Preparation of novel thermal conductive nanocomposites by covalent bonding between hexagonal boron nitride nanosheet and well-defined polymer matrix

A series of novel thermal conductive nanocomposites consisting of styrene-acrylonitrile (SAN) copolymer and covalent functionalized hexagonal boron nitride (h-BN) nanosheet were prepared via Cu (I)-catalyzed azide alkyne cycloaddition reaction (click reaction). For this purpose, styrene-acrylonitrile (SAN) copolymer as polymer matrix with alkyne functionality was synthesized via atom transfer radical polymerization. Then, mechanically exfoliated hexagonal boron nitride obtained in nanosheet (BNNS) form was subjected to successive chemical modification steps resulting azide functionalized BNNS (BNNS-N3). The third step consists of the reaction between BNNS-N3 and alkyne functionalized polymer matrix resulting in the corresponding thermal conductive nanocomposites via click reaction. SAN-BNNS nanocomposites with different BNNS loading fractions (wt %) were prepared in a quantitative yield in moderate conditions and their structural, thermal, and electrical properties were investigated in detail. SAN-BNNS nanocomposite was also formulated as a thermal interface material (TIM). The formulated TIM having 59% (wt. %) BNNS showed sevenfold higher thermal conductivity (0.740 W/mK) in through-plane direction than that of native SAN copolymer (0.098 W/mK), and volume resistivity of nanocomposite is 1014 Ω cm.