Under the joint supervision of Professor Li Liangbin and Associate Researcher An Minfang, our team's doctoral student Guo Wenhao and colleagues focused on molecular structure design. By establishing structure-property relationships, they successfully developed a novel polyamide-imide (PAI) film that combines high optical transparency, excellent thermal stability, and a low coefficient of thermal expansion. This achievement provides an innovative solution to critical material challenges in flexible display technology and is expected to drive the rapid development of fields such as foldable smartphones and wearable electronics. The related work has been published in the journal ACS Applied Polymer Materials.
In this work, a series of diamine monomers containing amide bonds and bulky substituents (such as methyl groups) were designed and copolymerized with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) via a two-step polycondensation method to prepare novel poly(amide-imide) films. Experimental results demonstrate that the precise introduction of methyl substituents near the imide ring can significantly inhibit the formation of charge transfer complexes (CTC). Simultaneously, it increases the molecular chain spacing and reduces close packing through the steric hindrance effect. The optimized material (3-AMB-TFMB/6FDA) exhibits outstanding performance, featuring excellent optical properties (Ttot=89.0％，YI=0.73), thermal dimensional stability (CTE = 39.6 ppm·K⁻¹), and a high glass transition temperature (Tg=356 ℃). This research resolves the trade-off between optical transparency and thermal stability through molecular design, providing key material support for the development of large-size foldable screens and advanced human-machine interfaces.
This work was supported by the Major Science and Technology Project of Hefei City, Anhui Province under the Open Competition Mechanism (Grant No. 2022-SZD-005), the Hefei Major Special Directed and Commissioned Project Research and Development of Polyvinyl Butyral (PVB) Film for Automotive Safety Glass, the Hefei Natural Science Foundation (Grant No. 202311), and the Chinese Academy of Sciences (Grant No. JZHKYPT-2021-04).
Guo W, Han X, Tan Z, et al. Influence of Bulky Substituents on Optical Transparency and Dimensional Stability of Polyamide-imide[J]. ACS Applied Polymer Materials, 2025.
Paper Link: https://pubs.acs.org/doi/full/10.1021/acsapm.5c00598
