Synthesis Of Functional Polyacrylate Emulsion By UV-initiated Polymerization

Polyacrylate emulsions have been in a wide range of applications due to their excellent properties. Three kinds of polyacrylate emulsion were successfully prepared by UV-initiated emulsion polymerization, which combined with advantages of UV polymerization and emulsion polymerization. The results were exceptional:we not only obtained emulsion latex with small particle size (about 20～50 nm), but also found that the polymerization could be performed within 15 min at room temperature and displayed high conversion.Firstly, a fluorine-containing polyacrylate emulsion was synthesized by UV-initiated emulsion polymerization in the presence of Irgacure 2959 as a hydrophilic photoinitiator. The effects of photoinitiator and emulsifier concentration on the polymerization were discussed. Compared to the corresponding thermal polymerization, UV-initiated emulsion polymerization could be accomplished at a much higher speed. The polymerization conversion in UV-initiated polymerization reached 95% within 10 min at an emulsifier concentration of 0.6 wt%, photoinitiator concentration of 0.4 wt%, and monomer concentration of 10 wt%.Afterwards, a core-shell fluorine-containing polyacrylate emulsion was successfully prepared by UV-initiated seeded emulsion polymerization. The core was prepared from MMA in the presence of water-soluble photoinitiator Irgcure 2959, and the shell was prepared from BA/HFBA/MAA in the presence of oil-soluble photoinitiator Irgcure 184. Both of the two stage polymerizations could be completed within 15 min and displayed a conversion above 94%. The average particle sizes of the PMMA seed emulsion and the core-shell emulsion were measured to be 25 nm and 40 nm, respectively. The core-shell fluorine-containing polyacrylate latex film which was composed of fluorine-free core and fluorine-containing acrylate shell exhibited better hydrophobicity and hgher thermal stability compared with fluorine-free latex film.Finally, the polyacrylate emulsions with different hydroxy values were successfully prepared by UV-initiated emulsion polymerization withβ-hydroxypropyl methacrylate (HPMA) as a hydroxy monomer. The polymerizations could be completed within 15 min and displayed a conversion above 96%. The particle size could be as small as 45 nm, but the latex had a wide particle size distribution. The emulsions were used as hydroxy component in two component waterborne polyurethane coatings and the films had excellent properties. The effects of the hydroxy value and molar ration of NCO and OH groups on film performace were discussed. The film had acceptable properties and cost when the hydroxy value was 100 mgKOH/g, and molar ration of NCO and OH groups was 1.3:1.