmuir 2002, 18, 1688-1694.

Attenuated Total Reflection Spectroscopy:Waveguide Experiments

Air n1

Film n2

Substrate n3

Substrate n3

Air n1

Film n2m=0 m=1 m=2

β0 + β1 + mπ = kzd

β0, β1 = phase shiftsm = mode orderkz = wave vector

d = thickness

• Guided optical waves – waveguide modes (reflectivity as a function of angle θc)

• Kretschman configuration• Total internal reflection where n1<n2 and n3> n2 for

waveguide layer (n2 and thickness, d), n3, substrate, n1, air.

y : the direction of polarized lightnx, nz are calculated by TM-mode (p-wave)ny is calculated by TE-mode (s-wave)

Langmuir 2002, 18, 1688-1694.

Evanescent Waveguide Results

30 40 50 60 70

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95 p -po l

50 % P A M A M -A zo + P S be fo re a fte r 4 h r

Ref

lect

ivity

In c ident A ng le [deg ]

3 0 4 0 5 0 6 0 7 00 .6 5

0 .7 0

0 .7 5

0 .8 0

0 .8 5

0 .9 0

0 .9 5s -p o l

5 0 % P A M A M -A z o + P S b e fo re a fte r 4 h r

Ref

lect

ivity

In c id e n t A n g le [d e g ]

3 0 4 0 5 0 60 7 00 .0

0 .2

0 .4

0 .6

0 .8

1 .0 p -p o l

5 % P A M A M -A zo + P S b e fo re a fte r 4 h rs

Ref

lect

ivity


3 0 4 0 5 0 6 0 7 0

0 .3

0 .4

0 .5

0 .6

0 .7

0 .8

0 .9

1 .0 s -p o l

5 % P A M A M -A z o + P S b e fo re a fte r 4 h rs

Ref

lect

ivity


50% PAMAM-azoPolarization Irradiation

Timenx ny nz nx - ny Thickness

TM (p-wave) 0 hr 1.5047 1.5000 0

2596 nm4 hrs 1.5040 1.4900

TE (s-wave) 0 hr 1.5047 0.0033

4 hrs 1.5007

50 % PAMAM-azo + PS

The ny (same direction with polarization) is decreasing as the irradiation time increases. The nxdoes not change much, but nz (perpendicular to polarization) is decreasing. This result supports the photoalignment result (decreasing of A90).

Little birefringence (nx – ny) observed which is also consistent with photoalignment results.

R. Advincula, D. Patton, M.K. Park, S. Wang “Evanescent Waveguide and Photochemical Characterization of Azobenzene Functionalized Dendrimer Ultrathin Films ”-Langmuir 2002 18(5),1688-1694.

Total Dendrimer SynthesisTotal Dendrimer Synthesis

Two main approaches: Two main approaches: ConvergentConvergent and and DivergentDivergent

Jean M. J. Fréchet* Jean M. J. Fréchet* Chem. Rev.Chem. Rev. 2001,2001, 101,101, 38193819

Project 5b.Project 5b. Total Convergent Synthesis of an Total Convergent Synthesis of an AllAll--azoazo--benzene benzene dendrimerdendrimer

Target dendrimer molecule -The dendrimer is constructed by photo-sensitive azobenzene groups- The azobenzene groups are linked through benzyl ester bonds.

N NC

C

C

C

OO

OO

O O

OO

CC

NN

OO

OO

C

C

O

O

NN

OEt

EtO

CC

OO

N

OEt

EtO

N

C

C

NN

O

OO

O C

C

NN

O

OO

O

C

C

O

ONN

EtO

EtO

C

C

O

O

N OEt

EtO

N

C

CN N

O

O O

O

C

C

O

ON N

OEt

EtO

C

C

O

O

N

OEt

OEt

N

C

CN N

O

OO

O

CC

N N

OO

OO

CCO

NN

OEtEtO

C

C

O

ON

OEt

EtON

CC

NN

OO

OO

C

C

O

O

NN

EtO

OEt

CC

OO

N

EtO

OEt

N

C

C

NN

O

OO

OC

C

NN

O

O O

O

C

C

O

ON N

OEt

OEt

C

C

O

O

NEtO

OEt

N

C

CNN

O

OO

O

C

C

O

ONN

EtO

OEt

C

C

O

O

N

OEt

EtO

N

C

CNN

O

OO

O

CC

NN

OO

OO

CCO

O

NN

EtOOEt

C

C

O

ON

EtO

OEtN

NN CH2OH

EtOOC

EtOOC

NN CH2OH

HOOC

HOOC

NN

COOH

COOHHOOC

HOOC

G-1-OH

AB2-OH

AB4

• Target Molecule: generational control of azobenzene groups• Intelligent molecule: molecular shape and size could be changed upon irradiation

