Properties of poly(dimethylsiloxane) chains and gels in toluene and in toluene/ methanol mixtures

Abstract

AbstractFour different samples of α‐dimethylvinylsilyl‐ω‐vinylpoly(oxydimethylsilanediyl) (α,ω‐divinylPDMS) chains of different molar masses have been endlinked in the absence of solvent to form “model” polymer networks. These networks have been subjected to swelling experiments at 30°C in toluene and toluene/methanol mixtures. The volume fraction of polymer in the gel at equilibrium swelling v3 is determined gravimetrically. The preferential sorption coefficient λ is found using interferometry. Large preferential sorption effects prevent the solvent mixtures from being treated as pseudo‐one‐component solvents. The variation of swelling and preferential sorption with network and solvent composition is discussed. The thermodynamic properties of α,ω‐divinylPDMS chains in dilute solution with toluene, toluene/methanol mixtures, and tetrahydrofuran are determined at 30°C using intrinsic viscosity measurements. Polymer‐solvent interaction parameters and Mark‐Houwink constants as well as unperturbed dimensions are determined in both the pure solvents and solvent mixtures.