Cold plasma modification of boron nitride fillers and its effect on the thermal conductivity of silicone rubber/boron nitride composites

Hexagonal boron nitride (h-BN) fillers were first coated with low-molecular-weight polydimethylsiloxane (PDMS) by solution dispersion and then treated in argon plasma for different times. The modified h-BN fillers were characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and contact angle analysis. The results revealed that a thin PDMS film several nanometers thick was tightly coated on the surface of the h-BN filler after plasma treatment, and this thin film could not be removed by 48 h Soxhlet extraction with n-hexane at 120°C. Furthermore, the effect of plasma modification on the h-BN filled silicone rubber composites was investigated. The results indicated that the plasma modification improved the interfacial interaction between h-BN and the matrix, but hardly affected the distribution state of the h-BN in the composites. The composites filled with the modified h-BN exhibit significantly higher thermal conductivity than the composites filled with untreated h-BN.