Seongkyun Kim , Taeyeop Kim , Jaehyun Sung , Yongjun Kim , Dongwoo Lee and Seunghyun BaikMaterials Horizons
Thermal rectification is an asymmetric heat transport phenomenon where thermal conductance changes depending on the temperature gradient direction. The experimentally reported efficiency of thermal rectification materials and devices, which are applicable for a wide range of temperatures, is relatively low. Here we report a giant thermal rectification efficiency of 218% by maximizing asymmetry in …
C. MUHAMMED AJMAL, SEOKJAE CHA, WONJOON KIM, K. P. FASEELA, HEEJUN YANG, AND SEUNGHYUN BAIKScience Advances
The dependence of the electrical resistance on materials’ geometry determines the performance of conductive nanocomposites. Here, we report the invariable resistance of a conductive nanocomposite over 30% strain. This is enabled by the in situ–generated hierarchically structured silver nanosatellite particles, realizing a short interparticle distance (4.37 nm) in a stretchable silicone rubber matr…
K. P. Faseela, C. Muhammed Ajmal, Seokjae Cha, Seunghyun BaikAdvanced Functional Materials
Copper (Cu) is an attractive low-cost alternative to silver or gold. However, it is susceptible to oxidation in air. Here, facile in situ regeneration of oxidized Cu flakes (CuFLs) for the synthesis of highly conductive non-oxidized nanocomposites is reported. The oxidized CuFLs are regenerated into non-oxidized CuFLs and Cu nanosatellite (CuNS) particles by formic acid-aided in situ etching and r…
Shabas Ahammed Abdul Jaleel, Taehun Kim, Seunghyun BaikAdvanced Materials
Phase-change materials (PCMs) have received considerable attention to take advantage of both pad-type and grease-type thermal interface materials (TIMs). However, the critical drawbacks of leaking, non-recyclability, and low thermal conductivity (κ) hinder industrial applications of PCM TIMs. Here, leakage-free healable PCM TIMs with extraordinarily high κ and low total thermal resistance (Rt) are…
Membrane separation of oil and water with high purity and high permeability is of great interest in environmental and industrial processes. However, membranes with fixed wettability can separate only one type of surfactant-stabilized emulsion (water-in-oil or oil-in-water). Here, we report on Janus graphene oxide (J-GO) sponges for high purity and high permeability separation of both water-in-oil and oil-in-water emulsions. Millimeter-scale reduced GO sponges with a controlled pore size (11.2 or 94.1 μm) are synthesized by freeze drying, and the wettability is further controlled by fluorine (hydrophobic/oleophilic in air) or oxygen (hydrophilic/oleophilic in air) functionalization. J-GO sponges are prepared by the fluorine functionalization on one side and oxygen functionalization on the other side. Interestingly, the oil wettability of oxygen-functionalized surface turns into an oleophobic surface when immersed in water, which is explained by Young’s theory. This effect is further used in the separation of both water-in-oil and oil-in-water emulsions by changing the flow direction. The purity of the separated oil and water is very high (≥99.2%), and the permeability is more than an order of magnitude greater than those of the other Janus membranes reported. J-GO sponges can be reused with an excellent repeatability, demonstrating feasibility in practical applications.
