Chemically linked metal-matrix nanocomposites of boron nitride nanosheets and silver as thermal interface materials

• Published in: Nanotechnology 2018-03, Vol.29 (10), p.105706-105706
• Main Authors: Nagabandi, N, Yegin, C, Feng, X, King, C, Oh, J K, Scholar, E A, Narumanchi, S, Akbulut, M
• Format: Article
• Language: English
• Subjects: 2-D nanomaterials; boron nitride nanosheets; MATERIALS SCIENCE; nanocomposites; NANOSCIENCE AND NANOTECHNOLOGY; nanostructured materials; thermal interface materials; thermal management
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/aaa668

Herein, novel hybrid nanocomposite thermal interface materials (TIMs) relying on the chemical linkage of silver, boron nitride nanosheets (BNNSs), and organic ligands are reported. These TIMs were prepared using a co-electrodeposition/chemisorption approach where the electrolytic reduction of silver ions into silver nano-/micro-crystals was coupled with the conjugation of ligand-coated nanosheets onto silver crystals. Furthermore, the influence of the bond strength of silver/nanosheet links on the thermal, mechanical, and structural properties is investigated using a combination of techniques including laser flash analysis, phase-sensitive transient thermoreflectance, nanoindentation, and electron microscopy. The internal nanostructure was found to be strongly dependent on the linker chemistry. While the chemical grafting of 4-cyano-benzoyl chloride (CBC) and 2-mercapto-5-benzimidazole carboxylic acid (MBCA) on BNNSs led to the uniform distribution of functionalized-nanosheets in the silver crystal matrix, the physical binding of 4-bromo-benzoyl chloride linkers on nanosheets caused the aggregation and phase separation. The thermal conductivity was 236-258 W m−1 K and 306-321 W m−1 K for physically and chemically conjugated TIMs, respectively, while their hardness varied from 400-495 MPa and from 240 to 360 MPa, respectively. The corresponding ratio of thermal conductivity to hardness, which is a critical parameter controlling the performance of TIMs, was ultrahigh for the chemically conjugated TIMs: 1.3 × 10−6 m2 K−1 s for MBCA-BNNS and 8.5 × 10−7 m2 K−1 s for CBC-BNNS. We anticipate that these materials can satisfy some of the emerging thermal management needs arising from the improved performance and efficiency, miniaturization, and/or high throughput of electronic devices, energy storage devices, energy conversion systems, light-emitting diodes, and telecommunication components.