Electropolishing is one of the most widely applied metal polishing techniques for passivating and deburring metal parts. Copper is often used as cathode electrode for electropolishing due to its low electrical resistance and low flow values. However, during the electropolishing process, elution of the cathode electrode caused by the electrolyte and remaining oxygen gas also causes critical water pollution and inhibits electropolishing efficiency. Therefore, to achieve an efficient and eco-friendly electropolishing process, development of a highly corrosion resistive and conductive electrode is necessary. We developed a highly oriented graphene nanoplatelet (GNP) electrode that minimizes water pollution in the electropolishing process. We functionalized GNP by a one-step mass-productive ball-milling process and non-covalent melamine functionalization. Melamine is an effective amphiphilic molecule that enhances dispersibility and nematic liquid crystal phase transformation of GNP. The functionalization mechanism and the material interaction were confirmed by Raman spectroscopy after high-speed shear printing. After the electropolishing process by melamine-functionalized GNP electrodes, 304 stainless steel samples were noticeably polished as copper electrodes and elution of carbon was over 50 times less than was the case when using copper electrodes. This electropolishing performance of a highly oriented GNP electrode indicates that melamine-functionalized GNP has great potential for eco-friendly electropolishing applications.

Owing to the increasing generation of waste coffee powder and the biochar from this waste being considered as alternative conductive carbon fillers, we developed eco-friendly and electrically conductive cementitious composites using biochar from waste coffee beans, which were directly pyrolyzed into eco-friendly and electrically conductive biochar. Via carbonization and graphitization, cyclic organic carbon precursors were transformed into sp2-bonded carbon structures and then functionalized with melamine. The non-covalent functionalization process driven by the electromagnetic process accelerated the mass production and enhanced the monodispersive properties of the cementitious composites. Thus, the melamine-functionalized biochar cementitious composites exhibited an electrical conductivity of 3.64 × 10−5 ± 1.02 × 10−6 S/cm (n = 6), which corresponded to an improvement of over seven orders of that of pure concrete. Furthermore, the percolation threshold of biochar was between 0.02 and 0.05 wt.%; thus, an effective conductive network could be formed using low additions of functionalized biochar. As a result, in this study, electrically conductive cementitious composites were developed using waste coffee powder converted into carbon nanomaterials through a newly introduced process of non-covalent functionalization with melamine.

The main challenges in developing zeolites as cosmetic drug delivery systems are their cytotoxicities and the formation of drug-loading pore structures. In this study, Au-decorated zeolite nanocomposites were synthesized as an epidermal delivery system. Thus, 50 nm-sized Au nanoparticles were successfully deposited on zeolite 13X (super cage (α) and sodalite (β) cage structures) using the Turkevich method. Various cosmetic drugs, such as niacinamide, sulforaphane, and adenosine, were loaded under in vitro and in vivo observations. The Au-decorated zeolite nanocomposites exhibited effective cosmetic drug-loading efficiencies of 3.5 to 22.5 wt% under various conditions. For in vitro cytotoxic observations, B16F10 cells were treated with various cosmetic drugs. Niacinamide, sulforaphane, and adenosine-loaded Au-decorated zeolite nanocomposites exhibited clear cell viability of over 80%. Wrinkle improvement and a reduction in melanin content on the skin surface were observed in vivo. The adenosine delivery system exhibited an enhanced wrinkle improvement of 203% compared to 0.04 wt% of the pure adenosine system. The niacinamide- and sulforaphane-loaded Au-decorated zeolite nanocomposites decreased the skin surface melanin content by 123% and 222%, respectively, compared to 2 and 0.01 wt% of pure niacinamide and sulforaphane systems, respectively. As a result, Au-decorated zeolite nanocomposites show great potential as cosmetic drug epidermal delivery systems for both anti-aging and lightening effects.

We report the preparation of a highly-oriented graphene-based film prepared from liquid crystal dispersion of graphene oxides (GOs). We observed that the liquid crystal behavior of GOs is highly affected by the lateral size of GO flakes: the critical concentration for liquid crystal formation decreased with the increase of the lateral size of GO flakes, which is in a good agreement with Onsager’s theory. As a result, we were able to obtain highly-ordered graphene assemblies with large-sized GO flakes (150 ± 29 μm) at relatively low concentrations. By applying the shear force, we were able to obtain highly-oriented films from liquid crystal GO flakes. After hydrogen iodide (HI) reduction, GO films showed excellent mechanical strength and electrical conductivity, which were 278% and 283% higher, respectively, than those of films made from smaller sized GO flakes (28 ± 24 μm).