Polyester From Ring-Opening Copolymerizations Of Epoxide And Anhydride Catalyzed By Series Of Asymmetrical Bis-Schiff-Base Transition Metal Catalysts

Polyesters based on epoxide and anhydride or dianhydride, due to their good biodegradability and biocompatibility, are currently of interest because of their potential applications in biomedical devices and coatings materials. However, the reported catalysts displayed relatively low catalytic activities, needing the development of high performance catalysts as a breakthrough to polyester.Series of asymmetrical bis-Schiff-base ligands based PMBP and their manganese(?) asymmetrical bis-Schiff-base complexes were synthesized and characterized by element analysis, infrared spectra, nuclear magnetic resonance spectra, X-ray single-crystal diffraction and thermo-gravimetric analysis. All the nine complexes (1-9) as the catalysts were used for the ring-opening copolymerization of epoxide and anhydride. On the other hand, catalysts6-9were further used for the ring-opening copolymerization of epoxide and dianhydride. Another series of asymmetrical bis-Schiff-base ligand based on Cl-PMBP and its chromium(?) cobalt(?) manganese(?) complexes were prepared and characterized by element analysis, infrared spectra, nuclear magnetic resonance spectra, X-ray single-crystal diffraction and thermo-gravimetric analysis, where they were used for the ring-opening copolymerization of styrene oxide and maleic anhydride. Moreover, manganese(?) diallyl-modified Salen-type Schiff-base Catalysts were obtained and also characterized. From which, the complexes were used as the catalysts for the ring-opening copolymerization of cyclohexene oxide and maleic anhydride. As to the totally obtained copolymers, their microstructure were characterized by the FT-IR and1H NMR, and the molecular weight sizes and the molecular weight distribution indexs were determined by gel permeation chromatography (GPC). Especially, the relationship between the molecular structures and the catalytic behaviors was checked, and the optimal polymerization process based of the selected catalyst was also investigated. The ring-opening copolymerization behaviors of CHO and MA in bulk and solution were studied in detail by series of catalysts [Mn(Ln)Cl](n=1-4), where the catalyst9showed the better catalytic activity under the conditions applied, due to its large steric effects and the electronic effects. Using the selected9as the suitable catalyst, its solution copolymerization showed that the number molecular weight of the obtained copolymer was18225g·mol-1and the PDI was1.03. The ring-opening copolymerization of epoxide and dianhydride in solution were former studied also using catalysts [Mn(Ln)Cl] as the catalysts, where also due to its large steric effects and the electronic effects, catalyst9as the suitable catalyst could endow the number molecular weight of4837g·mol-1and the PDI of1.08for the copolymer from the solution copolymerization. On the other hand, as to its use for the solution (DMF) copolymerization of CHO and ODPA in presence of n-Bu4NBr as the co-catalyst, the optimal polymerization conditions are composed of the molar ratio of CHO, ODPA,9and n-Bu4NBr of250:125:1:1, the polymerization time of300min and the reaction temperature of110?.The ring-opening copolymerization of SO and MA in bulk and solution were also studied by another chromium(?) cobalt(?) manganese(?) asymmetrical bis-Schiff-base catalysts. It is obviously that the anion effect of Cl" is better than the anion effect of OAc-, the results of solution polymerization is better than the bulk polymerization. The higher molecular weight and the lower molecular weight distribution index were achieved by solution polymerization. Using the selected20as the suitable catalyst, the molecular weight of solution copolymer was5118g·mol-1and the PDI was1.07. Of all catalysts, the chromium-based catalysts performed the best under the conditions applied, followed by the cobalt and manganese catalysts.The ring-opening copolymerization of CHO and MA in bulk and solution were studied in detail by using Manganese(?) diallyl-modified Salen-type Schiff-base Catalysts. It is obviously that the anion effect of Cl-performed the best under the conditions applied, followed by the OAc-, the anion effect of N3-proved to be the least active under the applied conditions, the effect of1,2-diaminocyclohexane is the best in the three linkers. The effect of solution polymerization is better than the bulk polymerization. The higher molecular weight and the lower molecular weight distribution index were achieved by solution polymerization. Using the selected2as the suitable catalyst, the molecular weight of solution copolymer was14657g-mol"1and the PDI was1.04.In sum, the catalyst with the withdrawing electronic group or having a larger steric group showed superior catalytic activities to copolymerization of epoxide and anhydride and epoxide and dianhydride. The anion effect of Cl" performed the best under the conditions applied, followed by the OAc-, the anion effect of N3-proved to be the least active under the applied conditions. Of all catalysts, the chromium-based catalysts performed the best under the conditions applied, followed by the cobalt and manganese catalysts. The better catalytic performances were obtained from the copolymerization procedure of the molar ratio of epoxide, anhydride, catalyst and co-catalyst of250:250:1:1, the polymerization time of150min and the reaction temperature of110?in bulk. The better catalytic performances were obtained from the copolymerization procedure of the molar ratio of epoxide, anhydride, catalyst and co-catalyst of250:250:1:1, the polymerization time of300min and the reaction temperature of110?in toluene.