LIQUID-LIQUID PHASE-SEPARATION AND ORIENTED GROWTH OF POLY(ARYL ETHERETHER KETONE) ON FRICTION-TRANSFERRED POLY(TETRAFLUOROETHYLENE) SUBSTRATES

The morphology and orientation of poly(aryl ether ether ketone) (PEEK) crystallized in the presence of friction-tranferred PTFE layers have been studied by optical and electron microscopy, electron diffraction, and FTIR. Deposition and orientation of PEEK is successfully achieved by a two-stage procedure involving (i) liquid-liquid phase separation by slow absorption of water in a dilute methanesulfonic acid solution and (ii) aggregation-crystallization of the polymer-enriched droplets . PTFE substrates are shown to induce the crystallization of PEEK at a very early stage of the phase separation process. Electron diffractio n and FTIR investigations demonstrate that the as-deposited PEEK films have a single crystal-like structure, with the chain axes of both pol ymers oriented parallel to each other and the PEEK zigzag plane orient ed parallel to the (100) PTFE substrate surface. This well-defined pol ymer/polymer epitaxial relationship rests on a very good matching betw een (a) the chain axis periodicities and, (b) more importantly, the de posit and substrate interchain distances.