Surface active microgels: dual functioning soft stabilisers

Emulsions are stabilised by either surfactants or solid particles which sit at the interface between the phases. Particles irreversibly adsorb to an interface whereas surfactants detach under small perturbations. Due to their enhanced stability, particle-stabilised emulsions are used as a base for many products such as foods and pharmaceuticals. Furthermore, particles impart elasticity to interfaces, a quality which enhances the sensory performance of foods without the need for excessive amounts of fat [1]. Personal care products are another potential application as they require enhanced sensory properties and tuneable stability.

However, particle-stabilised interfaces can become unstable when dilated or compressed, processes which are common in processing. This instability, known as buckling, occurs when colloids jam together causing films to collapse.

We present work done on a commercial microgel system, composed of an amphiphilic polymer called Sepimax Zen (SZ). We show that SZ microgels stabilise an oil-water interface forming elastic films which are immune to buckling and can also be used to thicken suspensions.

[1] Husband, F. et al. Gums and Stabilisers for the Food Industry 17: The Changing Face of Food Manufacture: The Role of Hydrocolloids 17, 230 (2014).