Interchain bridging

It has been hypothesized that cross-linked polymers would have better mechanical properties if interchain bridges were located at the ends rather than the center of chains. To test this, low molecular weight polyesters were synthesizedf... 

Warshawsky and coworkers have recently reported the synthesis of a class of compounds which they call polymeric pseudocrown ethers . A chloromethylated polystyrene matrix is used here as in 6.6.2, but instead of adding a crown to the backbone, a strand of ethyleneoxy units is allowed to react at two different positions on the chain, thus forming a crown. Such systems must necessarily be statistical, and the possibility exists for forming interchain bridges as well as intrachain species. Nevertheless, polymers which could be successfully characterized in a variety of ways were formed. A schematic representation of such structures is illustrated below as compound 30. ... 

These results suggest that a non-linear (i.e. superlinear) p(T) is caused by a filamentary flow of the current in the chain layer through interchain bridges formed by a residual amount of 0(5). Breaking the interchain links (by low temperature annealing, for example) leads to an increase of the magnitude of p(T) oc T2 in the chain layer, and consequently to a higher (but linear) total resistivity which is dominated by the planes. 

Figure 19-8 A portion of the L[Gd Cy chain in Gd2Cl3. Interchain bridging chlorine atoms at the top and bottom are duplicates.

Fig. 2. View down a showing unit cell contents and the F(2) interchain bridging in Agl and AuF3 (Reprinted with permission from J. Am. Chem. Soc.. 113. May 1991, pp. 4192-4198. Copyright 1991 American Chemical Society.)...

Figure 2. View down a showing unit cell contents and the F(2) interchain bridging in AgFs and AUF3,...

A review of recent studies indicate that mucoadhesion of polymers, especially hydrogels, involves a combination of surface and diffusional phenomena that contribute to the formation of semipermanent interchain bridges between the polymer and the mucosal... 

Conductivity. Many workers have attempted to measure the dc conductivity of K2Pt(CN)4Bro.3(H20)x (40,166,246,253,258,270,273,309,310,364a, 435). Conductivity (303, 503) is a transport measurement and, therefore, is extremely sensitive to impurities and defects which may interrupt and/or interconnect chains. The defects may arise from cracks or fissures in the crystal or from solvent or impurity occlusions which affect the electron flow. A qualitative measure of crystalline quality is reflected by the anisotropic conductivity ratio, ct, jaj. Better morphology and lower impurity levels suggest fewer interchain bridges and intrachain breaks, allowing the anisotropic ratio to increase to its intrinsic value. Because the measured conductivity is a function of crystalline perfection, only the better characterized measurements are described, Table IV. 

Figure 12. Pr / Ru Left - a side view of one chain of condensed dusters with edge-bridging iodine. Line widths approximate bond populations. Right - a projection down the chains with the interchain bridging. Pr is shaded, Ru is crossed and iodine is open ellipsoids.

Figure 14. A pair of the quashinfinite chains built from square-antiprismatic dusters in Y Br Os. The face capping and interchain bridging rde of bromine is also shown.

Figure 1.8a Suggested arrangement of S—S interchain bridges in human IgGl, IgG2, IgG3, and IgG4. The exact number of interchain bonds in IgG3 is uncertain. ...

Figure 1.10. The site of specific cleavage of human fi chain by trypsin. Fab and Fc t are defined as the fragments obtained by tryptic digestion of IgM at 60 °C, whereas (Fab )2 is the analogous dimeric fragment obtained with trypsin at 37 C at which temperature Fc t is degraded to peptides Fc is a pentamer because of the presence of intersubunit (IS) disulphide bonds (see text). Also shown is the site of specific cleavage of human yl chain by papain, trypsin and pepsin the Fc fragment may be a monomer or dimer depending on the state of the H— H interchain bridges.

Figure 1.11 Suggested arrangement of S—S interchain bridges of human IgM.

Figure 1.17 Amino add sequence around interchain bridges of human IgD and the N terminus of the Fc fragment Residue No. 1 indicates the beginning of Fc. ( ) tentative (...) undetermined.

In addition, no separated chains were found among the reaction products, proving that each monomer unit in esterified insulin actually contains one interchain bridge unreactive towards the sulphite at pH 7 ... 

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