department of mechanical engineering, department … · flame resistant without altering any other...

N T F RNANOCOMPOSITE THIN FILMS FOR REDUCEDFLAMMABILITY FOAM AND FABRIC

JAIME C. GRUNLAN

DEPARTMENT OF MECHANICAL ENGINEERING,DEPARTMENT OF CHEMICAL ENGINEERINGDEPARTMENT OF CHEMICAL ENGINEERING

& MATERIALS SCIENCE AND ENGINEERING PROGRAMTEXAS A&M UNIVERSITY

Copyright © 2008 by Jaime C. GrunlanCopyright © 2010 by Jaime C. Grunlan

6th Triennial IFCSRC – Atlantic City, NJ – 27 October 2010

Polymer NanoComposites (PNC) Lab (http://nanocomposites.tamu.edu)

Polymer NanoComposites (PNC) Lab

Nanoparticle Stabilization

Polymer Composites

Thin Film Assemblies

Gas BarrierACS Appl Mater Interf 2010

Clay-Carbon-EpoxyAd F i l M 2007 ACS Appl. Mater. Interf. 2010

(featured in C&EN 11 Jan 2010)Anti-FlammableACS Nano 2010(f t d i C&EN 7 J 2010)

pH-ResponsiveNano Letters 2006 (featured in N M i l 2006)

Adv. Functional Mater. 2007Macromol. Rapid Comm. 2009Carbon 2009Conductive Emulsions

(featured in C&EN 7 June 2010)AntimicrobialLangmuir 2008Electrically Conductive

Nature Materials 2006)J. Coll. Interf. Sci. 2008ThermoresponsiveJ. Am. Chem. Soc. 2009

Advanced Materials 2004Polymer 2008Macromol. Chem. Phys. 2008Energy Harvesting


yLangmuir 2008J. Phys. Chem. C 2010

“Solid Surfactant”Carbon 2009

gy gNano Letters 2008ACS Nano 2010

Polymer NanoComposites (PNC) Lab (http://nanocomposites.tamu.edu) 2

Acknowledgements

Polymer NanoComposites Lab – Summer 2010


NIST

Polymer NanoComposites (PNC) Lab (http://nanocomposites.tamu.edu) 3

Southern Regional Research Center

Outline

Overview of layer-by-layer (LbL) assembly

Growth and microstructure of clay-based assemblies

Flame retardant behavior of coated substrates

Initial results with new systems…

C l iConclusions

Copyright © 2008 by Jaime C. GrunlanCopyright © 2010 by Jaime C. Grunlan 4

Layer-by-Layer Deposition Overview

Layers of positively and negatively charged materials are alternately deposited from water to create functional thin films.

- -- -+ + +

+ + + + + + ++ + + + + + +

- - - -- -- -- -

- -- --

--

- -- - -

+ + + + + + +

+ + + + + + + + + + + + + +

+ + + + + + ++ + + + + + ++ + + + + + + +

++

++

+

+ + + + + + + + + + + + + +

+ + + + + + +

+ + + + + + ++ + + + + + +

+ + + + + + +

+ + + + + + +Dry- -- -- -- - - -- -

- -- - - -- -- -- - - -- -- -- -

-- - -- -

-

--

-

- -- -

++ + + + + + ++ + + + + + + + + + + + + + + + + + + + +

S b- - - - - -

- -- - - -- -- -- - - -- -- -- -- -One bilayer}

Substrate

Ambient Processing Tunable Properties Nanoscale Control


Decher, G. Science 1997, 277, 1232.Bertrand, P., Jonas, A., Laschewsky, A., Legras. R. Macromol. Rapid Comm. 2000, 21, 319.

g p

Layer-by-Layer Assembly of Clay and PEI

BPEI 0.1 wt.%

branched polyethylenimine

BPEI MMT

branched polyethylenimineMw ~25,000

= BPEI = MMT

MMT platelet

MMT 0.2 wt. %

Montmorilloniteh ik h


Si8(Al3.33Mg0.67)O20(OH)4],0.67Na+ ∙ nH2O

6

Suh, J.; Paik, H. J.; Hwang, B. K., Bioorg. Chem. 1994, 22, 318. Grim, R. E., Science 1962, 135, 890.Ploehn, H. J.; Liu, C., Ind. Eng. Chem. Res. 2006, 45, 7025.Annabi-Bergaya, F., Microporous Mesoporous Mater. 2008, 107, 141.

pH Tailored Film Growth of PEI-MMT

13pH10(PEI10/MMT)

