Investigation of poly(dimethyl siloxane) (PDMS)–solvent interactions by DSC

Low temperature DSC was used to study the state of several solvents in poly(dimethyl siloxane) (PDMS) membrane and the influence on the sorbed solvents on PDMS crystallinity. No phase transition was detected on the DSC thermograms until −130°C, when the solvent content in polymer is low, independently of the solvent nature. This suggests a dispersion of the solvents as individual molecules in the PDMS matrix. At high solvent contents, part of the solvent crystallizes. Most of the crystallized solvent melts at a temperature close to the melting point of the bulk solvent, while the rest melts at a lower temperature. The DSC thermograms also show the change in crystallinity of swollen PDMS in different solvents. The poor solvent and the solvent of moderate power increase PDMS crystallinity due to the solvent-induced crystallization effect, while the good solvent reduces polymer crystallinity because of the solution effect.