Biomimetic polyimide nanotube arrays with slippery or sticky superhydrophobicity

In this paper, we report the fabrication of superhydrophobic polyimide (PI) nanotube arrays with different topographies, which possess slippery or "sticky" superhydrophobicity. The PI nanotube arrays were fabricated by the porous alumina membrane molding method. We regulated three kinds of solvent evaporation and drying processes, which controlled different congregated and noncongregated topographies of PI nanotube arrays. Large scale comb-like congregated topography possesses a small sliding angle (SA<5 degrees), small scale comb-like congregated topography possesses a medium sliding angle (SA is about 30 degrees), noncongregated topography possesses a large sliding angle (strong adhesive force to water droplet). Moreover, the as-prepared superhydrophobic PI nanotube arrays have remarkable resistivity to acid, weak base, high temperature (up to 350 degrees C) and various organic solvents. Our work provides a facile and promising strategy to fabricate superhydrophobic surfaces with controlled sliding angles by utilizing self-organization effect, and such high performance superhydrophobic PI nanotube arrays can be used as coating materials in various harsh conditions.