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

Abstract

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 a,x-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 1 H-NMR spectroscopy, whereas the effectiveness of the incorporation of a,x-dihydroxy-(EO-PDMS-EO) into the copoly-mer 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 swelling behavior of polyurethane networks based on hyperbranched polymer

“…The peak at 3.78 ppm is assigned to the -CH 2 -protons from the MDI residues, while aromatic protons of MDI appear at 7.06 and 7.32 ppm. Two peaks at 8.56 and 9.48 ppm result from the urethane protons [13,17]. In the 1 H-NMR spectrum of PU2-30 ( Figure 6) and other extracted sol fractions (not presented) the same signals can be observed, except two signals belonging to the NH urethane protons which were not detected.…”

“…Before the synthesis, EO-PDMS-EO was dried over molecular sieves (0.4 nm). Using the 1 H-NMR, M n was calculated and the obtained value of 1200 g/mol was used for the calculations of the reaction mixtures [13]. 4,4'-Methylenediphenyl diisocyanate (MDI) was supplied by Aldrich (purity > 98%) and used as received.…”

Surface and thermomechanical characterization of polyurethane networks based on poly(dimethylsiloxane) and hyperbranched polyester

“…Therefore, the degree of polymerization of PDMS-block in the EO-PDMS and HP-PDMS prepolymers was 12.8 and 10.6. The M n of the prepolymer EO-PDMS was 1200 g/mol [22], while for the prepolymer HP-PDMS it was 960 g/mol. 4,4#-Methylenediphenyl diisocyanate (MDI) (supplied from Aldrich, Steinheim, Germany), with an isocyanate content of 33.6 wt%, was used as received.…”

Silicone containing copolymers: Synthesis, properties and applications

“…The structure and composition of the copolymers were determined by 1 H-NMR. DSC analyses clearly showed the formation of microphase separated systems with a clear T g around -120 °C for PDMS segments and crystallization and melting peaks for PCL and PBT segments(171).PDMSpolyester segmented copolymers were also prepared by the transesterification reactions ofα,ωhydroxyalkylether terminated PDMS oligomers(1000 g/mol), dimethylterephthalate and 1,4butanediol(173).Copolymers withPDMS content between 10 and 60% by weight were prepared. The effect of the polymer composition on crystallinity and thermal stability of the copolymers were investigated.…”