(488a) Surface-Initiated Polyhomologation to Prepare Superhydrophobic Films

Surface-initiated polymerizations provide an effective approach to engineer surface properties. Inspired by the versatile solution-phase method, polyhomologation, we have developed a new surface polymerization strategy that yields superhydrophobic polymethylene (PM) films from a variety of substrates, including gold and silicon. Surface-initiated polyhomologation (SIPH) presents rapid growth in relation to other solution-phase surface-initiated reactions, producing PM films thicker than 200 nm after 2 min of reaction and 3 μm after 24 h of reaction. These films exhibit advancing water contact angles greater than 160º, dramaticially different than 103º measured for smooth PM films, and hysteresis values ranging from 2º to 40º, depending on the substrate. These superhydrophobic PM films provide remarkable resistances greater than 10¹⁰ Ω?cm2 against the transport of aqueous redox probes and capacitances that are comparable to those of smooth PM films that are 70% thicker. The exceptional barrier properties of PM films grown from SIPH is attributed to the combination of nanoscale and microscale surface morphologies that enables modeling the surface as a composite of PM and the air trapped in the grooves of the film. The ability to grow PM films on different substrates, combined with the special morphology of the films, makes SIPH an attractive strategy to modify surface properties for targeted applications.