Achieving Enhanced Optical Transparency and Low-dielectric Properties in Meta-substituted Copolyimides for Flexible Substrates

Zi-Yang Liu; Yan-Yu Gao; Cheng Wang; Qian-Qian Yu; Zhi-Long Zhang; Lin-Ge Wang

doi:10.1007/s10118-025-3505-5

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Achieving Enhanced Optical Transparency and Low-dielectric Properties in Meta-substituted Copolyimides for Flexible Substrates

RESEARCH ARTICLE | Updated：2026-01-30

- Achieving Enhanced Optical Transparency and Low-dielectric Properties in Meta-substituted Copolyimides for Flexible Substrates
- Achieving Enhanced Optical Transparency and Low-dielectric Properties in Meta-substituted Copolyimides for Flexible Substrates
- Chinese Journal of Polymer Science 2026年44卷第2期页码：341-351
- Affiliations：
  
  a.South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, Guangdong Basic Research Center of Excellence for Energy and Information Polymer Materials, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China
  b.School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
  c.Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering Jieyang Center, Jieyang 522031, China
- Author bio：
  
  yanyugao@gdut.edu.cn (Y.Y.G.)
  zzhang@scut.edu.cn (Z.L.Z.)
  lingewang@scut.edu.cn (L.G.W.)
- Funds：
  
  This work was financially supported by the National Key R&D Program of China (No. 2023YFB3812400), the National Natural Science Foundation of China (No. 51890871), and the GJYC Program of Guangzhou (No. 2024D02J0004).;Structural characterization of diamine (1H-NMR, 13C-NMR) and PI (FTIR, 1H-NMR, DFT, etc.), and performance characterization of PI (TGA, solubility, molecular weight, contact angle, etc.) are included in the electronic supplementary information (ESI), which are available free of charge in the online version of this article at http://doi.org/10.1007/s10118-025-3505-5.
- DOI：10.1007/s10118-025-3505-5
  中图分类号：
- 收稿：2025-10-08，
  
  修回：2025-11-09，
  
  录用：2025-11-17，
  
  网络出版：2026-01-16，
  
  纸质出版：2026-02-05
- Accepted：
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Liu, Z. Y.; Gao, Y. Y.; Wang, C.; Yu, Q. Q.; Zhang, Z. L.; Wang, L. G. Achieving enhanced optical transparency and low-dielectric properties in meta-substituted copolyimides for flexible substrates. Chinese J. Polym. Sci. 2026, 44, 341–351

Zi-Yang Liu, Yan-Yu Gao, Cheng Wang, et al. Achieving Enhanced Optical Transparency and Low-dielectric Properties in Meta-substituted Copolyimides for Flexible Substrates[J]. Chinese Journal of Polymer Science, 2026, 44(2): 341-351.
Liu, Z. Y.; Gao, Y. Y.; Wang, C.; Yu, Q. Q.; Zhang, Z. L.; Wang, L. G. Achieving enhanced optical transparency and low-dielectric properties in meta-substituted copolyimides for flexible substrates. Chinese J. Polym. Sci. 2026, 44, 341–351 DOI： 10.1007/s10118-025-3505-5.

Zi-Yang Liu, Yan-Yu Gao, Cheng Wang, et al. Achieving Enhanced Optical Transparency and Low-dielectric Properties in Meta-substituted Copolyimides for Flexible Substrates[J]. Chinese Journal of Polymer Science, 2026, 44(2): 341-351. DOI： 10.1007/s10118-025-3505-5.

摘要

In this work

five colorless polyimides films exhibite concurrent low dielectric constant and high transparency

making them suitable candidates for next-generation flexible electronic substrates.

Abstract

The development of high-performance transparent substrates is critical for next-generation flexible electronic devices. Herein

we designed two novel meta-substituted diamines incorporating trifluoromethyl (―CF

) and methyl (―CH

) groups to synthesize colorless copolyimide (CPI) films

via

copolymerization with 4

4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)/3

3′

4′-biphenyltetracarboxylic dianhydride (BPDA). The combination of meta-substituted architecture and substituents enables the simultaneous attainment of an ultralow dielectric constant (

) and high transparency. The meta-substitution geometry and electronic effects of ―CF

/―CH

effectively suppressed charge-transfer complex (CTC) formation

expanded fractional free volume (FFV)

and restricted

-electron conjugation

as validated by DFT calculations and wide-angle X-ray diffraction (WAXD) analysis. The optimized CPI film (PIA

-6FDA/BPDA(10/0)) achieved outstanding transmittance (

450

=88.15%)

ultralow dielectric constant (

=2.08 at 1 kHz)

and minimal dielectric loss (

=0.0012)

while maintaining robust thermal stability (

d5%

523 °C) and mechanical strength (

= 87.5 MPa). This work establishes a molecular engineering strategy to concurrently enhance the optical and dielectric properties

positioning meta-substituted CPIs as promising candidates for transparent flexible devic

es.

关键词

Keywords

references

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