Synthesis of MCPU-PMMA hybrid emulsion through seeded emulsion polymerization
A kind of anionic micro-cellular polyurethane (MCPU)dispersion containing unsaturated double bonds in the soft segments was synthesized with modified castor oil, and it was used as polymerizable emulsifier and seed composition for emulsion copolymerization of MCPU and methyl methacrylate (MMA).1H NMR spectrum showed that double bonds existing in MCPU disappeared after it was copolymerized with MMA.Various factors that affect the seeded emulsion copolymerization were investigated through measuring the conversion of monomers, average particle size and amount of agglomeration, water and toluene resistance of the film.The results showed that when taking potassium persulfate as initiator, the emulsion copolymerization had higher conversion, the average particle size was smaller and the film had better water and toluene resistance.It was proper to keep the reaction temperature at 70℃.The activation energy of the copolymerization was 164.86 kJ·mol-1.Copolymerization rate Rp∝[I]1.0856,and the dosage of initiator should be 0.5% of the total polymerizable composition.