Silicone oil grafted hydrophobic paper assisted oil-water separation and gas sensing

• Silicone brush grafting is demonstrated on cellulose-based filter paper. • Optimisation of the silicone brush grafting demonstrated through fluorescence studies. • The grafting resulted in a mechanically and chemically stable coating of silicone brushes. • The hydrophobicity and porosity of the grafted paper were utilised for ammonia gas sensing. • Oil-water separation and selective oil absorption were demonstrated with the grafted paper. The emerging research area of paper-based cost-effective technologies for diverse applications, from droplet assay platforms to clinical diagnosis, necessitates tailoring the hydrophilic nature of the surface. In this work, we present the optimized conditions for thermal-grafting of the silicone brushes onto the cellulose chemistry of the paper so as to make the surface hydrophobic. The optimization of the grafting density of silicone brushes is confirmed using the fluorescence studies of dye molecules. The characterization studies confirm the covalent attachment of hydrophobic silicone brushes to the paper, exhibiting a water contact angle (WCA) of ∼ 130 °, indicative of effective water repellence. In addition, the hydrophobic paper shows high mechanical stability against abrasion studies and mechanical durability under wetting conditions. Further, the porous nature of the hydrophobic paper is further explored for ammonia gas sensing applications. By exploring the hydrophobic and oleophilic nature of the fabricated paper, the oil-water separation application is demonstrated for various oils such as n-hexane, dicholoromethane, and n-decane. The simple and facile fabrication of mechanically robust and porous paper could expand the application horizons of the paper-based technologies that include sensors, the food industry, and paper-based separation applications.