Colloidal-encapsulated polymeric

To increase the bioavailabiUty of proteins and peptides is a major concern during oral absorption because of the low absorption and instability of proteins in the gastrointestinal tract (GIT). Colloidal-encapsulated polymeric nanoparticles are an important... 

Adsorption behavior and the effect on colloid stability of water soluble polymers with a lower critical solution temperature(LCST) have been studied using polystyrene latices plus hydroxy propyl cellulose(HPC). Saturated adsorption(As) of HPC depended significantly on the adsorption temperature and the As obtained at the LCST was 1.5 times as large as the value at room temperature. The high As value obtained at the LCST remained for a long time at room temperature, and the dense adsorption layer formed on the latex particles showed strong protective action against salt and temperature. Furthermore, the dense adsorption layer of HPC on silica particles was very effective in the encapsulation process with polystyrene via emulsion polymerization in which the HPC-coated silica particles were used as seed. 

Also, here, the effect of the adsorption layer of HPC on encapsulation of silica particles in polymerization of styrene in the presence of silica particles has been investigated. Encapsulation is promoted greatly by the existence of the adsorption layer on the silica particles, and the dense adsorption layer formed at the LCST makes composite polystyrene latices with silica particles in the core (7.). This type of examination is entirely new in polymer adsorption studies and we believe that this work will contribute not only to new colloid and interface science, but also to industrial technology. 

Figure 6.8 Schematic representation of a cytochrome P450 mimic in which catalytic manganese porphyrins are captured in the bilayer of polymerized vesicles. Colloidal platinum encapsulated in the vesicles in combination with molecular hydrogen serves as a reductant.

A polymeric nanosphere may be defined as a matrixtype, solid colloidal particle in which drugs are dissolved, entrapped, encapsulated, chemically bound or adsorbed to the constituent polymer matrix. These particles are typically larger than micelles having diameters between 100 and 200 nm and may also display considerably more polydispersity (Fig. 3.21). 

Particulates are commonly classified into micro- and nanoparticles based on the size of the particles. Nanoparticles are colloidal particles ranging from 10 to 1,000 run, in which drag may be entrapped, encapsulated, and/or absorbed. Microparticulates are drag-containing small polymeric particles (erodible, non-erodible or ion-exchange resins) within the size of 1-10 /on, which are suspended in a liquid carrier medium. 

Nanoparticles Nanoparticles have been among the most widely studied particulate delivery systems over the past three decades. They are defined as submicrometer-sized polymeric colloidal particles ranging from 10 to 1000 nm in which the drug can be dissolved, entrapped, encapsulated, or adsorbed [206]. Depending on the preparation process, nanospheres or nanocapsules can be obtained. Nanospheres have a matrixlike structure where the drug can either be firmly adsorbed at the surface of the particle or be dispersed/dissolved in the matrix. Nanocapsules, on the other hand, consist of a polymer shell and a core, where the drug can either be dissolved in the inner core or be adsorbed onto the surface [207],... 

In this section the concentrated emulsion polymerization method is employed to encapsulate submicron inorganic powders. In a first step, a stable colloidal dispersion of the powder in an aqueous solution of a monomer containing an appropriate dispersant and a suitable initiator was prepared. This colloidal dispersion was subsequently employed as the dispersed phase of a concentrated emulsion whose continuous phase, decane, contained a surfactant. 

Zhao X, Zhou S, Chen M, et al. (2009) Effective encapsulation of Sudan black B with polystyrene using miniemulsion polymerization. Colloid Polym Sci... 

Bouanani F, Bendedouch D, Hemery P, et al. (2008) Encapsulation of montmorillonite in nanoparticles by miniemulsion polymerization. Colloid Surf A Physicochem Eng Asp... 

Mirzataheri M, Mahdavian A, Atai M (2009) Nanocomposite particles with core-shell morphology IV an efficient approach to the encapsulation of Cloisite 30B by poly (styrene-co-butyl acrylate) and preparation of its nanocomposite latex via miniemulsion polymerization. Colloid Polym Sd 287 725-732... 

Emulsion polymerization is the polymerization technique that starts with emulsified monomer in the continuous aqueous phase. Polymer formation takes place in the micelles and is initiated by water-soluble initiators. The monomers are insoluble or sparingly soluble in water. Emulsion polymerization is used very frequently in order to perform encapsulation of inorganic particles with polymers where water-based coatings are required. For the encapsulation of inorganic particles, seeded emulsion polymerization is performed hydrophobic inorganic particles are dispersed with normal surfactants or protective colloids in the aqueous phase. As polymerization on the surface of inorganic particles is always in competition with secondary particle formation, the concentration of the surfactants should be lower than their critical micelle concentration. However, homogeneous nucleation can also occur, which... 

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