Silica Assisted Superhydrophobicity of Cardanol Polybenzoxazine Coated Cotton Fabric and its Oil–Water Separation Behavior.

In this study, different amounts of SiO₂ have been hybridized with cardanol-diaminodiphenylmethane (C-ddm) benzoxazine monomer to create superhydrophobic/superoleophilic cotton surfaces. Hybridization of silica with the C-ddm monomer has been carried out through both in-situ and ex-situ methods. Tetraethylorthosilicate (TEOS) was added as a silica precursor in the case of in-situ method, while pre-prepared mesoporous silica (SBA-15) was added separately in the case of ex-situ approach. Silane cross-linker was used in both approaches to create the organic–inorganic hybrid coating. Subsequently, the surface properties and characteristics of the modified cotton fabrics have been analyzed. The in-situ SiO₂/poly(C-ddm) modified fabric showed a water contact angle (WCA) of 153° and a low sliding angle of 9°, which was higher than the ex-situ SBA-15/poly(C-ddm) modified fabric. Microscopic analysis showed that controlling the chain entanglement of the cardanol carbon chain was favored with the in-situ hybridization of silica. We found that the in-situ modified cotton fabric with 5% SiO₂/poly (C-ddm) was effective in separating oil–water mixtures, with a separation efficiency of 99.1% and a flux value of 13,500 L/m²h. This study highlights the importance of a silica hybrid network in achieving superhydrophobic surfaces for oil–water separation applications, and suggests further investigations into the molecular arrangements involved in hybrid coatings. [ABSTRACT FROM AUTHOR]