Advancing Renewable\nAmines: Furan-Derived Polybenzoxazines

Bioderived synthons are promising precursors, and their\nuse as\nfeedstock is considered a well-established strategy for developing\nsustainable polymers. Furan, a prominent biochemical, plays a significant\nrole in producing green polymers, including polybenzoxazine (PBz)\nthermosets. Among phenolic resins, polybenzoxazine has gained considerable\nattention due to its ability to engineer molecular structures and\ntune properties, surpassing those of many existing polymers. In the\ncurrent work, two biobased polybenzoxazines were prepared from industrially\nderived natural feedstocks, hydroxymethylfurfural (HMF)-sourced carbohydrate\namines (mono- and diamine-based on furan, “fa” and “fda”,\nrespectively) and cashew nut waste-sourced renewable phenol (saturated\ncardanol, C). After the successful synthesis of furan-diamine (fda),\nthe benzoxazine monomer was synthesized in a single step. Structural\nconfirmation of the diamine and monomers (C-fa and C-fda) was achieved\nby spectroscopy (FTIR, <sup>1</sup>H, <sup>13</sup>C, and 2D NMR)\nand mass spectrometry. The HMF-sourced amine-derived bisbenzoxazine\nmonomer, C-fda, exhibited a lower ring-opening polymerization (ROP)\ntemperature compared to monobenzoxazine (C-fa) and other reported\ncardanol amine-based Bz monomers with similar functionality. Poly(C-fda)\nexhibited excellent adhesive performance compared to poly(C-fa) in\nwater. The developed polybenzoxazines also demonstrated appreciable\nthermal performances and glass transition temperatures. Furthermore,\nboth polybenzoxazines outperformed commercial phenol formaldehyde\n(PF) resins in terms of adhesion properties attributed to additional\nnoncovalent interactions (chain entanglements and extensive hydrogen\nbonding) within the covalent framework. This work underscores the\npotential of furan-based precursors, particularly furan amines, as\npromising candidates for the design of high-performance carbohydrate-derived\npolybenzoxazines.