Study of secondary relaxation transitions in polysulfone and polycarbonate by a method of conformational probes

Abstract

Introduction. Local molecular dynamics and secondary relaxation transitions in glassy polymers hold great practical and theoretical interest because their mechanical, thermal, dielectric, and diffusion properties, in particular, the penetration of small molecules through protective coatings, layers, and separating membranes, depend considerably on the types of molecular mobility occurring in the polymer. Local molecular dynamics in the glassy polymers polymethylmethacrylate, polyvinylacetate, polyvinyltrimethylsilane, polytrimethylsilylpropyne, and polyesterimides, which are used as gas-separating membranes, were studied earlier using an IR spectroscopic method of conformational probes [1]. Herein polysulfone (PSF) and polycarbonate (PC), which are used for membrane micro- and ultrafultration separation of mixtures of compounds [2], are investigated. Experimental. Powdered PSFs (MW = 35,000 and Mη = 16,000) and PC (MW = 64,000) (Aldrich) had glassification temperatures 463 and 423 K. The conformational probes were 1,2-dichloroethane, ClCH2–CH2Cl (DCE);