Scalable Exfoliation Process for Highly Soluble Boron Nitride Nanoplatelets by Hydroxide-Assisted Ball Milling

TLDR

Scalable production of large‑size, highly soluble two‑dimensional h‑BN remains a key challenge despite extensive research. The study proposes a scalable hydroxide‑assisted ball‑milling exfoliation process to produce hydroxyl‑functionalized BN nanoplatelets. The process uses ball milling of BN powders with sodium hydroxide, combining chemical peeling and mechanical shear to exfoliate the material. The hydroxide‑assisted ball milling yields large, high‑yield (18 %) OH‑BNNPs (~1.5 µm) with minimal structural damage, stable dispersions, improved polyethylene barrier properties, and is scalable and transferable to other layered materials.

Abstract

The scalable preparation of two-dimensional hexagonal boron nitride (h-BN) is essential for practical applications. Despite intense research in this area, high-yield production of two-dimensional h-BN with large-size and high solubility remains a key challenge. In the present work, we propose a scalable exfoliation process for hydroxyl-functionalized BN nanoplatelets (OH-BNNPs) by a simple ball milling of BN powders in the presence of sodium hydroxide via the synergetic effect of chemical peeling and mechanical shear forces. The hydroxide-assisted ball milling process results in relatively large flakes with an average size of 1.5 μm with little damage to the in-plane structure of the OH-BNNP and high yields of 18%. The resultant OH-BNNP samples can be redispersed in various solvents and form stable dispersions that can be used for multiple purposes. The incorporation of the BNNPs into the polyethylene matrix effectively enhanced the barrier properties of the polyethylene due to increased tortuosity of the diffusion path of the gas molecules. Hydroxide-assisted ball milling process can thus provide simple and efficient approaches to scalable preparation of large-size and highly soluble BNNPs. Moreover, this exfoliation process is not only easily scalable but also applicable to other layered materials.