Construction Of Polyphosphoesters With Main Chain Of Rigid Backbone And Stereostructure Via Organocatalyzed ROP

Organic polymer materials have been widely used in people’s life because they can meet the requirements of various uses.At present,common polymer materials such as polyethylene glycol,polyester,etc.,have a high application prospect in the fields of plastics,fibers,adhesives,etc.Among them,polyphosphate is considered to be one of the most promising polymers.For organisms,phosphorus is the key to cell metabolism and population genetic variation.This means that compounds containing phosphorus can play a unique role in organisms.Polyphosphate was first known for its good flame retardancy.With the research of many researchers,it is found that the polymer materials with phosphorus in the main chain have good biocompatibility and biodegradability in vivo.This makes the phosphorous polymer have great potential in the field of medicine.Compared with other polyesters,the central phosphorus atom of polyphosphate ester has a valence of five,which means that multiple groups can be connected in the main chain of polyphosphate ester.People can easily get polyphosphate ester with multiple functions by introducing functional groups into the polymer chain.In the early stage,the synthesis of polyphosphate is mainly through the catalysis of metal catalyst.This method often uses complex catalysts,and there are some problems such as low catalytic efficiency and serious metal residue,which makes the biological application of polyphosphate more difficult.With the in-depth study of scientific researchers,it has been found that organic catalysts can replace of metal based catalysts and have the advantages of high efficiency,controllable and pollution-free.Up to now,polyphosphate has many applications in tissue engineering,gene delivery and drug delivery.However,the flexible chain segment of polyphosphate limits the application of this material.At present,most of the reports are side chain functional modification of polyphosphate,but there is little research on the structure and functional development of the main chain of polyphosphate.This thesis is based on the design of the structure and properties of the main chain of polyphosphate.The specific research content of this paper is as follows:The first part: the synthesis of cyclophosphate monomers with different optical activities and the preparation of polyphosphates with different stereoregularity.The factors influencing the rate of ring opening polymerization of phosphate monomers were studied in detail.The composition of the product polymer was analyzed reasonably.The reaction mechanism and experimental proof of the side reaction transesterification in the polymerization were provided,which provided a new synthesis idea for the functional modification of polyphosphate in the main chain.In the second part: the properties of polyphosphate esters with different structured prepared by ring opening polymerization with organic catalyst were tested.The kinetics of ring opening polymerization was studied by in-situ infrared method.In addition,the initial activation energy of the reaction was obtained by testing several temperatures.The thermal properties of this kind of polyphosphate ester were tested.It was found that this kind of polyphosphate ester had better thermal stability in accordance with the design concept system.The influence of high stereoregularity on materials was studied.