Role of dynamic surface tension of silicone polyether surfactant-based silicone coatings on protein adsorption: An insight on the 'ambiguous' interfacial properties of Fouling Release Coatings

Non-toxic antibiofouling coatings are currently developed to avoid the negative impacts of the settlement of (micro)organisms on any water immersed surfaces. In some industries such as microalgae culture, marine sensors or even contact lenses, in addition to the need for antibiofouling efficiency, transparency and non-toxicity are prerequisite surface properties. In this work, seven amphiphilic transparent antifouling coatings have been elaborated using silicone polyether copolymer surfactants mixed in a polydimethylsiloxane-based elastomer matrix. Average molar masses (1.3-11.7 kDa) and molar mass distributions of each surfactant were assessed by pulse-field gradient spin-echo (PGSE) diffusion NMR. Surface and bulk properties of the designed coatings were characterized by measuring their surface roughness (0.03-0.07 mu m), Young's modulus (1.4-2.2 MPa) as well as their wetting behavior. Results obtained from different wetting techniques have shown that coatings had initially a low surface free energy (around 20 mJ/m2) and that their surface became amphiphilic in contact with water (from 21 to 42 mJ/m2). Fitting of water contact angle measurements with the so-called O'Brien-Paranjape dynamic surface tension (DST) model enabled the calculation of the surfactant's diffusivities within the PDMS elastomer matrix (ranging from 9.96 x 10-15 to 1.77 x 10-13 m2 & sdot;s-1) while providing a comprehensive insight on the kinetic interfacial variation of the overall amphiphilic coating. Coatings with the highest rates of water contact angle variation have been shown to positively affect the bovine serum albumin (BSA) protein adsorption.