Inside the Polymer-Free Gels Built From Two Networks at Once

A gel is usually understood as a single structural event: a polymer chain locks water in place, or a wax network stiffens an oil. A study in the International Journal of Cosmetic Science describes a cosmetic gel built from two separate gelling events happening at once, at different size scales, inside the same jar.

The team, led by Andrea Gregorio Gomes with Lea Broche, Bruno Payre, Emile Perez, Celine Picard and Sophie Franceschi, started with an oil-in-water emulsion made hot, then cooled it down. Dissolved in the oil phase was 12-hydroxystearic acid (HSA), a well-known organogelator that self-assembles into a fibrous network as it cools, turning each liquid oil droplet into a small solid, gelled particle. Those particles then pack together and interact to form a second network at the scale of the whole formula, a colloidal hydrogel built not from a single gelling polymer but from a dispersion of gelled oil particles suspended in water.

The researchers tested two emollients with distinct profiles familiar to formulators, sweet almond oil and phytosqualane, and paired each with one of three surfactants: anionic, cationic, or nonionic. Every combination produced a stable colloidal hydrogel once HSA was present, according to the paper, meaning the gelation itself was reliable regardless of which oil or surfactant chemistry was in the mix. What varied was everything downstream of that: the firmness, cohesiveness, and spreadability of the resulting texture.

That variation is the part with practical weight for formulators. The nonionic surfactant consistently produced firmer gels than the charged surfactants did, the authors report, a finding they tie to differences in how each surfactant type organizes at the oil-water interface and how that interface then templates the HSA fiber network inside each particle. In other words, the surfactant was not a passive dispersing agent sitting on the sidelines of the formulation. It was shaping the internal architecture of the gel particles themselves, and therefore the final texture, alongside the oil and the organogelator.

The authors characterized these systems with microscopy to examine particle microstructure, rheology to measure firmness and flow behavior, and sensory evaluation to assess how the gels actually felt on application, tying each texture back to a specific oil-surfactant pairing. The result reads as a map of a formulation system rather than a single ingredient story: change the surfactant charge, and the fiber network inside each gelled oil droplet reorganizes; change the oil, and the same surfactant produces a different cohesion.

The appeal the authors describe is a texture built without added thickening polymers, since the structuring work is done by the oil-soluble HSA network and the surfactant-templated particle architecture instead. For a formulator weighing a carbomer-free or polymer-free claim, that is the detail worth sitting with: the firmness on a test panel's fingertips traces back to which surfactant class was chosen to disperse the HSA-gelled oil droplets, not to any single headline ingredient.