Fluorinated Polymer Brush-Grafted Silica Nanoparticles: Robust and Durable Self-Cleaning Coating Materials

Development of highly hydrophobic surfaces having excellent self-cleaning abilities has found diverse applications in the recent years in several fields like architecture, textiles, electronics, etc. In this work, we have demonstrated a simple and easy procedure to construct a stable, self-cleaning, highly hydrophobic composite coating material. Two different types of fluorinated polymers, namely, poly(pentafluorostyrene) (pPFS) and poly(pentafluorophenyl acrylate) (pPFPA), were grown on the silica nanoparticle (SiNP) surface for the preparation of FPB-g-SiNP. Further, FPB-g-SiNPs were used as nanofillers to constitute a coating with multiscale roughness on the bare polystyrene (PS) surface, and the resulting composite coating (FPB-g-SiNP/PS) yielded a very highly hydrophobic surface with contact angle values as high as ∼143°. The presence of fluoropolymer chains in the composite coating material imparts excellent chemical durability, mechanical stability, and robustness to it. The composite coating material is also in close proximity of hydrophobic (fluorinated chains) and hydrophilic (free hydroxyl groups) regions on FPB-g-SiNP that resulted in a heterogeneous surface which helped in achieving strong water repellence along with reasonable wettability, leading to self-cleaning ability similar to a superhydrophobic surface. The highly hydrophobic characteristic of the coating material can be tuned by changing the weight % of FPB-g-SiNP added to the bare polystyrene. The uniqueness of our current work is that we have readily achieved the highly hydrophobic characteristic of a robust and durable coating that has high potential to be a superhydrophobic or slippery liquid-infused porous surface.