Bioinspired Design Provides High‐Strength Benzoxazine Structural Adhesives

Abstract

A synthetic strategy to incorporate catechol functional groups into benzoxazine thermoset monomers was developed, leading to a family of bioinspired small‐molecule resins and main‐chain polybenzoxazines derived from biologically available phenols. Lap‐shear adhesive testing revealed a polybenzoxazine derivative with greater than 5 times improved shear strength on aluminum substrates compared to a widely studied commercial benzoxazine resin. Derivative synthesis identified the catechol moiety as an important design feature in the adhesive performance and curing behavior of this bioinspired thermoset. Favorable mechanical properties comparable to commercial resin were maintained, and glass transition temperature and char yield under nitrogen were improved. Blending of monomers with bioinspired main‐chain polybenzoxazine derivatives provided formulations with enhanced shear adhesive strengths up to 16 MPa, while alloying with commercial core–shell particle‐toughened epoxy resins led to shear strengths exceeding 20 MPa. These results highlight the utility of bioinspired design and the use of biomolecules in the preparation of high‐performance thermoset resins and adhesives with potential utility in transportation and aerospace industries and applications in advanced composites synthesis.

Mussel‐Inspired Alternating Copolymer as a High‐Performance Adhesive Material Both at Dry and Under‐Seawater Conditions

“…[ 14 ] However, despite great progress, the bonding strength of most reported CFPs on metal substrates is smaller than 15 MPa. Recently, Messersmith and co‐workers [ 15 ] and Detrembleur and co‐workers [ 16 ] separately reported the synthesis of catechol‐functionalized polybenzoxazines and polyhydroxyurethanes, which were used to prepare thermoset adhesive materials with excellent bonding strength of 20.5 MPa on aluminum and 22.1 MPa on stainless steel, respectively. To our knowledge, these two polymers represent the best adhesive materials among CFPs for dry‐state adhesion on metal substrates up to now.…”

Molecular design principles of Lysine-DOPA wet adhesion

“…A unique feature of these interfacial proteins is the presence of large amounts of post-translationally modified amino acid 3,4-dihydroxyphenylalanine (DOPA), a catechol-containing residue that is believed to be a major contributor to wet adhesion [7][8][9][10][11] . Bioinspired design principles based on mimicking these interfacial proteins have been employed extensively and resulted in a variety of catechol functionalized polymers for bio-compatible adhesives, self-healing hydrogels, and surgical wound closure materials [12][13][14][15][16][17][18][19][20][21][22] .…”

Innovative Hyperbranched Polybenzoxazine-Based Graphene Oxide—Poly(amidoamines) Nanomaterials

“…Polybenzoxazines (PBZs) are a unique class of thermoset resins that in many cases surpass the phenolic and epoxy resin properties in terms of thermal resistance, UV and chemical stability, water absorption, void formation, and volumetric shrinkage during the curing process [ 1 , 2 , 3 ]. These remarkable features of PBZs are generated by the rich molecular flexibility of the benzoxazine monomers that allows the synthesis of complex polymerizable structures for tailored properties [ 4 ].…”