Preparation And Performance Of Polymenthide And Its Elastomers From Menthide Via Organocatalyzed Ring-opening Polymerization

Degradable polyester elastomers play an important role in tissue engineering and biomedical applications for their good degradability,biocompatibility and mechanical properties.Noncrystalline polymenthides(PMs)obtained from the ring-opening polymerization of biobased menthol derived lactone monomer are excellent soft segments for preparing degradable polyester elastomers.There are relatively few studies on polymenthide,most of which focused on the preparation of block copolymers.Therefore,there are still enough margins to develop in the near future on the systhesis of cross-linked elastomer of menthide.The reported ring-opening polymerizations(ROPs)of menthide are all catalyzed by metal catalysts.Considering the high cost,unstable properties of metal catalysts and metal residues in polymers,the resultant polymers are limited in practical application.With advangtages of lower sensitivity,higher availability,lower toxicity,and easy to separation from the system,metal-free organocatalysts have gradually become a hot research area in ring-opening polymerization catalysts of cyclic lactone.This thesis is devoted to the synthesis and properties of polymenthide and its cross-linked elastomer.It is the first time that metal-free organocatalyst cyclic trimeric phosphazene base(CTPB)was used to catalyze the ring-opening polymerization of menthide,and the cross-linked elastomer of polymenthide was prepared under UV irradiation.The main contents are as follows:1.The ROP of menthide was studied in the presence of Bn OH or glycerol as initiator and CTPB as catalyst.It was found that the polymerization could be performed well at 80 °C by optimizing the polymerization conditions.Polymenthides with different molecular weights had been prepared by changing the ratio of monomer and initiator.The moleculer weight of polymenthides was up to 100.7 kg/mol.However,there is intramolecular transesterification during the polymerization process,leading to the cyclic by-products confirmed by MALDI-TOF MS.Introducing urea into the polymerization system to form the CTPB/urea binary catalytic system,the transesterification reaction was significantly inhabited and the polymerization proceeded in a more controlled manner.Eventually,the hydroxyl-terminated star shaped polymenthide was successfully synthesized with glycerol as initiator.2.The hydroxyl-terminated star shaped polymenthide was acrylated with acryloyl chloride.And the hydroxyl-terminated polymers were successfully transformed into acrylate-terminated polymers proved by 1H NMR.The star shaped precursor polymer with terminal double bonds could be cured under UV irradiation,and the cross-linked elastomer based on polymenthide was successfully prepared.Through DSC,TGA,tensile test and degradation test,it was proved that the thermal stability of cross-linked elastomer was generally good,and the mechanical properties were matched with soft body tissues,and it could be degraded in alkaline aqueous solution.