Modeling adsorption and stability of polymer coatings on heterogeneous surfaces

IRENE ADROHER-BENÍTEZ; TATIANA I. MOROZOVA; NICOLÁS A. GARCÍA; JEAN-LOUIS BARRAT; GUSTAVO S. LUENGO; FABIEN LÉONFORTE

Santiago de Compostela

Conferencia; IX Iberian Meeting on Colloids and Interfaces - RICI9; 2022

Polymers are key ingredients in most cosmetic products. In order to reconcile our daily needs with the preservation of a resource-limited planet, for some years now cosmetic industry has been making a great effort to improve sustainability and performance in new formulations. In the case of hair care, cosmetic performance is determined by the way polymers adsorb in the hair surface, which is highly conditioned by the physico-chemical properties of its external structure. However, despite the large amount of experimental work already done in this direction, it remains to be known which physical quantities play a determining role in polymer adsorption onto hair-like substrates, as well as in the stability of these polymeric coatings.With this aim, in our group we have worked to develop a computational framework to analyze the polymer adsorption dynamics in realistic surfaces and the stability of the formed layers for different chain composition and architecture. First, we modeled semi-flexible linear chains in which each bead corresponds to a monomer. With this model we aimed to study the performance of simple molecules of natural origin. Then, we created a branched stiff polymer model with 17 beads per monomer. This more complex system was intended to mimic some of the macromolecules currently used in the cosmetic industry.For these models we have performed implicit-solvent Molecular Dynamics simulations to study the quantities involved in polymer adsorption, such as chain length, polymer architecture and concentration. We have analyzed the structure of the resulting coating and compared the results for the three types of polymers. Then, we have used Brownian dynamics simulations to apply a linear shear flow on the adsorbed polymer layer. This way we have tested the stability of the coating and we have analyzed the dynamics of the polymer desorption.