An ultrathin, highly thermally conductive heat spreader has been fabricated by layer-by-layer stacking of hydroxylated boron nitride nanosheets (HBNNS) for the first time. HBNNS were prepared by a molten hydroxide-assisted liquid exfoliation from hexagonal boron nitride powder. The as-prepared heat spreader of HBNNS exhibits a high thermal conductivity of 51.1 W m −1 K −1 along the in-plane direction, and can be further enhanced 14% by annealing for de-hydroxylation. This heat spreader with 10-30 µm in thickness possessed excellent thermal stability with negligible weight loss at wide temperature range up to 700 °C, resulting in promising applications for heat dissipation in electronic components operated at high working temperature.
Here, we describe a simple method to prepare oil-repellent surfaces with inherent reactivity. Liquid-like copolymers with pendant reactive groups are covalently immobilized onto substrates via a sequential layer-by-layer method. The stable and transparent nanocoatings showed oil repellency to a broad range of organic liquids even in the presence of reactive sites. Functional molecules could be covalently immobilized onto the oil-repellent surfaces. Moreover, the liquid repellency can be maintained or finely tailored after post-chemical modification via synergically tailoring the film thickness, selection of capping molecules, and labeling degree of the capping molecules. Oil-repellent surfaces that are capable of post-functionalization would have technical implications in surface coatings, membrane separation, and biomedical and analytical technologies.
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