Soap-Free Emulsion Composed of Polymer Solutions and an Aqueous Clay Suspension

Novel emulsification was found in the system of aqueous suspension of a clay mineral (a synthetic hectorite) and a solution of polyvinyl butyral in 1-butanol without using surface-active agents. Droplets of the oil phase exhibited different sizes depending on the concentration of polyvinyl butyral solution and aqueous clay suspension. Shearing force produced from the high viscosity of the clay suspension was a factor to lead oil droplets to size smaller. The clay mineral was confirmed to be in the water phase, not at the oil and water interface. The emulsion showed useful thermal stability up to 80 °C. The present emulsion was successfully applied as a platform of the photochromic reaction of spiropyran.