by UV light• Controlled azobenzene group density, a “macrodye”- quantifiable absorbing species• Controlled aggregates or “particulate chromophores” a nanoparticle• Globular shape change and translational movement within the matrix

(environment)

Synthesis: best route!

• Due to synthesis difficulties … design a new AB2 monomer for generation growth

TBDPSOH2C NN

COOH

COOH

-AB2 monomer : two activated carboxylic groups for generation growth and one hydroxymethyl group protected by tert-butyldiphenylsilane chloride (TBDPSCl)

-The protected group TBDPSCl - easy to remove and Stable towards acidic reaction conditions (acetic acid)

AB2

HOH2C NO2 TBDPSOH2C NO2

TBDPSOH2C NO

COOH

COOH

H2N

TBDPSClimidazoleDMF

1) Zn, 33-36 oC, N2

2-metoxyethanol

2) FeCl3, 0 ~5 oC ethanol, N2

acetic acidrt

~0 oC

96%

82%

TBDPSOH2C NN

COOH

COOH

91%

• do nitroso coupling-condensation with aniline

• Higher yields and reproducible towards convergent approach

• Generation growth:Esterification with benzyl alcohol (DCC/DMAP) and deprotect, repeat …

Example: Synthesis of G-4-OH

C

C NNO

OO

O

CC

OO

NN

OEt

EtO

C

C

O

ON

OEt

OEt

NC

CN N

O

OO

O

CC

NN

O OOO

CC

OO

NN

OEt

EtOCC

OO

N

OEt

EtON

CC

NN

O OOO

C

CO

O

NN

OEt

EtOC

C

OO

N

OEt

EtO

N

C

C

NN

O

OO

OC

C

NN

O

OO

O

C

C

O

ONN

EtO

EtO

C

CO

O

N OEt

EtO

N

CC

NN

OH

OOO

G-4-OH

G-3-OH + AB2DCC/DPTS G-4-OSPDBT HF-pyridine

Overall yield 64%The Dendron G-4-OH was easily obtained by coupling G-3-OH with AB2 monomer, using the same coupling reaction condition, in presence of DCC/DPTS, followed by de-protection with HF-pyridine in overall 64% yield.

MALDI-TOF-MS: [M + K] 4723.1 (calcd. for C257H216 N30O60, 4684.5).

All- azobenzene Dendrimer Shape Anisotropic “Organic Nanoparticle”

G-3-OH

NN

HOOC

HOOCCOOH

COOH

+ DCC/DPTS

38%

G-3-4AB4

The first example of photo-responsive all-azobenzene dendrimers bearing up to 29 azobenzene groups for 4 generations were prepared by a convergent approach…

MALDI-TOF-MS: [M+K] 9179.3 (calcd. for C500H418N58O120, 9158.2).

NN

EtO OO

NN

O

O

O

O

OEt

N N

EtOO

O

OEt

NN

EtO

O

O

N

O

OO

O

OEt

NN

EtO

O

O

EtO

NO

N

O

O

O

N

O

N

O

O

ON

O

O

O

O

NN

OEt

O

O

NN

O

OO

O

OEt

NN

OEt

O

O

OEt

NNEtO

O

O

NO

OO

O

OEt NN

EtO

O

OOEt

N

O

NO

O

ON

NN

OEtOO

NN

O

O

O

O

EtO

NN

OEtO

O

EtO

NN

OEt

O

O

N

O

OO

O

OEt

NN

OEt

O

O

OEt

NO

N

O

O

O

N

NN

EtO

O

ON NO

O O

O

EtO

NN

OEt

O

O

EtO

N NOEt

O

O

NO

OO

O

EtON

N

OEt

OOEtO

N

O

N O

O

O

N

Wang, S. and Advincula, R. “Design and Synthesis of Photoresponsive Poly(benzyl ester) Dendrimers with all-Azobenzene Repeating Units, Organic Letters; 2001, 3(24), 3831-3834.

