Synthesis And Application Of Anionic Polymerizable Surfactants

After emulsion polymerization, conventional surfactants adsorb in physical action to the surface of latex particles. The adsorption is so weak that the surfactants would desorb from the surface of latex particles in some situations. And desorption of surfactants can cause the destabilization of the latex. During the formation of the films, the surfactants can also migrate through the film, segregate and concentrate in pockets, which increase the percolation by water and in general water sensitivity. Polymerizable surfactants, which contain a polymerizable group, can be bound covalently to the surface of latex particles, and then adverse effects caused by conventional surfactants can be avoided. By using polymerizable surfactants, the stability of the latex and water resistance of the film can be improved.Sodium monoalkyl maleates polymerizable surfactants (named series A), sodium monoalkylpolyoxyethylene maleates polymerizable surfactants (named series B) and N-methyl-N-monododecylfumaroyl taurine polymerizable surfactants (named series D) are synthesized, by using normal fatty alcohols, alkyl poly(ethylene oxide) ether and maleic anhydride. The synthesis of series B and D polymerizable surfactants is investigated, and the optimal reaction conditions are obtained. The structures of the product are confirmed to be correct by IR, MS and NMR.Emulsifying capacities of polymerizable surfactants to polymer monomers system contained fluoromonomer are tested. Series A polymerizable surfactants lose emulsifying capacity when the pH value is about 3～4, and the surfactants with a moderate carbon chain length, have some emulsifying capacity when the pH value is about 7. Series B polymerizable surfactants, of which the ethylene oxide number reaches 9, have rather good emulsifying capacity independent of the pH value. Series D polymerizable surfactants with a moderate carbon chain length also have good emulsifying capacities even if the pH value is low.Some polymerizable surfactants, which show good emulsifying capacities of the three series, are applied in emulsion polymerization. As references, conventional surfactant sodium dodecylsulfate (SDS) or the mixture of surfactants sodium dodecylsulfate and nonylphenol polyoxyethylene ether (10) is used in the same polymer systems. Large amount of coagulum is producted during the polymerization, when the polymerizable surfactant from series A is used. It indicates that series A polymerizable surfactants are unsuitable for the polymerization here. Good results are obtained, when the surfactants from series B and D are used in the go-polymerizations with vinyl acetate, methyl methacrylate or styrene as the main monomer. Compared with conventional surfactants, using the polymeizable surfactants selected from series B or D, some of the latices stabilities are improved. The films made from polymeizable surfactants exhibit a better water resistance than made from conventional surfactants.