Neutron-Radiation-Induced Strengthening and Toughening of Hexagonal Boron Nitride Nanosheet/Covalent Organic Framework Composites for Polymer Coatings in Radiative Environments

Covalent organic frameworks (COFs) are a promising class of materials known for their exceptional in-plane mechanical properties. However, the absence of strong out-of-plane bonding limits their bulk mechanical performance. Additionally, COFs and other carbon-based materials are prone to mechanical degradation when exposed to neutron radiation. Developing a COF-based material with enhanced out-of-plane bonding and neutron radiation resistance would benefit coatings under extreme conditions. These polymer coatings could benefit the aerospace industry and oil and gas drilling. This study presents a hexagonal boron nitride (hBN)/COF nanocomposite and investigates its response to neutron radiation. Postirradiation X-ray photoelectron spectroscopy analysis reveals the formation of carbon-oxygen and carbon-nitrogen bonds, suggesting the establishment of out-of-plane bonding. Mechanical testing indicates significant improvements in the composite’s properties following neutron radiation exposure, with the elastic modulus increasing from 0.95 ± 0.024 GPa to 1.54 ± 0.061 GPa, hardness from 116 ± 11.1 MPa to 152 ± 10.8 MPa, and fracture toughness from 120.9 ± 20.7 kPa·m^1/2 to 178.5 ± 21.2 kPa·m^1/2. This work demonstrates the synthesis of an hBN/COF nanocomposite and highlights how neutron radiation exposure can enhance its mechanical performance, making it a promising candidate for polymer coatings in radiative environments like outer space and oil and gas drilling.