T4-186 EPF 2011, XII GEP Congress, 26th June - 1st July 2011, Granada, Spain

930

Synthesis and Properties of Novel Triptycene-Based Polyimides

Hui-Min Wang, Sheng-Huei Hsiao*

Department of Chemical Engineering and Biotechnology, National Taipei University of Technology , Taipei, Taiwan

shhsiao@ntut.edu.tw

Abstract: Two new triptycene containing bis(ether

amine)s, 1,4-bis(4-aminophenoxy)triptycene (4) and 1,4-

bis(4-amino-2-trifluoromethylphenoxy)triptycene (6), were

synthesized respectively from the nucleophilic chloro -

displacement reactions of p-chloronitrobenzene and 2-

chloro-5-nitrobenzotrifluoride with 1,4-

dihydroxytriptycene in the presence of potassium

carbonate, followed by pallad ium-catalyzed hydrazine

reduction of the din itro intermediates. The newly

synthesized bis(ether amine)s were polymerized with six

commercially available aromatic tetracarboxylic

dianhydrides to obtain two series of novel t riptycene-based

polyimides 8a-f and 9a-f by using a conventional two-step

synthetic method via thermal and chemical imidization. All

the resulting polyimides exhib ited high enough molecular

weights to permit the casting of flexible and strong films

with good mechanical propert ies. Incorporation of

trifluoromethyl groups in the poly imide backbones

improves their solubility without decreasing their physical

properties. Most of the polyimides derived from the

fluorinated monomer 6, especially those prepared via the

chemical imidization method, were soluble in aprotic polar

solvents. In general, the trifluoromethyl-substituted 9 series

polyimides showed a reduced color intensity, a slightly

lowered glass-transition temperature (Tg), and comparab le

thermal stability as compared to the corresponding 8 series

analogs. The fluorinated polyimides 9a-f showed high Tg in

the range of 272–335 oC and d id not reveal significant

decomposition before 500 oC in nitrogen or in air. The

fluorinated polyimides 9d and 9f derived from diamine 6

with 4,4-oxydiphthalic anhydride (ODPA) and 4,4‟-

(hexafluoroisopropylidene)diphthalic anhydride (6FDA),

respectively, could afford almost colorless thin films.

O

O

tolueneO

O

AcOH

HBr

OH

HO

1 2

2 2

Cl

NO2

DMF

K2CO3

2 2

Cl

NO2

DMF

K2CO3

F3C

H2, Pd/C

DMF

NH2NH2 H2O, Pd/C

EtOH+THF

3 4

5 6

OOO2N NO2 OOH2N NH2

OOO2N NO2

F3CCF3

OOH2N NH2

F3CCF3

Scheme 1. Synthetic route to the triptycene-containing

bis(ether amine)s.

4 or 6 OO

O

O

O

O

Ar

7

NN

O

O

O

O

Ar

n

8

9

1. DMAc. R.T.

2. -H2O

Ar = O SF3C CF3

O O O

a b c d e f

OO

NN

O

O

O

O

Ar

n

OO

CF3 F3C

Referenced polyimides:

NN

O

O

O

O

Ar

n

OO

10

Scheme 2. Synthesis of triptycene-containing polyimides.

Figure 1. Photographs of the polyimides 8f, 9f, 10f and

Kapton films (thickness～50 mm).

Figure 2. (a) DSC curves of polyimides 8b, 9b and 10b. (b)

TGA curves of polyimides 8c and 9c in both air and nitrogen

atmospheres. (c) TMA curves of polyimides 8a and 9a.

References 1. Wilson, D.; Stenzenberger, H. D.; Hergenrother, P. M., Eds.; Polyimides; Blackie: Glasgow and London, 1990. 2. Yang, J.-S.; Yan, J.-L. Chem Commun 2008, 1501-1512..

3. Bartlett, P. D.; Ryan, M. J.; Cohen, S. G. J Am Chem Soc 1942, 64, 2649-2653. 4. Yang, J.S.; Swager, T . M. J Am Chem Soc 1998, 120, 11864-11873. 5. Hsiao, S. H.; Chung, C.-L., Lee, M.-L. J Polym Sci Part A: Polym Chem 2004, 42, 1008-1017.

