Self-healing antifouling polymer brushes: Effects of degree of fluorination

Heavily fluorinated polymeric coatings are used by industry in the prevention of polymeric fouling. However, due to their potential toxicity and lack of durability, there is an increasing demand for sustainable alternatives. In this research, eleven polymer brushes with varying side chain lengths and degrees of fluorination have been developed, and their antifouling and self-healing performances have been compared. In all cases where damage was inflicted by a pH 3 solution, the coatings – including the non-fluorinated ones – showed full restoration of their contact angle upon placement in an oven at 120 °C, confirming the self-healing ability of this range of coatings. One coating, poly(C10-MAF0), was unharmed by the acidic conditions, hence no self-healing capability could be established. Investigation with four fluorescently labelled polymer solutions and confocal fluorescent microscopy confirmed that all coatings have antifouling properties towards organic polymers. The more heavily fluorinated polymer brushes performed better than the rest, and not the non-fluorinated but rather the singly fluorinated brushes showed the least antifouling capability. Determination of the critical surface tension confirmed this trend: the heavily fluorinated polymer brushes have the lowest critical surface tension, and the singly fluorinated polymer brushes have the highest. A lack of alignment of the side chains of the polymer brushes is the proposed reason for this, explaining the contrast with previously reported monolayer experiments. Finally, we explain why both fluorinated and non-fluorinated brushes display self-healing characteristics.