Solvent-thermal synthesis preparation of polylactic acid-polyethyleneglycol copolymer

The invention relates to a preparation method for the thermal synthesis of a solvent of polylactic acid-polyethylene glycol copolymer. In a high pressure reactor, lactide, polyethylene glycol, a catalyst, a stabilizing agent and a solvent with a certain proportion are added; the temperature and the time for the reaction are controlled to lead a system to be under a state which is similar to a supercritical state, thus leading the reagent, the catalyst, the stabilizing agent and the solvent to be fully contacted and completely reacted; then the washing and drying are carried out for obtaining the polylactic acid-polyethylene glycol copolymer with high molecular weight. The device used by the invention is simple; as the reaction is carried out under the supercritical state, the polylactic acid-polyethylene glycol copolymer with higher molecular weight can be obtained; in addition, the consumption of the solvent is less, thus being conveniently produced in a large scale.