Series of styrene‐methyl methacrylate and styrene‐methacrylic acid copolymer latices have been prepared by emulsion polymerisation using polyoxyethylene nonyl phenyl ether as emulsifier and potassium persulphate as initiator. the effects of surfactant concentration and monomer composition on the ultimate particle size and conversion were investigated. The ultimate particle diameters decreased with increasing surfactant concentration, while the conversions were found to be almost independent of surfactant concentration. The ultimate particle diameters were notably decreased by increasing the content of methacrylic acid. Trace carboxyl groups were detected both in polystyrene latex and styrene‐methyl methacrylate copolymer latices. The number of sulphate groups on the polystyrene latex surface was about five times that of carboxyl groups.

A series of poly(methylmethacrylate), acrylonitrile-methylmethacrylate copolymer, and acrylonitrile-styrene copolymer latex dispersions has been prepared by emulsion polymerization using various combinations of anionic and nonionic surfactants. The effect of surfactants present during the process of emulsion polymerization on the stability of latex dispersions has been investigated using simple electrolytes as coagulating agents. The particle diameter increases with an increase in the amount of nonionic surfactant in the surfactant mixture; the diameter also depends on the HLB value of the nonionic surfactant used. The values of critical coagulation concentration of latex dispersions increase with increasing proportion of nonionic surfactant in the surfactant blend, and also increase as the HLB values of the nonionic surfactants decrease. The f potential at critical coagulation concentration decreases with an increase in the proportion of nonionic surfactant.

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Styrene-acrylonitrile copolymer latices were prepared by emulsion polymerisation using sodium lauryl sulphate as emulsifier and potassium persulphate as initiator. The effect of polyoxyethylene nonyl phenyl ether on the stability of these copolymer latices has been investigated using magnesium chloride as a flocculating agent by measuring the rates of flocculation in the presence of various concentrations of surfactant. The values of the critical coagulation concentration (c.c.c.) were found to increase with increasing surfactant concentration for all latices. The rates of increase in C.C.C. with increasing surfactant concentrations were found to increase uniformly with increase in the content of acrylonitrile. The electrophoretic behaviour of these latices in the presence of surfactant has also been investigated. The values of mobilities at C.C.C. were found to decrease with increase in concentration of surfactant.