One-pot preparation of superhydrophobic polydimethylsiloxane-coated cotton via water/oil/water emulsion approach for enhanced resistance to chemical and bacterial adhesion

The current work reports a green and straightforward preparation of superhydrophobic cotton coated with polydimethylsiloxane (PMDS) via the water/oil/water (W/O/W) emulsion approach. The W/O/W emulsion containing Polyvinyl alcohol (PVOH)-water as the internal phase, PDMS as the dispersed phase, and water as the continuous phase is prepared in less than 5 min through a simple mechanical homogenization using PVOH as an emulsifying agent. The PDMS coating was prepared via the dip-coating of cotton fabric in the emulsion, followed by the heat treatment. The use of emulsion allows a uniform formation of PDMS coating on the fabric surface while minimizing the used coating amount. The prepared cotton sample has an excellent superhydrophobicity with a water contact angle (WCA) of up to 169 degrees. The prepared cotton effectively resisted the adhesion of and penetration of acidic and moderate-basic solutions. It also exhibited enhanced resistance against bacterial adhesion, whereby the number of bacteria adhering to the sample surface is reduced by many folds compared to untreated cotton. The PVOH concentration and the emulsion shelf time significantly impact the super -hydrophobicity of the prepared sample.