Five-membered Cyclic Carbonate Used For The Preparation And Modification Of Polyurethane

Polyurethane polymers with ureathane functional groups and outstanding properties were widly used in many domains. But they still have many problems in the application process due to raw materials used for the synthesis of polyurethane and the feature structures of polyurethane. Monomers with five-membered cyclic carbonate were prepared in this study and the kinetics, relationships between structures and properties of non isocyanate polyurethane (NIPU) had been investigated based on the reaction of carbonate monomers with amines. The graft modification of polyurethane to improve the thermal stability was also investigated. The novel study had been divided into the following parts:(1) Functionalized poly(ethylene glycol) methyl ether (mPEG) end capped with five-membered cyclic carbonate (mPEG-GC) was synthesized from mPEG (Mn=2000g/mol), succinic anhydride and glycerol-1,2-carbonate. Reaction rate constants and activation energy were evaluated from the model reaction between mPEG-GC with amines at different conditions. The reaction conditions were optimized. The reactions between five-membered cyclic carbonate with amines obeyed a second-order reaction kinetics model. The lowest activation energy was obtained when reacted with heptylamine (Ea=5.63KJ/mol). The conversion of five-membered cyclic carbonate increased with increasing of reaction time, temperature and concentration while decreased with further increase of the concentration.(2) Functionalized poly(caprolactone) diol (PCL) and poly(ethylene glycol) (PEG) end capped with five-membered cyclic carbonate (PCL-2GC and PEG-2GC) were synthesized from PCL (Mn=2000g/mol), PEG (Mn=2000g/mol), succinic anhydride and glycerol-1,2-carbonate. Small molecualr carbonate monomers were prepared by cycloaddition of CO2 to difunctional epoxids compounds. The molecular weight, structure and properties of linear NIPU polymers were studied through polycondensation of carbonates with 1,6-hexanediamine,4,4'-methylenedianiline,4,4'-methylenebis(aminocyclohexane) and Huntsman Elastamines(?). The relationships between thermal mechanical properties, phase structure and crosslink density of crosslinked NIPU/SiO2 polymers were investigated using silane coupling agents. The enhanced thermal stability of NIPUs was benefit from the pendant hydroxyl groups which could form a stable ring structure through hydroxyl bonding to the urethane groups. The number of hydroxyl groups and thermal stability of NIPUs decreased as the crosslink density increased. The highest molecular weight of NIPU (Mn=25647g/mol, Mw=56482g/mol) was obtained under 70℃for 24h when the reactants concentration was 1/3mol/L. TG analysis showed that the thermal stability of NIPU was higher than traditional PU due to intramolecular hydrogen bonds between hydroxyl and urethane groups. The thermal stability of crosslinked NIPUs decreased as the crosslinking density increased.(3) Two series of "click diols" bearing functional groups were easily synthesized based on the derivation ofβhydroxyl during the reaction of carbonate with amine. Therefore the graft modification of polyurethanes were obtained through one-pot in-situ polycondensation of isocyanate, polyol and "click diols". The thermal stability of modified polyurethanes was improved with out any loss of mechanical properties. The initial degradation temperature and thermal degradation activation energy of the graft-modified PUs improved up to 330℃and 386.1KJ/mol respectively and the mechanical properties kept well after degraded at 180℃for 30min.