Synthesis Of Polyacrylate Grafted Soybean Oil-based Waterborne Polyurethane

Epoxidized soybean oil is one of the common soybean oil derivatives.Its epoxy groups can be converted to hydroxyl groups through different methods to give soybean oil-based polyols,which can be used as polyols for synthesis of waterborne polyurethane(WPU)coatings instead of petroleum-based polyols.Compared with traditional solvent-based polyurethane,WPU also has the disadvantages of poor coating film performance,poor water and moisture resistance,low hardness,low thermal stability and poor mechanical properties.These shortcomings can be effectively overcome with acrylate-modified aqueous polyurethanes.In this paper,three soybean oil-based polyols were prepared using epoxy soybean oil as materials,and WPU was prepared using these soybean oil-based polyols.Methyl methacrylate(MMA),butyl acrylate(BA)and tridecafluorooctyl methacrylate(PFOMA)were grafted onto WPU for modification.First,chlorinated soybean oil-based polyol(SOL)was synthesized from epoxy soybean oil,and then a low-viscosity soybean oil acrylate(ACSO)was prepared using SOL and acryloyl chloride under low temperature without catalyst.A chlorinated soybean oil-based urethane acrylate polyol(ADSO)containing urethane bonds was synthesized by a condensation reaction of SOL and isoflurone diisocyanate(IPDI)modified with hydroxyethyl acrylate.SOL,ACSO and ADSO were characterized by infrared spectroscopy(FTIR)and nuclear magnetic resonance spectroscopy(NMR).Then,soybean oil-based waterborne polyurethane(ACSO-WPU)was synthesized by the reaction of SOL and ACSO with IPDI and 2,2-dimethylolpropionic acid(DMPA).Soybean oil-based waterborne polyurethane grafted polyacrylate(ACSO-PUA)emulsion was prepared by soap-free emulsion polymerization using double bonds in SWPU as reaction sites with MMA and BA as monomers.The results of Fourier transform infrared spectroscopy(FT-IR),laser particle size analyzer and transmission electron microscopy(TEM)showed that the grafted copolymer was successfully prepared,and the particle size was distributed between 100-300 nm.Furthermore,the effect of the ratio of MMA and BA on the properties of grafted copolymer films was studied.The results showed that in comparison with the ACSO-WPU film,the water absorption of ACSO-PUA film was significantly reduced,the hardness was obviously improved,and the mechanical properties and thermal stability were also improved.With the increase of MMA content,the water absorption decreased from 113% to 9%,the hardness increased from H to more than 3 H,the tensile strength increased from 2 MPa to 11 MPa,and the thermal decomposition temperature increased from 116 ℃ to about 210 ℃.Finally,soybean oil-based waterborne polyurethane(ADSO-WPU)was synthesized by the reaction of SOL and ADSO with IPDI and DMPA.Soybean oil-based waterborne polyurethane grafted polyacrylate(ADSO-PUA)emulsion was prepared by soap-free emulsion polymerization using double bonds in ADSO-WPU as reaction sites with MMA,BA and PFOMA as monomers.The test results of FTIR,laser particle size analyzer and TEM showed that the graft copolymer was successfully prepared.Furthermore,the effect of the ratio of PFOMA,MMA and BA on the properties of the graft copolymer film was studied.The results showed that as the content of PFOMA increased,the water absorption decreased from 108% to 10.17%,the hardness increases from 4H to 6H,and the tensile strength increases from 2 MPa to 6 MPa.The thermal decomposition temperature increased from 156 ℃ to about 190 ℃.