Superhydrophobic coating with ultrahigh adhesive force and good anti-scratching on elastomeric substrate by thiol-ene click chemistry

In this study, a Superhydrophobic (SH) surface with ultrahigh adhesive force and good anti-scratching property was created on elastomeric substrate by thiol-ene click chemistry. The elastomer substrate was prepared by solution mixing of styrene butadiene rubber (SBR), polar fluorinated monomer, multi-functional thiol, and photoinitiator. Then the silanized nano-silica was simply sprayed on the elastomer substrate to prepare the SH coating. Through UV irradiation, thiol-ene click reaction between multi-functional thiol and double bonds of SBR, fluorinated monomer and silanized nano-silica simultaneously occurs, leading to the crosslinking of SBR, the polymerization of fluorinated monomer, the graft of fluorinated monomer on silanized nano-silica, and the covalently bonding of fluorinated monomer with SBR substrate. As a result, the polymerized fluorinated monomer bonded silanized nano-silica is covalently bonded with the SBR substrate. Meanwhile, the silanized nano-silica forms the micro-nano structure on the substrate and the polymerized fluorinated monomer decreases the surface energy of the substrate. A stabilized SH coating with ultrahigh adhesive force (123 μN) to water was achieved. In addition, the SH surface shows strong interfacial bonding and a good anti-scratching property because of the covalent bonding of SH coating with the SBR substrate. This is a facile, simple and efficient method to fabricate SH coating on the elastomeric substrate, which may open a door to fabricate SH coating on other surfaces and provide more potential applications.