Jhe-Yong Lin (林哲永), Hui-Min Wang (王惠民), Sheng-Huei Hsiao (蕭勝輝)* Department of Chemical Engineering and Biotechnology, National Taipei University of Technology,

1 Chunghsiao East Road, Section 3, Taipei 10608, Taiwan

E-mail: shhsiao@ntut.edu.tw

A novel class of electroactive polyimides with ether-linked anthraquinone (AQ) units were prepared from the polycondensation reactions of a newly

synthesized CF3-containing AQ-dietheramine monomer with aromatic tetracarboxylic dianhydrides via a conventional two-step technique. The

fluorinated polyetherimides (PEIs) exhibited enhanced solubility and optical transparency and decreased dielectric constants because of increased free

volume caused by the CF3 substituents. Furthermore, the PEIs showed high thermal stability, with glass-transition temperatures of 263-312 oC and

decomposition temperatures in excess of 500 oC. These PEIs were also investigated by cyclic voltammetry and UV-visible spectroelectrochemistry.

Preliminary results reveal that these AQ-based PEIs are potentially useful as cathodically coloring red electrochromes.

Introduction

References

Results and Discussion

1. M. K. Ghosh, K. L. Mittal, Eds., Polyimides: Fundamentals and Applications. Marcel Dekker, New York, 1996.

2. J. de Abajo, J. G. de la Campa, Adv. Polym. Sci., 1999, 140, 23-59.

3. H.-J. Yen, G.-S. Liou, Polym. Chem., 2012, 3, 255-264.

4. E. M. Maya, I. Garcia-Yoldi, A. E. Lozano, J. G. de la Campa, J. de Abajo, Macromolecules, 2011, 44, 2780-2790.

5. Y. J. Cho, H. B. Park, Macromol. Rapid Commun. 2011, 32, 579-586.

6. J.-G. Liu, M. Ueda, J. Mater. Chem., 2009, 19, 8907-8919.

7. K. Fukukawa, M. Ueda, Polym. J. 2008, 40, 281-296 .

8. A. L. Rusanov, E. G. Bulycheva, M. G. Bugaenko, V. Yu Voytekunas, M. J. M. Abadie, Russ. Chem. Rev. 2009, 78, 53-75.

9. H.-J. Yen, C.-J. Chen, G.-S. Liou, Adv. Funct. Mater., 2013, 23, 5307-5316.

10. J. Q. Chambers, S. Patal, Z. W. Rappoport. The Chemistry of Quinonoid Compounds, Vol. II, Chap. 12, 1988.

11. A. Babaei, P. A. Connor, A. J. McQuillan. J. Chem. Educ., 1997, 74, 1200–1204.

12. R. M. F. Batista, E. Oliveira, S. P. G. Costa, C. Lodeiro, M. M. M. Raposo, Org. Lett., 2007, 9, 3201–3204.

13. E. H. van Dijik, D. J. T. Myles, M. H. van der Veen, J. C. Hummelen, Org. Lett., 2006, 8, 2333-2336.

14. S. Wang, E. K. Todd, M. Birau, J. Zhang, X.-H. Wan, Z.-Y. Wang, Chem. Mater., 2005, 17, 6388–6394.

15. W.-Q. Qiao, J. Zheng, Y.-F. Wang, Y.-J. Zheng, N.-H. Song, X.-H. Wan, Z.-Y. Wang, Org. Lett., 2008, 10, 641–644.

16. Y.-J. Zheng, J. Zheng, L. Dou, W.-Q. Qiao, X.-H. Wan, J. Mater. Chem., 2009, 19, 8470–8477.

Scheme 1. Synthetic route to CF3-containing AQ-dietheramine 3

Figure 1. (a) 1H NMR, (b) H-H COSY, (c) 13C NMR and (d) C-H HMQC spectra of monomer 3 in DMSO-d6 .

A reversible color change takes place upon reduction (gain of electrons) or oxidation (loss of electrons).

What is electrochromism ?

Suitable electron acceptor

Excellent electron mobility

Spectroelectrochemistry

S-H Hsiao,Y-R Kung. Polym. Int. 2013, 62, 573-580.

S-H Hsiao, W-J Guo, C-L Chung, W-T Chen.

Eur. Polym. J. 2010, 46, 1878–1890.

Table 1. Inherent viscosity and solubility behavior of PEIs

Polymer

codea

ηinh (dL/g)b Solventsc,e

PAAd Polyimide NMP DMAc DMF DMSO m-

Cresol THF

5a-T 1.21

- -- -- -- -- -- -- 5a-C - -- -- -- -- -- -- 5b-T

1.01 - -- -- -- -- -- --

5b-C - +- +- +- +- -- -- 5c-T

0.94 - -- -- -- -- -- --

5c-C - ++ ++ ++ ++ +- --

5’c-C - - +- -- -- -- -- --

5d-T 0.89

- -- -- -- -- -- -- 5d-C - +- +- +- +- -- -- 5e-T

0.77 - +- +- +- +- +- +-

5e-C 0.51 ++ ++ ++ ++ +- ++ 5f-T

0.85 - -- -- +- -- -- --

5f-C 0.76 ++ ++ ++ ++ +- ++ a T: polymer prepared by the thermal imidization method, C: by the chemical imidization method. bInherent viscosity measured at a concentration of 0.5 dL/g in DMAc at 30 oC.

cSolvent: NMP: N-methyl-2-pyrrolidone; DMAc: N,N-dimethylacetamide; DMF: N,N-dimethylformamide; DMSO: dimethyl

sulfoxide; THF: tetrahydrofuran. dPAA: Poly(amic acid). eThe 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.

