Research On Linear Guanidine Compounds And Quinolyl N,O-bidentate Magnesium Complexes In The Ring-opening Polymerization Of Cyclic Esters

Three big challenges that face society are the of potable water,clean energy,and safe food.Scientists,particularly chemists,chemical engineers,and materials scientists,can and should be working on research to solve the many technical problems associated with sustainable development.Polymer scientists and engineers have the expertise necessary to identify and design novel materials to meet these needs.In order for these new materials to compete with the fossil fuel based,largely nondegradable polymers that currently dominate the industry,they must be competitive from both performance and cost perspectives.The block polymer architectures will indubitably be instrumental in the creation of useful renewable and degradable materials.The adoption of these materials for high volume applications like packaging will help to address the very real problem of plastic pollution.While it is likely that some of the polymers used for these applications will be both renewable and degradable,in some cases it will be important to design materials that are robust,with properties that are currently best achieved by using hydrocarbon polymers from monomers that are most efficiently produced from petrochemical sources.As previously discussed,“unsustainable polymers” can play key roles in advancing sustainability.Based on the previous works,we report the synthesis and characterization of a series of organic catalyst and metal complexes,studied their catalysis in the ROP of ε-CL and lactide.We also studied the structure-activity relationship of the catalysts and deeply analyst its catalytic mechanism.The work described in this thesis is summarized as the following:Chapter 1 introduces the development history of the plastics industry and the research progress of biodegradable polyester materials,applies them in the direction of chemical recycling.The classification introduces various organic catalysts containing various elements such as nitrogen,oxygen,sulfurand phosphorus in recent years.Scientific exploration of metal complexes with elements such as alkali metals,magnesium,aluminum,zinc,calcium and titanium as catalysts.Chapter 2,the linear guanidine compounds were used as catalysts to study the controlled ring-opening polymerization of ε-caprolactone and lactide(rac-LA and L-LA)with the action of initiator.The results show that these compounds can effectively catalyze the polymerization of the above monomers.The structure of the compounds has some influence on the catalytic activity,and the polymerization initiated is a kinetic first-order reaction,which conforms to the coordination-insertion mechanism.Based on the analysis of the structure of the selected compound and the conclusion of the polymerization experiment,the reaction mechanism of the actual catalyzed polymerization of the linear guanidine compounds was proposed,and the transition state structure during the reaction was predicted.Chapter 3 designs and synthesizes a series ofβ-quinolylketone-enaminones ligands and magnesium complexes.All the complexes were characterized by 1H and 13 C NMR spectroscopy and elemental analysis.The polymerization experiments have found that the catalytic activity of these magnesium compounds on ε-caprolactone and rac-lactide is not high,so the experimental conditions for the catalytic polymerization to reach the full requirements are still explored.