ππ--Conjugated DendrimersConjugated Dendrimers

Luping Yu* Luping Yu* JACSJACS 1997,1997, 119,119, 90799079Klaus Müllen* Klaus Müllen* Chem. Rev.Chem. Rev. 1999,1999, 99,99, 17471747Jeffrey S. Moore* Jeffrey S. Moore* Acc. Chem. Res.Acc. Chem. Res. 1997,1997, 30,30, 402402

Conjugated dendrimers with rigid structures, such as phenylacetylene, phenylene vinylene, and polyphenylene dendrimers have also been developed in recent years.

Project 5 c.Project 5 c. Synthesis and Deposition of Thiophene Synthesis and Deposition of Thiophene DendrimersDendrimers

S

BuLi/C6H13Br

S C6H13

(1)

NBS/DMF

S C6H13Br

(2)

(1) Mg

NidpppCl2

S

Br

Br

SC6H13

S SC6H13

(3) 3T

BuLi/Bu3SnCl SC6H13

S SC6H13

Bu3Sn

(4)

S

Br

Br

Pd(PPh3)4

S

S

C6H13

S

SC6H13

S

S C6H13

S

C6H13

(5) 7T

S

S

C6H13

S

SC6H13

S

S C6H13

S

C6H13

Bu3Sn

(6)

S

S

C6H13

S

S

C6H13

S SC6H13

S S

S

SS

C6H13

S

C6H13

S

C6H13

S C6H13

S C6H13

(7) 15T

Xia, C.; Fan, X.; Locklin, J.; Advincula, R. C.; “A First Synthesis of Thiophene Dendrimers”, Organic Letters 2002; 4(12); 2067-2070.

BuLi/CuClBuLi/CuCl2 2 Coupling to Thiophene DendrimersCoupling to Thiophene Dendrimers

BuLi/CuCl2S

C6H13

S SC6H13

SC6H13

SSC6H13

(8) 6T

BuLi/CuCl2S

S

C6H13

S

S C6H13

S

SC6H13

S

C6H13

S

S

C6H13

S

SC6H13

S

SC6H13

S

C6H13

(9) 14T-1

SC6H13

S SC6H13

(3) 3T

S

S

C6H13

S

SC6H13

S

S C6H13

S

C6H13

(5) 7T

Synthesis of Thiophene DendrimersSynthesis of Thiophene Dendrimers

S

Br

Br S

Br

BrS

Br

BrLDA/CuCl2

(11)

(4), Pd(PPh3)4

(6), Pd(PPh3)4 DMF S

S

C6H13

S

SC6H13

SS C6H13

S

C6H13

S

S

C6H13

S

SC6H13

SSC6H13

S

C6H13

(12) 14T-2

S

SC6H13 S

S

C6H13

S

S

C6H13

SS

S

S

SC6H13

SC6H13 S

C6H13

SC6H13

S

C6H13

S

S

C6H13

S

S

C6H13

S

S

C6H13

S S S

S

SC6H13

S

C6H13

S

C6H13

SC6H13

S C6H13

(13) 30T

11H NMR of the DendrimersH NMR of the Dendrimers

6T

7T

15T

14T-1

14T-2

30T1H-NMR spectra of 6T, 7T, 15T, 14T-1, 14T-2, and 30T in THF-d8 at 290K. For 6T, 14T-1, 14T-2, and 30T, the interior protons on the thiophene ring show singlets downfield; and the exterior protons show doublets upfield. For 7T and 15T, two doublets were found for the two protons at the focal thiophene, one at the most down field, and the other hidden in the singlets.