140pH10(PEI10/MMT)PEI10/MMT PEI10/MMT

Ellipsometric Growth Mass Deposited (QCM)

high

10

11

12

µg/c

m2 )

PpH8P(PEI8/MMT)

80

100

120

ss (n

m)

0pH9

pH8

pH7

(PEI9/MMT)(PEI8/MMT)(PEI7/MMT)

PEI9/MMT

PEI8/MMT

PEI7/MMT

PEI10/MMT

PEI8/MMT

pH

high

+

+

7

8

9

Mas

s (µ

20

40

60

Thic

kne

low +++

+

+

634 35 36 37 38 39 40 41

Number of Layers

00 5 10 15 20 25 30 35 40 45

Number of Bilayers

Filled = PEI Unfilled = MMT

Copyright © 2008 by Jaime C. GrunlanCopyright © 2010 by Jaime C. Grunlan Grunlan. et al., ACS Applied Materials & Interfaces 2010, 2, 312. 7

TEM Cross-Sections of PEI-MMT Films

40 BL films of pH 10 PEI MMT were grown on polystyrene


40 BL films of pH 10 PEI-MMT were grown on polystyrene and cured in epoxy prior to sectioning.

8Grunlan. et al., ACS Applied Materials & Interfaces 2010, 2, 312.

Surface Microstructure via AFM

H i h PhHeight Phase

(PEI8/MMT)10

RMS Surface Roughness:2 1nm2.1nm

(PEI /MMT)(PEI10/MMT)10

RMS Surface Roughness:3.6nm


pH Tailored Oxygen Barrier

40 BL films of PEI-MMT on 7-mil PET8.42

7.648

9

6

7

y/at

m)

4.53

4

5

c/m

2 /day

2

3

OTR

(c

0.34

0

1


0pH 7 pH 8 pH 9 pH 10

Grunlan. et al., ACS Applied Materials & Interfaces 2010, 2, 312.

Oxygen Transmission Rate of PEI-MMT at pH 10

5.60

5

6Number of

BilayersOTR

(cc/(m2·day·atm))Film Thickness

(nm)Film Permeability

(10-6 cc/(m·day·atm))10 5.596 28.27 0.914

4

5

ay·a

tm)) 20 3.007 59.62 0.553

30 1.485 101.90 0.36640 0.339 134.12 0.09550 0.129 166.87 0.04460 0 036 194 31 0 014

3.013

c/(m

2·da

60 0.036 194.31 0.014

Lowest reported permeability for a polymer – clay film < 200 nm thick

1.482

OTR

(cc polymer clay film 200 nm thick

0.340.13 0.04 <0.005

0

1O


10 20 30 40 50 60 70Number of Bilayers

Grunlan. et al., ACS Applied Materials & Interfaces 2010, 2, 312. 11

Barrier Mechanism

Classical Tortuosity Reflective TortuosityCussler et al. J. Membrane Sci. 1988, 38, 161.Nielsen, L. E. J. Macromol. Sci. 1967, A1, 929.

( )φ−φα

μ+=1

1PP 22

oαφ+=1PPodilute (φ<<1

and αφ<1)semi-dilute (φ<<1 and αφ>1)

B i k ll i t t ith t d “ lit ” li it diff i i thBrick wall microstructure with staggered “slits” limits diffusion in three ways:

tortuous wiggles to get around platelets α = aspect ratio


tight slits between plateletsresistance when transitioning from wiggle into slit

μ = geometric factor

φ = vol. fraction12

Flame Retardant Foam and FabricOur recent paper on this topic was featured on the ACS website and highlighted in C&EN on 7 June 2010.

“Creation of a barrier surface layer is believed to be a key mechanism


Creation of a barrier surface layer is believed to be a key mechanism in flame retardancy imparted by the addition of clay.”

Gilman et al. Polym. Adv. Technol. 2006, 17, 263.

Clay Reduction of Peak Heat Release

TEM of nanocomposite Combustion studies

EVA MMT 5 wt%

2∼5 % clay loading resulted in 70 80 % reduction of peak HRR.


Charred ceramic surface act as an insulator during burning. G. Camino et al. Chem. Mater. 2002, 14, 881.

14

Mechanism of Clay Flame Suppression


G. Camino et al. Chem. Mater. 2002, 14, 881.

Why LbL of Clay and Polymer?

