Ring Opening Polymerization Of O-Carboxyanhydride (OCA) Monomer Catalyzed By Tertiaryamine

Five-membered O-Carboxyanhydride（OCAs）can be connected with different modification groups to obtain PAHA with many different functions.It is necessary to develop a simple and efficient catalytic system for the controlled ring opening polymerization of OCAs.At present,most of the research results are linear polymers,but few ring polymers.Due to the topological differences between linear polymers and ring polymers,they have different properties in density,glass transition temperature and decomposition temperature.The three hydrogen atoms of amino group of tertiary amine are replaced by electron donor group,which has high catalytic activity and is widely used in ring opening polymerization of cyclic monomers.Therefore,in this paper,a tertiary amine catalytic system was studied to enable the controlled ring opening polymerization of OCA monomer.At the same time,cyclic and linear polyesters were synthesized by changing the types of protic substances to obtain materials with specific and different properties.1.The binary catalytic system of 1-aza-dioxane（ABCO）with different protic substances was used to catalyze the controllable ring opening polymerization of _L-Phe OCA monomer at room temperature.Charactered the structure of the polymer,the results showed that the composite catalyst system of ABCO/Benzyl alcohol（Bn OH）formed cyclic polymer;the combination of ABCO/fatty alcohol and ABCO/2,6-xylenol（DEP）to generate the polymer with proton initiated and carbonate capped;the composite catalyst system of ABCO/acid formed proton initiated polymer and hydroxyl terminated polymer.2.The interaction between the catalytic systems was studied by ¹H NMR and ¹³C NMR.The polymerization process was monitored by ¹H NMR.The kinetics was studied by in situ IR spectra and the possible mechanism was proposed.Protic substances providing protons can reduce the nucleophilicity of ABCO in varying degrees and improve the nucleophilicity of protic substances,so polymers with different topologies will be formed.3.The applicability of the catalytic system was studied.It was found that the ring opening polymerization of _L-Phe OCA monomer catalyzed by DABCO,TMEDA,TEA and protons with similar structure to ABCO had the same topological morphology as that of ABCO.