Study On The Synthesis Of Three-arm Star Copolyether And Its Application In Preparation Of Polyether Polyurethane

The star polymer is the branched polymer which contains above three or three linearpolymer chais that chemically bonded to the same point, and there is no distinction betweenthe main chain and the branched chain. Compared with the same molecular weight linearpolymers, star polymers have a unique spatial structure, special performances such as higherfunctionality, smaller hydrodynamic volume, lower diffusion coefficient, viscosity andcrystallinity which have widespread theoretical significance and industrial application. In thispaper, three-arm propylene oxide/tetrahydrofuran (PO/THF) star copolyether and three-armpolyethylene glycol/tetrahydrofuran (PEG/THF) star copolyether were synthesized bycationic ring-opening polymerization, and the synthesized copolyether was characterizedthrough infrared spectroscopy (IR), gel permeation chromatography (GPC) and nuclearmagnetism resonance test (1H NMR). Moreover, polyurethane elastomers were prepared withthree-arm star copolyether, and their mechanical properties and thermal properties werestudied, and the expected results were attained. The main results are as follows:After characterized by IR,1H NMR and GPC, it was found that three-arm PO/THF starcopolyether was synthesized through tetrahydrofuran (THF) cationic ring-openingpolymerization by using glycerol as initiator, boron trifuoride ether (BF3·OEt2) as catalyst,and propylene oxide (PO) as assistant for ring-opening. The suitable reaction conditions are asfollowing: the amount of glycerin accounts for3%of all the reactants, the catalyst for5%ofTHF molar amount, the PO for12%of THF molar amount, reaction time is6h. GPC resultsshow that the synthesized polyether has a narrow molecular weight distribution.The produced three-arm PEG/THF star block copolyether was characterized by IR,1HNMR and GPC. It was found that PEG/THF star block copolyether was prepared withthree-arm polyethylene glycol and tetrahydrofuran as main raw materials and boron trifluoride ether as catalyst by means of cationic ring-opening polymerization. The better synthesisconditions were determined by orthogonal experiment and single factor experiment. Thethree-arm star copolyether with higher molecular weight was obtained under the followingsuitable conditions: reaction time for1.5h, PEG for20g, the PO for12%of THF molaramount, the catalyst for4%of THF molar amount. The relative molecular mass ofcopolyether can be adjusted by the dosage of PEG.And then the polyurethane elastomers was synthesyed by one-step method withthree-arm star copolyether as one of raw materials,1,4-butanediol (BDO) as chain extender,toluene diisocyanate (TDI) as curing agent, dibutyltin dilaurate (DBTDL) as catalyst, and themechanical properties and thermal properties of polyurethane elastomer was studied. Theelastomers have satisfactory mechanical properties, low glass transition temperature，andgood thermal stability. Compared with linear polyether urethane elastomer, star copolyetherelastomers have better mechanical properties.