Worm-like structure

Interestingly, this behavior of the reaction mixture can be prevented by employing another principle of particle stabilization steric protection. Inclusion of pegylated comonomer (PEG-AEPD) into the reaction mixture did enable the formation of nonaggregating DNA particles. It also caused the particles to form worm -like structures (as judged by transmission electron microscopy) that have previously been observed with DNA complexes formed from block copolymers of PEL and PEG [98]. 

Figure 12.5 AFM images of thin PS-b-P4VP (20000 19000) films (3-pentanone solvent) with worm-like structures on mica substrates and height profiles of horizontal lines in these images, (a), (d) Before and (b), (e) after being doped with TCPP. (c), (f) TCPP-doped films irradiated with fluence of about ISOmJcm in air. (d)-(f) show the height profiles of the...

The collage of electron micrographs shown in Figure 19 Illustrates a probable transition from a nucleation and growth phase separation mechanism to a spinodal decomposition. The 7% PS sample shows more or less spherical PS domains, characteristics of nucleation and growth. However, a few domains appear to have some elliptical characteristics. When the PS content increases up to midrange, the shape of the PS domains becomes more obviously elliptical, suggestive of cross-sections of cylinders or other worm-like structures. As the PS content increases further, the... 

Also a hindering effect toward oxygen diffusion, owing to the intumescent char layer formed, may be responsible for CO increase when oxygen concentration is low, incomplete combustion is favored over a complete one. The char morphology in presence of EG is particular the char has the so-called worm like structure (Figure 25.4) due to the expansion of EG. 

Fig. 6.10 The sequence of STM pictures shows the nanoscale growth of Si in the SiCl4 (0.1 M)/[BMP]Tf2N on Au(lll) probed by in situ STM. Instead of a typical flat Au(111) surface, a worm-like structure is probed at —300mV vs. Fc/Fc+ (OCP) (a). When the electrode potential is reduced a...

Fig. 9.3 STM image in pure [Pyi JTFSA on an Au(lll) surface. Instead of a typical flat Au(lll) surface, a rough surface with worm-like structures is observed at —0.4V (OCP). ...

Davenport et al. [14] have shown that a worm-like structure of gold oxide appears on a crystalline gold surface oxidized electrochemically. By comparing in-situ STM images with electrochemical data it was evident that monolayers of gold oxide were formed at anodic potentials and that a slow reduction of the gold oxide at cathodic potentials recovered the bare surface. The gold surface, however, is not oxidized solely by electrochemical methods. 

Soot, or amorphous carbon, is the material that remains upon decomposition of hydrocarbons. Though it has long been known that soot is produced during the decomposition of hydrocarbons over Fe catalysts, it wasn t until 1953 that Davis, Slawson and Rigby also observed the presence of carbon fibers (20). These fibers existed within a sample of amorphous carbon that formed from the decomposition of CO at Fe surfaces. These fibers were described as worm-like structures that form during the decomposition of CO at about 450°C in the presence of Fe. The iron could be small iron particles present in, or even in macroscopic iron samples. It was clear that the Fe played the role of catalyst in the formation of these carbon stractures. Today, the process of growing carbon nanotubes from the decomposition of a hydrocarbon precursor at an iron catalysts is conunoirly known as thermal chemical vapor deposition (CVD). 

A direct application of these results to the behavior of high polymeric substances is not, however, feasible, because we seldom meet with rigid rods in the latter, but usually have to assume the existence of more or less mobile thread or worm-like structures. For this reason, Eirich and Sverak have extended their experiments to flexible model materials, which could be realized in the form of swollen fine filaments of artificial silk, or as thin flexible filament crystals (cholesterol, azo dyes etc.). Such preparations prove to be very uniform in regard to length and axial ratio of the separate particles, but they offer an irregular aspect under the microscope because of their flexibility. 

Jain and Bates found that the hydrophobic dimensions of spherical and worm-like structures formed by PEO-PBD diblock copolymers followed the 2/3-power law. For PEO-based diblock copolymer amphiphiles, Dalhaimer et al. measured the d of the worm-like micelles using Cryo-TEM images and found a scaling dependence of d on the length of the hydrophobic chain, d... 

Image of extruded worm-like structures to visualise flexibility (left) P(3HB)/PCL 70/30 wt% (flakes) exhibits bendable properties, (right) pure P(3HB) shows a brittle fracture. ... 

In the case of diblock copolymers containing a charged block, the structure of the micellar aggregates can be controlled by addition of salt, and transitions from spherical micelles to rod- and worm-like structures have been observed at high salt concentrations [36]. 

Some differences between BCP/surfactant systems and surfactant/co-surfactant mixtures arise from the large difference in size and from the polymer-specific chain entropy contributions to the free energy of the systems. Moreover, in contrast to simple surfactant-based samples, the polydispersity of the polymer chains is also an important issue for structure formation. Polydispersity might lead to coexistence of different structures (e.g., spheres and worm-like structures) in the same polymer solution. This is due to the fact that small differences in the degree of polymerization of one of the blocks might lead to different packing parameters for a part of the size distribution. 

Three different models i.e. worm-like structure by Wegner... 

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