Emulsion polymerization particle surface character

Mention has been made of the fact that the polar character of polymer surfaces is strongly affected by the ionic polymer end groups that are residues of initiator-derived ion radicals, when persulfates are used in emulsion polymerizations. Variation of the initiator type between those that yield ionic and nonionic end groups is an effective way to control particle stability and avoid complications due to migration of surfactant from one polymer surface to another [25]. This method can also be supplemented by copolymerization with polar monomers to affect surface hydrophilicity. 

The mechanism of the continuous emulsion polymerization of vinyl chloride was discussed in Ref. [117]. Here, the effects of the feeding rate and/or the reaction time on the size of latex particles were followed. Variations in the particle size or number have an undulating character. The emulsifier is continuously fed into the reactor and adsorbed on the free sites on the particle surface. Under these conditions, the covering degree of the latex particles is very high (close to 100%) as it was shown in the surface tension measurements. The surface tension (a) of the PVC latex during the continuous emulsion polymerization of VC varies between 38 to 46mN/m [118]. From the surface tension... 

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