Polymer-Surfactant Phase and Surface Interactions Leading to New Models for Cationic Polymer Chemistries

Cationic polymers are used in anionic surfactant formulations to deposit
and co-deposit actives on hair or skin surfaces. A series of cationic polymers, natural and synthetic, were investigated with surface and bulk techniques, turbidity measurements and in situ null-ellipsometry on silica surfaces in order to understand three key areas: the relation between the complex that is formed at a surface and the concentrated phase in the bulk solution, the relation between molecular adsorption of cationic polymer and/or surfactant and co-deposition of actives like silicone emulsions, and
the optimization of the formulation to achieve maximum deposition to
drive product performance. Key findings were: (1) under most conditions
an adsorbed layer of polymer and/ or surfactant is formed at the surface, but this depends greatly on the phase separation in the bulk, (2) the adsorbed amount and ability to deposit actives follows the variation in bulk phase separation because both events are governed by the cationic polymersurfactant binding isotherm, and (3) the hydrophobicity of the cationic polymer can be used to adjust the range of surfactant concentrations to where a maximum phase separation and adsorption is obtained. This led to a model for the development of a new cationic polymer, polyquaterium-76, which delivers superior wet and dry conditioning.