Experimental investigation of a polymer coating in sliding contact with skin-equivalent silicone rubber in an aqueous environment

A study on the effect of a brush coating of polyacrylic acid (PAA) grafted with poly(ethylene glycol) (PEG) (PAAg- PEG) on friction was done for a sliding system that involves silicone skin L7350: a silicone rubber used by the Fédération Internationale de Football Association (FIFA) for the determination of skin-surface friction in combination with artificial grass. Friction experiments were carried out using a reciprocating flat-on-flat test setup with the selected brush coating and compared with PAA-coated and fluoroalkane-coated samples. The experiments were focused on the effect of water. Results for the coatings tested at dry conditions showed a coefficient of friction above 1. Effective lubrication by water was able to reduce friction to a coefficient of friction below 0.01 at low sliding velocities. The results are currently used to further develop low-friction products for sliding interactions with human skin; for example, artificial grass and possibly medical textiles.