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Hollow capsules fabrication

A broad variety of sacrificial colloidal cores have been used for hollow capsule fabrication. They are inorganic or organic particles from tens of nanometers and up to tens of micrometerss, like melamine formaldehyde (MF), polysterene spheres, CaCC>3 and MgCQ3 particles, protein and DNA aggregates, small dye... [Pg.145]

Fig. 8 Hollow capsule fabrication by the polyelectrolyte LbL self-assembly. The core is alternately coated with polycation and polyanion, followed by core dissolution and capsule formation... Fig. 8 Hollow capsule fabrication by the polyelectrolyte LbL self-assembly. The core is alternately coated with polycation and polyanion, followed by core dissolution and capsule formation...
Different colloidal cores can be decomposed after multilayers are assembled on their surface. If the products of core decomposition are small enough to expel out of polyelectrolyte multilayer the process of core dissolution leads to formation of hollow polyelectrolytes shells (Fig. 2.1, d-f). Up to now, various colloidal templates such as organic and inorganic cores, like MF-particles, organic crystals, carbonate particles and biological cells were used as templates for hollow capsule fabrication. Decomposition can be done by different means, such as low pH for MF- and carbonate particles [43], organic water miscible solvents for organic crystals [44] and... [Pg.395]

There are a variety of routes currently utilized to fabricate a wide range of hollow capsules of various compositions. Among the more traditional methods are nozzle reactor processes, emnlsion/phase-separation procednres (often combined with sol-gel processing), and sacrificial core techniques [78], Self-assembly is an elegant and attractive approach for the preparation of hollow capsules. Vesicles [79,80], dendrimers [81,82], and block hollow copolymer spheres [83,84] are all examples of self-assembled hollow containers that are promising for the encapsnlation of various materials. [Pg.515]

Hollow and porous polymer capsules of micrometer size have been fabricated by using emulsion polymerization or through interfacial polymerization strategies [79,83-84, 88-90], Micron-size, hollow cross-linked polymer capsules were prepared by suspension polymerization of emulsion droplets with polystyrene dissolved in an aqueous solution of poly(vinyl alcohol) [88], while latex capsules with a multihollow structure were processed by seeded emulsion polymerization [89], Ceramic hollow capsules have also been prepared by emulsion/phase-separation procedures [14,91-96] For example, hollow silica capsules with diameters of 1-100 micrometers were obtained by interfacial reactions conducted in oil/water emulsions [91],... [Pg.515]

The foregoing results demonstrate that the thickness of the capsule wall can be controlled at the nanometer level by varying the number of deposition cycles, while the shell size and shape are predetermined by the dimensions of the templating colloid employed. This approach has recently been used to produce hollow iron oxide, magnetic, and heterocomposite capsules [108], The fabrication of these and related capsules is expected to open up new areas of applications, particularly since the technology of self-assembly and colloidal templating allows unprecedented control over the geometry, size, diameter, wall thickness, and composition of the hollow capsules. This provides a means to tailor then-properties to meet the criteria of certain applications. [Pg.521]

The next two chapters concern nanostructured core particles. Chapter 13 provides examples of nano-fabrication of cored colloidal particles and hollow capsules. These systems and the synthetic methods used to prepare them are exceptionally adaptable for applications in physical and biological fields. Chapter 14, discusses reversed micelles from the theoretical viewpoint, as well as their use as nano-hosts for solvents and drugs and as carriers and reactors. [Pg.690]

Antipov AA, Sukhorukov GB, Fedutik YA, Hartmann J, Giersig M, Moehwald H (2002) Fabrication of a novel type of metallized colloids and hollow capsules. Langmuir 18 6687-6693... [Pg.160]

Figure 6.21 Schematic description of the steps used for fabricating hollow capsules (coated inside with potassium persulfate initiator) and grafting-from polymerization of styrene sulfonate (SS) inside the capsules. (After Choi et al., 2005.)... Figure 6.21 Schematic description of the steps used for fabricating hollow capsules (coated inside with potassium persulfate initiator) and grafting-from polymerization of styrene sulfonate (SS) inside the capsules. (After Choi et al., 2005.)...
MANGANESE CARBONATE PARTICLES PREPARATION BY COLLOIDAL AGGREGATION FOR HOLLOW POLYELECTROLYTE CAPSULES FABRICATION... [Pg.349]

Method for synthesis of monodisperse spherical-like manganese carbonate (MnCOs) particles by colloidal aggregation process is developed. Hollow polyelectrolyte capsules have been prepared by means of layer-by-layer absorption of charged polyelectrolytes on microsized MnCOs particles with the subsequent decomposition of a micrometer nucleus. The use of inorganic templates is a way for clean capsules fabrication. The manganese carbonate particles and capsules obtained were investigated by SEM, SFM, XRD, and confocal fluorescent microscopy. [Pg.349]

