GAS AND VAPOR PERMEATION AND SORPTION IN POLY(TRIMETYLSILYLPROPYNE)

Permeability coefficients were determined and sorption properties were studied for poly(1-trimethylsilyl-1-propyne) (PTMSP), the most permeable of the known (rubbery or glassy) polymers. The values measured for PTMSP are compared with those for poly (vinyltrimethylsilane) (PVTMS), another glassy polymer with similar structure, which has high permeability, although lower than that of PTMSP and high diffusion coefficients. It was shown that permeability coefficients differ by 1-3 orders in favor of the former, depending on the nature of the diffusant molecules. This is due to the increase in diffusivity and sorption parameters or solubility coefficients. One can conclude that non-equilibrium free volume in a polymer with bulky Si(CH3)3 substituents is larger when the backbone chain is stiff (PTMSP) than when it is more flexible (PVTMS).