Application of reactive siloxane prepolymers for the synthesis of thermoplastic poly(ester-siloxane)s and poly(ester-ether-siloxane)s

Abstract

Thermoplastic poly(ester-siloxane)s (TPES) and poly(ester-ether-siloxane)s, (TPEES), based on poly(butylene terephthalate) (PBT) as the hard segment and different siloxane-prepolymers as the soft segments, were prepared. The TPES and TPEES were synthesized by catalyzed two-step transesterification from dimethyl terephthalate, (DMT), 1,4-butanediol, (BD) and a siloxane-prepolymer. Incorporation of dicarboxypropyl- or disilanol-terminated poly(dimethylsiloxane) s (PDMS) into the polar poly(butylene terephthalate) chains resulted in rather inhomogeneous TPES copolymers, which was a consequence of a prononuced phase separation of the polar and non-polar reactants during synthesis. Two concepts were employed to avoid or reduce phase separation: 1) the use of siloxane-containing triblock prepolymers with hydrophilic terminal blocks, such as ethylene oxide (EO), poly(propylene oxide) (PPO) or poly(caprolactone) (PLC) when the terminal blocks serve as a compatibilizer between the extremely non-polar PDMS and the polar DMT and BD, and 2) the use of a high-boiling solvent (1,2,4-trichlorobenzene) during the first phase of the reaction. Homogeneity was significantly improved in the case of copolymers based on PCL-PDMS-PCL.

U okviru ovog rada su sintetisani termoplastični poli(estar–siloksani) (TPES) i poli(estar–etar–siloksani) (TPEES), sa tvrdim segmentima na bazi poli(butilentereftalata) (PBT) i mekim segmentima na bazi različitih siloksanskih pretpolimera. TPES i TPEES su sintetisani katalizovanom reakcijom dvostepene transesterifikacije, iz dimetilterftalata (DMT), 1,4-butandiola (BD) i odgovarajućeg siloksanskog pretpolimera. Pri ugradnji dikarboksipropil- ili disilanol-terminiranih poli(dimetilsiloksana) (PDMS) u polarne poli(butilentereftalatne) lance dobijeni su prilično nehomogeni TPES kopolimeri, što je bila posledica loše menjivosti reaktanata tokom odigravanja reakcije. Primenjena su dva koncepta da bi se izbeglo ili smanjilo fazno razdvajanje reakcione smene tokom sinteze organo–siloksanskih kopolimera: 1) primena siloksanskih triblok-pretpolimera kod kojih su hidrofilni terminalni blokovi, izgrađeni od etilenoksida (EO), poli(propilenoksida) (PPO) ili poli(kaprolaktona) (PLC), imali funkciju kompatibilizatora između nepolarnog PDMS-a i polarnih reaktanata, DMT-a i BD-a i 2) primena rastvaranja visoke temperature ključanja (1,2,4-trihlorbenzena) za vreme izvođenja prve faze reakcije. Značajno povećanje homogenosti postignuto je kod kopolimera na bazi PCL–PDMS–PCL segmenata.