Sinteza estar-siloksanskih multiblok kopolimera

U radu je opisana sinteza blok kopolimera sa poli(butilentereftalatnim) tvrdim segmentima i poli(dimetilsiloksanskim) mekim segmentima. Cilj rada je da se ispita iproveri da lije primenljiva klasična metoda dvostepene transesterifikacije/polikondenzacije u rastopu, koja se koristi za dobijanje estar-etarskih blok kopolimera i u slučaju estar-siloksanskih blok kopolimera. Pošto reaktant koji sadrži siloksansku komponentu može da ima različite završne grupe, ispitana su dva karakteristična slučaja: a) reaktant sa estarskim završnim grupama, dimetil-estar a, (ù-dikarboksipropil-poli(dimetilsil oksana), i b) reaktant sa hidroksilnim završnim grupama, α, ω-dihidroksi-poli(propilenoksid-di metilsiloksan-propilenoksid). Sintetizovane su tri serije kopolimera, pri čemu su kao reaktanti korišćeni poli(dimetilsiloksani) sa estarskim (dve serije) i hidroksilnim završnim grupama. Struktura i sastav kopolimera određeni su 1H NMR spektroskopijom. Predložen je mehanizam, odnosno redosled reakcionih koraka koji vode formiranju kopolimera

Primena reaktivnih siloksanskih pretpolimera za sintezu poli(ester-siloksana) i poli(ester-etar-siloksana)

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

Synthesis and characterization of copolymers based on poly(butylene terephthalate) and ethylene oxide-poly(dimethylsiloxane)-ethylene oxide

A series of thermoplastic elastomers based on ethylene oxide- poly(dimethylsiloxane)-ethylene oxide (EO-PDMS-EO), as the soft segment, and poly(butylene terephthalate) (PBT), as the hard segment, were synthesized by catalyzed two-step, melt transesterification reaction of dimethyl terephthalate (DMT) with 1, 4-butanediol (BD) and α, ω-dihydroxy-(EO-PDMS-EO). Copolymers with a content of hard PBT segments between 40 and 90 mass % and a constant length of the soft EO-PDMS-EO segments were prepared. The siloxane prepolymer with hydrophilic terminal EO units was used to improve the miscibility between the polar comonomers, DMT and BD, and the nonpolar PDMS. The molecular structure and composition of the copolymers were determined by 1HNMR spectroscopy, whereas the effectiveness of the incorporation of α, ω-dihydroxy-(EO-PDMS-EO) into the copolymer chains was verified by chloroform extraction. The effects of the structure and composition of the copolymers on the melting temperatures and the degree of crystallinity, as well as on the thermal degradation stability and some rheological properties, were studied. It was demonstrated that the degree of crystallinity, the melting and crystallization temperatures of the copolymers increased with increasing mass fraction of the PBT segments. The thermal stability of the copolymers was lower than that of PBT homopolymer, because of the presence of thermoliable ether bonds in the soft segments

Synthesis and characterization of poly(ester ether siloxane)s

A series of novel thermoplastic elastomers based on ABA-type triblock prepolymers, poly[(propylene oxide)–(dimethylsiloxane)–(propylene oxide)] (PPO-PDMS-PPO), as the soft segments, and poly(butylene terephthalate) (PBT), as the hard segments, was synthesized by catalyzed two-step melt transesterification of dimethyl terephthalate (DMT) with 1,4-butanediol (BD) and α,ω-dihydroxy-(PPO-PDMS-PPO) (Mn = 2930 g mol−1). Several copolymers with a content of hard PBT segments between 40 and 60 mass% and a constant length of the soft PPO-PDMS-PPO segments were prepared. The siloxane-containing triblock prepolymer with hydrophilic terminal PPO blocks was used to improve the compatibility between the polar comonomers, i.e. DMT and BD, and the non-polar PDMS segments. The structure and composition of the copolymers were examined using 1H NMR spectroscopy, while the effectiveness of the incorporation of α,ω-dihydroxy-(PPO-PDMS-PPO) prepolymer into the copolyester chains was controlled by chloroform extraction. The effect of the structure and composition of the copolymers on the transition temperatures (Tm and Tg) and the thermal and thermo-oxidative degradation stability, as well as on the degree of crystallinity, and some rheological properties, were studied

Synthesis and characterization of poly(ester ether siloxane)s

A series of novel thermoplastic elastomers based on ABA-type triblock prepolymers, poly[(propylene oxide)-(dimethylsiloxane)-(propylene oxide)] (PPO-PDMS-PPO), as the soft segments, and poly(butylene terephthalate) (PBT), as the hard segments, was synthesized by catalyzed two-step melt transesterification of dimethyl terephthalate (DMT) with 1,4-butanediol (BD) and α,ω-dihydroxy-(PPO-PDMS-PPO) (M̄ n = 2930 g mol -1 ). Several copolymers with a content of hard PBT segments between 40 and 60 mass% and a constant length of the soft PPO-PDMS-PPO segments were prepared. The siloxane-containing triblock prepolymer with hydrophilic terminal PPO blocks was used to improve the compatibility between the polar comonomers, i.e. DMT and BD, and the non-polar PDMS segments. The structure and composition of the copolymers were examined using 1 H NMR spectroscopy, while the effectiveness of the incorporation of α,ω-dihydroxy-(PPO-PDMS-PPO) prepolymer into the copolyester chains was controlled by chloroform extraction. The effect of the structure and composition of the copolymers on the transition temperatures (T m and T g ) and the thermal and thermo-oxidative degradation stability, as well as on the degree of crystallinity, and some rheological properties, were studied