Polymer-coated particles

Coelectrodeposition with conducting polymers from a material-monomer slurry submitted to electropolymerization conditions. Thus, Rolison (1990) prepared uniform particle-polymer coatings from a drop of zeolite suspension in a pyrrole solution in Et4NC104/MeCN (see also Bessel and Rolison, 1997a). 

Exxon products appear to release via a unique mechanism. Like other polymer-coated technologies, the penetration of water iato the granule is purely by diffusion. However, as water enters the particle, an osmotic pressure is created as the fertilizer is solubilized. This pressure causes an expansion of the elastomeric coating and the particle swells to many times its original diameter. As the particle swells, the coating becomes increasingly thinner to the point where it caimot contain the internal pressure and the nutrient is released. 

FIG. 4 Sterically stabilized colloidal particles are coated with short polymer brushes. A hard sphere-like interaction arises. 

Polymer-Coated Adsorbents for the Separation of Biopolymers and Particles... 

Another method to synthesize hollow nanocapsules involves the use of nanoparticle templates as the core, growing a shell around them, then subsequently removing the core by dissolution [30-32]. Although this approach is reminiscent of the sacrificial core method, the nanoparticles are first trapped and aligned in membrane pores by vacuum filtration rather than coated while in aqueous solution. The nanoparticles are employed as templates for polymer nucleation and growth Polymerization of a conducting polymer around the nanoparticles results in polymer-coated particles and, following dissolution of the core particles, hollow polymer nanocapsules are obtained. 

For trace analysis in fluids, some Raman sensors (try to) make use of the SERS effect to increase their sensitivity. While the basic sensor layout for SERS sensors is similar to non-enhanced Raman sensors, somehow the metal particles have to be added. Other than in the laboratory, where the necessary metal particles can be added as colloidal solution to the sample, for sensor applications the particles must be suitably immobilised. In most cases, this is achieved by depositing the metal particles onto the surfaces of the excitation waveguide or the interface window and covering them with a suitable protection layer. The additional layer is required as otherwise washout effects or chemical reactions between e.g. sulphur-compounds and the particles reduce the enhancement effect. Alternatively, it is also possible to disperse the metal particles in the layer material before coating and apply them in one step with the coating. Suitable protection or matrix materials for SERS substrates could be e.g. sol-gel layers or polymer coatings. In either... 

Water-soluble QDs now are available from a number of manufacturers (Invitrogen, Evident Technologies, and Crystalplex). Each supplier uses their own proprietary methods of surface pacification to create biocompatible particles. Even coated QD clusters are available that contain hundreds of particles bound together in a polymer matrix (Crystalplex). These form intensely bright labels for biomolecules, because the nanocrystals do not quench when clustered together at high density. 

For Gg (b), a reasonable (although not strictly correct) procedure is to replace the Stern potential in one of the standard equations for Gg by the zeta potential of the polymer-coated particles this assumes that the plane of hydrodynamic shear corresponds to the periphery of the adsorbed layer. 

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