Modification And Properties Of Poly (Butylene Succinate) Based On Click Chemistry

With the white pollution and non-renewable energy crisis becoming more and more serious,research and development of biodegradable plastics have become an effective way to alleviate this problem.Polybutylene succinate(PBS)has become a research hotspot in degradable plastics due to its good heat resistance and processability.However,PBS synthesized by polycondensation has low relative molecular weight,poor mechanical properties and high crystallinity,which limit its popularization and application.In view of the above problems,the chain extension modification and copolymerization cross-linking modification of PBS were carried out in this paper,and the effects of two modification methods on the mechanical properties,thermal stability,crystallization and degradation properties of PBS were discussed.Firstly,PBS was modified by thiol-ene click reaction,and the effect of chain extension on the properties of PBS was studied.The terminal modification of hydroxyl-terminated PBS with undecylenic acid(UA)was carried out to obtain double bonded polyester(PBS-UA).Then the PBS-UA was extended with ethanedithiol(EDT)as chain extender by thiol-ene click reaction to obtain PBS-s-PBS.The PBS-g-PBS was prepared and extended with hexamethylene diisocyanate(HDI).Then the products PBS-s-PBS、PBS-g-PBS and pure PBS were compared.The results show that the molecular weight of prepolymer has the most obvious effect on the end-capping ratio of double bond.The molecular weight of prepolymer is 3601 g/mol with the catalyst of tetrabutyl titanate,and the end-capping ratio can reach 41.7%when the reaction time is 3.5 h.The melting temperature,crystallization temperature and thermal stability of PBS-s-PBS and PBS-g-PBS obtained by chain extension of EDT and HDI are enhanced compared with those of pure PBS,and the initial decomposition temperature is increased by 18℃and 24℃,respectively.The crystallization ability of PBS-s-PBS and PBS-g-PBS decreased slightly,and the degradation of PBS-s-PBS was better than that of PBS-g-PBS.Secondly,double bonds were introduced into the main chain of PBS,and PBS was copolymerized and crosslinked by thiol-ene click reaction.A series of Poly(butylene succinate-co-butylene itaconic)(PBIS)with controllable properties were synthesized by adjusting the content of the chain segments of succinic acid and itaconic acid using itaconic acid(IA)as copolymer.Crosslinked polyester(CPBIS)was prepared by thiol-ene click reaction using trimethylolpropane tris(3-mercaptopropionate)as crosslinking agent.Its structure and properties were characterized by ~1H-NMR,FT-IR,DSC and XRD.The results show that the crystallinity of PBIS decreases with the increase of IA content,but its thermal performance decreases.When IA content exceeds 50%,the copolyester PBIS changes from solid state to viscous flow state at room temperature.The thermal stability and mechanical properties of cross-linked polyester CPBIS are improved and good degradation is maintained.The C-S bond in the crosslinked polyester CPBIS can be degraded by the interaction of glutathione and lipase.The weight loss of CPBIS in the above degraded solution can reach 12%after 7 days of degradation.