Microwave-assisted Ring-opening Polymerization Of 2, 2-Dimethyltrimethylene Carbonate And ε-Caprolactone

Microwave chemistry has developed to become a rising and crossed subject, which studies the application of microwave in chemistry. In recent decades, microwave has been applied in various fields of chemistry widely with the continuous development of microwave chemistry and a series of delightful fruits are achieved. Microwave heating has promoted many reactions due to its unique characteristics. The applications of microwave in polymer chemistry are reviewed in this paper.Biodegradable polycarbonates and poly(ε-caprolactone) (PCL) are promising well to be used in the biomedical fields, such as surgical sutures, bone-fixed materials, drug controlled release, and so on. This dissertation is focused on the polymerization of 2, 2-dimethyltrimethylene carbonate (DTC) and s-caprolactone (ε-CL) under microwave irradiation.The remaining of heavy metallic catalysts in polycarbonates is not safe potentially when being used as biomedical materials. It is very important to use non-toxic catalysts with high activity during the preparation of polycarbonates for extending the applications of polycarbonates in medical fields. With zinc D, L-lactate as catalyst, which is safe to body, PDTC with Mw as 700000g/mol was prepared when the reaction mixture was irradiated for 75min under 180W microwave power. This method was proved to be ideal for preparing PDTC with high molar mass. The resulting polymer's molar mass was still very high and polymer yield and monomer conversion increased a little when prolonging irradiation time to a degree at low power. Compared zinc D, L-lactate with LaCl3, the former has higher catalytic activity. And the resulting polymer degrades later and more slightly with the appropriate extension of the irradiation time with zinc D, L-lactate as catalyst.Microwave-assisted ring-opening polymerizations of DTC were carried successfully with lanthanum chloride (LaCl3) and stannous octoate (Sn(Oct)2) ascatalyst and the highest weight average molar mass (Mw) of the obtained PDTC were 66800g/mol and 14600g/mol, respectively. Compared with that of Sn(Oct)2, LaCl3 had higher catalytic activity. The temperatures of the reaction mixtures ranged smoothly under microwave irradiation and no super-hot point occurred. Higher microwave power, higher temperature. Microwave power and irradiation time influenced polymer molar mass, polymer yield and monomer conversion to different extent. Lower microwave power and shorter irradiation time were more propitious to obtain products with higher molar mass. Higher microwave power and longer irradiation time were possible to lead to the degradation of products.Polycarbonates usually degrade very slowly, which confines the further expansion of their applications. Poly(ethyl glycol) (PEG) is usually incorporated into the main chain of polycarbonates in order to enhance the hydrophilicity, which is promising to improve their the degradability. Catalyzed by LaCl3, a series of PDTC-PEG-PDTC copolymers with different molar mass and content of PEG were synthesized by microwave-assisted copolymerization of DTC and PEG with two terminated hydroxyls. Component and molar mass could be regulated to a certain extent by changing the quantity of PEG. The results of water absorption showed that the hydrophilicity of copolymers increased accompanying with the increasing of PEG contents and it was more obvious for PEG6000 to enhance the hydrophilicity than PEG4000. The determination of DSC suggested that the incorporation of PEG minished the difference between two melting phases of PDTC and reduced the degree of crystal.Microwave-assisted ring-opening polymerization (MROP) of ε-caprolactone (ε-CL) was initiated by maleic acid in the absence of any metallic catalyst. Molar mass of the obtained poly(s-caprolactone) (PCL) was beyond 12000 g/mol. Microwave irradiation improved the polymerization obviously compared with conventional heating method. Both the molar mass of PCL and the rate of polymerization were enhanced greatly. Based on the above-mentioned results, the MROP of ε-CL containing...