Poly(dimethylsiloxane) crosslinked in different conditions Part I. Sorption properties in water–ethyl acetate mixtures

Abstract

Poly(dimethylsiloxane)s (PDMS) of different crosslinking degrees were synthesized by varying the ratio of B(crosslinker)/A(vinyl-type PDMS) in the mixture to be crosslinked, and by varying the crosslinking temperature. The swelling degrees of the polymer in pure water, pure ester (ethyl acetate) and their mixture decrease when the B/A component ratio or the crosslinking temperature increases. The ester component is selectively sorbed from its mixture with water (the sorption extent is two orders of magnitude higher for the ester than for water). The sorption selectivity increases with the B/A component ratio and the crosslinking temperature. We attributed these changes in properties to a change in the degree of crosslinking in the network, which increases with the B/A component ratio or the crosslinking temperature. The ester sorption in PDMS from the water–ester mixture (ternary system) can be correctly described by the Flory model for the pseudo-binary mixture (ester–PDMS). The value of the Flory interaction parameter increases with the B/A component ratio. The water sorption from water–ester mixtures cannot be described using the same approach.