Nanoindentation and Molecular Simulation Study of Chemical Doped-Induced Stiffening of a Poly (p-phenylene vinylene) Film

A combined experiment and molecular simulation study was performed to understand the mechanism of mechanical change in doped poly (p-phenylene vinylene) (PPV) film. PPV with a partial quinoid structure was obtained using oxidation of ferric chloride. its chemical structure was determined by FT-IR, Raman and UV-vis spectra. The nanomechanical properties of the neutral PPV film and the chemical-doped PPV films were investigated by nanoindentation test. The critical bending radius of films based on the flexible base was evaluated from the results of the nanoindentation test. The relationship between the benzoid/quinoid ratio of PPV and its inter-molecule interaction was investigated with molecular simulation and the changes of the geometry of PPV single chain and the cohesive energy density (CEO) of the multi-PPV. The result suggests that the quinoid PPV has higher CED and rigid chain structures.