Highly Oriental Thin Films of Polysilanes by Friction Transfer

Highly oriented thin films of poly(dimethylsilane)(PDMS) were prepared by friction'transfer method. The thin films were characterized mainly by ultraviolet absorption spectroscopy. The polymer chains were aligned in the sliding direction. The properties of PDMS films strongly depended on the preparation temperature. At a temperature higher than 210��, uniform ultrathin films with extremely high orientation were obtained. The highly oriented films had longer sigma-conjugation than poorly oriented films. Other polysilanes, such as poly(diethylsilane)(PDES), poly(di-n-hexylsilane), poly(di-n-butylsilane)(PDBS), and poly (methylphenylsilane) can also be processed into oriented films by the same method. However, the oriented films of polysilane, except PDMS and PDES, were not uniform. The orientational structure of the PDMS and PDBS films was evaluated by total reflection X-ray diffraction method. The orientational distribution of PDMS molecular chains in the thin film was found to be very narrow. The crystallites of PDMS were also oriented toward the substrate plane.