RADICAL POLYMERIZATION OF A CATIONIC LIPI DLIKE MONOMER AT WATER AIR INTERFACE

Radical polymerization of N,N-diallyl(N-cetyl)dodecylammonium bromide, which is a cationic monomer containing two hydrocarbon chains, in a m onolayer at water-air interface was studied using two-dimensional dila tometry. The polymerization rate decreased with an increase in lateral pressure in expanded monolayer and condensed monolayer with high pack ing density; however, it increased in a condensed layer with low densi ty of the molecular packing. This behavioral pattern was explained by the effect of packing density on the charge and mobility of the reacti ng species. The effect of various compounds (an electrolyte, ethanol, surfactant, and water-soluble polymers) on monomer polymerization in t he condensed monolayer with low packing density was investigated. In t he presence of these compounds, the polymerization rate decreased. In the case of ethanol and surfactant, this was due to the dilution of mo nolayer, whereas when sodium bromide, poly(ethylene glycol), or poly(a crylic acid) were added, some of the monomer was found to become nonpo lymerizable.