flexible polyimide aerogel cross-linked by poly(maleic

Flexible polyimide aerogel cross-linked by poly(maleic anhydride-alt-alkylene)

Haiquan Guo Ohio Aerospace Institute

Mary Ann B. Meador NASA Glenn Research Center

Brittany Wilkewitz NASA Glenn Research Center LERCIP internship 2013

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National Aeronautics and Space Administration

www.nasa.gov

Mar-17-2014

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http://royal-tarts.deviantart.com/art/Olaf-GIF-4-Melting-Request-426015061

http://delicious-to-c.blogspot.com/2013/12/frozen-2013.html

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Why aerogels?

• Made by removing solvent from wet gels without collapsing the structure

• High porous solids • Low density • High surface area • Good thermal insulation material

• reduces heat transfer (convection, conduction, and radiation)

Sol Aerogel Gel

http://en.wikipedia.org/wiki/Aerogel


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Potential applications of aerogels


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http://spinoff.nasa.gov/spinoff2001/ch5.html

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Inflatable aerodynamic decelerators

Astronaut EVA suits

Habitat structures Cyrotanks

Potential applications of aerogels National Aeronautics and Space Administration

www.nasa.gov http://spinoff.nasa.gov/spinoff2001/ch5.html

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What should be considered for real application?


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• Flexible • Strong • Less dusty • Hydrophobic • Low cost

ybic

Silica aerogel is fragile • Light weight • High porous • High surface area • Low thermal

conductivity

ww

Hydropho• Low cost

bicermal tivity

Better mechanical properties and environmental stability are needed…

Cross-linked polyimide aerogels Cross-linkers

M. A. B. Meador and H. Guo, LEW-18864-1, US patent application No. 61/594,657


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octa(aminophenyl)silsesquioxane (OAPS)

1,3,5-triaminophenoxybenzene (TAB)

O O

H2N NH2O

H2N

OOO

O

O

O +

O O

COOH

HR

H O O

HOOC

O

O

O

O

N N

25 H2N R NH226

25

polyimide oligomer

OAPS

catalyst

OAPS

• Two cross-linkers with amine functional groups

• Various polyimide oligomer backbones using different dianhydrides and diamines

• Chemical imidization

H. Guo, et al. ACS Appl. Mater. Inter., 2012, 4, 5422. M. A. B. Meador, et al. ACS Appl. Mater. Inter., 2012, 4, 536. H. Guo, et al. ACS Appl. Mater. Inter., 2011, 3, 546.

• Low density and shrinkage • High porosity, surface area, and

modulus • Moisture resistant • Low dielectric constant and

thermal conductivity • Can be metalized with gold • Flexible thin film

Cross-linked polyimide aerogels National Aeronautics and Space Administration

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M.A. B. Meador, et al. ACS Appl. Mater. Inter., 2012, 6346.

Problems of previous cross-linked polyimide aerogels

• OAPS cross-linker is expensive • TAB cross-linker is not commercially available, requires custom

synthesis • Contact angle for the moisture resistant polyimide aerogel is 85-90o


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• Explore commercially available and less expensive cross-linkers

• Look for less expensive monomers that might impart flexibility, hydrophobicity, etc.


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Objectives

12


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Commercially available poly(maleic anhydride)s as cross-linkers

poly (maleic anhydride-alt-1-octadecene) (PAMO) Mn 30,000-50,000

poly (isobutylene-alt-maleic anhydride) (PIMA) Mw ~6000

poly(ethylene-alt-maleic anhydride) (PEMA) Mw 100,000-500,000

Network formation using poly(maleic anhydride)s as cross-linkers


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polyimide oligomer 13

R: H, CH3, CH2(CH2)xCH3 R’: H, CH3

Cross-linker

imidization

BPDA

Polyimide oligomer

• n=20,10 w/w% • Polyimide oligomers • ODA+BPDA • three cross-linkers ODA

PMAO

PIMA

O NH2H2N +

OH2N NH

O

CO

HOOC

CHN

COOH

O NH2

(n+1) n O O

O

O O

O

n

PEMA

H. Guo and M. A. B. Meador LEW-19108-1

NMR and FTIR spectra prove imidization was completed

13C nuclear magnetic resonance (NMR)


