Submicron Emulsion Droplets as Nanoreactors

Nanoparticles enjoy great popularity in chemical, pharmaceutical, cosmetic, and textile industry due to their unique properties related to the small particle size x 100 nm) and high specific surface area. Nevertheless, the control of nucleation 

Particles modified with methacrylic acid 3-trimethoxysilane 

There are two process paths to precipitate nanopartides with the miniemulsion technique. The first requires the production of two water-in-oU emulsions where the dispersed phases are loaded with one predpitation precursor, respectivdy. Controlled coalescence of droplets containing the predpitation reactants results in a product of low solubility and - in case of supersaturation - homogeneous nudeation is induced. As high-pressure homogenization results in high coalescence rates (see Section 5.3.2), this is the process of choice. 

The second process path involves the preparation of one emulsion. A water-soluble reactant is provided within the emulsion droplets, whereas an oil as well as a water-soluble reactant is mixed into the emulsion and the predpitation reaction is induced once the reactant diffuses via the droplet interface into the emulsion droplet This process is considered to be controlled by mass transfer [72]. Mixing efficiency may influence the partide size and structure of the final products in precipitation reactions [73]. Influencing mixing effidency and time is realized by SEM nozzles. 

The continuous phase, 57 w/w% of the emulsion, consisted of n-decane, whereas the watery precursor suspension served as dispersed phase (40 w/w%). The miniemulsions were stabilized by the emulsifier Glissopal EM-23. 

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