Two-dimensional hierarchical porous silica film and its tunable superhydrophobicity

Based on a monolayer polystyrene (PS) colloidal crystal, large-scale two-dimensional (2D) hierarchical porous silica (orderly arranged macropores and disordered mesopores in its skeleton) with a high specific surface area was fabricated by the sol-gel technique. Such material has demonstrated superhydrophilicity with a water contact angle (CA) of 5 degrees and superhydrophobicity with a water CA of 154 degrees after surface modification with fluoroalkylsilane. More interestingly, the water CA can be increased to 165 degrees using a heat-deformed PS template, which suggests that the superhydrophobicity can be controlled by the template with different heat-deformed extents. Such silica films have applications in fields of adsorbent, catalytic,