Assembly of Latex Supraparticles by Using Emulsion Droplets as Templates
O. D. Velev, K. Furusawa and K. Nagayama
We applied a novel technique, that allows the assembly of different types of colloid particles into ordered multicomponent clusters ("supraparticles"). We control the size and the composition of the supraparticles during the assembly by gathering and confining their components in a restricted, colloid-size 2D or 3D space, provided by emulsion droplets. After the supraparticles are assembled and fixed, the emulsion droplets are dissolved and the supraparticles are extracted as a colloid suspension. The process is carried out by controlling and modifying the colloid interactions within the particle/droplets system - an approach that we call "interaction tailored colloid assembly". Typically, the following steps are performed: 1) modification of particle surface charge and properties, so the microspheres are able to adsorb onto/into the droplets but without homocoagulation; 2) adsorption and structure formation onto/into the emulsion drops; 3) sterical protection of the particle/droplet complexes against flocculation; 4) "binding" of the assembled microspheres by strong coagulant; 5) removal of the carrier droplets by dissolving them in the environment. When the drops are successively introduced into different suspensions they can gather and assemble multicomponent clusters.
Different types of supraparticles and composites from mm-sized negatively charged (sulfate) or positively charged (amidine) latexes were assembled. Examples of obtained colloid structures are presented in the Figure below:
Scale bar = 10 mm
a, b) 2D Ordered hollow spherical shells from sulfate latexes. c) Ordered hollow spherical shells from amidine latexes. d) Small ordered 2D sheets of latex particles. e) Spherical ball-like 3D aggregates from amidine latex. f) Composite supraparticles with aggregated amidine latex core and sulfate latex shell.
The obtained supraparticles can find application as novel materials in catalysis, medicine, etc. We were also able to scale the process down to nanometer scale by assembling ferritin molecules onto liposomes. Further development in this area holds promises for nanoparticle and nanodevice technologies.
O.D. Velev, K. Furusawa and K. Nagayama, "Assembly of Latex Particles by Using Emulsion Droplets as Templates 1. Microstructured Hollow Spheres", Langmuir, 12, 2374 (1996).
O.D. Velev, K. Furusawa and K. Nagayama, "Assembly of Latex Particles by Using Emulsion Droplets as Templates 2. Ball-like and Composite Aggregates", Langmuir, 12, 2385 (1996).
O.D. Velev and K. Nagayama, "Assembly of Latex Particles by Using Emulsion Droplets 3. Reverse (Water in Oil) Systems", Langmuir, 13, 1856 (1997).
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