Shearing Friction Behaviour of Synthetic Polymers Compared to a Functionalized Polysaccharide on Biomimetic Surfaces: Models for the Prediction of Performance of Eco-designed Formulations

The substitution of natural, bio-based and/or biodegradable polymers for those of petrochemical origin in consumer formulations has become an active area of research and development as the sourcing and destiny of material components becomes a more critical factor in product design. These polymers often differ from their petroleum-based counterparts in topology, raw material composition and solution behaviour. Effective and efficient reformulation that maintains comparable performance to existing products requires a deep understanding of the differences in behaviour between polymers. In this work, we simulate the tribological behaviour of three topologically distinct polymers in simplex solutions in presence of surfactants and in contact with hair-biomimetic patterned surfaces: a strongly charged polyelectrolyte poly-(diallyldimethylammonium chloride) (Merquat 100TM, Polyquaternium 6), a zwitterionic copolymer of acrylic acid, 3-trimethylammonium propyl methacrylamide chloride and acrylamide, (Merquat 2003TM, Polyquaternium 53) and one generic functionalized polysaccharide. Merquat 100TM is a relatively simple linear cationic homopolymer. Merquat 2003TM is a pseudorandom block copolymer with a hydrophilic linear block and a brush-like cationic block. The chosen polysaccharide is a highly branched, amphiphilic and quanternized polymer with a cellulose-like backbone. Such topological differences are expected to affect rheological properties, as well as their direct interaction with structured biological substrates. Using a refined Martini-style coarse-grained model we describe the polymer-dependent differences in aggregation behaviour as well as selective interactions with the surface depending on the structure. Finally, we introduce a formalism to characterize the response of the solution to shear as an initial study on lubrication properties, that define the sensorial performace of these systems in cosmetics (i.e. , manageability, touch, etc.). The tools and techniques presented in this work illustrate the strength of molecular simulation in eco-design of formulation as a complement to experiment. These efforts help advance our understanding of how we can relate complex atomic-scale solution behaviour to relevant macroscopic properties. We expect these techniques to play an increasingly important role in advancing strategies for green polymer formulation design by providing an understanding for how new polymers could reach and even exceed the level of performance of existing polymers.