Polystyrene silica

It was apparent that the dense adsorption layer of HPC which was formed on the silica particles at the LCST plays a part in the preparation of new composite polymer latices, i.e. polystyrene latices with silica particles in the core. Figures 10 and 11 show the electron micrographs of the final silica-polystyrene composite which resulted from seeded emulsion polymerization using as seed bare silica particles, and HPC-coated silica particles,respectively. As may be seen from Fig.10, when the bare particles of silica were used in the seeded emulsion polymerization, there was no tendency for encapsulation of silica particles, and indeed new polymer particles were formed in the aqueous phase. On the other hand, encapsulation of the seed particles proceeded preferentially when the HPC-coated silica particles were used as the seed and fairly monodisperse composite latices including silica particles were generated. This indicated that the dense adsorption layer of HPC formed at the LCST plays a role as a binder between the silica surface and the styrene molecules. 

Figure 10. Electron micrograph of composite silica-polystyrene latex system,SPL(-), prepared by using bare silica particles as the seed.

Figure 12. Gel permeation chromatogram of latex polymer separated from composite silica-polystyrene latex system, SPL(HPC).

Nonpolar interactions (hydrophobic) typical octadecyl-modified silica, polystyrene-divinyl benzene copolymers, or carbon-based sorbent. 

Over the years, a variety of stationary matrices have been investigated. Most notably, these solid supports are composed of silica, polystyrene, or miscellaneous polymeric lattices. 

Notes The solid support of the stationary phase is known as the matrix, which includes cellulose, dextran, agarose, polyacrylamide, silica, polystyrene, polyvinyl, polyether and resins. The matrix of differing porosity and stability varies in the degree of cross-linkages. It is modified to confer specific properties the chemical attachment of various functional groups. 

BaUly B, Donnenwitth AC, Bartholome C, et td. (2006) Silica-polystyrene nanocomposite particles synthesized by nitroxide-mediated polymerization and their encapsulation through miniemulsion polymerization. J Nanomater 2006 1—10... 

Fig. 2 Le/i Silica/polystyrene composite particles elaborated through emulsion polymerization using MPTMS as silane coupling agent. Right TEM images reproduced (a) from [25] (scale bars 200 nm) with permission of Wiley-VCH, (b) from [26] with permission of Springer, (c) from [27] with permission of American Chemical Society, and (d) from [28] with permission of Wiley-VCH...

Fig. 6 Left Elaboration of silica/polystyrene raspberry-like colloids through emulsion polymerization using a MMA-terminated poly(ethylene oxide) macromonomer (PEGMA) as coupling agent. Right SEM and TEM pictures of the raspberry-like particles. Adapted from [40] with permission of American Chemical Society...

General porosity of cake over the usual range of pressure difference for filtration 0.9 silica, polystyrene 0.8-0.85 talc, zinc sulfide 0.7 calcium carbonate 0.6 titanium dioxide ignition plug 0.5 kaolin 0.42 iron carbonyl. 

The activity of the liquid phase polyhalogenated metalloporphyrins (Co, Mn, Fe) and supported catalysts (silica, polystyrene) and the cationic metalloporphyrins encapsulated in NaX zeolite are founded to be active for cyclooctane oxidation with molecular into ketone and alcohol with primary ketone formation. At the last case the ration c-one/c-ol is higher than at the use supported on silica and polystyrene catalysts and in fact coincide with results, which are received with the cationic metalloporphyrins in solution. [54]. 

SPE is used both for preconcentration and cleanup of analytical samples. It offers a great variety of different sorbents, which are based on silica, polystyrene, and pyrrolidone polymers and copolymers. SEE could be useful for the cleanup of essential oils before GC analysis or for less polar constituents such as ginkgo terpenes and kavalactones from kava-kava. 

Silica/Polystyrene Nanocomposite Particles The polymerization reactions were carried out in batch at 70 °C for up to 24 hours... 

TEM Images of Klebosol 30N50 silica/polystyrene composite particles obtained for different MPS grafting densities, (a) without mps, (b) Q ps — 0.95 p,mol m and(c)QMPs = 1 9p.mol m The images were recorded at low (bottom) and high magnifications (top). 

The mechanism of formation of the silica/polystyrene composite particles using... 

Apart from the nse of a polymerizable alkoxysilane, silica/polystyrene composite particles with a raspberry-like morphology have been elaborated in the presence of a methyl methacrylate-terminated polyethylene glycol macromonomer. This macromonomer is mainly hydrophilic due to the presence of ethylene oxide repeat units (n 23), which are able to form hydrogen bonds with the silanol groups of silica and adsorb on its snrface. In addition, this molecnle contains a methacrylate functionality able to copoljmerize with styrene thus... 

F re4.7 Electron micrograph of silica-polystyrene composite particles showing large silica particles surrounded by small heterocoagu-lated polystyrene particles. The silica beads have been made hydrophobic through the adsorption of hydroxypropyl cellulose. Reprinted from [56] 1986, with permission from Else-... 

Figure4.28 Daisy-shaped and multipod-like silica/polystyrene particles produced by emulsion polymerization. The silica particles have been surface-modified by a moderate amount of the MPS silane coupling agent...

S. Gu, J. Onishi, E. Mine, Y. Kobayashi, M. Konno, Preparation of multilayered gold-silica-polystyrene core-shell particles by seeded polymerization,/. Colloid Inter/. Sci. 2004, 279,284-287. 

New nanoporous carbons with extremely high mesopore volumes and a highly dispersed distribution of metals on the carbon surface have been obtained using mesoporous silica. Polystyrene sulfonic acid-based organic salts were used as carbon precursor. The precursor chemistry was modified by cation exchange with catalytically active metals (i.e., copper, nickel, cobalt), prior to carbonization. The carbons have pore sizes predominantly in the range of 10-50 nm. 

The friction coefficient, is very difficult to measure and it is known just for the system silica-polystyrene [42] at 153 C. Estimation of Co was based on the theoretical analysis given by Subbotin et aL [105]. Thus, one can establish a relation for the reptation time of a surface adsorbed chain as follows ... 

Bourgeat-Lami, E. and Lang, J. (1999) Encapsulation of inorganic particles by dispersion polymerization in polar media 2. Effect of silica size and concentration on the morphology of silica-polystyrene composite particles. Journal of Colloid and Interface Science, 210,281-289. 

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