Controlled Ring-opening Polymerization Of Lactone Monomers With Polyols As The Initiator

In recent years,with the introduction of the"plastic ban"at home and abroad,to prohibit the use of non-degradable materials,thus biodegradable materials ushered in a broad prospect for development.However,at present,the performance of most biodegradable materials cannot meet people’s needs.For example,biodegradable lunch boxes and straws will be seriously deformed in high temperature environment due to poor heat resistance,which greatly limits their development.Therefore,it is urgent to modify biodegradable materials.Compared with other types of polymers,the star polymer has better heat resistance and mechanical strength,does not require chemical crosslinking,is simple to prepare,and can be recycled.Therefore,this paper hopes to construct star polymer to obtain more excellent physical properties,such as heat resistance,rigidity and flame retardancy.In this paper,1-butanol was used as initiator to synthesize linear L-polylactic acid,linear polycaprolactone and linear polytrimethycarbonate.Then,by changing the initiator into polyols,star L-polylactic acid（s-PLLA_n）,star polycaprolactone（s-PCL_n）and star polytrimethycarbonate（s-PTMC_n）with clear structure,precise molecular weight and narrow molecular weight distribution were prepared by means of first nucleus and then arm.Specific research contents are as follows:1.Different polyols were used as initiators to conduct ring-opening polymerization with L-Lactide（LLA）under the catalysis of t-Bu-P₂ solution to synthesize star-shaped L-pllan（s-PLLA_n）with different arm numbers.s-PLLA_n was characterized by ¹H NMR,stroma-assisted laser desorption flight mass spectrometry（MALDI-TOF MS）,dimensional rejection chromatography,differential refraction detector and eight-angle light scattering system（SEC-RI-MALS）.The results showed that the polymer structure was clear.The measured molecular weight(M_n,MALS)is basically consistent with the theoretical molecular weight(M_n,calcd),and the molecular weight distribution（M_w/M_n）is basically within 1.2.These results indicate that a star-shaped L-polylactic acid（s-PLLA_n）with clear structure and controllable molecular weight can be prepared by using polyols as initiators.2.Star polycaprolactone（s-PCL_n）of different arms was synthesized in ring-opening polymerization with caprolactone（?-CL）under the catalysis of diphenyl phosphate（DPP）,with different polyols as initiators.s-PCL_n was characterized by ¹H NMR,matter-assisted laser desorption flight mass spectrometry,dimensional rejection chromatography（MALDI-TOF MS）,differential refraction detector and eight-angle light scattering system（SEC-RI-MALS）.The results showed that the polymer structure was clear.The measured molecular weight(M_n,MALS)is basically consistent with the theoretical molecular weight(M_n,calcd),and the molecular weight distribution（M_w/M_n）is basically within 1.2.This indicates that star polycaprolactone（s-PCL_n）with clear structure and controllable molecular weight can be prepared by using polyols as initiators.3.Using different polyols as initiators,ring-opening polymerization was carried out with trimethycarbonate（TMC）under the catalytic action of t-Bu-P₂ solution to synthesize star-shaped polytrimethycarbonate（s-PTMC_n）with different arm numbers.s-PTMC_n was characterized by ¹H NMR,stroma-assisted laser desorption flight mass spectrometry（MALDI-TOF MS）,dimensional rejection chromatography,differential refraction detector and eight-angle light scattering system（SEC-RI-MALS）.The results showed that the polymer structure was clear.The measured molecular weight(M_n,MALS)is basically consistent with the theoretical molecular weight(M_n,calcd),and the molecular weight distribution（M_w/M_n）is basically within 1.2.These results indicate that star polytrimethycarbonate（s-PTMC_n）with clear structure and controllable molecular weight can be prepared by using polyols as initiators.