Polycarbonate-polydimethylsiloxanes with main-chain disilylethylene groups

Polycarbonate-polysiloxanes containing disilaethylene moieties in siloxane blocks (PC-PDMSE) were synthesized under heterophase conditions by the interaction of oligodioxycarbonates and previously unknown α,ω-bis(methylene chloroformate)oligodimethyldisilaethylenesiloxanes. As the molecular mass of the parent oligomers increases, the rate of polycondensation declines; however, the process significantly accelerates upon addition of catalytic amounts of triethylamine. The resulting block copolymers possess a two-phase morphology, with the glass transition temperature of the organosilicon phase being -91°C. Depending on the composition and length of PC and PDMSE blocks, the tensile stress of copolymer films varies within 7-23 MPa and their elongation at break is in the range 130-780%. For PC-PDMSE films, perm-selectivity relative to O 2 /N 2 is 1.5 times higher than the corresponding value for the common PC-PDMS block copolymers.