Cross-linking groups

The system is capable of almost infinite variation, for the proportion of cross-links in the structure can be varied over a wide range. Firstly, it can be changed by altering the proportion of potential cross-linking groups (carboxyl and... 

In films cured initially at 175°C, determination by infrared spectroscopy of the concentration of anhydride groups indicated that all potential cross-linking groups had reacted. 

Direct Patterning of Photosensitive Polyimides. Photosensitive polyi-mides (PSPIs) are recently developed materials that can be directly photo-patterned like a negative photoresist (80,85,88,146-148). The most common PSPIs are polyamic acids that have been esterified with photoreactive alcohols and combined with photoinitiators to form a polymer that will crosslink under exposure to UV radiation and become insoluble. The unexposed material is selectively dissolved in a developer solution, and the patterned film is then cured to convert the cross-linked polyamic acid to a polyimide and drive off the cross-linking groups. 

Figure 8 Two strategies to cross-link kinases with their substrates, involving either photo-cross-linking groups (a) or a mechanism-based annulation reaction (b).

Binuclear clathrochelate iron(II) oximehydrazonates may be synthesized by the main methods used for the synthesis of macrobicycles of this type proposed for clathrochelate tris-dioximates by a direct template reaction on a metal ion the cross-linking of initial nonmacrocyclic complexes a cross-linking group exchange reaction and a ligand modification reaction. The template condensation of a mononuclear complex to a binuclear one followed by the encapsulation of another metal ion and capping reaction may be also used for the preparation of these compounds. The main methods for the synthesis of these complexes are shown in Scheme 88 [193]. 

A plot of QS versus q> for each type of cross-linking groups retaining a certain common shape represented in Fig. 15 slightly shifts along the QS axis. The magnitude of this shift can by found using the above-proposed equations. 

The ii Sn Mossbauer spectra of tin-capped complexes contain a singlet with nearly the same QS as that for the corresponding K2SnHale salts. This suggests that the capping tin atoms have an octahedral environment. The IS values increase in the cross-linking group order ... 

As a new macromolecular backbone of immobilized artificial enzymes, we have prepared poly(chloromethylstyrene-co-divinylbenzene) (PCD) (36). Here, chlo-romethylstyrene monomer contains ca. 70% and 30%, respectively, of meta- and para-isomers and divinylbenzene is a mixture of isomers. Divinylbenzene serves as a cross-linking group and, therefore, PCD is highly branched. The shape of PCD synthesized with 2 mol% of divinylbenzene taken by scanning electron microscopy is illustrated in Figure 1. 

A FIGURE 12.41 Cross-linking of polymer chains. The cross-linking groups (red) constrain the relative motions of the polymer chains, making the materiai harder and less flexible than when the cross-links are not present. 

Fig. 11 Scanning electron micrographs of sPEEK-silica membranes containing 20 wt. % colloidal silica surface functionalised with aminophenyl cross-linking groups a no surface functionalisation, b colloidal silica/aminophenyltrimethoxysilane 90/10 wt.%, c colloidal sUica/aminophenyltrimethoxysilane 80/20 wt. %...

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