Interchain cross-linkages

The presence (or not) of stable intrachain and/or interchain cross-linkages, e.g. disulphide bonds. 

The structure must somehow accommodate the various unusual covalent bonds (e.g., hydroxylamine-sensitive ester-type bonds, 7-car-boxylglutamyl and e-aminolysyl peptide linkages, see Section V) which have been reported in collagen and gelatin and which may possibly be involved in interchain cross-linking. 

Intrachain S—S (disulfide) cross-bridges between cysteine residues in the polypeptide chain are cleaved. (If these disulfides are interchain linkages, then step 2 precedes step 1.)... 

A variety of polymeric subunits is used to make polyurethanes. These include polyesters and polyethers. The major interchain linkages are molecular forces such as hydrogen bonding and the London force. Depending on the type of chain extender and processing temperature, there also may be biuret or allophanate cross-links. 

Figure 27 Double cross-linked chains of bonded Mo shown in NaMo204 shown in bold face. Intra and interchain Mo-0 linkages indicated in light lines...

Nevertheless, the resulting PPPs are not structurally perfect, as the aromatization process gives rise to mixed para and ortho linkages (15% ortho) and to interchain side-reactions leading to cross-linking. A nonbacterial synthesis of ci.v-diesters of cyclohexadiene followed by a stereospecific polymerization has been developed by Grubbs and coworkers to prepare a totally para precursor polymer [90] (Fig. 9.9). 

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