• halogenated compounds-harmful for environment• carbon nanotubes and clays-increase processingcarbon nanotubes and clays increase processing

viscosity and alter mechanical properties of final foam or fabric when used in-situ

• Layer-by-layer assembly provides the benefits of

Kashiwagi, K. et al. Nat. Mater. 2005, 4, 928.Gilman, J. W. et al. Chem. Mater. 2000, 12, 1866.

y y y y pclay without the drawbacks

Fabric


Cone Calorimeter Results for Foam

The thin, conformal clay coating can easily coat three-dimensional objects (e.g., foam) to render them

Foam Fabric

objects (e.g., foam) to render them flame resistant without altering any other intrinsic properties.

Polyurethane foam was coated 3500

4000

4500

(W)

ControlSample 1S l 2

ControlClay-PDDACl PA with 20-bilayers of two different

clay-polymer compositions. 2000

2500

3000

elea

se R

ate

( Sample 2Clay-PAm

The PDDA coating is just 25 nm, while the PAm coating is 150 nm.500

1000

1500

Hea

t Re


00 50 100 150 200 250

Time (s)Gilman, Rahatekar, Zammarano (NIST)

Grunlan et al. “Layer-by-layer assembly of flame retardant coating for foam” Polym. Mater. Sci. Eng. 2008, 98, 772. 17

Foam Appearance After Cone Test

Foam

Foam squares were exposed to an external heat flux of 11 kW/m from the cone heater and a direct flame for 20 seconds.

Foam

20 BL Clay-PAm150 nm thick coating

Gilman


20 BL Clay-PDDA25 nm thick coating

Bare Foamno coating

RahatekarZammarano

(NIST)18

Coated Cotton Fabric Before Burning

500 µm


Fabric coated with 5 BL of 0.1% BPEI pH 7/ 1% MMT

Li, Y. -C., Schulz, J., Mannen, S., Zammarano, M., Grunlan, J. C. ACS Nano 2010, 4, 3325.

Vertical Flame Test of Coated Fabrics

BPEI pH 10/MMT 0.2wt%


BPEI pH 10/MMT 1.0 wt%

BPEI pH 7/MMT 1.0 wt%Control


ASTM D 6413‐ 08Test shown at 5 seconds after ignition on 20 BL films.20Li, Y. -C., Schulz, J., Mannen, S., Zammarano, M., Grunlan, J. C. ACS Nano 2010, 4, 3325.

Vertical Flame Test – Post Burn



BPEI pH 10/MMT 1.0 wt%

BPEI pH 7/MMT 1.0 wt%Control


ASTM D 6413‐ 08Post burn images on 20 BL films.

21Li, Y. -C., Schulz, J., Mannen, S., Zammarano, M., Grunlan, J. C. ACS Nano 2010, 4, 3325.

Images of Fabric After Vertical Flame Test

20 BLControl

BPEI pH10/ 1 %MMT 500 µm500 µm

20 BL5 BL

Copyright © 2008 by Jaime C. GrunlanCopyright © 2010 by Jaime C. Grunlan BPEI pH7/ 1 %MMT 500 µmBPEI pH7/ 1 %MMT 500 µm

22

SEM Images of Virgin and Coated Fabric

5 BLUncoated 5 BL BPEI pH10/ 0.2 %MMT

Before burning

Afterburning

Copyright © 2008 by Jaime C. GrunlanCopyright © 2010 by Jaime C. Grunlan 23Li, Y. -C., Schulz, J., Mannen, S., Zammarano, M., Grunlan, J. C. ACS Nano 2010, 4, 3325.

Colloidal Silica Based AssembliesColloidal Silica-Based Assemblies


Vertical Flame Testing of Coated Fabric

ControlLudox CL ‐Ludox SM

Ludox CL ‐Ludox TM PEI ‐Ludox SM PEI ‐Ludox TM


ASTM D6413Post burn images on 10 BL films.

Laufer, G.; Martinez, R.; Grunlan, J. C., submitted to ACS Applied Materials & Interfaces. 25

POSS Based AssembliesPOSS-Based Assemblies


SEM of AP-POSS Coatings

5BL 10BL 20BL

Beforeburning

afterburning

Copyright © 2008 by Jaime C. GrunlanCopyright © 2010 by Jaime C. Grunlan Li, Y. C.; Mannen, S.; Schulz, J.; Grunlan, J. C., to be submitted. 27

Conclusions

⌦ Clay-based assemblies can exhibit extremely low oxygen transmission rates (foil replacement)

⌦ Processing is environmentally friendly (green)

⌦Ability to conformally coat complex geometries

⌦ Renders foam and fabric/fibers flame retardant


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