Preparation Of RAFT-Synthesized Macro-surfactants And Their Application In Emulsion Polymerization

Water-based paint is environmentally friendly paint because of it's low VOC and low toxicity. Currently, water-based acrylic resin coating have became the most widely used varieties in water-borne coatings because of their excellent performance. Having advantage of small negative factors to film-forming resin, wide source of raw materials, low prices, the application of macro-surfactant in Emulsion is getting more and more attention.In this paper, different methacrylic acid(MAA) content of macro-surfactants P(MMA-co-MAA-co-n BA) were synthesized by UV-visible photoinitiation RAFT bulk polymerization. Their chemical structure were characterized by 1H-NMR and FT-IR. The molecular weight and distribution of polymer were characterized by GPC.The study to micelle behavior of macro-surfactant solution found that when the content of MAA is less than 5.0(mol)% in macro-surfactant, it can not be neutralized into hydrosol effectively; with N,N-dimethylethanolamine(DMAE) as the neutralizer,the particle size of micelle is small, it have a narrow size distribution and good emulsion stability, the cloud point of the solution is greater than 80?; with triethylamine as the neutralizer, it have a large particle size and a wide size distribution; it will have poor stability when the emulsion is neutralized by sodium hydroxide. When the content of MAA is more than 10.0%, the pH value have a small affection on the latex particle size, the particle size of micelle has no change when the pH value increased. When the concentration of macro-surfactant is less than 0.5%, the particle size of micelle decreases with the increase of concentration, when the concentration is between 0.5% and 15%, the particle size of micelle increases with increase of concentration.The study to the conditions of the emulsion polymerization found that it was best when the reaction temperature is 80? and the amount of initiator is 0.2wt%. Under this condition, the P(MMA-co-MAA-co-nBA) with the content of MAA is 10.0%, 15.0%, 20.0% used as an emulsifier for emulsion polymerization is studied. The higher the acid content of the emulsifier, the higher the emulsion polymerization conversion rate; the higher the emulsifier concentration, the higher the conversion rate; the higher the solids content, the lower the conversion rate. The lower the acid content of the emulsifier, the emulsion latex particle size is smaller; the greater the concentration of emulsifier, the greater the latex particle size; the higher the solids content of the emulsion, latex particle size is smaller.In this paper, the low acid content of macro-surfactant was synthesized by one-pot method. This method have the advantage of simple experimental operation, high reaction efficiency and the emulsion coating synthesized with macro-surfactant have good water resistance.