Table 3. Optical properties of the PEIs

Polymer code Film thickness

(μm)

Color coordinatesb λ0

(nm)c

λ at 80%

transmission

(nm) a* b* L*

Imidization

methoda (T) (C) (T) (C) (T) (C) (T) (C) (T) (C) (T) (C)

Blank － -0.6 0.3 96.5 － －

5a － － － － － － － － － － － －

5b 47 － 20.7 － 66.2 － 64.4 － 429 － 539 －

5c 43 － 12.4 － 52.3 － 75.9 － 425 － 539 －

5d 44 － 7.3 － 43.1 － 75.2 － 423 － 537 －

5e 48 42 5.8 -3.8 30.3 26.7 82.3 84.5 417 423 521 473

5f 43 47 1.3 -3.2 36.0 22.1 80.8 85.6 425 425 506 468

Kapton 41 - 2.0 － 99.7 － 81.0 － 462 － 534 －

5’f - 45 - 12.3 - 57.1 - 64.5 - 490 - 580

a T: polymer prepared by the thermal imidization method, C: by the chemical imidization method. b 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. c Absorption edge from the UV–vis spectra of the polymer thin films.

5f-C 5’f-C

Table 2. Thermal properties of PEIs

Polymer

codea

Tg ( oC )b

Td at 5 %

weight loss

( oC )c

Td at 10 % weight loss

( oC )c

Char yield

N2 Air N2 Air (wt %)d

5a 312 513 507 558 535 54

5b 289 565 557 595 587 56

5c 275 545 540 577 571 53

5d 263 547 541 580 574 53

5e 276 451 493 492 521 50

5f 281 536 531 557 552 51

5’f 285 565 549 592 578 56

a All the polymer films were heated at 300 oC for 1 h to DSC and TGA experiments. b Midpoint temperature of the baseline shift on the second DSC heating trace (rate= 20 oC/min) of the sample after quenching

from 400 to 50 oC (rate= 20 oC/min) in nitrogen. c Decomposition temperature at which a 10% weight loss was recorded by TGA at a heating rate of 20 oC/min.

d Residual weight % at 800 oC at a scan rate 20 oC /min in nitrogen.

Figure 2. TGA and DSC curves of PEI 5c

at a heating rate of 20 oC/min.

5g

Figure 3. Cyclic voltammograms of model compound 5g (1x10-3 M) in 0.1 M

Bu4NClO4/ DMF at a scan rate of 100 mV/s.

Basic Properties Thermal Properties Optical Properties

Electrochemical Properties Table 4. Redox potentials and energy levels of PEIes

Code Thin film (nm) Reduction potential (V)

Bandgaps

(eV)

λmaxabs λonset

abs EonsetRed E1/2

Red,1 E1/2Red,2 E1/2

Red,3 E1/2Red,4 E1/2

Red,5 Eg

opt

5a 341 365 -0.64 -0.71 -1.19 3.40

5b 340 364 -0.59 -0.68 -1.03 -1.22 3.41

5c 336 359 -0.60 -0.68 -0.81 -1.10 -1.28 -1.64 3.45

5d 339 362 -0.54 -0.69 -1.15 -1.31 3.43

5e 353 382 -0.52 -0.65 -0.81 -0.99 -1.29 3.25

5f 348 393 -0.46 -0.66 -1.01 -1.13 3.16

5g - - -0.60 -0.65 -1.25 -

Experimental

Abstract

Polym. Eng. Sci. 2008, 48, 2224. E. S. Lee et al. Sol. Energy Mater. Sol. Cells, 2002, 71, 465. www.gentex.com

H-M Wang, S-H Hsiao. JPSA. 2011, 49, 337-351.

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S-H Hsiao,Y-R Kung. Polym. Int. 2013. 62, 573-580.

Spectroelectrochemistry

(b)

(c) (d)

Figure 4. Cyclic voltammograms of the cast films of PEIs (a) 5a, (b) 5b, (c) 5c, (d) 5d, (e) 5e and (f) 5f

in 0.1 M Bu4NClO4/ DMF at a scan rate of 50mV/s.

(e) (f)

(c) (b) (a)

(d) (a)

Table 5. Electrochromic properties of PEI 5d

Polymer λmax

a

(nm) Δ%T

Response timeb ΔODc Qd

d(mC/cm2) CEe(cm2/C)

tc (s) tb (s)

5d 563 36 5.0 7.9 0.199 1.74 114

Figure 6. Potential step absorptiometry of the cast film of 5d on the ITO-glass slide (coated area: 1.0 cm2)(in DMF

with 0.1M Bu4NClO4 as the supporting electrolyte)by applying a potential step (a) 5d at potential 0.0 V ~ -1.25 V and

cycle time 12 s, and (b) optical switching for 5d at λmax = 563 nm as the applied voltage was stepped between 0.0 V

and -1.25 V (vs. Ag/AgCl).

aWavelength of absorption maximum. bTime for 90% of the full-transmittance change. cOptical Density (ΔOD) = log[Tbleached /Tcolored ], dQd is ejected charge, determined from the in situ experiments. eColoration efficiency (CE) =ΔOD/Qd .

(b)

Figure 5. Spectroelectrochemistry of 5d

thin film on the ITO-coated glass substrate

in 0.1 M Bu4NClO4/ DMF under negative

potential scanning.

5’f

Polyimide Films

(a)

Property comparison