Abstract/Summary

This research project reports a new approach to thermoplastic composite matrix design, in which a low-MW polymer additive acts as a plasticiser and flow-promoter at high temperatures, but as a non-covalent cross-linking agent at lower temperatures. Thus, poly(aryl ether ketone)s (PAEKs) are functionalised with π-electron rich terminal groups and blended with π-electron deficient polyimides. A non-covalent charge-transfer stacking interaction between the two polymers forms a self-assembled supramolecular network. Carbon fibre composites with matrices composed of these supramolecular polymer blends were produced, and the thermomechanical performance of these materials are reported. In designing functionalised PAEKs, novel benzoyl-pyrene and -perylene derived compounds were synthesised. The synthesis of these compounds and their subsequent use as functional end-groups in polycondensations are also discussed. During the course of polymer synthesis, the effect of varying polymerisation conditions involving different alkali metal carbonates was systematically investigated. It was found that monomer sequence distribution in PAEKs can be controlled by changing the alkali metal cation used in the nucleophilic synthesis. The mechanism of modifying monomer sequence distribution is presented herein. Investigating the interaction of polycyclic aromatic molecules pyrene and perylene with binary co-polyimides containing both strongly-binding and weakly-binding diimide sequences results in the emergence of fractal-like patterns in the 1H NMR spectra of the polyimide. The polyimide spectrum at high intercalator loadings shows self-similarity over a range of different length scales.