Evaluation of novel synthetic conditioning polymers for shampoos

Physicochemical Aspects of the Performance of Hair-Conditioning Formulations

Most of the currently used products for repairing and conditioning hair rely on the deposition of complex formulations, based on mixtures involving macromolecules and surfactants, onto the surface of hair fibers. This leads to the partial covering of the damaged areas appearing in the outermost region of capillary fibers, which enables the decrease of the friction between fibers, improving their manageability and hydration. The optimization of shampoo and conditioner formulations necessitates a careful examination of the different physicochemical parameters related to the conditioning mechanism, e.g., the thickness of the deposits, its water content, topography or frictional properties. This review discusses different physicochemical aspects which impact the understanding of the most fundamental bases of the conditioning process.

Design of eco-friendly fabric softeners: Structure, rheology and interaction with cellulose nanocrystals

HYPOTHESIS

Concentrated fabric softeners are water-based formulations containing around 10-15 wt% of double tailed esterquat surfactants primarily synthesized from palm oil. In recent patents, it was shown that a significant part of the surfactant contained in today's formulations can be reduced by circa 50% and replaced by natural guar polymers without detrimental effects on the deposition and softening performances. We presently study the structure and rheology of these softener formulations and identify the mechanisms at the origin of these effects.

EXPERIMENTS

The polymer additives used are guar gum polysaccharides, one cationic and one modified through addition of hydroxypropyl groups. Formulations with and without guar polymers are investigated using optical and cryo-transmission electron microscopy, small-angle light and X-ray scattering and finally rheology. Similar techniques are applied to study the phase behavior of softener and cellulose nanocrystals considered here as a model for cotton.

FINDINGS

The esterquat surfactants are shown to assemble into micron-sized vesicles in the dilute and concentrated regimes. In the former, guar addition in small amounts does not impair the vesicular structure and stability. In the concentrated regime, cationic guars induce a local crowding associated to depletion interactions and leads to the formation of a local lamellar order. In rheology, adjusting the polymer concentration at 1/10th that of the surfactant is sufficient to offset the decrease of the elastic property associated with the surfactant reduction. In conclusion, we have shown that through an appropriate choice of natural additives it is possible to lower the concentration of surfactants in fabric conditioners by about half, a result that could represent a significant breakthrough in current home care formulations.