Facile Approach to Recycling Highly Cross-Linked Thermoset Silicone Resins under Ambient Conditions

Abstract

Silicone resins are traditional thermoset polymers with an inorganic backbone, affording chemical inertness and high thermal stability, which also makes them inherently difficult to recycle by traditional methods. Here, we demonstrate that catalytic amounts of fluoride ion at room temperature solubilize highly cross-linked silicone resins initially cured up to 250 °C. After solubilization equilibria are achieved, solvent is removed to reform the polymer network. Coatings on aluminum substrates and monoliths of virgin and recycled silicone resins were evaluated for hydrophobicity, wear resistance, substrate adhesion, and thermal stability. Silicones recycled under optimized conditions retained nearly 100% wear resistance, thermal stability, and adhesion properties. In some instances, the recycled coatings offer properties superior to the initial materials.