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Typical Fourier transform infrared (FTIR) spectrum of aerogels

Absent • 1860 cm-1 unreacted anhydride • ~1807 & 980 cm-1 isoimide • ~1660 cm-1 ⱱ amic acid C=O • ~1535 cm-1 ⱱ amide C-N

1774 cm-1 asymmetric ⱱ imide C=O

1377 cm-1 ⱱ imide C-N

1716 cm-1

symmetric ⱱ imide C=O

CH2 stretching vibrations

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imide carbonyl

aromatic ether carbon of ODA

aliphatic carbons

aromatic carbon

PMAO

PIMA

PEMA

Density, shrinkage, and porosity National Aeronautics and Space Administration

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PEMA PIMA PMAO

Den

sity

(g/c

m3 )

0.00

0.05

0.10

0.15

0.20

PEMA PIMA PMAO

Shrin

kage

(%)

0

5

10

15

20

25

PEMA PIMA PMAO

Poro

sity

%

0

20

40

60

80

100

• PMAO cross-linked aerogel has the lowest shrinkage

• PEMA cross-linked aerogel has the highest density, the highest shrinkage, and the lowest porosity

PEMA PIMA PMAO

Sur

face

Are

a (m

2 /g)

0

100

200

300

400

500

Pore Size (nm)

7 10 20 30 40 50 60 70 80P

ore

Vol

ume

(cm

3 /g)

0.0

0.5

1.0

1.5

2.0PMAO PIMA PEMA

N2 adsorption/desorption shows the aerogels have mesoporous structure

• PMAO cross-linked aerogels have no pores larger than 40nm


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23nm

Scanning electron microscope (SEM) images

• PMAO and PEMA cross-linked aerogels have µm size cavities • The polymer fibers in the cavities are much longer than the polymer

fibers outside of the cavities • PIMA cross-linked aerogels have more densely packed structure


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Small weight loss before decomposition of polyimide backbone is due to cross-linker


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www nasa gov1

PMAO

PIMA

PEMA

PEMA PIMA PMAO

Mod

ulus

(MPa

)

10

100

Compression tests were performed on the aerogels by compressing to 80%

• Higher or similar modulus compared to TAB or OAPS cross-linked polyimide aerogels made with BPDA and ODA


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Strain

0.0 0.2 0.4 0.6 0.8

Stre

ss (M

Pa)

0

2

4

6

8

10

PMAOPIMAPEMA

Density (g/cm3)

0.05 0.10 0.15 0.20 0.25

Mod

ulus

(MPa

)

1

10

100

TAB-ODA OAPS-ODAPMAO-ODA


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PMAO was down selected as the cross-linker for the following study

• Lower density

• Higher porosity

• Lowest shrinkage

• Highest modulus

PMAO

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• Same or even higher flexibility

• Further reduce cost

• Increase hydrophobicity

Replacing ODA by PPG-230 or PPG-400 in polyimide oligomers

poly(propylene glycol) bis(2-aminopropyl ether) Mn 230 or 400

(PPG-230 or PPG-400)


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Polyimide oligomers made with combination of of PPG/ODA and BPDA


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NH2 +

NH

O

CO

HOOC

CHN

COOH

(n+1) n O O

O

O O

O

H2N X

H2N X

n

X NH2

polyimide oligomer R: CH2(CH2)xCH3 R’: H

imidization

BPDA

Polyimide oligomer

O NH2H2N

PPG-230 or PPG-400,0-60%

ODA

H. Guo and M. A. B. Meador LEW-19108-1

• n : 10-30 • 10 w/w% • PMAO as cross-linker • Polyimide oligomers: PPG/ODA +BPDA

