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Dissertation
Continuous-flow strategies towards bio-based glycerol carbonate
Authors: --- --- --- ---
Year: 2017 Publisher: Liège Université de Liège (ULiège)

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Abstract

This work aims at developing new routes for the production of glycerol carbonate from bio-based glycerol using dimethylcarbonate or urea derivatives as green acyl-donors. The valorization of glycerol into glycerol carbonate offers large opportunities to many application fields. Both micro-wave and continuous flow strategies were investigated using additives such as catalysts to improve glycerol carbonate synthesis. A convenient LC-MS analytic method was set up to determine glycerol carbonate yield for dimethylcarbonate route. Regarding to dimethylcarbonate as acyl donor, experiments using Bu4NBr, K2CO3, and ILs as catalysts candidates were optimized in microwave reactors conducting the reaction at several time reactions, temperature and mol\% catalyst. Only 1 mol\% of Bu4NBr affords glycerol carbonate in quantitative yields after 2 min at 170 °C. Regarding to urea derivatives as acyl donor, catalysis screening was set up for urea and dimethylurea. Promising results were obtained using Cu2O as catalyst for urea reaction, whereas pressure issues were encountered in micro-wave reactors. Cyclocarbonation of glycerol by urea was implemented in micro-fluidic reactors using either ethanol or formic acid as co-solvent and a packed-bed reactor made of dispersion of Cu2O in glass beads. Using EtOH, two main impurities (named X1 and X2) were unfortunately detected in the medium, but promising results were obtained for 10 min residence time at 180 °C under 34 bar. Using HCOOH, glycerol conversion was totally completed but GC formation was negligible. Instead of the formation of GC, a significant amount of X1 was observed. We noticed that the two main impurities encountered in flow were not observed in microwave experiments. In order to prevent any leaching issues in flow experiments, a convenient method was finally tested to prepare Cu2O on glass beads.


Book
Microscale Surface Tension and Its Applications
Authors: ---
ISBN: 3039215655 3039215647 Year: 2019 Publisher: MDPI - Multidisciplinary Digital Publishing Institute

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Building on advances in miniaturization and soft matter, surface tension effects are a major key to the development of soft/fluidic microrobotics. Benefiting from scaling laws, surface tension and capillary effects can enable sensing, actuation, adhesion, confinement, compliance, and other structural and functional properties necessary in micro- and nanosystems. Various applications are under development: microfluidic and lab-on-chip devices, soft gripping and manipulation of particles, colloidal and interfacial assemblies, fluidic/droplet mechatronics. The capillary action is ubiquitous in drops, bubbles and menisci, opening a broad spectrum of technological solutions and scientific investigations. Identified grand challenges to the establishment of fluidic microrobotics include mastering the dynamics of capillary effects, controlling the hysteresis arising from wetting and evaporation, improving the dispensing and handling of tiny droplets, and developing a mechatronic approach for the control and programming of surface tension effects. In this Special Issue of Micromachines, we invite contributions covering all aspects of microscale engineering relying on surface tension. Particularly, we welcome contributions on fundamentals or applications related to:Drop-botics: fluidic or surface tension-based micro/nanorobotics: capillary manipulation, gripping, and actuation, sensing, folding, propulsion and bio-inspired solutions; Control of surface tension effects: surface tension gradients, active surfactants, thermocapillarity, electrowetting, elastocapillarity; Handling of droplets, bubbles and liquid bridges: dispensing, confinement, displacement, stretching, rupture, evaporation; Capillary forces: modelling, measurement, simulation; Interfacial engineering: smart liquids, surface treatments; Interfacial fluidic and capillary assembly of colloids and devices; Biological applications of surface tension, including lab-on-chip and organ-on-chip systems. We expect novel as well as review contributions on all aspects of surface tension-based micro/nanoengineering. In line with Micromachines' policy, we also invite research proposals that introduce ideas for new applications, devices, or technologies.

Keywords

electrodynamic screen --- soft tissue --- microstructure --- mist capillary self-alignment --- droplet --- lab-on-a-chip --- mixing --- nanoprecipitation --- asymmetric surfaces --- gecko setae --- oil-water interface --- non-invasive control --- self-cleaning surface --- corrosive resistance --- micropipette-technique --- hydrophobic --- wettability gradient --- lung-surfactants --- hydrophilic --- dynamic --- vibrations --- superhydrophobic --- microasssembly --- adsorption --- wetting --- photochemical reaction --- contact line oscillation --- 355 nm UV laser --- capillary --- computational fluid dynamics --- bearing --- solutal Marangoni effect --- relaxation oscillations --- superhydrophilic --- microtexture melting --- rigid gas permeable contact lenses --- hydrophilic/superhydrophobic patterned surfaces --- polydimethylsiloxane (PDMS) replication --- microfabrication --- actuation --- droplet transport --- “droplet-interface-bilayers” --- microfluidics --- electrosurgical scalpels --- continuous-flow reactor --- air-water surface --- micromanufacturing --- surface treatment --- liquid bridge --- stereolithography --- super-hydrophobic --- two-phase flow --- hot drop --- durable --- insoluble lipids --- anti-sticking --- smart superhydrophobic surface --- droplet manipulation --- “black lipid films” --- condensation --- pick-and-place --- wettability --- gas-microbubbles --- soft robotics --- capillary pressure --- superomniphobic --- self-lubricating slippery surface --- electrowetting --- soluble surfactant --- anisotropic ratchet conveyor --- Nasturtium leaf --- droplets --- photoresponsible surfactant --- two-photon polymerization --- contact angle --- adhesion --- transport --- pick and place --- surface tension --- oil-microdroplets --- micromanipulation --- laser die transfer --- capillary gripper --- equilibrium

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