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

Poly(dimethylsiloxane)s (PDMS) of different crosslinking degrees were synth esized by varying the ratio of B(crosslinker)/A(vinyl-type PDMS) in the mix ture to be crosslinked, and by varying the crosslinking temperature. The sw elling degrees of the polymer in pure water, pure ester (ethyl acetate) and their mixture decrease when the B/A component ratio or the crosslinking te mperature increases. The ester component is selectively sorbed from its mix ture 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 chang es in properties to a change in the degree of crosslinking in the network, which increases with the B/A component ratio or the crosslinking temperatur e. The ester sorption in PDMS from the water-ester mixture (ternary system) can be correctly described by the Flory model for the pseudo-binary mixtur e (ester-PDMS). The value of the Flory interaction parameter increases with the B/A component ratio. The water sorption from water-ester mixtures cann ot be described using the same approach.