Using benzoxazine chemistry and bio-based triblock copolymer to prepare functional porous polypeptide capable of efficient dye adsorption

Abstract

A new biocompatible poly(ε-caprolactone-b-ethylene oxide-b-tyrosine) triblock copolymer (PCL-b-PEO-b-PTyr) has been synthesized through ring opening polymerization (ROP) employing PCL-b-PEO-NH₂ as a macro-initiator. The phenolic OH groups on the side chains of the PTyr block were subjected to Mannich condensations with CH₂O and aniline to form benzoxazine (BZ) units, which underwent thermal ROP to give the triblock copolymer PCL-b-PEO-b-PTyrBZ. This thermal crosslinking process formed a three-dimensional network structure, featuring a functional porous PTyr structure with phenolic OH and amide units, that enhanced the thermal stability of the triblock copolymer and allowed selective thermal cancelation of the PCL-b-PEO block segment. This functional porous PTyr displayed high adsorption capacity toward methylene blue (MB) in an aqueous solution, the result of hydrogen bonding between the nitrogen atom in the aromatic ring of MB and the phenolic OH or amide groups of the porous PTyr structure.