MALDIMALDI--TOFTOF--MS CharacterizationMS Characterization

1000 2000 3000 40000

5000100001500020000250003000035000400004500050000

30T

Cou

nts

Mass

05000

1000015000200002500030000

14T-2

Cou

nts

05000

1000015000200002500030000

14T-1

Cou

nts

1 8 1 0 1 8 1 5 1 8 2 0 1 8 2 5 1 8 3 0 1 8 3 5 1 8 4 0

3 7 9 0 3 7 9 5 3 8 0 0 3 8 0 5 3 8 1 0 3 8 1 5 3 8 2 0 3 8 2 5 3 8 3 0

1 8 1 0 1 8 1 5 1 8 2 0 1 8 2 5 1 8 3 0 1 8 3 5 1 8 4 0

The MALDI-TOF analysis verified monodispersed masses for 14T-1, 14T-2, 15T, and 30T giving: 1824.0, 1823.6, 1905.3, and 3809.5, respectively. These are consistent with the calculated values: 1823.6, 1823.6, 1905.6, and 3809.2.

Size Exclusion ChromatographySize Exclusion Chromatography

44 46 48 50 52 54Elution Volume

30T14T-114T-2

15T 7T

1.0053202.63809.53809.230T

1.0041791.11905.31905.615T

1.0011903.61823.61823.614T-2

1.0041955.11824.01823.614T-1

1.007989.7___913.57T

DPIMnMALDIMass

UVUV--vis and Photoluminescencevis and Photoluminescence

250 300 350 400 450 500 550 600

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

3T

3T 6T

6T

PL

Inte

nsity

(Nor

mal

ized

)

Abso

rban

ce (N

orm

aliz

ed)

Wavelength (nm)250 300 350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

7T

14T-1

7T

14T-1

14T-2

14T-2

PL

inte

nsity

(nor

mal

ized

)

Abso

rban

ce (N

orm

aliz

ed)

Wavelength (nm)

250 300 350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

30T

15T

30T

15T

PL

Inte

nsity

(Nor

mal

ized

)

Abso

rban

ce (N

orm

aliz

ed)

Wavelength (nm)

Broad absorption spectraand finite photoluminescence

Size and configuration dependence

Summary of Optical and Electrochemical PropertiesSummary of Optical and Electrochemical Properties

2.542.5054349730T

___2.6252947315T

2.672.7354945414T-2

2.572.4853450114T-1

___2.825004407T

___2.714764586T

___3.334493723T

Eg (eV) from CV

Eg (eV)PL (nm)Absorption Onset (nm)

-2.5 -2.0 0.0 0.5 1.0 1.5

14T-1

Fc+/Fc

Potential (V)

14T-2

0.5μA/ m m 2

30T

Xia, C.; Advincula, R.*; Locklin, J.; Giess, A.; Nonidez, W. “Characterization, Supramolecular Assembly, and Nanostructures of Thiophene Dendrimers” J. Am. Chem. Soc. 2004, 126, 8735-8743.

Nanoparticle Aggregates on Mica: 14 TNanoparticle Aggregates on Mica: 14 T--11

14T-1, drop casted from 1.1μM solution in THF after slow evaporation

Globular aggregates formedwith different sizes

500nm

Nanoparticle Aggregates on Mica: 30TNanoparticle Aggregates on Mica: 30T

150nm

30T, drop casted from 0.58μM solution in THF after slow evaporation

Small aggregates or individual molecules

Nanoparticle SelfNanoparticle Self--Assembly of 30T on Graphite (HOPG)Assembly of 30T on Graphite (HOPG)

100nm

30T, drop casted from 0.58μM solution in THF after slow evaporation

Epitaixal registry on graphite, Conformation?Molecular modeling needed

Self-assembled structure of TG2-12 on HOPG. STM topographic image. The unit cell dimensions are a=(6.4±0.1)nm, b=(5.4±0.1)nm, α=(78±2)°Tunneling conditions for the STM image: Ut=0.1V, set point current=1nA.

SelfSelf--Assembly of Assembly of 14T14T--11 on HOPGon HOPG

14T-1 on HOPG, films prepared from (a) 0.11μM solution; (b) 1.1μM solution. The solvent was allowed to evaporate very slowly.

Self-assembled structure of 14T on HOPG. STM topographic image. The unit cell dimensions are a=(6.4±0.1)nm, b=(5.4±0.1)nm, α=(78±2)°Tunneling conditions for the STM image: Ut=0.1V, set point current=1nA.

