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 (Qm/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.

Synthesis and characterization of siloxane-containing benzoxazines with high thermal stability

“…25 The siloxane-containing benzoxazines were synthesized from aminopropylsiloxane 26 –28 or from hydrosilylation reaction of allyl-containing benzoxazines 29,30 or phenols. 31,32 The generated siloxane-containing polybenzoxazines possessed flexible propyl in the main chain and methyl or enthoxyl substituents on silicon, which resulted in low glass transition temperature ( T g ) and limited the further improvement of the thermal stability. The benzoxazines containing phenyl or phenoxyl substituents on silicon have rarely been studied.…”

Recent development on bio‐based thermosetting resins

“…After fabricating composite with commercial melamine sponge, the material could effectively separate oil and water. 121 Materials with high cardanol content exhibited better oil-water separation performance. 181,182 For example, Peng and coworkers invented a melamine sponges modified by cardanol-based benzoxazine, which showed ultrahigh oil/water separation efficiency (higher than 99.9%) and satisfactory permeation flux (1300 Lm À2 h À1 ).…”

“…Liu et al adopted tetramethylsiloxane synthesizing a series of main-chain type eugenol-based benzoxazine combining with different types of diamines and capping agent, and revealed their potential applications in organic coating and green composites. [119][120][121] Nebhani and coworkers prepared several difunctional benzoxazine using siloxane-containing diamines, the products showed high thermal stability (R 800 range from 49% to 70%) and considerable fire resistance (LOI of 37%-45%). 122 In addition, they also tried to modify silica with different biophenols, and the improved dispersion effects was observed.…”

Synthesis and thermal properties of silicon-containing benzoxazine

“…[19][20][21] Since the silicon (Si) can serve as an important bridge between the organic and inorganic materials, recently, the Si-containing polybenzoxazines have received considerable attention. [22][23][24][25][26][27][28][29][30][31] Si could move toward matrix surface under heat (basing on the low surface energy of Si element). The formed silica layer on the matrix surface can prevent heat and oxygen gas transferring to the polymer matrix.…”