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1. A Surfactant-Free Microfluidic Process For Fabrication Of Multi-Hollow Polyimide Aerogel Particles

   Yao, Y.; Joo, P.; Jana, S.C. (October 2020, International polymer processing)

   This work focuses on fabrication of multi-hollow polyimide gel and aerogel particles from a surfactant-free oil-in-oil emulsion system using a microfluidic droplet generator operating under dripping mode. The multi-hollow gel and aerogel particles have strong potential in thermal insulation. Under jetting and tip-streaming regime of microfluidic flows, droplets are generated with no occluded liquid phase. The present study investigates a means of designing polyimide gel particles with plurality of internal liquid droplets by strategically manipulating the flow rates of the continuous and dispersed phase liquids through the microfluidic droplet generator. The multi-hollow polyimide aerogel particles obtained after supercritical drying of the gel particles present mesopores, high BET surface area, and excellent prospect for thermal insulation. 

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2. In-Situ Investigation of Electron Beam-Induced Gas-Phase Polymerization Using Closed-Cell Transmission Electron Microscopy

   https://doi.org/10.1093/mam/ozaf048.939  

   Cai, Zizhen; Koo, Kunmo; Hu, Xiaobing; Dravid, Vinayak P (July 2025, Microscopy and Microanalysis)

   Electron beam-induced polymerization (EBIP) has been widely explored in coatings, adhesives, and nanostructure fabrication, relying on electron irradiation to generate reactive species that initiate polymerization via radical pathways [1]. While its efficiency in solid and thin-film systems is well established [2], real-time observation of gas-phase polymerization at the nanoscale remains challenging due to the lack of suitable experimental platforms. In this study, we employ a custom-built ultrathin (UT) membrane gas-cell chip for in-situ closed-cell environmental transmission electron microscopy (ETEM). This platform offers enhanced reciprocal and spectral visibility, enabling precise tracking of crystallinity through diffraction patterns and gas composition through electron energy loss spectroscopy (EELS) [3-5]. By allowing real-time observation of polymerization kinetics under controlled electron irradiation, this work aims to elucidate the fundamental mechanisms governing EBIP in the gas phase, addressing a critical knowledge gap in electron beam-driven chemical reactions. 

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3. Plasmon-driven photocatalytic molecular transformations on metallic nanostructure surfaces: mechanistic insights gained from plasmon-enhanced Raman spectroscopy

   https://doi.org/10.1039/d1me00016k  

   Chen, Kexun; Wang, Hui (April 2021, Molecular Systems Design & Engineering)

   null (Ed.)

   Optically excited plasmonic nanostructures exhibit unique capabilities to catalyze interfacial chemical transformations of molecules adsorbed on their surfaces in a regioselective manner through anomalous reaction pathways that are inaccessible under thermal conditions. The mechanistic complexity of plasmon-driven photocatalysis is intimately tied to a series of photophysical and photochemical processes associated with the radiative and non-radiative decay of localized plasmon resonances in metallic nanostructures. Plasmon-enhanced Raman spectroscopy combines ultrahigh detection sensitivity with unique time-resolving and molecular finger-printing capabilities, ideal for detailed kinetic and mechanistic studies of photocatalytic interfacial transformations of molecular adsorbates residing in the plasmonic hot spots. Through systematic case studies of several representative reactions, we demonstrate how plasmon-enhanced Raman spectroscopy can be judiciously utilized as a unique in situ spectroscopic tool to fine-resolve the detailed molecule-transforming processes on the surfaces of optically excited plasmonic nanostructures in real time during the photocatalytic reactions. We further epitomize the mechanistic insights gained from in situ plasmon-enhanced Raman spectroscopic measurements into several central materials design principles that can be employed to guide the rational optimization of the photocatalyst structures and the nanostructure-molecule interfaces for plasmon-mediated surface chemistry. 

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4. Gas-phase electron microscopy for materials research

   https://doi.org/10.1557/s43577-023-00588-3  

   Unocic, Raymond R.; Stach, Eric A. (August 2023, MRS Bulletin)

   Abstract Detailed studies of interfacial gas-phase chemical reactions are important for understanding factors that control materials synthesis and environmental conditions that govern materials performance and degradation. Out of the many materials characterization methods that are available for interpreting gas–solid reaction processes,in situandoperandotransmission electron microscopy (TEM) is perhaps the most versatile, multimodal materials characterization technique. It has successfully been utilized to study interfacial gas–solid interactions under a wide range of environmental conditions, such as gas composition, humidity, pressure, and temperature. This stems from decades of R&D that permit controlled gas delivery and the ability to maintain a gaseous environment directly within the TEM column itself or through specialized side-entry gas-cell holders. Combined with capabilities for real-time, high spatial resolution imaging, electron diffraction and spectroscopy, dynamic structural and chemical changes can be investigated to determine fundamental reaction mechanisms and kinetics that occur at site-specific interfaces. This issue ofMRS Bulletincovers research in this field ranging from technique development to the utilization of gas-phase microscopy methods that have been used to develop an improved understanding of multilength-scaled processes incurred during materials synthesis, catalytic reactions, and environmental exposure effects on materials properties. Graphical abstract 

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5. Refractive Laser Beam Measuring Diffusion Coefficient of Concentrated Battery Electrolytes

   https://doi.org/10.1149/1945-7111/ad2954  

   Betts, Katherine; Heenkenda, Kushanie Yasasvie; Jacome, Bryan; Kim, Sohyo; Tovar, Michael; Feng, Zhange (February 2024, Journal of The Electrochemical Society)

   Abstract A thorough understanding of electrolyte transport properties is crucial in the development of alternative battery technology. As a key parameter, the diffusion coefficient offers important insights into the behavior of electrolytes, especially for fast charge of high-energy batteries. Existing methods of measurement are often limited by redox species or offer questionable accuracy due to side reactions and/or disruption of the diffusion profile. This work provides a novel optical method for measuring diffusion coefficients of liquid-phase concentrated battery electrolytes without electrochemical reactions. The method relies on the deflection of a refractive laser beam passing through an electrolyte of a minor concentration gradient in a triangular diffusion column. The diffusion coefficient, D, for a range of zinc sulfate electrolytes was successfully extracted by correlating the position of the laser beam to its concentration. Several other physicochemical properties of the same electrolytes are studied to correlate to the concentration-dependent diffusion coefficients, including viscosity, conductivity, and microstructure analysis based on vibrational spectroscopy (infrared and Raman). Also included is the future application of the triangular column for in situ electrochemical measurements. 

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