Interfacial Tension Hysteresis of Eutectic Gallium-Indium

When in a pristine state, gallium and its alloys have the largest interfacial tensions of any liquid at room temperature. Nonetheless, applying as little as 0.8 V of electric potential across eutectic gallium indium (EGaIn) placed within aqueous NaOH (or other electrolyte) solution will cause the metal to behave as if its interfacial tension is near zero. The mechanism behind this phenomenon has remained poorly understood because NaOH dissolves the oxide species, making it difficult to directly measure the concentration, thickness, or chemical composition of the film that forms at the interface. In addition, the oxide layers formed are atomically-thin. Here, we present a suite of techniques which allow us to simultaneously measure both electrical and interfacial properties as a function of applied electric potential, allowing for new insights into the mechanisms which cause the dramatic decrease in interfacial tension. A key discovery from this work is that the interfacial tension displays hysteresis while lowering the applied potential. We combine these observations with electrochemical impedance spectroscopy to evaluate how these changes in interfacial tension arise from chemical, electrical, and mechanical changes on the interface, and close with ideas for how to build a free energy model to predict these changes from first principles

초소수성 표면을 이용한 하이드로젤 중공 캡슐 제조

A single-step synthetic method for preparing hydrogel hollow capsules on a superhydrophobic surface was successfully developed. Aqueous microdroplets of a mixture of hydrogel monomer and cross-linker solutions were deposited on the superhydrophobic surface, which was situated under the hydrocarbon oil layer containing photoinitiator. When exposed to UV light, the aqueous microdroplets were converted to hollow capsules with a polymerized hydrogel shell, formed due to the diffusion of photoinitiators at the oil/water interface. This method for producing hydrogel hollow capsules on superhydrophobic surfaces is simple and efficient, rendering easy encapsulation of colloidal nanoparticles, drugs, or biological cells.11Nsciescopuskc

LOW-LYING ELECTRONICALLY EXCITED-STATES OF C-60 AND C-70 AND MEASUREMENT OF THEIR PICOSECOND TRANSIENT ABSORPTION IN SOLUTION

Low-lying electronically excited states of C60 and C70 were identified in picosecond transient absorption measurements extending in wavelength down to 1000 nm. Spectral features in the near-infrared region were found to be significantly different from the results of previous studies. The lifetimes for S1 states of C60 and C70 Were determined to be 1.3+/-0.2 ns and 0.7+/-0.05 ns, respectively. A simple energy diagram for electronic states of C60 and C70 is presented