Supplemental Material 1: Experimental section and other supplementary material

Experimental section and Other supplementary material: Additional TEM, SEM, and cross-sectional SEM images of BNNS, rGO, and BNNS-rGO hybrids; particle size distribution of BNNS; digital photographs and Tyndall effect images of filler dispersions; EDS elemental mapping of BNNS-rGO; high-resolution XPS spectra (O 1s, C 1s, N 1s, B 1s, Si 2p) with peak fitting; digital images of flexible PDMS-based TIMs; infrared thermal images and temperature-time profiles during thermal response testing; 3D cross-sectional reconstructions from ImageJ analysis; molecular dynamics (MD) simulation models of fillers and interfaces; phonon density of states (PDOS) for BNNS-rGO and BNNS-KH550/rGO; electrostatic potential (ESP) analysis of PDMS; and relative elemental composition and amide bonding efficiency data.