1. Cosmetics

We are making novel organic and inorganic colloids for cosmetics. The research focuses on producing light blocking materials against UV, blue light, near-infrared lights that might be harmful to human skins under repetitive or long-time irradiation. We are also making colloids based on hydrogel, lipid, and ceramide to strengthen the skin barrier function and/or to retain the skin moisture. We are trying to develop the microplastic-free cosmetic ingredients and products for safe and preventive cosmetic systems.

2. Smart windows

We are making organic and inorganic nanostructures for smart window systems. It is known that the energy consumed for the air conditioning, heating/cooling, and ventilation of buildings and houses accounts for 30-40% of the world's energy consumption. It is recently known that the effective control of incident sunlight into the building by smart windows can save building energies. Smart windows can modulate the incident sunlight according to external stimulus (such as electricity for electrochromic smart windows) and temperature changes (thermochromic smart windows).  We are trying to make novel smart windows not only by utilizing thermodynamic behaviors of polymer-water or solute-water pairs but also based on the laboratory’s technologies to fabricate organic/inorganic patterns and plasmonic nanostructures for manipulating the sunlight and to purifying contaminants/polluted air. These technologies can contribute to developing the future window/optical systems for buildings and automobiles. 

3. Energy and Environment

We are making noble-metal nanoparticles to absorb broad spectrum of sunlight, from visible to infrared light. As such, the nanoparticles can produce significant amount thermal energy. The thermal energy can be used to produce electricity (thermoelectricity). The photo-thermal effect can be also used for evaporation of water to harvest pure water from wastewater and seawater. In addition, the noble metal nanoparticles can increase the reaction rates of some organic reactions by lowering activation energy. The activation energy can be lowered due to the catalytic role of the nanoparticles and also by increasing the temperature of reaction medium. For this reason, the noble metal nanoparticles can be used as a photo-thermal catalyst by utilizing sunlight or low-powered visible light. By combining the noble metal nanoparticles with filters and absorbers to treat wastewaters, the nanoparticles can contribute to making multi-functional filters/absorbents to simultaneously separate, detect, and degrade the wastes. Wastes include the organic pollutants and microplastics. We are also recycling synthetic polymers through chemical and physical routes. 

Selected Publications

Cho, E. C.†, Kim, J.-W.†, Fernández-Nieves, A., and Weitz, D. A.*, Highly Responsive Hydrogel Scaffolds Formed by 3-Dimensional Organization of Microgel Nanoparticles. Nano Letters 2008, 8, 168−172 (†: equally contributed).

Cho, E. C., Camargo, P. H. C., and Xia, Y.*, Synthesis and Characterization of Noble-Metal Nanostructures Containing Gold Nanorods in the Center. Advanced Materials 2010, 22, 744−748. (It was featured in Materials Views, Wiley Science).

Cho, E. C., Zhang, Q., and Xia, Y.*, The Effect of Sedimentation and Diffusion on Cellular uptake of Gold Nanoparticles. Nature Nanotechnology 2011, 6, 385−391. (It was highlighted in the News & Views of Nature Nanotechnology 2011, 6, 332−333; Nanowiki on May 2; Newsroom of Washington University in St. Louis on May 3.)

Lim, S., Song, J. E., La, J. A, and Cho, E. C.*, Gold Nanospheres Assembled on Hydrogel Colloids Display a Wide Range of Thermoreversible Changes in Optical Bandwidth for Various Plasmonic-Based Color Switches, Chemistry of Materials 2014, 26, 3272−3279.

Song, J. E., H. Kim, S. W. Lee*, Cho, E. C.*, Nanoscale Structural Switching of Plasmonic Nanograin Layers on Hydrogel Colloidal Monolayers for Highly Sensitive and Dynamic SERS in Water with Areal Signal Reproducibility, Analytical Chemistry 2017, 89, 11259−11268.

Pyun, S. B.†, Song, J. E.†, Kim, J. Y., and Cho, E. C.*, Hydrochromic Smart Windows to Remove Harmful Substances by Mimicking Medieval European Stained Glasses, ACS Applied Materials & Interfaces 2020, 12, 16937−16945 (†: equally contributed).

Pyun, S. B., Kim, M. G., Kim, S. W., Song, J. E., Jeon, H. Y., Kim, S., Park, S.-J. and Cho, E. C.*, Optically Left-Handed Nanopearl Beads with Inductance-Capacitance Circuits at Visible–Near-Infrared Frequencies Based on Scalable Methods, ACS Applied Materials & Interfaces 2022, 14, 7121−7129.

Kim, J. H.†, Pyun, S. B.†, Choi, M. J., Yeon, J. W., Hwang, Y. J. and Cho, E. C.*, Synthesis of Linear Black Gold Nanostructures Processable as Sunlight and Low-Energy Light Collecting Films for Photo-Thermoelectricity, Advanced Science 2023, 10, 2207415 (†: equally contributed).