Heterogeneous Cross-Linking of Polymer Latexes

The preparation of a porous material by cross-linking of latex particles is described. The particles were obtained by the concentrated emulsion procedure. A concentrated emulsion of methyl methacrylate with an internal phase ratio of 0.91 was prepared first, by using an aqueous solution of sodium dodecyl sulfate as the continuous phase. When the polymer conversion reached about 20%, the concentrated emulsion was dispersed in a dilute aqueous solution of hexamethylenediamine. The latexes flocculated in the presence of diamine, upon heating at 40 degrees C. However, the flocculated solid became insoluble in benzene only after subsequent heating at 150 degrees C. IR, HPLC, and swelling studies suggest that cross-linking, produced by the diamine, is responsible for insolubilization. The materials thus obtained exhibit higher equilibrium swelling and faster swelling than the bulk cross-linked materials.