The structure of polysiloxanes: Solvent swelling of soluble polymethylsiloxanes

Abstract

Abstract Viscosity–molecular weight relationships for polymethylsiloxanes of Me/Si from 2.0 to 1.5 have been determined in a variety of solvents. It has been found that, at M w = 10 6 , in going from an ideal solvent to the best solvent used, 2.0, 1.8, and 1.5 Me/Si polymers expand volumetrically by factors of 3.8, 2.0, and 1.15, respectively. This is consistent with the hypothesis that the 1.8 and 1.5 Me/Si materials are internally crosslinked to a high degree, and are probably spherical in shape. The solvent‐polymer interaction parameters for the linear polymer in several solvents are calculated, and estimates of the solubility parameters of the various polysiloxanes are obtained.