Template spherulites

The morphology of zeolites can also be strongly influenced by the variation in different synthesis parameters. Aluminium content, template/silica ratio, water content, nature of cations present, alkalinity and degree of polymerization of the silica are all major factors which can influence the crystallization and hence the morphology of zeolites [5 - 7]. These particle morphological types can generally be characterized as either spherulitic (polycrystalline spherical) or lath-shaped (polyhedral) in nature. In both cases... 

The formation of nanoparticles from microemulsions need not essentially follow the template shape. Pileni [32] (as quoted by Ganguli and Ganguli) has shown that with water/isooctane/Cu( AOT)2 shapes like sphere to cylinder to mixed spherulites and cylinders to other polydisperse shapes were possible with increasing to. According to Pileni [33], the presence of salt anions can control the shape while chloride ions favour formation of nanorods, nitrate ions hinder it. The surfactant content also can have a say on the shape of nanoparticles. The infrequently observed morphologies of nanoparticles, viz. wires, trigons, hexagons, cubes etc. have so far no specific and reliable reasons for formation in micro emulsion templates. 

Figure 3.13 shows a complete series of mostly previously unpublished micrographs of the remarkable ability of the PLLA block (and homo-PLLA) to form spherulites at temperatures where the PCL block is molten, thus templating the spherulitic morphology that will characterize the sample upon cooling, since PCL crystallizes within the interlamellar region of the previously formed spherulites.The PLLA block crystallized in a... 

Similarly, a combination of the mineralization under control of low molecular weight polyelectrolytes and a foreign static template such as air bubbles has been explored for the generation of macroporous BaCOs spherulites [230], which is similar to that found in the microemulsion system reported by Mann et al. [354]. 

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