An investigation of the thermodynamic interactions of oligomeric cyclic methylphenylsiloxanes in siloxane melts and blends

Abstract

Listen

Translate article

The miscibility of cyclic poly(methylphenylsiloxanes) (PMPS) with molar masses less than 1000 g mol −1 have been studied in mixtures with either cyclic or linear poly(dimethylsiloxane) (PDMS). In all cases, an upper critical solution temperature (UCST) was observed and interaction parameters were determined from the phase boundaries. The results were compared with those from our previous studies of linear–linear PDMS–PMPS and cyclic–linear PDMS–PMPS polymer blends. The cyclic–linear PMPS–PDMS and cyclic–cyclic PMPS–PDMS blends in this investigation were found to have higher interaction energy density parameters than the corresponding linear–linear PDMS–PMPS homopolymer blends that we have reported elsewhere. An isomer effect upon the phase separation behavior was also seen for the isolated pure stereoisomers of cyclic PMPS in mixtures with linear PDMS.