Polymer crystallisation of a reinforcement mechanism for polymer-carbon nanotube composites

Abstract

Two semi-crystalline polymers, poly(mphenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) (PmPV) and poly(vinyl alcohol) (PVOH), have been doped with carbon nanotubes. In the case of PmPV, well-graphitised arc discharge multi-walled nanotubes were used as the filler material. While attempts to detect the changes in polymer morphology using X-Ray diffraction had limited success, dynamic differential scanning calorimetry of thin films has verified a 35% increase in polymer crystallinity with the addition of 3 vol% of arc produced multiwalled carbon nanotubes. A basic model of the system fitted to the crystallinity data yielded a thickness of 23 nm for the crystalline region adjacent to the nanotube. Furthermore, photoluminescence measurements have shown that the photoluminescence quantum yield in the composites decreases with increasing nanotube content. The crystallinity model was further developed to assume a decrease in polymer photoluminescence as distance from the nanotube surface decreases with total extinction at the polymer/nanotube interface. A coating thickness of 32 nm was calculated from the fit in reasonable agreement with the values calculated by calorimetry (23 nm) and TEM (25 nm). FTIR data is used to provide additional evidence for nanotube-induced alteration of polymer conformation.