Surface crosslinking effects on contamination resistance of functionalised polymers

We have applied a theoretical modelling approach to aid in the rational design of contamination resistant coatings. Using in silico nano-indentation we have characterised the adhesion between a contaminant particle and engineered polymer surfaces that include functionalised-surface-crosslinked and functionalised non-surface-crosslinked polyesters. The roughness, density and morphology of the surfaces were dynamically monitored as the coatings responded to the approaching particle. Our results suggest that surface crosslinking provides a stable platform for incorporation of functional groups that would otherwise migrate into the bulk substrate upon aging. However surface crosslinking with rigid cyclic curing agents renders the coatings far too stiff, which can result in slip whereby surface crosslinkers shift to the side of the incoming contaminant particle, leading to both the exposure of the flexible substrate and the envelopment of the contaminant. This type of deformation negates steric repulsions of the functional groups, crucial for preventing undesirable adhesion. In contrast, functionalisation combined with flexible acyclic surface crosslinks results in superior contamination resistance.