Tailoring Interfacial Bonding in PEEK Composites via Custom Macromolecular Silane Coupling Agents: From Synthesis to Enhanced Thermomechanical Properties

This study addresses the poor compatibility between resin and reinforcement and the weak interfacial bonding in poly(ether ether ketone) (PEEK)-based composites by preparing several macromolecular silane coupling agents. Three types of coupling agents with different structures were synthesized using hydroxyl-terminated PEEK oligomers, and their structures were confirmed by FT-IR, NMR, and XPS analyses. The molecular weights were determined by GPC, and TG analysis showed that all three coupling agents exhibited good thermal stability. Glass fibers and carbon fibers were surface-modified with these coupling agents. SEM and EDS analyses revealed uniform coatings on the fiber surfaces, accompanied by increases in the characteristic elements of the coupling agents. Mechanical tests showed that the tensile and flexural strengths of the treated composites were higher than those of the untreated ones. DSC and TG results indicated significant improvements in crystallinity and thermal properties. These enhancements are attributed to improved fiber–matrix compatibility and interfacial bonding. Overall, this work establishes a structure-tailored macromolecular silane coupling strategy, providing new insights into structure–property relationships and offering an effective approach to enhance the performance of PEEK-based composites.