Preparation and properties of hydrophobic filter paper and cotton fabric with reversible solvent response

The preparation of hydrophobic surfaces has been extensively studied, but the reversible responsive hydrophobic surface has received less attention. In this paper, poly(styrene-random-methyl methacrylate-random-acrylic acid) (P(St-r-MMA-r-AA)) was prepared by conventional free radical polymerization, and the filter paper and cotton fabric were immersed in P(St-r-MMA-r-AA) methanol solution to construct a hydrophobic surface. The hydrophobic property, chemical composition and surface morphology of the hydrophobic filter paper and cotton fabric surface were characterized by contact angle, Gibbs free energy, infrared spectroscopy and scanning electron microscopy. The optimum conditions for constructing hydrophobic filter paper and cotton fabric surface were investigated. When the surfaces of hydrophobic filter paper and cotton fabric were treated with methanol, tetrahydrofuran and deionized water respectively, the semihydrophobic-hydrophobic-hydrophilic reversible transformation could be achieved. After ten cycles of experiments, the contact angles under the three solvent stimulations had no significant change, and the hydrophobic properties of the hydrophobic cotton fabric were superior to that of hydrophobic filter paper. The Gibbs free energy calculation of the hydrophobic surface indicated that the change in surface hydrophobic property was due to the inversion between the hydrophobic PS segment, the PMMA segment, and the hydrophilic PAA segment.