Synthesis Of Cyclic Polyester Or Polyester-based Block Copolymer And Theirs Property

In this dissertation,we initially studied the synthesis of?,?-functionalized poly(?-caprolactone)(PCL)with reactive groups used for synthesizing cyclic poly(?-caprolactone)(cPCL).cPCLs were succefully prepared by utilizing an intermolecular anthracene(An)photodimerization.In addition,atom transfer radical polymerization(ATRP)and ring-opening polymerization(ROP)were combined to synthesize amphiphilic diblock copolymers NB-PDLA-b-PDMAEMA.The main researches are as follows.1.An norbornene/anthracene and a disulfide group on the?-and?-ends of the PCL chain was synthesized,and the reduction of disulfide bonds to the thiol were investigated in detail where we found that terminated norbornene/anthracene gourp were involved in the reaction in the reduction process,and polyester was even reduced in some cases.Although some approaches were taken,the expected linear?-norbornene/anthracene–?-thiol functionalized PCL precursors are not available2.The cPCLs have been synthesized via An group photodimerization.It was found that the ring size of cPCLs could be tuned simply by adjusting the concentration of An-PCL-An in THF.The structure and thermal properties of cPCLs were determined by ~1H NMR,Uv-vis,Gel-permeation chromatography(GPC),differential scanning calorimetry(DSC)and Thermogravimetric Analysis(TGA).The dimeric An moieties can switch back to the unimolecular state by thermal disassociation,that is,the reversible dimerization of An induced by heating and Uv light irradiation enables the cyclic PCL to possess a switchable“on-off”capability.3.The norbornene-based multifunctional initiator,2-hydroxymethyl-3-(2-bromoisobutyryl-oxymethyl)-5-norbornene(HO-NBE-Br),was prepared.This initiator could prompt the Atom Transfer Radical Polymerization(ATRP)and ring opening polymerization.The influence of order of synthesis of segment on the amphiphilic diblock copolymer was investigated.The results show that linear amphiphilic diblock copolymers of NB-PDLA-b-PDMAEMA synthesized by ROP of LLA followed by ATRP of DMAEMA present much better structural control and lower polydispersity.