Epitaxial Packing of Epitaxial Packing of 14T14T on HOPGon HOPG

S

S

S

S

S

S

S

S

S

S

S

S

S

S

Xia, C.; Advincula, R.*; Locklin, J.; Giess, A.; Nonidez, W. “Characterization, Supramolecular Assembly, and Nanostructures of Thiophene Dendrimers” J. Am. Chem. Soc. 2004, 126, 8735-8743.

Outline of Projects







• Conclusions

Project 6

Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena

Welch Foundation

CdSe Nanoparticles

www.qdot.com

- Spatial confinement of electronic excitation to physical dimensions of the nanocrystals (particle in a box)

-Strong absorbers (ε = 36,000 -700,000) depending on size

- High surface/volume ratio nanoparticles

Fluorescence efficiency and stability is strongly affected by capping agent

Ligands for Semiconducting Nanocrystals

Some Typical Organic Ligands• Phosphine/Phosphine Oxide, e.g.

trioctylphosphine/trioctyl phosphine oxide

• Alkylamine, e.g. octadecylamine• Dendrimers, e.g. poly(amidoamine)• Electroactive surfactants, e.g.

oligothiophenes, perylene based stabilizers

The nature of the capping agent can have a profound effect on the photophysics of the nanoparticles

– Organic and inorganic capping agents have been employed– Organic ligands offer improved solubility in common organic

solvents

Some Typical Inorganic Shells• Higher band gap materials, e.g. ZnSe• Using this approach, fluorescence

quantum yield has been increased by more than 50%

CdSe

ZnSeCore-shell Structure

Gold Nanoparticles

• Potential applications in optoelectronics, electronics, catalyst, biosensors, etc.

Surface Functionalization of Au NPs Surface Functionalization of Au NPs

OrganicOrganic--inorganic Hybrid Nanostructures: inorganic Hybrid Nanostructures: Advantages and ApplicationsAdvantages and Applications

• From the strong interaction between metal nanoparticles and conjugated polymers, unique photophysical and electrochemical properties are expected to arise leading to a wide range of potential applications in electronic and optoelectric devices

Electroluminescence EnhancementWith Polyfluorene/Au NP nanocomposites

Chem. Mater. 2004, 16, 688.

Recognition and Detection of Biomolecules

JACS 2002, 124, 9606.

Project 6a. Dendron Stabilized Quantum Dot Nanoparticles

Wang et al. JACS 2002, 124, 2293Guo et al. JACS 2003, 125, 3901

Advantages of dendron capping:•Increased thermal, chemical, and photochemical stability•More reliable workup (processing) procedures

Linear- TOPO capped Hyperbranched- Dendron capped

Synthesis and Spectroscopic Properties of Branched P7T

S S C6H13

SBr C6H13

Mg/Ether2,3-dibromothiopheneNi(dpp)Cl2

BuLi, THF, -78oCbromohexane NBS/DMF

S

S

S

C6H13

C6H13 3TS

S

SBu3Sn

C6H13

C6H13

BuLi, THF, -78oCBu3SnCl

S

S S

S

S

S

SP O

HO

OH

C6H13

C6H13

C6H13

C6H13

P7T7T

S

S S

S

S

S

S

C6H13

C6H13

C6H13

C6H13

2,3-dibromothiophenePd(PPh3)4, DMF

BuLi, THF, -78oCdiethylchlorophosphate

BrSiMe3, CH3OH

300 400 500 600 700

Pho

tolu

min

esce

nce

[a.u

.]

Abs

orba

nce

Wavelength, nm

QY = 25 %ε = 23,301Eg = 2.66 eV

Broad Absorbance SpectrumEmission λmax = 521 nm

P7T Ligand Exchange

300 400 500 600 700

0.0

0.2

0.4

0.6

0.8

1.0A

bsor

banc

e

Wavelength, nm

-Deconvolution: ~30 dendrons per nanocrystal- FT-IR can use to follow changes on the P=O stretching region. Peak at 796 cm-1 impt.- Photoluminescence of nanocrystal and dendron are quenched: electron transfer between

ligand and nanoparticle- Synthesis of TOPO-caped CdSe using Peng et. al. procedure J. Am. Chem. Soc. 2001, 123, 183.

