Bio‐Based Polybenzoxazine Modified Melamine Sponges for Selective Absorption of Organic Solvent in Water

Abstract Melamine sponge (MS) has drawn increasing attention in the field of oil/water separation. To realize the selective absorption of oil, lots of efforts have been made to change its hydrophilicity to hydrophobicity. Here, several bio‐based main‐chain type benzoxazines with extremely low surface tension are synthesized from a renewable feedstock and loaded on the skeleton of MS through a simple dipping–squeezing–curing process. Consequently, a series of polybenzoxazine‐modified MSs (PB–MSs) are fabricated. With the benzoxazine loading content ranging from 0.13% to 30.4%, the PB–MSs show a high water contact angle (WCA) of 137.8° ± 1.5° to 144.5° ± 1.0° and excellent gravimetric absorption capacity (Q_m/m) of 117.0 ± 1.59 to 140.64 ± 0.68 g g⁻¹ when chloroform is used as the oil phase. After 15 absorbing–squeezing cycles, the 67.47% to 76.29% retentive absorption capacity is observed. Notably, the excellent absorption selectivity is reflected by the trace amount of water (ppm grade) in the separated oil phase. The bio‐based benzoxazine shows great potential to functionalize MSs for effective oil/water separation and the application of bio‐based materials in the field of environmental pollution treatment is demonstrated.