Study On The Synthesis And Properties Of Aromatic Cyclic Carbonates And Related Non-isocyanate Hybrid Polyurethanes

Isocyanate is used in the preparation of traditional polyurethane(PU)However,the production,use and residue of isocyanate in the final product will contaminate the environment and endanger people's health;Thus,nonisocyanate polyurethane(NIPU)has been extensively studied by scientists over the past decades.Among them,polyhydroxyurethane(PHU)prepared from alkyl carbonates and amines has attracted the most attention.However,there are many drawbacks in the traditional methods of synthesizing cyclic carbonates,such as relying on high pressure,lack of a suitable catalytic system and inability to fabricate on a large scale.What's more,the synthesis of PHU normally carried out in a solvent,which means that long reaction time is required and side reactions in the system are uncontrollable due to the addition of catalysts.Nevertheless,commercial epoxy/PHU hybrid coatings have been successfully applied,which brings new ideas to our research.In this dissertation,a novel method for synthesizing aromatic 5CCs was designed and the conditions of the ammonolysis of cyclic carbonate/amine were optimized.Hybrid non-isocyanate polyurethane materials(HNIPUs)were prepared based on high melting point aromatic 5CCs,and their properties were also studied.The specific work content is as follows:Firstly,hydroquinone-type bicyclic carbonate(H-2CC)with a melting point of 178? is prepared by using catalytic HCl removal and transesterification of hydroquinone and 3-chloro-1,2-propanediol(CPDL),-the corresponding bicyclic carbonates(BisA-2CC and BisS-2CC)were also prepared by treating bisphenol A and bisphenol S in the same way.all of this can prove diphenols can be converted into aromatic 5CCs efficiently by using this method,which is facile and does not require a complicated catalyst system compared with the epoxy-CO2 method.Secondly,a catalyst-free bulk method is used to obtain a series of linear polyhydroxy polyurethanes(PHUs)by reacting aromatic 5CCs(H-2CC,BisA-2CC,BisS-2CC)with hexamethylene diamine,the reaction temperature is lower than 120? and reaction time is relatively short.the test results of IR,DSC and NMR reveals that the amount of side reactions during the reaction process is low and the molecular weight of the prepared oligomers is slightly higher than the theoretical value.The higher molecular weight may result in the occurrence of side reactions at higher reaction temperatures and the volatilization from HAD.Finally,three kinds of amino-terminated PHUs were cured and modified by 1,4-butanediol diglycidyl and E51 to produce HNIPUs with different structures.Changes in monomer cyclic carbonate structure,urethane feed ratio and epoxy type cause changes in material properties.Experimental reaults reveal that HNIPU-H1 has better resistance to solvents;HNIPU-A7 possesses the highest tensile strength,which can reach 59.56 MPa;and HNIPUS4 exhibits better thermal stability.this work explores the application of HNIPUs in coatings and other relevant aspects.