R: H, CH3, CH2(CH2)xCH3 R’: H, CH3

Cross-linker

imidization

BPDA

Polyimide oligomer

• n=20,10 w/w%• Polyimide oligomers • ODA+BPDA • three cross-linkers ODA

PMAO

PIMA

O NH2H2N +

OH2N NH

O

CO

HOOC

CHN

COOH

O NH2

(n+1) n O O

O

O O

O

n

PEMA Polyimide oligomers

0

10

20

30

40

50

60

10

1520

2530

01020304050

Shrin

kage

(%)

nPPG %

0.000.050.10

0.15

0.20

0.25

0.30

0.35

10

1520

2530

01020304050

Den

sity

(g/c

m3 )

n

PPG%

Density, Shrinkage, and Porosity


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PPG-230 PPG-400

70

75

80

85

90

95

100

10

1520

2530

01020304050

Poro

sity

(%)

n

PPG%

• Type and percentage of PPG affect the density, shrinkage and porosity

• At 60% PPG-400, the aerogels shrink the most, resulting in high density and low porosity

• The higher the PPG-230 %, the larger the pore sizes • The higher the PPG-400 %, the lower the pore volume

Increment of % and molecular weight of PPG decrease the surface area


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0

100

200

300

400

500

10

1520

2530

01020304050

Surfa

ce a

rea

(m2 /

g)

n

PPG%

PPG-230 PPG-400

Pore size (nm)7 10 20 30 40 50 60 70 80

Por

e V

olum

e (c

m3 /

g)0.0

0.5

1.0

1.5

2.0 no PPG30 % PPG-230 60 % PPG-230 30%-PPG-40060%- PPG-400

Increasing % or molecular weight of PPG causes densely packed fiber structures


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0% PPG 30 % PPG-230

60% PPG-230 30% PPG-400

TGA curves show Td and char yield decrease with increasing aliphatic groups


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Compression tests show aerogels with n=20 have a higher modulus


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1

10

100

10

1520

2530

01020304050

Mod

ulus

(MPa

)

n

PPG-230 %

• The higher the density, the higher the modulus • The aerogels with PPG-230 have lower modulus than the

aerogels without PPG-230

Density (g/cm3)

0.00 0.05 0.10 0.15 0.20 0.25

Mod

ulus

(MPa

)

1

10

100

TAB-ODA OAPS-ODAPMAO-ODAPMAO-PPG/ODA

60% PPG-230, 124o 30% PPG-400, 121o 30% PPG-230, 99o

Contact angle testing shows more hydrophobic aerogels were produced


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0 10 20 30 40 50 60 70

Con

tact

ang

le (o

)

0

25

50

75

100

125

150

PPG-230 PPG -400

Summary • New aerogels made with amine capped polyimide oligomers and cross-

linked by poly(maleic anhydride)s were synthesized

• The poly(maleic anhydride) cross-linked ODA capped aerogels have higher or similar modulus values compared to TAB or OAPS cross-linked ODA aerogels

• PMAO cross-linked aerogels have lower density and higher porosity, the lowest shrinkage and the highest modulus

• Addition of PPG alters the properties of the aerogels, such as density, shrinkage, porosity, and modulus

• Aerogels with more than 30% PPG are hydrophobic with contact angles 90-124o

• Aerogels shrink the most with 60% PPG-400, resulting in the highest density, lowest porosity, and lowest surface area


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Dan H.

Acknowledgement Aerogel team members Dr. Mary Ann B. Meador Dr. Baochau Nguyen Stephanie L. Vivod Dr. Jarrod C. Williams Rocco P. Viggiano Drying & characterization Daniel Haas Linda S. McCorkle Daniel A. Scheiman Nathan G. Wilmoth Summer Intern Brittany Wilkewitz Funding Fundamental Aeronautics Program Hypersonic Inflatable Aerodynamic Decelerator Program (HIAD)

Dan S. DDDann SSSSSSSSSSSSSSSSSSSSSSSSSSSS.Linda LLLiiinnndddaaa

Brittany BBBBBBBBBBBrrrrrrrrrrriiiiiiiiiiiiittttttttttttttaannnnyyyy

Stephanie

Mary Ann

Baochau BBBBBBBBaaoocccchhhhhhhhhhhhhhhhhhaaaaaauuuuu

Jarrod

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flexible polyimide aerogel cross-linked by poly(maleic

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