Efficient stripping and hydroxylating of h-BN filler by plasma bubble treatment for composite insulation improvement

Hexagonal boron nitride (h-BN) has emerged as a critical thermal management material in electrical insulation systems due to its superior thermal conductivity and dielectric properties. Nevertheless, suboptimal filler-matrix interfacial compatibility hinders both thermal conductivity enhancement and dielectric performance in composites. This study introduces an innovative plasma bubble treatment strategy, utilizing the discharge within bubbles to simultaneously achieve h-BN exfoliation and surface hydroxylation. By producing plasma in a 3% H2O2 solution with Ar/O2 mixed gas, hydroxyl groups are successfully grafted onto h-BN surfaces. This surface modification improves the silane grafting efficiency with KH560, resulting in improved filler dispersion within the epoxy resin (EP) and the introduction of deep charge traps in interfacial regions. Under 9.77 W discharge power, composites containing 20 wt% h-BN treated for 10 min exhibits optimal performance characteristics. The modified composite attains a 327% thermal conductivity of pure EP while showing superior dielectric properties with a 12.4% increase in breakdown strength relative to untreated composite. These findings present an effective surface engineering approach for developing high-performance polymer composites for electrical insulation applications.