Hollow microspheres applications

In another specific application that of hot melt adhesives, the choice of filler has an effect on adhesion (Figure 8.54). Four types of spheres (K-20, S-22, Z-light, and ML 3050) increase adhesion compared with unfilled adhesive. The first two (K-20 and S-22) are hollow microspheres of very low density. The remaining two have a lower density than glass but have thicker walls. Three fillers (CaCOa, Zeospheres, and aluminum) are solid products. All fillers which decrease adhesion have substantially higher thermal conductivity than the fillers which increase adhesion. From the studies of crystallization profiles, it is apparent that longer crystallization times allow the network to orient itself on the substrate, resulting in better adhesion. ... 

Other recent papers indicate that PAn-like materials can in fact be grown from chemical oxidation of aniline in basic solutions of aqueous NaOH.7172 These species again possess unique nanostructures such as nanotubes and hollow microspheres that may have exciting potential applications in nanoscience. 

H. Zhu, J. Wang, and G. Xu, Fast synthesis of CU2O hollow microspheres and their application in DNA biosensor of Hepatitis B virus. Crystal Growth and Design 9, 633-638 (2009). 

Cao, A.-M., et al. [2005]. Self-assembled vanadium pentoxlde (V2O5] hollow microspheres from nanorods and their application In llthlum-lon batteries. An ew. Chem. Int. Ed, 44[28] pp. 4391-4395. 

Organic spheres are predominantly polymeric, consisting of synthetic or natural polymers. The field of polymeric nano- and microparticles is vast, comprising, for instance, latex particles for coatings, hollow particles for syntactic foams, and microcapsules for foaming and additive release. In addition, there are core-shell microbeads and coated polymeric particles, where the particles can exhibit multiple functionalities, thanks to the individual features of their different layers 1]. As fillers in thermosets and thermoplastics, hollow microspheres and expandable microcapsules are among the most frequently used in commercial applications. 

Han, J., Liu, Y. and Guo, R. (2009). Reactive Template Method to Synthesize Gold Nanoparticles with Controllable Size and Morphology Supported on Shells of Polymer Hollow Microspheres and Their Application for Aerobic Alcohol Oxidation in Water, Adv. Fund Mater., 19, pp.1112-1117. 

Cao AM, Hu JS, Liang HP, Wan LJ (2005) Self-assembled vanadium pentoxide (V2O5) hollow microspheres fixrm nanorods and their application in lithium-ion battraies. Angew Chem Int Ed 44(28) 4391-4395. doi 10.1002/anie.200500946... 

DL Wilcox, M Berg, T Bemat, D Kellerman, JK Cochran, eds. Hollow and Solid Spheres and Microspheres Science and Technology Associated with Their Eabrication and Application. Vol 372. Pitsburgh Materials Research Society Proceedings, 1995. 

Initially glass microspheres were used in the 1970s to overcome severe lost circulation problems in the Ural Mountains. The technology has been used in other sites [1189]. Hollow glass beads reduce the density of a drilling fluid and can be used for underbalanced drilling [1199-1201]. Field applications have been reported [73]. 

By changing the ultrasound power, changes in the mesoporosity of ZnO nanoparticles (average pore sizes from 2.5 to 14.3 nm) have been observed. In addition to the changes in mesoporosity, changes in the morphology have also been noted [13]. Recently, Jia et al. [14] have used sonochemistry and prepared hollow ZnO microspheres with diameter 500 nm assembled by nanoparticles using carbon spheres as template. Such specific structure of hollow spheres has applications in nanoelectronics, nanophotonics and nanomedicine. 

Schmitt, M.L., J.E. Shelby and M.M. Hall, Preparation of hollow glass microspheres from sol-gel derived glass for application in hydrogen gas storage. /. Non-Crystalline Solids, 352, 626-631,2006. 

Solid and hollow glass microspheres have been made for many years for a variety of applications. Fabrication techniques involving formation of microspheres were pioneered by Beck7 and later expanded by Howell8 and Marshall9. 

A final biomedical use for polyphosphazenes is as components in microspheres, vesicles, and micelles for use in drug-delivery applications. Microspheres are pseudo-spherical constructs that range in size from 1 to 600 microns. Vesicles (lipozomes) are hollow, water-filled bilayer spheres with diameters that range from 0.03 tolO microns. Micelles typically have diameters near 1 micron (100 nanometers). Idealized representations of these three structures are shown in Figure 3.23, together with the location of trapped drug molecules. 

Wilcox DL, Berg M, Bernat T, Kellerman D, Cochran JK (eds) (1995) Hollow and solid spheres and microspheres science and technology associated with their fabrication and application, vol 372. Materials Research Society Proceedings, Pittsburgh... 

In general, microgels obtained by radiation methods can be used in various applications in the same way as conventional synthesized systems, e.g., as drug delivery templates, for encapsulation, or as microreactors [29, 30], PAAm for example can be used as template material to synthesize hollow cadmium selenide nanospheres [24], and PVP can be used for the incorporation of ferromagnetic nanoparticles to obtain magnetic hydrogel microspheres [13],... 

Room temperature ionic liquids (RTILs) are molten salts whose melting points are below room temperature. RTILs are formed when the constituent ions are sterically mismatched, thereby hindering crystal formation [17]. As polar solvents, RTILs have unique applications as tunable and environmentally benign solvents with very low volatility, high fire resistance, excellent chemical and thermal stability and wide liquid temperature range and electrochemical windows [17-19]. Solvent applications of RTILs include, for example, organic synthesis [17,20, 21], separations [22, 23], storage and transportation of hazardous chemicals [24], polymeric electrolytes [25, 26], dissolution of natural products [27] and synthesis of hollow metal oxide microspheres [28]. 

Syntactic foam is made by dispersing hollow microballoons into a liquid polymer and then solidifying it. Microballoons are typically hollow glass or hollow phenolic microspheres, and the most common liquid polymer is an epoxy prepolymer, which is then cured. Although some products are notably woodlike in their properties and machinability, primary applications are high-performance products such as deep-sea instrumentation. 

In the last decade hollow spheres are extensively studied in the context of application as containers of prolonged action for substances of the different chemical nature dmgs, cosmetics, dye. A number of methods for preparation of microspheres with the sizes ranging from nanometers to micrometers and consisting of various materials are developed. Polyelectrolye capsules have been produced by sequential adsorption of oppositely charged polyelectrolytes, also known as Layer-by-Layer (LbL) assembly onto the surface of colloidal particles followed by core dissolution [1-2]. Most of the capsules applications imply their chemical or physicochemical modification by influence of the ionic strength [3], pH [3], temperature... 

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