1

NN

O

O

O

O

Ar

n

OO

N

O

O

O

O

ArOO

n

Inter-molecular Charge Transfer

Intra-molecular Charge Transfer

Synthesis and Properties of Novel Triptycene-Based PolyimidesSynthesis and Properties of Novel Synthesis and Properties of Novel TriptyceneTriptycene--Based Based PolyimidesPolyimidesHui-Min Wang (王惠民), Sheng-Huei Hsiao (蕭勝輝)

Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3 Chunghsiao East Rd., Taipei 10608, TaiwanE-mail: shhsiao@ntut.edu.tw

2. Major Disadvantages of Polyimides

Novel triptycene-based polyimides were prepared from the conventional two-step polycondensation reactions of 1,4-bis(4-aminophenoxy)triptycene and 1,4-bis(4-amino-2-trifluoromethylphenoxy)triptycene, respectively, with six commercially available aromatic tetracarboxylic dianhydrides. All the resulting polyimides could afford flexible and strong films with good mechanical properties. In comparison with the nonfluorinated analogues, the trifluoromethyl-substituted polyimides showed enhanced solubility, reduced dielectric constant and lowered color intensity while retaining high Tg values and good thermal stability. One of the fluorinated polyimides derived from the fluorine-containing diamine with 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) could be cast into a highly transparent and essentially colorless film.

O NH2H2N OO

O

O

O

O

N N

O

O

O

O

On

KaptonPMDA4,4’-ODA

1. Useful Properties of Polyimides

High melting/softening temperaturesLimited solubility Light-yellow to amber color of PI films

Outstanding thermal stabilityGood mechanical propertiesHigh chemical stability Excellent electric insulation

NN

O

O

O

O

Ar

n

NN

O

OO

O

O

n

Semi-aromatic PolyimidesKapton λo = 426 nm

Toshihiko Matsumoto, High Perform. Polym.,1997, 11, 367-377.

λo = 320~362 nm

3. Coloration of Polyimide FilmsMolecular Structures

Conjugation length of aromatic structuresIntra-molecular charge-transfer complex (CTC)

Acceptor

Donor

O

O

O

O

NN

O

O

O

O

N N

O

O

N

O

O

N

N

O

N

O

O O

N

O

N

O

O O

N

O

N

O

O ON

O

N

O

O O

Inter-molecular charge-transfer complex (CTC)

1.632.001.231.71－

2.101.42－

－

－

－

－

PDI

47,00020,00032,50038,000

－

23,50055,500

－

－

－

－

－

Mn

77,00040,00040,00065,000

－

49,50079,000

－

－

－

－

－d

Mw

GPC data of polyimidesb

0.64

0.50

0.86

0.81

0.77

0.90

Tensile Properties of the polyimides filmsηinha(dL/g)

Polymer Code

1.85910.619f1.95930.510.779e1.76990.459d1.961090.640.789c2.06120－9b2.151050.521.089a1.85970.688f1.7696－1.248e1.38108－8d1.8696－0.818c1.59128－8b1.76101－c1.498a

Initial Modulus(GPa)

Elongation at Break (%)

Tensile Strength(MPa)

PIPAA

a Measured at a polymer concentration of 0.5 g/dL in DMAc at 30 oC. b Determined in THF relative to polystyrene standards. c Insoluble in DMAc. d

Insoluble in THF.

Inherent Viscosity, Molecular Weights and Tensile Properties of chemically imidization Polyimides

Optical Properties and Dielectric Constants

4. Motivation and Molecular DesignIncorporation of Triptycene structure in the Polyimides

High Thermal Stability

High Thermal Stability

Good Solubility

Good Solubility

Low-color Films

Low-color Films

462375403

381

422

407

432

401

434

402

457

426

457－

λ0

(nm)

2.8289.938.5-10.8509c

2.6787.811.6-1.1599b

2.8486.951.8-10.7589a

3.1482.623.42.2858f

3.5979.154.9-3.9848e

3.3682.623.51.3858d

3.4282.586.5-5.3648c

3.2582.337.1-3.0678b

3.1278.194.70.5638a

3.372.052.89

2.28

－

Dielectric Constant(at 1 MHz)

Color coordinatesaFilm thickness

(μm)Polymer

Code

82.492.285.2

91.3

96.5

L*

0.7-0.7-2.9

-2.4

-0.6

a*

375050

47

－

b*

99.11.8

12.5

10.2

0.3Blank

Kapton9f9e

9d

Polyimides may stack like this allowing the carbonyls of the acceptor on one chain to interact with the nitrogens of the donoron adjacent chains

Carbonyl group suckelectron density awayfrom the acceptor unit

Nitrogen atoms have a higher electron densitythan the carbonyl groups and lend it to theacceptor unit

