The Copolymerization Of Carbonyl Sulfide With Oxetane

The copolymerization of COS with oxetane(OX)was investigated comprehensively in this dissertation,including:(1)the catalytic synthesis of poly(trimethylene thiocarbonate)(PTMMTC);(2)the exploration of the effect of the extent of the oxygen-sulfur exchange reaction on the solubility and crystalline behaviors of the resultant PTMMTCs.Semicrystalline PTMMTC was successfully synthesized through the copolymerization of COS with OX using binary(salen)CrCl/base catalyst systems.There were some factors were studied,including the reaction temperature,the catalyst promotors,solvents,ligand types and axial ions,to figure out the effect on copolymerization of COS with OX.FT-IR and high temperature NMR spectra were used to identify the structure of PTMMTC.The initial decomposition temperature of PTMMTC was 228.5°C,determined by TGA.DSC and XRD were utilized to characterize the crystalline behavior of PTMMTC.The range of the melting point(Tm)of PTMMTC is from 110 to 125°C,and the range of corresponding melting enthalpy(?Hm)of PTMMTC is from 30 to 50 J/g.According to the XRD profile,two spiculate peaks were observed,2 theta(?)s were 19.0 and 22.9°.The crystallinity of PTMMTC was calculated by Jade 6.5 and up to 71%according to the XRD profile.High temperature GPC was used to determine the number average molecular weight(Mn)and the polydispersity index(PDI)of PTMMTC.Mns were 4.9-55.7 kg/mol with PDI of 1.6-2.4.The solubility and the crystalline behaviors of the COS/OX copolymers were investigated by tuning the extent of the oxygen-sulfur exchange reaction(O-S ER).NMR and high temperature NMR were used to determine the structure of DCM-soluble and DCM-insoluble portion of the copolymer.As for the related factors to O-S ER,the reaction temperature and catalyst promotors were investigated to illustrate the impact of the extent of O-S ER on the microstructure of the resultant copolymers.The mass ratio of the DCM-soluble portion of the copolymer increased and its Tg declined with raising the reaction temperatures from 140 to 155?,meanwhile the mass ratio of the DCM-insoluble portion of the copolymer decreased,Tm&Tg also descended.The structure producing by O-S ER and the solubility of the copolymers were affected by catalyst promotors,as well as the crystalline behaviors of the copolymers,including its Tg,Tm and ?Hm.The solubility and the crystalline behaviors of the copolymers was strikingly affected by the extent of O-S ER.In conclusion,semicrystalline PTMMTC was successfully synthesized by copolymerizing of COS with OX employing binary(salen)CrCl/base catalyst systems,which broadens the types and the potential applications of polythiocarbonates.