Enhancing Hydrolysis Resistance and Thermal Conductivity of Aluminum Nitride/Polysiloxane Composites via Block Copolymer-Modification

Abstract

The preparation of thermally conductive silicone rubber composites incorporating aluminum nitride (AlN) as fillers has attracted considerable attention. However, the high susceptibility of AlN to hydrolysis and its limited compatibility with the silicone rubber matrix present significant challenges that hinder the enhancement of the composite's thermal conductivity. In this work, AlN was modified through surface functionalization via grafting with divinylbenzene-acryloyl chloride block copolymer (PDVB-b-PACl), followed by compounding with poly(methylhydrosiloxane) (PMHS) to fabricate thermally conductive AlN@PDVB-b-PACl/PMHS composites. The modification significantly improved the hydrophobicity of AlN@PDVB-b-PACl, as demonstrated by a contact angle of 134.1°compared to 26.4° for unmodified AlN. When the molecular weight of PDVB-b-PACl is 5000 g/mol, the grafting amount is 0.8 wt%, and the loading of AlN@PDVB-b-PACl is 85 wt%, the AlN@PDVB-b-PACl/PMHS composite exhibited an optimal thermal conductivity of 1.82 W/(m·K), an 810% improvement over that of PMHS (0.20 W/(m·K)), and outperformed AlN/PMHS composites (1.58 W/(m·K)) with the same AlN loading. Additionally, the tensile strength of the composite was 0.58 MPa, approximately 2.4 times greater than that of PMHS (0.24 MPa).