Network conformations

FIGURE 6.3.7 A conformable network of pressure sensors. A plastic film with organic transistors and pressure-sensitive rubber is processed mechanically to form a unique net-shaped structure, which makes a film device extendable by 25%. A magnified view of extended net structures is also shown. 

One point further remains to be considered. Even if the two networks were completely compatible, so that only one phase was formed in the classical sense, an important topological difference between the networks still remains, which would permit the polymerization sequence to be established. We refer here to the fact that the first network formed is swollen, so that its chains have an extended and less probable conformation. Network... 

In the course of pseudorotation and ring inversion of boat-chair conformations, intermediate conformational minima of a different type, e.g. a chair, may be visited. This chair conformation will have its own pseudorotation cycle and ring inversion process, which is thus linked to the boat-chair cycle. There are likely to be further different, less stable conformational types, some of them little populated no doubt, but linked into the total conformational network by an interconversion process. 

Therefore the 28 analytes and their enantiomers were encoded by the conformation-dependent chirality code (CDCC) and submitted to a Kohoiien neural network (Figure 8-1 3). They were divided into a test set of six compounds that were chosen to cover a variety of skeletons and were not used for the training. That left a training set containing the remaining 50 compounds. 

Figure 13.10 Rearrangements of the hydrogen bond network between strands 1, 2, and 3 in the p sheet of Go. as a consequence of the switch from the GDP (blue) to the GTP (green) conformation. Strand P3 pulls away from pi and disrupts two hydrogen bonds in order to bring Gly 199 into contact with the y-phosphate of GTP. As a consequence new hydrogen bonds are formed between P2 and P3. (Adapted from D. Lambright et al.. Nature 369 621-628,...

To understand the global mechanical and statistical properties of polymeric systems as well as studying the conformational relaxation of melts and amorphous systems, it is important to go beyond the atomistic level. One of the central questions of the physics of polymer melts and networks throughout the last 20 years or so dealt with the role of chain topology for melt dynamics and the elastic modulus of polymer networks. The fact that the different polymer strands cannot cut through each other in the... 

Later we will describe both oxidation and reduction processes that are in agreement with the electrochemically stimulated conformational relaxation (ESCR) model presented at the end of the chapter. In a neutral state, most of the conducting polymers are an amorphous cross-linked network (Fig. 3). The linear chains between cross-linking points have strong van der Waals intrachain and interchain interactions, giving a compact solid [Fig. 14(a)]. By oxidation of the neutral chains, electrons are extracted from the chains. At the polymer/solution interface, positive radical cations (polarons) accumulate along the polymeric chains. The same density of counter-ions accumulates on the solution side. 

Perez et al. [128] investigated the crystal structure of 4-(4 -ethoxybezoy-loxy)-2-butoxy-4 -(4-butoxysalicylaldimine)azobenzene. This compound contains four rings in the main core and a lateral alkoxy branch on one of the inner rings. The lateral butoxy chain is nearly perpendicular to the long axis of the main core. This molecular conformation induces the molecules to make a very complex network in the solid. The crystal cohesion is due to van der Waals interactions. The change of the lateral chain conformation in the solid and nematic phases is discussed. 

D-TEM gave 3D images of nano-filler dispersion in NR, which clearly indicated aggregates and agglomerates of carbon black leading to a kind of network structure in NR vulcanizates. That is, filled rubbers may have double networks, one of rubber by covalent bonding and the other of nanofiller by physical interaction. The revealed 3D network structure was in conformity with many physical properties, e.g., percolation behavior of electron conductivity. 

In the case of filled rubbers, the network is represented by a huge chain of contour length L = NL, where N is the number of primary chains of length L. The observable (macroscopic) free energy is given by Equation 22.9, where Z(n) is the replicated partition function that is estimated by functional integration over the continuous chain conformations ... 

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