Biobased Superwetting Cotton Fabric with Self-Healing Capacity and pH-Responsive Wettability Enabled by Dynamic Vitrimer Chemistry for On-Demand Oil/Water Separation

The development of advanced superwetting fabrics for oil/water separation is often hampered by limitations in durability, lack of smart responsiveness, and the use of nonsustainable materials. To address these challenges, this study presents a sustainable and smart superhydrophobic cotton fabric (SHCF) fabricated through a three-step process involving cellulase etching, coating with a biobased epoxy vitrimer (EVD), and grafting of octadecylamine (ODA) via dynamic imine bond exchange. The resulting SHCF exhibits excellent superhydrophobicity (WCA: 157.9°) and remarkable durability against boiling water, solvents, and salt. Importantly, the dynamic imine bonds confer self-healing properties to recover superhydrophobicity after mechanical damage and enable pH-responsive wettability. The SHCF can be switched to a hydrophilic state (dSHCF) under acidic conditions, showing underwater superoleophobicity, and critically, can be fully regenerated to a superhydrophobic state (rSHCF) under alkaline conditions. This pH-responsive wettability allows for on-demand oil/water separation: superhydrophobic SHCF effectively separates heavy oil/water mixtures with high efficiency (>93%), while hydrophilic dSHCF separates light oil/water mixtures with exceptional efficiency (>99%) and high flux. The fabric maintains high performance over multiple cycles, demonstrating its great potential for adaptive and sustainable oil/water separation applications.