Constructing a novel controllable interface structure through the anchoring effect of α-cyclodextrin at cryogenics to enhance and toughen the mechanical properties of epoxy resin

The fracture toughness of an epoxy resin (EP) often decreases under cryogenic conditions, primarily because of performance degradation caused by molecular chain freezing. In this study, a high-tensile-strength and high-fracture-toughness EP-based nanocomposite (EP/CPN–CuO) was synthesized using α-cyclodextrin (α-CD) for anchoring. The α-CD immobilized flexible linear polymers grafted onto the surface of CuO nanorods (NRs) with negative thermal expansion within a novel interface with the EP. The composite exhibited enhanced mechanical properties because the α-CD effectively hindered the curling of polymer chain segments and considerably improved the chemical bonding between the EP and CuO. Experimental results demonstrated the enhanced mechanical performance of EP/CPN–CuO under cryogenic conditions compared with that of other materials reported in the literature. EP/CPN-CuO-2.0 exhibited a tensile strength of 111.40 MPa, a Young's modulus of 6.67 GPa, and a fracture toughness of 2.69 MPa·m^1/2, marking increases of 67.4 %, 10.8 %, and 100.7 % compared to pure EP. Thus, this study effectively resolved the trade-off between the tensile strength and fracture toughness of an EP under cryogenic conditions, providing a new pathway for the widespread application of EPs in cryogenic environments.