SOME EVIDENCE ON PORE SIZES IN POLY(DIMETHYLSILOXANE) ELASTOMERS HAVING UNIMODAL, BIMODAL, OR TRIMODAL DISTRIBUTIONS OF NETWORK CHAIN LENGTHS

Unimodal, bimodal, and trimodal networks were prepared by end linking functionally-terminated chains of poly(dimethylsiloxane). The resulting materials were characterized using a ''thermoporometric'' technique in which freezing points or melting points are determined for solvent absorbed into the network stuctures. The extent to which the normal melting point is suppressed depends on how much the solvent is constrained within the network pores. Several well-defined melting points were observed for some of the multimodal networks, which is consistent with their unusual distributions of network chain lengths.