References

Introduction

Abstract

Results and Discussion

1. D. Wilson, H.D. Stenzenberger, P.M. Hergenrother, editors. Polyimides. Glasgow and London: Blackie; 1990.

2. M.K. Ghosh, K.L. Mittal, editors. Polyimides: fundamentals and applications. New York: Marcel Dekker; 1996.

3. R. A. Dine-Hart, W. W. Wright, Makromol. Chem. 1971, 143, 189.

4. S. Ando, T. Matsuura, S. Sasaki, Polym. J. 1997, 29, 69.

5. M. Hasegawa, K. Horie, Prog. Polym. Sci. 2001, 26, 259.

6. P.D. Bartlett, M.J. Ryan, S.G. Cohen, J. Am. Chem. Soc. 1942, 64, 2649.

Experimental

Polymer SynthesisMonomer Synthesis

665896192622899c656036292743039b595966262963359a665725902753018f

646056302522729d615585462822989e

Td at 10 wt% ( oC )cPolymer Code

696076212652848d675955952732988c

595705842662909f

635815553023128e

736116172943128b695826103313548a

Char yield (wt %)dIn airIn N2

Ts ( oC )bTg ( oC )a

Thermal Properties of Polyimides

a Midpoint temperature of the baseline shift on the second DSC heating trace (rate = 20 oC/min) of the sample after quenching from 400 oC to 50 oC (rate = -200 oC/min) in nitrogen. b

Softening temperature measured by TMA with a constant applied load of 10 mN at a heating rate of 10 C/min. c Decomposition temperature, recorded via TGA at a heating rate of 20 oC/min and a gas-flow rate of 30 cm3/min. d Residual weight percentage at 800 oC in nitrogen.

Ar : Triptycene

Ar

Timothy M. Swager. Acc. Chem. Res. 2008, 41, 1181-1189

Triptycene unit attached to polymer backbone

DSC, TGA and TMA curves

Ar

Solubility Behavior of Polyimides

－＋ －＋ ＋＋＋＋ ＋＋ ＋＋ ＋9c(C)－－＋ －＋＋＋＋＋9c(H)－－－－－－－＋ －9b(C)－－－－－－－－9b(H)－＋ －＋ ＋＋＋ ＋＋ ＋＋ ＋＋ ＋9a(C)

＋ －＋ －＋ ＋＋ －＋＋ －＋ ＋＋9a(H)＋＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋8f(C)＋＋ ＋＋ ＋＋＋＋ ＋＋ ＋＋ ＋8f(H)－－＋ －＋＋ ＋＋ ＋＋ ＋＋ ＋8e(C)－－－－－＋＋＋8e(H)－－－－－－－－8d(C)－－－－－－－－8d(H)

＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋＋ ＋9f(C)

－－－－－－－－8c(C)－－－－－－－－8c(H)－－－－－－－－8b(C)－－－－－－－－8b(H)－－－－－－－－8a(C)－－－－－－－－8a(H)

＋ ＋

＋ －

＋ －

＋ ＋

＋ ＋

CHCl3

＋ ＋

＋ ＋

＋ ＋

＋ ＋

＋ ＋

THF

＋ ＋

＋ ＋

＋ ＋

＋ ＋

＋

m-Cresol

＋

＋ ＋

＋

＋ ＋

＋

DMSO

＋ ＋

＋ ＋

＋ ＋

＋ ＋

＋ ＋

DMF

＋ ＋

＋ ＋

＋ ＋

＋ ＋

＋ ＋

DMAcSolvents bPolymer

Code

－＋ ＋9e(C)－＋9e(H)

＋ ＋＋ ＋9f(H)

＋＋ ＋9d(C)＋＋9d(H)

TolueneNMP

a The qualitative solubility was tested with 10 mg of a sample in 1 mL of stirred solvent. + +, soluble at room temperature; +, soluble on heating; ±, partially soluble; －, insoluble even on heating.

Wide-angle X-ray Diffraction Patterns of Polyimides

Structural Characterization

4 or 6 OO

O

O

O

O

Ar

7

NN

O

O

O

O

Ar

n

8

9

1. DMAc. R.T.

2. -H2O

Ar = O SF3C CF3

O O O

a b c d e f

OO

NN

O

O

O

O

Ar

n

OO

CF3 F3C

Referenced polyimides:

NN

O

O

O

O

Ar

n

OO

10

(a) 1H NMR and (b) 13C NMR spectra of diaminemonomer 6 in DMSO-d6.

O

O

toluene O

O

AcOH

HBrOH

HO

1 2

2 2

Cl

NO2

DMF

K2CO3

2 2

Cl

NO2

DMF

K2CO3

F3C

H2, Pd/C

DMF

NH2NH2 H2O, Pd/C

EtOH+THF

3 4

5 6

OOO2N NO2 OOH2N NH2

OOO2N NO2

F3CCF3

OOH2N NH2

F3CCF3

Transmission UV-vis spectra

a The color parameters were calculated according to a CIE LAB equation. L* is the lightness, where 100 means white and 0 implies black. A positive a* means a red color, and a negative a* indicates a green color. A positive b* means a yellow color, and a negative b* implies a blue color.