Synthesis, transport, and sorption properties and free volume of polystyrene derivatives containing Si and F

Gas permeation, sorption, and free volume was studied in a series of glassy vinylic type Si-containing polymers. They included p-substituted derivativ es of polystyrene, which were compared with polystyrene, and poly(vinylphen yldimethyl silane). The strongest increase in permeability and diffusion co efficients were observed for the polymer containing the SI(CH3)(3) group di rectly attached to phenylene ring. An introduction of spacers between pheny lene ring and Si(CPI3)(3) group results in much lower gas permeability. Pos itron annihilation study of free volume in these polymers showed that lifet ime spectra are composed of four components. It implies that size distribut ion of free volume in these polymers, which are characterized by a modest l evel of gas permeability, is bimodal, a feature previously observed only fo r extra large free volume and permeability materials such as poly(trimethyl silyl propyne). (C) 2000 John Wiley & Sons, Inc.