Solvent-Free Partially Biobased Structural Adhesive with High Strength, Tolerance to Harsh Environments, and Multisubstrate Compatibility

Biobased adhesives compatible with different substrates are gaining increasing attention for their sustainability and practicality. However, their low adhesion strength and poor durability in harsh environments limit their broader application. This work constructs three-dimensional network structures within hyperbranched furfurylamine derivative polymers through a deamination reaction between furfurylamine derivative and melamine or urea, followed by cross-linking with an epoxy compound. The resulting adhesive exhibits robust adhesion strengths on various substrates (e.g., 42.28 MPa on steel and 2.31 MPa on Teflon) and surpasses the performance of conventional commercial adhesives. Moreover, its lap shear strength remains above 9 MPa after immersion in various solvents, and it maintains durable adhesion across a wide temperature range (−196 to 100 °C). This adhesive shows great potential for structural materials exposed to extreme environments such as those found in aerospace and marine applications.