Tg-mismatch driven dual polyamic acid interphase: A morphology-guided approach to strengthen carbon fiber/thermoplastic interfaces
Yining Wang, Yu Deng, Qiming Wang, Jingyi Cheng, Mingyuan Ma, Hailong Li, Cheng Liu, Xigao Jian, Yousi Chen
Abstract
Interfacial engineering plays a pivotal role in tailoring interfacial interactions and governing the performance of carbon fiber reinforced thermoplastic composites. However, constructing a tunable and robust interfacial architecture without the aid of inorganic fillers remains a significant challenge. In this study, we propose an interfacial design strategy based on a binary water-soluble poly(amic acid) salt (PAA) system. By exploiting the disparity in glass transition temperatures (Tg) and segmental mobility between the two components, an interfacial film with a hierarchical microstructure is induced on the carbon fiber surface. During hot-press processing, this film evolves into a morphologically complex interface exhibiting phase-separated characteristics, which substantially improves interfacial wettability, mechanical interlocking, and interfacial adhesion strength. When applied to two representative thermoplastic matrices, PEI and PEEK, the resulting composites exhibit systematic enhancements in flexural strength, interlaminar shear strength, and high-temperature mechanical performance, demonstrating the broad applicability of this approach. Further investigations reveal that these composites not only possess excellent structural integrity but also exhibit superior wear resistance, electromagnetic shielding capability, and rapid Joule-heating-based deicing responsiveness. These multifunctional properties highlight the potential of this system for integrated structural-functional applications. The morphology-driven, filler-free interfacial engineering paradigm presented herein offers a scalable and generalizable platform for the development of high-performance composite materials.