ABSTRACT:An alkali-hydrolysable surfactant,(1-tetradecyloxycarbonylmethyl)trimethylammonium chloride, was used as an emulsifier for emulsion polymerization of styrene in water. The polymerization yielded a high molecular-weight polymer almost quantitatively. Addition of a small amount of NaOH to the resulting latex solution precipitated the polymer immediately. Analysis of the centrifuged solid indicated almost perfection of both recovery of the polymer and removal of surface-active species from it. Minimization of ionic species in the polymer solid was confirmed by a high contact angle of the polymer film with water.

Emulsion polymerizations of several vinyl monomers, styrene, methyl methacrylate, butyl methacrylate, butyl acrylate, and vinyl acetate, in water using alkali-hydrolysable cationic surfactants with a betaine ester group, (1-alkoxycarbonylmethyl)trimethylammonium chlorides, as emulsifiers were carried out and properties of the resulting latices and the polymers recovered by hydrolysis and salting out were investigated. There were little influences of the surfactants and monomers used here on the polymerizations, forming stable and monodisperse latices with a mean diameter of ca. 70 nm and giving a high molecular weight of polymers at high yields. All polymers were precipitated and recovered by adding a small amount of sodium hydroxide into the latex solutions contained little amount of ionic species. Solvent-cast films of the polymers were found to have surfaces as hydrophobic as those for the corresponding pure polymers prepared by bulk polymerization.

Adsorption of polystyrene latices containing an alkali-hydrolysable cationic emulsifier on filter papers pretreated with sodium carbonate was examined. Hydrolysis of the emulsifiers synchronized with adsorption of the latices on the paper could fix, or coat, polystyrene on the paper surface rapidly and efficiently at room temperature, and little amounts of polymers were desorbed by rinsing. In contrast, a smaller amount of the latices were adsorbed on the surface of the nonpretreated paper and most of them were desorbed from the surface by rinsing. The polymer-coated paper surface gained both water resistance and ''quick drying.'' V

Surface-active properties of cleavable surfactants with a betaine ester group-(n-alkyloxycarbonylmethyl)trimethylammonium chlorides, used as separation reagents-were investigated. Critical micelle concentrations, dispersing powers, and foaming powers were comparable to those of alkyltrimethylammonium chlorides with the same total number of carbon atoms. On the other hand, the solubilities of the four hydrophobic dyes N,N-dimethyl-3-nitroaniline, naphthalene, pyrene, and oil orange SS in the former surfactant solutions were equal to or slightly smaller than those in the solutions of the latter surfactants with the same alkyl chain length. The alkali hydrolysis yields of the formers approached 100% in aqueous buffer solution at pH 10 and 25°C within 10 min, and the yield at pH 9 was dependent on the alkyl chain length. This type of surfactant was also found to be as an efficient separation reagent which disperses carbon black and solubilizes the above dyes into aqueous neutral solution and then separates them instantaneously and almost perfectly as precipitates when a small excess of NaOH is added.

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