Functionalized hexagonal boron nitride nanoplatelets for advanced cementitious nanocomposites

Portland cement-based nanocomposites were successfully fabricated with low volume fractions of hexagonal boron nitride (hBN) nanoplatelets, exfoliated and functionalized using a combination of ball milling and sonicated-assisted dispersion. Surface topography, thickness, lateral dimension, and number of layers of the hBN nanoplatelets were evaluated by AFM and Raman analysis. The identification of functional groups attached onto the functionalized hBN was performed through FTIR. The results show that the functionalization successfully exfoliates the hBN nanoplatelets to few-layer thicknesses, resulting in suspensions with high colloidal stability. The grafted hydroxyl and carboxyl groups on the hBN surface interact with the Ca2+ ions of calcium silicate hydrates (CSH), improving the load-transfer efficiency from the cement matrix to the hBN nanoplatelets. Overall, the hBN reinforced cementitious composites demonstrated significant enhancement in flexural strength by -50%, compressive strength by -17%, Young's modulus by -56%, and fracture energy by -76%.