Epoxy Compounds And Polymeric Anhydride Alternating Asymmetrical Development And Application Salen-Cr Catalyst

Many researchers focus on the field of ring-opening copolymerization of epoxides with anhydrides, because the obtained polyesters have many valuable features such as the biodegradability, biocompatibility. Currently, the main applications of polyester are in materials, packaging materials, surgical sutures, drug capsules packaging materials, and other aspects of bone nailing. The polyester can generally be synthesized by the chain-growth method, which can be further modified by physical and chemical methods, and the polymer molecular weight is relatively high, the molecular weight distribution is relatively narrow. The catalyst is particularly important in the synthesis of polyester, and the widely used catalytsts are complexes (Salen)MX. Herein, series of asymmetric bis-Schiff-base Cr(III) complexes were designed and synthesized and were used to ring-opening polymerization of epoxide and anhydride or dianhydride in this thesis.Firstly, unilateral Schiff base ligand(OP)was synthesized by condensation reaction of1-phenyl-3-methyl-4-benzoyl-2-pyrazolin-5-one(PMBP)and o-phenylenediamine, then series of asymmetric bis-Schiff (HyL", n=a-e) ligands were obtained from the further condensation reaction of OP and one of aldehyde derivatives (salicylaldehyde,5-Br-salicylaldehyde,3,5-di-Br-salicylaldehyde, o-vanillin,5-Br-o-vanillin). All the compounds were characterized by element analysis, infrared spectra and X-ray diffraction analysis. Secondly, the series of asymmetric bis-Schiff-Cr(III) catalysts were synthesized from Schlenk system.In order to explore the catalyst activities, the obtained catalysts were used for two types of copolymerization reaction. One is the copolymerization of anhydride (MA or PA) and epoxide (CHO or SO), and the other is the copolymerization of dianhydrides (ODPA, BTDA or DTDA) and epoxide (CHO or SO). In addition, the obtained different copolymers were also characterized by FT-IR,1H NMR and GPCFinally, the effect of polymerization process on the copolymerizations was investigated. For the copolymerization of MA and CHO in melting condition, the optimum condition for complex-c/DMAP system is as following:the polymerization time of150min, the polymerization temperature of110℃, the molar ratio of monomer catalyst of250:250:1:1; from which, the largest catalytic activity is7.00×103g·(mol·h)-1; Mn is26.567×103g-mol-1and PDI is2.11for the polymers. As to the ODPA and CHO solution copolymerization, the optimum condition for complex-c/DMAP is:the polymerization time of300min, the polymerization temperature of110℃, the molar ratio of monomer and catalyst of125:250:1:1, where the largest catalytic activity is7.88×1O3g·(mol·h)-1, Mn is2.903×103g-mol"1and PDI is2.02for the copolymers.