Spherical nanopartides

The formation of Ag triangular nanoprisms from spherical nanopartides in the presence of trisodium citrate and bis(p-sulfonatophenyl)phenylphosphine (BSPP) (dipotassium salt) with fluorescent light [245] has been described, as has that of Au nanoprisms [246]. 

Chrissafis et al. [302] compared four different nanopartides to produce nanobiocomposites based on PLA two layered silicates (Cloisite Na and Qoisite 20A MMTs), spherical nanopartides (fumed silica Si02) and MWCNTs. AH nanopartides induced a substantial enhancement of Young s modulus and TS compared to neat PCL. From TGA analysis it was also observed that modified MMT and fumed silica accelerate the decomposition of PCL owing to respective aminolysis and hydrolytic reactions. On the other hand, carbon nano tubes and unmodified MMT slowed the thermal degradation of PCL due to a shielding effect. 

Gold nanostructures of various sizes and morphologies were synthesized at room temperature using naturally occurring biodegradable plant surfactants [ 76]. The sizes and shapes (spherical, prisms, and hexagonal) of the synthesized nanopartides were dependent on the concentration of the gold ions and the type of plant surfactant used for preparation. 

Spherical and uniform Pt nanopartides, 3.5-4.0 nm supported on carbon, were prepared by microwave irradiation [177]. The products exhibited very high electro-catalytic activity in the room-temperature oxidation of liquid methanol. The preparation method was similar to that of Komarneni [175], namely, a polyol reduction. 

As an example, spray drying of nanosized porous particles yields spherical agglomerates with a bimodal pore size distribution the pores according to the primary particles (intraparticle pores) and the secondary pores (interparticle pores) made by the void fraction of the agglomerated nanobeads. Figure 3.19 shows spherically agglomerated nanoparticles that build up a porous bead. For a given size dp of the nanopartides the pore diameter of the interstitial pores... 

During the past two decades, the synthesis or preparation of II-VI semiconductor nanopartides has experienced an enormous development, to the point where the pubhshed material related to the topic has become virtually unmanageable. Nevertheless, the aim of this chapter is to provide a chronological overview of some of the major historical lines in this area, starting with the earliest studies with CdS nanocrystals prepared in aqueous solution. At several points in the story - mostly when successful preparations are first described - the chapter branches into evolving sub-fields, leading to Sections 3.2.1.2 and 3.2.I.3. The remainder of the review then relates to matters distinct from these preparational approaches. More complicated nanoheterostructures, in which two compounds are involved in the build-up of spherically layered particles, are detailed in Sections 3.2.1.4 and 3.2.1.5. 

Figure 3.145 Zero-field-cooled (ZFC) and field-cooled (FC) magnetization scans for the 2 nm spherical iron nanopartides and the 2nmx11nm iron nanorods at the applied magnetic field of 100 Oe. Reproduced with permission from Ref. [82] 2000, American Chemical Society.

It is clear that mixed polymer brushes attached to nanopar-tides or planar supports have many properties in common. However, binary brashes anchored to spherical supports provide additional benefits similar to homopolymetic brashes, the attachment to partides creates large surface areas that can be used as carriers for nanopartides or guest molecules (see Section 6.07.5). The carrier partides can also add spedal properties (see Section 6.07.2.1). Moreover, the immobilization onto a strongly curved support might have a strong impact on the phase behavior of the mixed brash. 

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