Orientation behavior in a comblike polysilane having long alkyl side chains

The orientation behavior of poly(methyloctadecylsilylene) (PMOdS), a combli ke polysilane having long alkyl side chains, was studied by the measurement s of polarized ultraviolet (UV) and polarized Fourier transform infrared (F TIR) spectra. The oriented films were prepared by drawing on supporting pol ymer substrates, mechanical deposition, and crystallization on highly orien ted polymer substrates. The main chains of PMOdS are oriented parallel to t he drawing direction in the film drawn on polypropylene (PP) films and in t he mechanically deposited film. Stretching PMOdS on polyethylene (PE) films however induces side-chain orientation along the drawing direction. The or ientation behavior of PMOdS on the polymer substrates is discussed in relat ion to the surface morphology of the PP and PE substrates.-When PMOdS is cr ystallized on highly oriented poly(dimethylsilylene) and poly(tetrafluoroet hylene) films, the side chains tend to align in the orientation direction o f the substrate polymer. Thus, the side-chain orientation competes with the main-chain orientation, depending upon the processing technique used. It i s also shown that the silicon chains of PMOdS consist of various conformati ons and that the extended conformation orients more highly to the mechanica l direction than the disordered conformation. The result of the polarized f luorescence measurement suggests that the electronic energy is transferred from the disordered conformation to the extended conformation with higher t rans content.