Direct observation of the nanocomplex surface reorganization of antifouling silicones containing a highly mobile PEO-silane amphiphile†
While nanocomplexity derived from surface reorganization in aqueous biofouling environments is known to give rise to antifouling behavior, quantification of this process is limited. In this work, the surface of an antifouling polymer matrix – a silicone modified with a highly mobile PEO-silane amphiphile – was characterized while undergoing dynamic surface reorganization in aqueous solution via off-resonance tapping mode atomic force microscopy (AFM) and while monitoring surface changes at a rate >25 μm2 min−1. Utilizing multimodal analysis during incubation in aqueous solution and surface force spectroscopic mapping before and after incubation, we directly observed the nanoscopically complex surface of the matrix and its five distinct stages of surface reorganization. Pre- and post-incubation nanomechanical mapping revealed a marked increase in Young's modulus and surface area, as well as increased adhesion and dissipative properties for the post-incubated surface. The observed topographic and viscoelastic changes are explained in terms of surface–air and surface–water interactions. These findings are compared to the bulk matrix reordering observed by immersion dynamic mechanical analysis (DMA) and enhanced protein resistance with increased submersion times as determined by confocal microscopy.