CHCl3

Inert Atmosphere

300 400 500 600 700

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Abso

rban

ce

Wavelength, nm

Nanocrystal before P7T/CdSe complex

Photovoltaic Cells: Hybrid Materials

-Nanocrystals are good electron acceptors

- Nanocrystal visible band gap, both conjugated polymer and nanocrystal contribute to absorption

PREVIOUS:Major factor with CdSe photovoltaic cells is the aggregation (phase separation) of CdSe nanocrystals within conjugated polymer matrix.

Huynh, W. et al. Science 2002, 295, 2425

Hybrid Material: Current-Voltage Response of Film

0.0 0.3 0.6

-0.002

-0.001

0.000

Pin= 0.1 mW/cm2

Dark

Cur

rent

(mA

/cm

2 )

Voltage (V)

Voc = 0.62 VIsc = 1.56 x 10-6 A/cm2

FF = 0.3Pin = 0.1 mW/cm2

Power Conversion Efficiency, ηe = 0.29 %

Glass

CdSe capped with thiophene dendronsAl

ITO

Chem. Mater. 2004, 16, 5187-5193

CdSe PS

S

S

S

S

S

S

C6H13

C6H13

C6H13

C6H13

OO

OP

SS

S

S

S

S

S

C6H13

C6H13

C6H13

C6H13

OO

O

P

S

SS

S

S

S

S

C6H13

C6H13C6H13

C6H13

OO O

P

S

SS

S

S

S

S

C6H13

C6H13 C6H13

C6H13

O OO

Energy Transfer in Gold Nanoparticles Capped with α−Functionalized Thiophene Dendrons

Previous Project: Functionalization of PAMAM Dendrimer

S

S S

NHCH2

= tertiary amine

=

=

= unreacted NH2

SC6H13

SSC6H13

POCl3

SC6H13

SSC6H13

CHO G4NH2S

C6H13

SSC6H13

CN G4

H

3T6C

DMF

3T6C-CHO

SC6H13

SSC6H13

CH2 NH G4

+

G4(3T6C)

