Miniemulsion polymerization with cationic and nonionic surfactants: A veryefficient use of surfactants for heterophase polymerization

The principle of miniemulsion polymerization is extended to cationic surfac tants, i.e., CTAB, CTMA(2) tartrate, and CTMA(2) terephthalate, and nonioni c surfactants, i.e., Lutensol AT50. Similar molecular amounts of the cation ic surfactant CTAB compared to the anionic surfactant SDS result in similar particle sizes. The cationic counterion-coupled gemini surfactants (cocoge ms) show only moderate activity in miniemulsification. Surface tension meas urements were used to determine the surface coverage and therefore the effi ciency of the surfactants in the miniemulsification process. The data for t he different latexes show that the underlying energetic rules of miniemulsi ons are different from microemulsions. It is speculated that for miniemulsi ons the ability for surface spreading is advantageous whereas low absolute interface energies and a high area requirement per surfactant are favorable for microemulsions. Reaction calorimeter data are also presented to show t hat the concept of the miniemulsion polymerization is essentially a 1:1 cop ying of the original droplets, possessing no complicated dependence of kine tics and particle size on the amount and locus of initiation as found for e mulsion polymerization.