Mechanochemical Grafting of Polydimethylsiloxane for All Dry Rapid Fabrication of Superhydrophobic Surfaces

Superhydrophobic (SHP) surfaces are non-wettable by water and have great significance for a broad range of technological applications. Existing methods of fabricating SHP surfaceshave limitations in terms of excessive usage of solvents, needfor tedious and lengthy chemical processes and cost of materials. Herein, we present mechanochemical grafting of methylterminated poly(dimethylsiloxane) (PDMS) to nanoparticlesfor practical and sustainable fabrication of SHP surfaces. Methyl-terminated polydimethylsiloxane is usually considered to beinert and, thus, not reactive with surfaces. The grafting of silicone to the nanoparticles is achieved by using a planetary ball mill. During the ball milling, collisions between tungsten carbideballs and walls of the chamber results in hydrolytic rupture ofsiloxane bonds and mechanochemical generation of free radicalsin the silicone, which grafts to the surface of nanoparticles. Theentire process consists of mixing of two widely available components, PDMS and nanoparticles, followed by agitation in aplanetary ball mill for 5 min. The SHP powder with a water contact angle of 165o and sliding angle of 2o is readily obtained atthe end of the process without need for any washing, separationand drying steps. The mechanistic force suggest that generationof free radicals induced by mechanochemical pathways enablescovalent grafting of PDMS. The use of non-functional and lowcost PDMS is an enabling aspect for applications. The superhydrophobic powder fabricated with a mechanochemical approachoffers enormous potential with scalability, sustainability, cost-effectiveness, simplicity, and universality.Keywords: Mechanochemistry, superhydrophobic surfaces,PDMS, sustainable