Onion morphology

Note The morphology is identical to onion morphology within a matrix of homopolymer... 

R = R = OC12H25, R = H) molecular conformations likely predominate to satisfy the geometrical requirements. The supramolecular disks or columns thus result from the molecular association of two or three dendrimers (depending on the aliphatic chain substitution) in the appropriate conformation, as depicted in Fig. 52 and these columns are packed in a hexagonal lattice. Moreover, considering the diblock, alternated chemical nature of these octopus dendrimers, an onion morphology for the columns is most likely probable (Fig. 53) [264]. 

Polyamides toughened by reactive blending of an impact modifier commonly show inclusions of nylon in the particles of the modifier. These particles exhibit a so-called bull s-eye or onion morphology, which is thought to result from phase inversion during blending [111]. 

The mesophase pitch is then extmded and melt spun through spinnerettes into fibers. The flow pattern of the mesophase during fiber formation has a strong influence on the morphology of the fiber (52—54) and can result in fibers with radial, onion-skin, or random microstmctures. Commercially available PBCFs have a round cross section, but this can be easily modified by changing the cross section of the spinnerette holes. Multilobal and C-shaped fibers have been produced with exceptional mechanical properties (55). 

Let us note in addition that the layered sulfides M0S2 and WS2 have been found to form nanotubes and other fullerene-type structures, on account of their highly folded and distorted nature that favors the formation of rag and tubular structures. Such materials have been synthesized by a variety of methods [78] and exhibit morphologies, which were described as inorganic fiillerenes (IF), single sheets, folded sheets, nanocrystals, and nested IFs (also known as onion crystals or Russian dolls ). 

Transmission electron microscope (TEM) analysis of nanostructured carbon films shows that, at this scale, the morphology is reminiscent of the precursor clusters. TEM micrographs show the presence of an amorphous matrix with small closed shell particles and bundles of graphene sheets (Figure 2.4a). Large onion-like and tubular particles have also been observed. 

Are carbynes produced in laboratory carbon and C IC Ar vapors designed to simulate the properties carbon dust in astrophysical environments Field-emission scanning electron microscope (FESEM) and HRTEM studies of vapor-condensed carbon smokes showed a wide range of carbon morphologies that were free of metal impurities (at EDS detection limits), viz. 1. Ceo and higher fullerenes that agglomerated into amorphous soot grains, 2. fullerenic nanotubes and onions, 3. amorphous carbon sheets,... 

Second, the use of CNTs embedded in a membrane matrix to provide nanochannels for precise separations (Fig. 30). The last example illustrates the influence of processing on the morphology of spherical silica particles produced by variation of the conditions particles can be produced as onion rings or with a hexagonal internal structure. Carbon onions can be produced and are found to have durable tribological properties (128) (Fig. 31). 

Shapes of vesicular aggregates range from tubular to spherical, from more exotic large compound (LCV) and starfish vesicles to simpler extended lamellae. Both unilamellar [75] and multilamellar ( onions ) [47,76] vesicles have been observed. One of the possible morphologies formed in solution are tubular vesicles, also known as tubes (rods) [77,78], Soft, water-filled polymer tubes of nanometer-range diameters and several tens of millimeters in length have been prepared via self-assembly of amphiphilic ABA triblock copolymer in aqueous media (Fig. 4). The tubes were mechanically and chemically stable and could be loaded with water-soluble substances [23],... 

Addition of a graft copolymers is much less frequent. Some blends of this type were reported to have unusual onion-like morphology. This observation is not universally valid — the com-patibilizing effect must depend on the structure and composition of the copolymer. Owing to complexity of the these structures the theoretical analysis has not been attempted. 

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