Cross-linking chemistry

Fluorocarbon elastomers based on vinylidene fluoride can be cross-linked by ionic mechanism. However, if the polymer has been prepared in the presence of a cure site monomer (CSM) it can be cross-linked (cured) by a free radical mechanism. Moreover, many flnoroelastomers can be cross-linked by ionizing radiation (see Section 5.1.3.3). 

Flnorocarbon elastomers based on VDF/HFP and VDF/HFP/TFE can be cured by bis-nucleophiles, such as bisphenols and diamines. The mechanism, proposed in [18], is outlined as follows  

Formation of -C(Cp3)=CH- double bond by elimination of tertiary fluorine 

Double bond shift catalyzed by fluoride ion and formation of -CH=CF-double bond 

The general disadvantage of curing fluoroelastomers by ionic mechanism is that dehydrofluorination required for this reaction produces considerably more double 

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Acid generation in photoresist films add photogeneration vs. dose, 3233/ acid present after irradiation, 32,34r add present before irradiation, 32 quantum yield, 3234 Acid hardening resin resists cross-linking adivation energy determination, 87,89 cross-linking chemistry, 87 determination of acid generated, 87-88 effect of postexposure bake temperature and time, 87... 

The first section of this book deals with current topics in network theory directed toward explaining the relationship between molecular architecture and macroscopic physical properties. The closely related questions of network formation and degradation are also discussed in this section. Deformation, fatigue, and fracture are discussed in the second section. The third section includes recent advances in cross-linking chemistry several chapters outline applications of new systems and detail the relationship between network structure and application properties. 

SCHEME 18.17 Cross-linking chemistry of polyvinylsilazanes. Trarw-amination is not considered. 

Tomohiro, T., Hashimoto, M., Hatanaka, Y., Cross linking Chemistry and Biology Development of Multifunctional Photoaffinity Probes, Chem. Record 2005, 5, 385 395. 

The preceding section shows how it is possible to deerease the quantity of synthetic polymer while retaining the same fimetional properties. In this way the environmental footprint is diminished, but the produets are still not amenable to recycling processes because of the cross-linking chemistry used in the silicone phase. The feet feat these silicone coatings may be used for their barrier properties should motivate a transition toward this important area of packaging. 

Fig. 11. Branching (cross-linking) chemistry of pendant BCB-functionalized PS.

Figure 17.3. Methods for conjugating Qdots to biomolecules, (a) Traditional covalent cross-linking chemistry using EDAC (ethyl-3-dimethyl amino propyl carbodiimide) as a catalyst, (b) Conjugation of antibody fragments to Qdots via reduced sulfhydry 1-amine coupling. SMCC, succinimidyl-4-N-maleimidomethyl-cyclohexane carboxylate. (c) Conjugation of antibodies to Qdots via an adaptor protein, (d) Conjugation of histidine-tagged peptides and proteins to Ni-NTA-modified Qdots, with potential control of the attachment site and Qdotrligand molar ratios. [Reproduced with permission from Elsevier.)...

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