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To study the hydrodynamics of rising droplets (especially less than 1 mm) in quiescent water, a microfluidic device with co-flowing configuration was integrated to prepare micron-sized droplets. Soybean oil and toluene droplets of size from 100 to 600 µm were obtained by five co-flowing devices with different capillary sizes. It is found that the c...
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... They highlighted the abilities of asynchronous oil droplet generations, with the gap varying from a few microns to a few hundred microns in successive and rapid cycles. Deng, Huang [12] studied the hydrodynamics of rising droplets, i.e., soybean oil and toluene in quiescent water, using a co-flowing microfluidic Appl. Sci. ...
Water-in-oil droplets have huge importance in chemical and biotechnology applications, despite their difficulty being produced in microfluidics. Moreover, existing studies focus more on the different shape of microchannels instead of their size, which is one of the critical factors that can influence flow characteristics of the droplets. Therefore, the present work aims to study the behaviours of water-in-oil droplets at the interfacial surface in an offset T-junction microchannel, having different radiuses, using micro-PIV software. Food-grade palm olein and distilled water seeded with polystyrene microspheres particles were used as working fluids, and their captured images showing their generated droplets’ behaviours focused on the junction of the respective microfluidic channel, i.e., radiuses of 400 µm, 500 µm, 750 µm and 1000 µm, were analysed via PIVlab. The increasing in the radius of the offset T-junction microchannel leads to the increase in the cross-sectional area and the decrease in the distilled water phase’s velocity. The experimental velocity of the water droplet is in agreement with theoretical values, having a minimal difference as low as 0.004 mm/s for the case of the microchannel with a radius of 750 µm. In summary, a small increase in the channel’s size yields a significant increase in the overall flow of a liquid.
Aqueous polymer dispersions are commodity materials produced on a multimillion-ton scale annually. Today none of these materials are biodegradable because the process by which they are made is not compatible with the synthesis of biodegradable polymers. Herein, we report a droplet microfluidic encapsulation strategy for protecting a water incompatible ring-opening polymerization (ROP) catalyst from the aqueous phase, yielding biodegradable polymer particles dispersed in water. Polymerization yields 300 μm sized particles comprised of biodegradable poly(δ-valerolactone) with molecular weights up to 19.5 kg mol-1. The success of this approach relies on simultaneous precise control of the kinetics of polymerization, the rate of mass transfer, and fluid mechanics. The power of this methodology was demonstrated by the synthesis of cross-linked polymer particles through the copolymerization of bis(ϵ-caprolactone-4-yl)propane and δ-valerolactone, producing cross-linked polymer particles with molecular weights reaching 65.3 kg mol-1. Overall, this encapsulation technique opens the door for the synthesis of biodegradable polymer latex and processable, biodegradable elastomers.
