INTERPENETRATING POLYMER NETWORKS OF POLY(DIMETHYLSILOXANE) .1. PREPARATION AND CHARACTERIZATION

Model networks of alpha,omega-dihydroxy-poly(dimethylsiloxane) (PDMS) were prepared by tetrafunctional crosslinking agent tetraethyl orthosi licate (TEOS) and the catalyst stannous 2-ethylhexanoate. Hydroxyl-ter minated chains of PDMS having molecular weights 15 x 10(3) and 75 x 10 (3) mol-1 were used in the crosslinking reaction. Bimodal networks wer e obtained from a 50% (w/w) mixture of PDMS chains with M(n) = 15 x 10 (3) and 75 x 10(3) g mol-1. A sequential interpenetrating network of t hese PDMS chains was also prepared. Physical properties of the elastom ers were determined by stress-strain tests, swelling and extraction ex periments, and differential scanning calorimetry measurements.