In situ covalent bonding in polymerization to construct robust hydrogel lubrication coating on surface of silicone elastomer

With the great process of hydrogels-based lubricating materials, it is still a big challenge to controllably and firmly modify thin hydrogels lubrication film onto the surface of elastic/hydrophobic substrates with low surface energy. Herein, one novel strategy to grow firm hydrogels lubrication coating on the surface of PDMS elastomer is reported by the combination of surface catalytic initiated radical polymerization (SCIRP) method and in situ bridge molecule anchoring strategy. In typical case, PAAm/PAA hydrogels lubrication layer can be in situ generated and covalently anchored on the surface of PDMS by using –C=C groups as coupling sites in the assembled KH570 molecule at ambient temperature. Meanwhile, the thickness of the growth hydrogels layer is highly controllable and can be finely regulated from dozens of micrometers to several hundred micrometers. The bonding strength of the growth hydrogels layer against PDMS substrate can be achieved to 30 N/m. Correspondingly, the growth hydrogels layer demonstrates excellent water-lubrication and anti-wear properties based on these above characteristics. We believe that this method would exhibit potential applications in the fields of biomedical device, microfluidic and soft actuation.