One of the most influential innovations in the history of LbL technology so far must be LbL assembly on a colloidal particle with subsequent hoUow capsule preparation [220-223]. In the first decade of LbL technology, researchers regularly assembled films on a flat solid support of visible dimensions. However, the mechanism of the LbL assembly does not exert any limitations on the size of supports or their shape. Therefore, LbL assembly on microscopic solid surfaces dispersed in solution is reasonable, opening the way to fabrication of both three-dimensional structures and nano/micro-sized objects through the LbL process. As shown in Fig. 8, the concept of the assembly is simple. LbL films are assembled sequentially on a colloidal core in a similar way to conventional LbL assembly on a flat plate. Dissolution of the central particle core upon exposure of the particles to appropriate solvents then results in hollow capsules. [Pg.65]

Use of the LbL assembly is not limited to fabrication of thin films on fiat substrates. It can be applied to a microsized colloidal particle core to prepare hollow capsules, which are expected to be highly useful for DBS applications. In this innovative strategy, LbL films are assembled sequentially on a colloidal core similar to the conventional LbL assemblies on a fiat substrate. Destruction of the central particle core after completion of the LbL assembly results in formation of hollow capsule structures. Figure 2.2.7 illustrates one example to prepare a biocompatible polyelectrolyte microcapsule with DNA encapsulation by Lvov and coworkers [15]. In their approach, water-insoluble DNA/spermidine complexes were... [Pg.32]

A. Antipov, D. Shchukin, Y. Fedutik, A. I. Petrov, G. B. Sukhorukov and H. Moehwald, Carbonate microparticles for hollow poly electrolyte capsules fabrication. Colloids and Surfaces, A Physicochemical and Engineering Aspects, 224,175-184 (2003). [Pg.157]

Few years ago this concert of LbL assembling of charged species was transferred to coat micron and sub-micron sized colloidal particles [24-29]. The idea is to employ the nano-engineered properties of multilayers as shell structures formed on colloidal particles. This paper outlines the recent works on step-wise shell formation on various colloidal cores, fabrication and properties of hollow capsules, regulation of capsule wall permeability and approaches to encapsulate different materials into these capsules. [Pg.386]

To fabricate nano-engineered films on colloidal particles a layer-by-layer adsorption of oppositely charged macromolecules is used. Different templates can be coated with multilayer films and decomposed to form hollow capsules with defined size, shape and shell thickness. As example, polyelectrolyte capsules can be used as carrier for biological species, for a controlled release and targeting of drugs and as micro-containers to perform chemical reactions in restricted volumes. [Pg.528]

Figure 3 (a) Schematic procedure for the preparation of multilayers of 2D inorganic sheets on high-surface-area silica. (b) Schematic illustration showing the fabrication of multilayered hollow capsules containing drugs. [Pg.166]

Antipov AA, Shchukin D, Fedutik Y, Petrov AI, Sukhonikov GB, Mohwald H (2003) Carbonate microparticles for hollow polyelectrolyte capsules fabrication. Colloids Surf A 224 175-183... [Pg.391]

Kida T, Mouri M, Akashi M (2006) Fabrication of hollow capsules composed of poly(methyl methacrylate) stereocomplex films. Angew Chem Int Ed 45 7534—7536... [Pg.392]

Wang HG, Zheng XM, Ping C, Zheng XM. The fabrication of reactive hollow polysiloxane capsules and their application as a recyclable heterogeneous catalyst for the Heck reaction. J Mater Chem 2006 16 4701-4705. [Pg.205]

Inorganic nanoparticles themselves can be assembled into mesoscopic structures. Dinsmore et al. proposed an approach for the fabrication of solid capsules from colloidal particles with precise control of size, permeability, mechanical strength, and compatibility (Fig. 2.9).44 This unusual mesoscopic structure is called colloidosome and is prepared through emulsion droplets at a water-oil interface. Following the locking together of the particles to form elastic shells, the emulsion droplets were transferred to a fresh continuous-phase fluid identical to that contained inside the droplets. The resultant structures are hollow, elastic shells whose permeability and elasticity can be precisely controlled. [Pg.21]

S.B. Yoon, K. Sohn, J.Y. Kim, C.H. Shin, J.S. Yu, and T. Hyeon, Fabrication of Carbon Capsules with Hollow Macroporous Core/Mesoporous Shell Structures, Adv. Mater., 2002, 14, 19-21. [Pg.600]


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See also in sourсe #XX -- [ Pg.515 , Pg.516 , Pg.517 , Pg.518 , Pg.519 , Pg.520 , Pg.521 ]




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