Ring-Opening Polymerization Of Cyclic O-Carboxyanhydride Catalyzed By N-Heterocyclic Olefins

With the exploitation of fossil fuels,and the depletion of resources and the greenhouse effect,scientists are trying to find alternatives.In the polymer field,the polymer materials,which are based on petroleum derived monomers such as ethylene and propylene,have excellent properties and are applied in daily life and industrial production.But because of its source of monomer,lead to renewable monomers has caught the attention of human resources,has made certain progress in this field at present,such as the material such as poly?lactic acid??PLA?has been used in all walks of life,so,based on the requirement of environmental protection,renewable,biodegradable polymers has been the trend of The Times.The concept of green chemistry not only requires the monomer,but also the catalyst which is more efficient and more environmentally.In the past century,polymer synthesis of most of the use of transition metal catalysis,this kind of catalys had toxicity led to r metal residues.In recent years,the vigorous development of organic catalysts has made it more suitable for polymer synthesis.Structure of this article,we use different Nitrogen Heterocyclic Olefins as catalyst,catalytic O-carboxyanhydride?OCA?and N-carboxyanhydride?NCA?polymerization.The OCA monomer polymerization product its main chain is polyester structure,this provides a potential performance degradation and the polymerization products of NCA monomers have polyamino acid structure,which has certain applicability in the field of biomedicine.In exploring polymerization process,we through the regulation of monomer structure,structure of catalyst,the synthesis of high molecular weight of OCA polymer,polymer and NCA experiment by aggregating and nuclear magnetic response to explore the mechanism of polymerization,polymerization mechanism of different from other synthetic method is proposed,in this area further job provides a certain basis.?-pinene is a kind of natural molecular biomass which produces from pine trees,it consists a bicyclic of fused 4-and 6-member rings and a reactive exo-methylene moiety and readily undergo cationic ring-opening isomerizaiton polymerization to produce the poly??-pinene?.The polymer are widely used in food packaging and other fields.In our paper,the high molecular weight?Mn¹9000 g·mol-1?poly??-pinene?was synthetic by Al?C₆F₅?₃ catalyst system at room temperature.In addition,Al?C₆F₅?₃ conjugation with different of added bases to proved the structure of the intermediate by unsing Nuclear Magnetic Resonance Spectroscopy mass spectroscopy.The mechanism in cationic polymerization system was identified and the end group of polymer was proved by MALDI-TOF Mass Spectroscopy.The conclusions obtained in this work are of great significance for the study of the direction of cationic polymerization,which can provide theoretical support for the subsequent study of cationic polymerization mechanism.