Hydrophobic reinforced carbon foams from silicone-impregnated phenolic resins

Abstract

The demand for mechanically robust, cheap and easily recoverable carbon templates with tunable surface properties for specialty sorption and catalytic conversions is ever-increasing. This study aims to fill in this need, exploring a pyrolytic conversion route of an abundant thermoset foam waste stream. More specifically, the production of monolithic, highly porous carbon foams (ABET = 1800 m²/g, Vpore = 0.747 cm³/g) from phenolic resole insulation foam waste is demonstrated. A novel hydrophobization treatment is developed, involving the impregnation of the foams with vinyldimethicone oil blended with a Karstedt Pt catalyst, followed by co-pyrolysis. This process partially retains silicones within the carbon matrix, making the resulting foams water-repellent and mechanically resilient, though at the cost of reduced porosity. The study further reveals that initial variations in phenolic foam composition strongly influence the complex carbonization and decomposition processes, ultimately shaping the structural and functional properties of the carbon foams. This co-pyrolysis method eliminates the need for post-modification steps and offers new insights into the interactions between decomposing silicones and the developing carbon structure, providing a promising route for efficient one-step surface hydrophobization.