Microwave‐assisted ring‐opening copolymerization and property of polycarbonates

Abstract

AbstractRecently, the microwave‐assisted heating method has become a commonly used and environmentally friendly heating technology in the field of organic and polymeric synthetic chemistry. A series of poly(5,5‐dimethyl trimethylenecarbonate‐co‐2‐phenyl‐5,5‐bis[oxymethyl] trimethylenecarbonate) (P[DTC‐co‐PTC]) were synthesized by microwave‐assisted ring‐opening polymerization of 5,5‐dimethyl trimethylene carbonate (DTC) and 2‐phenyl‐5,5‐bis(oxymethyl) trimethylene carbonate (PTC) using tin(II) 2‐ethylhexanoate and aluminum isopropoxidase, the catalysts. These co‐polycarbonates were further reduced by a palladium‐carbon catalyst (Pd/C catalyst, 10%) to make partly deprotected polycarbonates (HPDPC). These two co‐polycarbonates were characterized by gel permeation chromatography, 1HNMR, Fourier transform infrared spectroscopy, UV, differential scanning calorimetry, and automatic contact‐angle measurements. The influences of the microwave irradiation time, microwave power, monomer feed molar ratio, different catalysts, and monomer/catalyst feed molar ratio on the molecular weights of co‐polycarbonates were also investigated. In vitro water absorption, degradation and drug release tests indicated that partly deprotected co‐polycarbonate HPDPC possessed greater hydrophilicity, faster degradation rate, and faster drug release rate than that of corresponding P(DTC‐co‐PTC). Therefore, microwave‐assisted polymerization is a clean and cheap heating method and can be used for ring‐opening copolymerization of carbonates, which enhances the hydrophilicity and biodegradation rate of aliphatic polycarbonates.