Emulsion Preparation with Microstructured Systems

Emulsion Preparation with Microstructured Systems, Fig. 1 Outline of some microfluidic emulsification geometries, (a) Cross section of a microchannel with a depth difference at the junction. The dispersed phase is pushed onto the terrace (indicated by the arrow) and an emulsion droplet is formed when the dispersed phase falls from the terrace into the deeper well (see also Fig. 2). (b) Top view of a T-Junction with a uniform... 

Emulsion Preparation with Microstructured Systems, Fig. 2 Impression of spontaneous droplet formation in terrace-based systems the entire system is covered with a top plate that is not shown for clarity reasons. In image (a), the to-be-dispersed phase is pushed through the channel on the left onto the terrace where it forms a disk. As soon as the disk reaches the end of the terrace (image (b)), the liquid can flow in a deeper part and assume... 

Emulsion Preparation with Microstructured Systems, Fig. 4 Snapshots of experiments left) and simulations (right) of droplet detachment at a T-junction. The flow rate of the continuous phase is 2 mL h and that of the to-be-dispersed phase is 0.2 mL h [5] (Reprinted with permission from Graaf, S. van der Nisisako, T. ... 

Emulsion Preparation with Microstructured Systems, Table 1 General comparison of shear-driven emulsification techniques ... 

Emulsion Preparation with Microstructured Systems, Table 2 Estimation of the device volume Vdevice and required area Adevice needed to handle oil at 1 m x h in various emulsification devices. The droplet size is between 5 and 10 pm ... 

Emulsion Preparation with Microstructured Systems, Fig. 6 Outlines of mass-parallelized microfluidic systems. Left, Y-junctions, top circular layout in the insert a single Y-junction with continuous-phase flow indicated by the light gray arrow and the dispersed-phase flow by the dark gray double-headed arrow. Bottom, linear layout, C and D represent the continuous-phase and dispersed-phase supply, respectively, and E the emulsion collecting area. Dimensions are not according to scale. Right top. 

Emulsion Preparation with Microstructured Systems, Fig. 7 Interfacial tension gas function of hexadecane flow rate for a. 3.0 wt% SDS solution ( ) at a constant continuous-phase flow rate of 0.23 mLh and for b. 0.15 (D), 0.25 (0), and 3.0 wt% SDS solution ( ) at continuous-phase flow rates varying... 

Emulsion Preparation with Microstructured Systems, Fig. 8 Left, overview of the coalescence chamber, with an image of coalescing droplets. Right, so-called film drainage profile the distance between the central points of the droplets is shown as function of time. Remarkably, the droplets stay in close proximity for 15 milliseconds prior... 

Macierzanka, A., Szelag, H., Moschakis, T., Mrtrray, B. S. Phase transitions and microstructure of emulsion systems prepared with acylglycerols/zinc stearate emulsifier. Langmuir. 2006 22(6) 2487-2497. Fitzhugh, O. G, Bourke, A. R., Nelson, A. A., Frawley, J. P. Chronic oral toxicities of four stearic acid emulsifiers. Toxicol. Appl. Pharm. 1959 1(3) 315-331. 

By far the most studied PolyHIPE system is the styrene/divinylbenzene (DVB) material. This was the main subject of Barby and Haq s patent to Unilever in 1982 [128], HIPEs of an aqueous phase in a mixture of styrene, DVB and nonionic surfactant were prepared. Both water-soluble (e.g. potassium persulphate) and oil-soluble (2,2 -azo-bis-isobutyronitrile, AIBN) initiators were employed, and polymerisation was carried out by heating the emulsion in a sealed plastic container, typically for 24 hours at 50°C. This yielded a solid, crosslinked, monolithic polymer material, with the aqueous dispersed phase retained inside the porous microstructure. On exhaustive extraction of the material in a Soxhlet with a lower alcohol, followed by drying in vacuo, a low-density polystyrene foam was produced, with a permanent, macroporous, open-cellular structure of very high porosity (Fig. 11). 

---