The impact of secondary channels on the wetting properties of interconnected hydrophobic nanopores

Pores in nanoporous materials can be interconnected in different ways; preliminary evidence exists that connecting channels can affect the overall hydrophobicity of the material thus providing an additional parameter in designing applications that require controlled wetting properties. In this work, we show that the length of secondary channels is a key parameter to tune the overall hydrophobicity of the material: short secondary channels make the main pore effectively more hydrophilic than a simple cylindrical pore, while long secondary channels enhance its hydrophobicity, producing the macroscopic effect of superhydrophobic textures. This rich behavior is rooted in the spontaneous filling of the secondary channels, which is unexpected based on classical capillarity. This length-dependent filling is explained by the formation of hydrogen bonds bridging the main pores which becomes less frequent with longer channels. These findings could be useful for designing nanoporous materials with tailored wetting properties.