Strength cross-linking approach

Figure 9.50. Notch-ligament length approach to the determination of the essential work of fracture shows doubled specific work of fracture for y-cross-linked X -(GVGIP)32o as compared with previously used X -(GVGIP)26o- Break stress data in Figure 9.20 suggest even more favorable break strengths are yet possible with chemical cross-linking approaches. (A) Stress-strain curves. (B) Essential work of fracture (intercept). (Reproduced with permission from Urry et al. )...

Polymerization is not possible in the complete absence of water or when reactions are carried out using monochlorosilanes. However, trichlorosilanes are attractive because it is possible to increase the strength of the adsorbed silane layer through cross-linking between adjacent molecules. The other approach, the exclusion of trace quantities of water, especially in solution, is extremely difficult and costly. 

The template, the functional monomers and the cross-linking monomers are dissolved in a non-polar solvent. The functional monomers and the template form complexes and the strength of these are reflected in the selectivity of the imprinted polymer. The choice of functional monomer is based on the template structure. Functional monomers are chosen for their ability to interact non-covalently with the template molecule. The most frequently used functional monomer so far is methacrylic acid (MAA). Also vinylpyridines have been frequently used. As cross-linking monomers, ethyleneglycol dimethacrylate (EDMA) or trimethylolpropane trimethacrylate (TRIM) are widely used. Several other types of functional and cross-linking monomers have been used in molecular imprinting experiments using the non-covalent approach. The choice of monomers is of course important to the... 

In the self-assembly approach to molecular imprinting (Fig. 7.1) studies have indicated that the solution structure of the monomer-template assemblies defines the subsequently formed binding sites.3 In other words, the amount and quality of recognition sites in the MIP depends on the number and strength of specific interactions occurring between the template and the monomers in the prepolymerisation mixture (Fig. 7.4). These are in turn influenced by the quality of the solvent, cross-linking monomer, temperature, and pressure used in the polymerisation. 

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