A novel high-temperature resistant Poly(arylene ether ketone) sizing agent containing graphene oxide: Achieve multiscale interfacial enhancement in CF/PEEK composites

Optimizing the interfacial adhesion in carbon fiber reinforced polyether ether ketone (CF/PEEK) composites is crucial for their mechanical performance, yet conventional enhancement strategies often face limitations in thermal stability, compatibility, and environmental impact. To overcome these challenges, a novel aqueous poly(aryl ether ketone)-based sizing agent (FPEKC), functionalized with trifluoromethyl (-CF₃) and phthalide moieties, was designed and synthesized through molecular engineering. The synthesized FPEKC exhibited outstanding thermal stability (T_{-5 %} = 500.45 °C), ensuring excellent structural integrity throughout typical composite processing conditions (∼380 °C). The environmentally sustainable, water-based FPEKC-GO sizing agent prepared via an emulsion-solvent evaporation technique formed uniformly dispersed nanoparticles with an average diameter of approximately 60 nm. The intrinsic structural compatibility between FPEKC and the PEEK matrix facilitated extensive molecular diffusion and interchain entanglement at the interface. Additionally, the introduction of graphene oxide (GO) nanosheets into the FPEKC slurry established robust chemical interactions at the fiber-matrix interface, including hydrogen bonds and π-π stacking, as well as nanoscale mechanical interlocking, achieving multi-scale interface enhancement. The interfacial shear strength (IFSS) of the CF/PEEK composite material was remarkably enhanced by 65.56 %, reaching a value of 92.38 MPa. Furthermore, the composite sizing agent simultaneously improved the tensile strength of individual carbon fiber filaments by 5.56 %, effectively mitigating interfacial defects and stress concentrations. This research demonstrates an innovative multiscale interface engineering strategy, providing new insights and practical methodologies for developing environmentally friendly, high-performance CF/PEEK composites.