Orientation Behavior in a Comblike Polysilane Having Long Alkyl Side Chains

Abstract

The orientation behavior of poly(methyloctadecylsilylene) (PMOdS), a comblike polysilane having long alkyl side chains, was studied by the measurements of polarized ultraviolet (UV) and polarized Fourier transform infrared (FTIR) spectra. The oriented films were prepared by drawing on supporting polymer substrates, mechanical deposition, and crystallization on highly oriented polymer substrates. The main chains of PMOdS are oriented parallel to the drawing direction in the film drawn on polypropylene (PP) films and in the mechanically deposited film. Stretching PMOdS on polyethylene (PE) films however induces side-chain orientation along the drawing direction. The orientation behavior of PMOdS on the polymer substrates is discussed in relation to the surface morphology of the PP and PE substrates. When PMOdS is crystallized on highly oriented poly(dimethylsilylene) and poly(tetrafluoroethylene) films, the side chains tend to align in the orientation direction of the substrate polymer. Thus, the side-chain orientation competes with the main-chain orientation, depending upon the processing technique used. It is also shown that the silicon chains of PMOdS consist of various conformations and that the extended conformation orients more highly to the mechanical direction than the disordered conformation. The result of the polarized fluorescence measurement suggests that the electronic energy is transferred from the disordered conformation to the extended conformation with higher trans content.