Dumbbell-like

The interpretation of the Langmuir experiments with the carbosilane den-drimers is supported by the results of molecular dynamics simulation. Figure 14 shows snapshots of a dumbbell-like conformation of carbosilane dendximers observed during lateral compression of a dendrimer monolayer on a polar sub-... 

AIN UFPs were synthesized (27) by injecting A1 powder with NH, gas into the tail of RF-plasma generated at 13.56 MHz. Composite UFPs of Ni-TiN with dumbbell-like or dicelike morphology were produced by using Ni-Ti alloy powder as the raw material (28). 

Jprgensen et al. 141 utilized this molecular organization process (dumbbell-like stacking) to incorporate tetrathiafulvalene (TTF a substrate currently of interest in such areas as molecular electronics and organomagnetism) within the central lypophilic region (Scheme 4.33) of the self-assembled, supramolecular structures. A multistage synthesis... 

As observed for block copolymers in the bulk [190-193], there is a detailed interplay between the order in the system and the chain linear dimension chains like to stretch out somewhat in the direction perpendicular to the lamellae. If one studies the mean square gyration radius component RgZ in the z-direction perpendicular to the walls, one hence observes an oscillatory dependence on thickness D for 1/T>0.5,since only for n ib=D (n=l,2,3,...) the parallel morphology fits nicely into the film, cf. Sect. 2.3, and the dumbbell -like block copoly-... 

Small-angle neutron scattering (SANS) studies of polyradical 50 in THF-dg at 170 K (slightly above melting point of the solvent) revealed the molecular structure (Fig. 31), which was analogous to that obtained from conformational searches.94 Since SANS is a relatively low-resolution technique and the information content of the data is rather low, the structure of 50 might be best described as dumbbell-like with overall dimensions of 2 x 3 x 4nm. Also, this result confirms that polyradical 50 existed as a monomer in solution at low temperatures. 

For a dumbbell-like particle consisting of two adjacent spheres of equal radius a, one has... 

Yu H et al (2005) Dumbbell-like bifunctional Au-Fe304 nanoparticles. Nano Lett 5(2) 379-382... 

Figure 14.14 shows the SEM micrograph of dynamically vulcanized EPDM/PP (75/25) blend fracture surfaces etched by hot xylene vapor. The microdomains of EPDM have the shape of dumbbell-like microgel of about 0.8-1.0 pm in size, where the dark portions represent the PP phase extracted out by hot xylene vapor. The morphology of the microgel domain of EPDM reveals the reason why the dynamically vulcanized blend can be processed and the dynamic vulcanization prevents the cross-linking of EPDM phase from tmly continuous network (24). 

A similar approach was used to construct a unique triblock copolymer having dendritic termini connected by linear segment. The synthesis of the dendritic-fe/oc/c-linear-fetocA -dendritic PS, referred to as the pom-pom structure due to its dumbbell-like shape, results from a convergent anionic polymerization procedure using dichlorodimethyl-silane as a coupling agent [119]. 

A further medical use of nanoscale devices is for targeting cancer cells. In this application the nanocapsule contains molecules lethal to tumors. The nanodevice is linked to a molecule that has a specific affinity for the receptors on the surfaces of cancer cells. Once at the site of the cancer, the nanocapsule dumps its lethal contents into the cancer cell. One method for releasing the contents of the nanocapsule is through a tiny valve developed at UCLA by Jeffrey I. Zink and his coworkers. The valves consist of dumbbell-like molecules that can be rotated by the energy from a single electron. 

By this way, polymers with Janus-type, sphere-type bottle brush-type shapes, or dumbbell-like, palm-tree-like contours were derived with excellent control and precise topological features. 

---