Atsushi Sogabe

Polymerization of a water‐swellable microgel by a novel inverse microemulsion polymerization and its application as a viscosity thickener for cosmetics

A water-swellable microgel was polymerized in the inverse micelle of a nonionic surfactant, namely a confined space. The microgel was polymerized using 2-acrylamido-2-methylpropanesulfonic acid, dimethyl-acrylamide, and methylene-bis-acrylamide. To determine a suitable polymerization system that appeared W/O microemulsion at around 65 degrees, the phase diagram of the pseudo-ternary system was studied. The microgel polymerized in the system was isolated by a reprecipitating method; consequently the samples were obtained as powder. The rheological properties of the microgel were studied after re-dispersing the powder sample in an aqueous medium. The viscosity-thickening effect of the crosslinked microgel was higher than that of the non-crosslinked sample. Moreover, a suitable crosslinking ratio was confirmed. The viscosity thickening effects of the microgel under various pH, salt concentration, and alcohol concentration conditions were also investigated. The study revealed that the microgel can be considered as a multi-purpose viscosity thickener for cosmetics.