NaBH3CN

Deng, S.; Advincula, R. C. et.al. J. Am. Chem. Soc. 2005, 127, 1744

1 2

3

4

5

6

7

89

101112

13

14

15

16

17

18

1920

21

Metal Nanoparticle in Dendrimer

Ligand DesignLigand Design

S

C6H13

SS C6H13

O

HN

HS

10

10

S

C6H13

SS C6H13

O

HN

HS

HSC23T6C HSC113T6C

S

O

HN

HS

C6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

HSC27T6CS

C6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

O

HN

HS

HSC117T6C

Ligand Synthesis: 3T and 7TLigand Synthesis: 3T and 7T

SC6H13

SSC6H13

O

OH

SC6H13

SSC6H13

1) n-BuLi

2) CO23) H3O+

NHO

O

O

EDC

SC6H13

S SC6H13

O

ON

O

O

S

C6H13

SS C6H13

O

HN

HSNH2

HS HSC23T6C

S

C6H13

SS C6H13

O

HN

HS10

HSC113T6C

NH2

HS

10

AC6H1

3

S

S

C6H13

S

S

C6H13

S

SC6H

13

SC6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

OH

O

SC6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

O

O

N

O

O

1) n-BuLi

2) CO23) H3O+

NHO

O

O

EDC

SC6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

O

O

N

O

O

NH2HS

S

O

HN

HS

C6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

HSC27T6C

10

SC6H13

S

S

C6H13

S

S

C6H13

S

SC6H13

O

HN

HS

HSC117T6C

NH2HS10

3T and 7T3T and 7TChain Length VariationChain Length Variation

Au NPs Synthesis and hybridizationAu NPs Synthesis and hybridization

Au

SO

HNS

C6H13

S

SC6H13

S

SC6H13

SS C6H13

S

OHN

S

C6H13

S

SC6H13

S

SC6H13

S

S

C6H13

S

OHN

S

C6H13

SS C6H13

S

S

C6H13

S

S

C6H13

S

O

NH

S

C6H13

S

S

C6H13

SS C6H13S

SC6H13

S

O

HN

S

C6H13

S

S

C6H13

SSC6H13 S

SC6H13

S

ONH

S

C6H13

S

S

C6H13

S

S

C6H13

S

S

C6H13

S

O NH

S

C6H13

SSC6H13

S

S

C6H13

S

S

C6H13

S O

NH

S

C6H13

S

SC6H13

S

SC6H13

SSC6H13

2) TBAB

1) AuCl3, DDAB

S

OHN

SH

C6H13

S

S

C6H13

S

S

C6H13

S

S

C6H13

S

S S

O

NH

HS

6.66, m6.85, d

2.76, m7.44, s

6.97, d

6.06, br

2.67, t

1.64, m

1.30, m

0.88, t

3.41, q

1.5

6.66, m

2.76, m

1.64, m

1.64, m1.64, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

0.88, t

1.30, m

S

S S

O

NH

S

6.66, m6.85, d

2.76, m7.44, s

6.97, d

6.06, br

2.67, t

1.64, m

1.30, m

0.88,t

3.41, q

6.66, m

2.76, m

1.64, m

1.64, m1.64, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

1.30, m

0.88, t

1.30, m

Au

NMR and IR ComparisonNMR and IR Comparison

4000 3500 3000 2500 2000 1500 1000

Abso

rban

ce (a

.u.)

Wavenumber (cm-1)

HSC23T6C Au-SC

23T6C

3500 3000 2500 2000 1500 1000

Ab

sorb

ance

(a.u

.)

Wavenumber (cm-1)

HSC11

3T6C Au-SC113T6C

UVUV--vis Spectra: Effects of Different Chain Lengths for 3Tvis Spectra: Effects of Different Chain Lengths for 3T

300 400 500 600 700

349

349

527

350

524

A

bsor

banc

e (a

.u.)

Wavelength (nm)

HSC23T6C HSC23T6C and Au-SC23T6C Au-SC23T6C

300 360 420 480 540 600 660 720 780

342

520

344

513

346

Abs

orba

nce

(a.u

.)

Wavelength (nm)

HSC113T6C HSC113T6C and Au-SC113T6C Au-SC113T6C

300 400 500 600 700

535

531

311

Abs

orba

nce

(a.u

.)

Wavelength (nm)

HSC27T6C HSC27T6C & Au-SC27T6C Au-SC27T6C

300 400 500 600

519

555

A

bsor

banc

e (a

.u.)

Wavelength (nm)

HSC117T6C HSC117T6C & Au-SC117T6C Au-SC117T6C

UVUV--vis Spectra: Effects of Different Chain Lengths for 7Tvis Spectra: Effects of Different Chain Lengths for 7T

MPCs vs. Optically Matched Mixtures

300 400 500 600 700

345 nm

523 nm

Abs

orba

nce

(a.u

.)

Wavelength (nm)

Au-SC23T6C Au NPs & HSC23T6C

Au

S

C6H13

S

S

C6H13

OHN

S

S

C6H13

S

S

C6H13

ONH

S

SC6H13

SS C6H13

O

HN

S

SC6H13

SSC6H13

O

NH

S

S

C6H13

S

S

C6H13

OHN

S

S

C6H13

S

S

C6H13

ONH

S

SC6H13 S

S

C6H13

O

HN

S

S C6H13S

S

C6H13

O

NH

S

Au-SC23T6C

Au OH

O

OHO

OH

O

HO O

OHOOH

O

HOOHO

O

Au NPs

S

C6H13

SS C6H13

O

HN

HS

HSC23T6C

Energy Transfer StudiesEnergy Transfer Studies

400 450 500 550 600

454.5

456.5

Inte

nsity

(a.u

.)

Wavelength (nm)

Au NPs & HSC23T6C Au-SC23T6C

90% fluorescence quenched

400 450 500 550 600 650

453

454

Inte

nsity

(a.u

.)

Wavelength (nm)

Au NPs & HSC113T6C AuSC113T6C


3T3T

7T7T

450 500 550 600 650 700 750

532.5

536

Inte

nsity

(a.u

.)

Wavelength (nm)



450 500 550 600 650 700 750

534.5

540

Inte

nsity

(a.u

.)

Wavelength (nm)



Conclusions

• Nanostructured Materials are important for improved properties and phenomena

• Nanotechnology owes both to organic and inorganic/metal materials and hybrids.

• Organic and Polymer Synthesis is essential to nanotechnology!• Nanoscale phenomena is observed in a variety of sizes, geometry,

and shapes: ultrathin films to nanoparticles

• An interdisciplinary approach is critical for future growth in this field.

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