Advancing Renewable Amines: Furan-Derived Polybenzoxazines

Abstract

Bioderived synthons are promising precursors, and their use as feedstock is considered a well-established strategy for developing sustainable polymers. Furan, a prominent biochemical, plays a significant role in producing green polymers, including polybenzoxazine (PBz) thermosets. Among phenolic resins, polybenzoxazine has gained considerable attention due to its ability to engineer molecular structures and tune properties, surpassing those of many existing polymers. In the current work, two biobased polybenzoxazines were prepared from industrially derived natural feedstocks, hydroxymethylfurfural (HMF)-sourced carbohydrate amines (mono- and diamine-based on furan, “fa” and “fda”, respectively) and cashew nut waste-sourced renewable phenol (saturated cardanol, C). After the successful synthesis of furan-diamine (fda), the benzoxazine monomer was synthesized in a single step. Structural confirmation of the diamine and monomers (C-fa and C-fda) was achieved by spectroscopy (FTIR, 1 H, 13 C, and 2D NMR) and mass spectrometry. The HMF-sourced amine-derived bisbenzoxazine monomer, C-fda, exhibited a lower ring-opening polymerization (ROP) temperature compared to monobenzoxazine (C-fa) and other reported cardanol amine-based Bz monomers with similar functionality. Poly(C-fda) exhibited excellent adhesive performance compared to poly(C-fa) in water. The developed polybenzoxazines also demonstrated appreciable thermal performances and glass transition temperatures. Furthermore, both polybenzoxazines outperformed commercial phenol formaldehyde (PF) resins in terms of adhesion properties attributed to additional noncovalent interactions (chain entanglements and extensive hydrogen bonding) within the covalent framework. This work underscores the potential of furan-based precursors, particularly furan amines, as promising candidates for the design of high-performance carbohydrate-derived polybenzoxazines.

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