Synthesis And Properties Of Poly(Butylene Succinate)-b-poly(Butylene Sebacate) Mublock Copolymer

Bio-based and biodegradable polymeric materials have received more and more attention in order to reduce the dependence on the petroleum resources and the pressure on the environment.In this dissertation,a new type of bio-based and biodegradable poly(butylene succinate)-b-poly(butylene sebacate)multiblock copolymers(PBS-b-PBSe),containing PBS segment and poly(butylene sebacate)(PBSe)segment,were successfully synthesized by the chain extension reaction of hydroxyl-terminated PBS(PBS-OH)and hydroxyl-terminated-PBSe-(PBSe-OH)using hexamethylene diisocyanate(HDI)as a chain extender.The chemical structures of the prepared copolymers were determined by both proton nuclear magnetic resonance(1H NMR)and fourier transform infrared spectroscopy,and the compositions were calculated by the peak area of 1H NMR spectra.PBS-b-PBSe multiblock copolymers had good thermal stability.PBS and PBSe crystallized separately in the crystalline region and showed their own crystallization peaks,respectively.The crystallization peaks of PBS and PBSe appeared in the higher temperature range and lower temperature range,respectively.In the amorphous region,PBS and PBSe showed good miscibility,because there was only one glass transition temperature.After the introduction of the PBSe segment,the melting point and equilibrium melting point of the copolymers decreased slightly,and the elongation at break was greatly improved.When the content of PBSe was 40%,the elongation at break of the copolymer reached 673.6± 22.2%,which was equivalent to 13 times that of 51.7± 0.8%for PBS,and the strength and modulus of the copolymer were not significantly decreased.The study of the crystallization behavior of the copolymers was performed.The results showed that in the multiblock copolymers,the crystallinity of the PBS segement reduced after the introduction of the PBSe segment.Similarly,the crystallinity of the PBSe segement also reduced with the increase of the PBS content.In the multiblock copolymers,both PBS and PBSe segements may crystallize separately;consequently,PBS-b-PBSe displayed the characteristic diffraction peaks of PBS and PBSe in the wide-angle X-ray diffraction profiles.The polarizing optical microscopy images proved that PBS crystallized first and filled the entire space during the cooling process,and then PBSe completed the crystallization inside the PBS spherulites.The introduction of the PBSe segment restricted the crystallization of PBS,and PBS still maintained the spherulitic morphology.In sum,PBS-b-PBSe with good comprehensive performance was successfully prepared through the chain extension reaction,which may promote the wider practical application of PBS and provide reference for related work.