Superhydrophobic coatings from macromolecular fluorinated silica nanoparticles through START polymerization and “grafting onto” strategy

Fluorinated substances are often introduced to enhance the hydrophobicity of surfaces of various materials. In this work, fluorinated macromolecular coupling agents (AB)nA-b-PIPMSAm are prepared via successive step transfer-addition and radical-termination (START) polymerization and photocontrolled iodine-mediated reversible deactivation radical polymerization (RDRP) at room temperature, which is then decorated on the surface of silica nanoparticles followed by iodine removal for preparing iodine-free macromolecular fluorinated silica nanoparticles (macro-F-SiNPs-I). Superhydrophobic coatings were produced simply by spin coating of the macro-F-SiNPs-I onto glass or dip coating on cotton substrates. The effect of a variety of parameters on surface superhydrophobicity, such as the solvent for spinning coating, concentration of macro-F-SiNPs-I, size of silica nanoparticles and chemical structures of (AB)nA-b-PIPMSAm, were studied in detail, and the superhydrophobic surfaces with water contact angle (WCA = 172.6°) could be facilely achieved under optimum conditions. In addition, the resultant macro-F-SiNPs-I coatings are quite stable against acidic (pH = 1), basic (pH = 13) or high salty solutions, and their excellent superhydrophobic performance was also confirmed by self-cleaning and oil/water separation experiments, which displayed fascinating promise in practical applications on a large scale.