Ko, Gwangmin, Jaehun Yang, Daewoo Suh, Yeongbin Kim, Hongdeok Kim, Mohamad Alayli, Sunghwan Hong, Jungsoo Lim, Joonmyung Choi, and Seunghyun Baik.ACS Applied Materials & Interfaces
The interfacial phonon transport tuning, depending on the phonon density of states (PDOS) of mating materials, has received considerable attention. However, it has been mainly implemented in nanoscale superlattice structures. Here, we report successful thermal conductivity (κ) modulation in bulk-scale multilayer composites. Single-layer silicone rubber composites, embedded with PDOS-mismatched AlN…
Jungho Ahn, Jaehun Yang, Byung Ho Lee, Moon Ki Kim , Seunghyun BaikInternational Communications in Heat and Mass Transfer Published
Thermal rectification has been intensively investigated at the nanoscale. However, it still needs to be explored in order to achieve a high thermal rectification efficiency (TR) in bulk materials. Here we report bulk-scale thermal rectification in bilayered silicon rubber (SR) composites by elastic modulus asymmetry and thermal radiation. The AlN filler concentration in the bottom layer is fixed a…
Seongkyun Kim, Dohyeong Lee, Seonghyun Bae, Yongseok Jeong, Minju Jeong, Changsik Song & Seunghyun BaikMaterials horizons Published
The temperature-dependent thermal conductivity (κ) variation has been actively investigated as a thermal rectification mechanism. However, the intrinsic κ modulation of solid materials is limited. Here we report a shape memory polymer composite (SMPC) by combining the shape-changing ability of cross-linked poly(ethylene-co-vinyl-acetate) with the electrical/thermal functions of silver flakes. The …
Yeonuk Kim, Mahboob Alam, Chaewon Lee, Brian J. Lee & Seunghyun BaikAdvanced Composites and Hybrid Materials Published
Digital light processing (DLP) 3D printing enables fabrication of complicated geometries, but the intrinsically insulating properties of photocurable polymeric resins have limited their electrical functionalities. Here we report an exceptionally high electrical conductivity (σ = 341 Scm-1) using a novel Ag+ ion resin, synthesized by incorporating AgNO3 into PEGDA-based resin. The small Ag+ ion (~ …
Mohamad Alayli, K. P. Faseela, Seunghyun BaikAdvanced Composites and Hybrid Materials
The electrical conductivity (σ) of composites varies significantly depending on matrix polymer even when identical conductive fillers are employed. Here we elucidate the governing parameter of the filler–polymer interaction and σ of composites. The σ of the AgPolymer composites, synthesized by dispersing silver flakes (AgFLs) in different elastomer, thermoplastic, or thermoset polymers, varies by …
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…
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 parameters of the Stefan–Boltzmann law for highly non-linear thermal radiation. The asymmetry in emissivity is realized by sputter-depositing manganese (ε = ∼0.38) on the top right half surface of a polyurethane specimen (ε = ∼0.98). The surface area of the polyurethane side is also dramatically increased (1302%) by 3D printing to realize asymmetry in geometry. There is an excellent agreement between the experimentally measured temperature profiles and finite element simulation results, demonstrating the reliability of the analysis. Machine learning analysis reveals that the surface area is a dominant factor for thermal rectification and suggests novel light-weight designs with high efficiencies. This work may find applications in energy efficient thermal rectification management of electronic devices and housings.
