Macroporous copolymer particles have a broad range of applications such as ion exchange resins and sorbents, catalyst supports, and carriers of biologically active species. Many of these applications require precise control of the dimensions of microbeads in the range from 50 to 100 µm and predetermined size of pores. This paper reports semicontinuous photoinitiated microfluidic synthesis of macroporous polymer particles with the designated dimensions and a range of internal structures. Comparison with microspheres synthesized by conventional suspension polymerization shows that microfluidic synthesis provides better control over the porous structure of the microbeads.
A silver/nylon 6,6 nanocomposite containing 1 wt % metallic silver has been produced from an aqueous solution of silver nitrate in the presence of ammonia and ethylene glycol by an ultrasound-assisted reduction method. The structure and properties of nylon 6,6 coated with silver have been characterized with X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray, X-ray photoelectron spectroscopy, Raman spectroscopy, and diffused reflection spectroscopy measurements. The nanocrystals of pure silver, 50-100 nm in size, are finely dispersed on the polymer surface without damaging the nylon 6,6 structure. This silver-nylon nanocomposite is stable to many washing cycles and thus can be used as a master batch for the production of nylon yarn by melting and spinning processes. The fabric knitted from this yarn has shown excellent antimicrobial properties.
Syntheses of macroporous polymer particles under certain conditions produce microbeads with a smooth nonporous "skin" layer. This effect limits the applications of porous microbeads by preventing solute molecules to permeate the dense particle surface and reach particle's porous interior. This paper reports a straightforward method thatswithout the adjustment of the composition of microbeadsscan be used to suppress the formation of the "skin" on the surface of macroporous polymer particles. The approach presented as a solubility parameter-interfacial tension "map" paves the way to the selection of a broader range of porogen solvents and hence better rationalization of the composition of the monomer mixtures used in the synthesis of macroporous particles.
Polymer-based porous hybrid materials (PHMs) carrying inorganic nanoparticles on the surface of pores have important applications in chemical and biological sensing, in chromatography, and in heterogeneous catalysis. This Feature Article provides an overview of the recent developments in the synthesis and fabrication of multifunctional PHMs using polymerizationinduced phase separation. Exemplary applications of a PHM coated with gold nanorods were demonstrated for the simultaneous detection of different analytes using surface enhanced Raman scattering (SERS) spectroscopy and fl uorescence microscopy.
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