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

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 degrees +/- 1.5 degrees to 144.5 degrees +/- 1.0 degrees 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.