Thiol-ene “click” networks from amphiphilic fluoropolymers: full synthesis and characterization of a benchmark anti-biofouling surface

Abstract

The synthesis of heterogeneous, amphiphilic crosslinked networks from photo-initiated thiol-ene chemistry and full characterization of the physicochemical, anti-biofouling, mechanical, and thermal properties of this system are reported. Although interest in coatings that present heterogeneous surface features is increasing, anti-biofouling performance is typically compared to homogeneous biocidal- or non-toxic polydimethylsiloxane-based paints, for the advancement of commercial and novel systems, which leaves a need for a benchmark to compare highly complex, heterogeneous composites with similar complexities. This system has been generated and rigorously analyzed to understand how microscopic and nanoscopic disorder, resistance to protein adsorption and surface mechanical properties can be fine-tuned and optimized through oligomer selection, blend ratios and process conditions. Solution-state studies of individual and blended constituents probed the relative fluorescence intensities based on concentration and neighboring species that were used to identify microscopic disorder on the surface. Incubation of a fluorescently labelled protein on the benchmark surface showed 42% and 72% less adsorption than on model surfaces that largely expressed a single component. The extent of reaction and the identification of unconsumed functionalities were found through infrared spectroscopy. The benchmark surface had a Young's modulus of approximately 0.5 GPa, 7 to 35 times higher than model surfaces, with 50 times the variation in modulus. Nanoscale surface adhesion force variation and bulk wettability and bulk thermal stability are also reported. This study provides an extensive list of metrics to be used for the development of complex, heterogeneous, anti-biofouling coatings, appropriate to both surface optimization and mechanical tunability, for implementation in real-world applications.