Polymer microbeads

We have recently deposited directly onto activated carbons and polymer microbeads by deposition-reduction method and have found that gold NPs on pol5mers exhibit remarkably high catalytic activity, which may exceed those of Au/activated carbons and Au/ fine Ce02. The type of polymers and their functional groups are critical to the catalytic activity. 

Polymer microbeads were also used for constructing an OP detection system using fluorescence response of the microbeads. Carboxylate-functionalized polymer microbeads that had been covered with a poly(vinylpyridine) (PVP) layer were modified with fluorescamine (FLA). When the microbeads were exposed to the vapor of diethyl... 

Amsden, B.G. Goosen, M.F.A. An examination of factors affecting the size, distribution and release characteristics of polymer microbeads made using electrostatics. J. Controlled Release 1997, 43 (2-3), 183-196. 

Polymer Synthesis Within Microfluidic Reactor, Fig. 1 (a-e) Scanning electron microscopy images of polymer microbeads obtained by polymerizing TPGDA in droplets obtained in regimes A, B, C, and D, respectively, after removing a SO core. Inset cross section of the... 

The objectives of this chapter are to review the studies on droplet formation mechanisms under the action of electrostatic forces and to determine key parameters critical for production of very small polymer microbeads (i.e., less than 100 p,m in diameter). Specifically, attention is given to the effects of applied potential, needle size, polymer concentration, and electrode spacing, and geometry. An overview of theoretical models and experimental correlations for predictions of droplet diameter is presented. 

Microfluidic generation of polymer particles starts from the emulsiflcation of liquid monomers, oligomers, or polymers. This step is followed by polymerization, cross-linking, or physical gelation of the molecules compartmentalized in droplets. Dimensions of polymer microbeads are predetermined by the dimensions of precursor droplets, which are in turn controlled by the geometry and dimensions of microchannels in MF droplet generator, the mechanism of droplet formation, the macroscopic properties of the droplet and continuous phases, and the relative volumetric flow rates of the continuous and droplet phases. 

Applications of microparticles can be found in medicine, biochemistry, colloid chemistry, and aerosol research [48]. Some uses include separation media for chromatographic application, high surface area substrates for immobilized enzymes, standards for calibration, spacers in optical cavities and liquid crystal displays, and three-dimensional microenvironments for cell encapsulation. It should be stressed that even a scaled-up MF synthesis enables generation of a relatively small amount of particles, in comparison with conventional emulsion, dispersions, or suspension polymerizations. Thus, most practical applications of such microbeads should utilize their high-value unique properties, for example, a uniform distribution of sizes and control of morphology, structure, and shape. Therefore, some of the demonstrated applications of polymer microbeads are still in the proof-of-concept stage. 

Microfluidic generation of polymer particles oflFers the ability to encapsulate molecules, nanoparticles, and large species such as cells or droplets in the interior of polymer microbeads. To achieve MF encapsulation, a host monomer or liquid prepolymer is mixed with the required species to form a solution, an emulsion, or a suspension. This solution is subsequently emulsified to produce precursor... 

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