Cross-linked polymeric structure

Thus a cross-linked polymeric structure is the final result when a primary diamine and a diepoxide react and all four N—H bonds on the two amine groups are broken. 

Polymers with a 3-D disordered structure are systems described as resins with a disordered cross-linked polymeric structure (Scheme 7). 

Evidence for this scheme is that chemically-bound nitrogen is found in the final product the rate of reaction is increased by the presence of phenols and anhydrous non-phenolic tertiary amines are not effective curing agents. Since bisphenol A-epichlorhydrin resins have epoxy groups at each end of the polymer the above scheme results in the formation of a cross-linked polymeric structure. 

Reaction between a bisphenol A-epichlorhydrin epoxy resin and a polyfunctional amine thus results in a cross-linked polymeric structure. The process is illustrated by the reaction with triethylenetetramine (which has six reactive hydrogen atoms) ... 

In the first step of the interfacial cross-linking polymerization, the polymer is dissolved into the solvent, which is the internal phase of the emulsion, and another phase with a nonsolvent to the polymer is produced then the aqueous phase is poured to the organic phase to produce the emulsion. Afterwards, a solution containing the cross-linking agent is added to the emulsion to form a rigid structure of the microparticles (Couvreur et al., 2002 Rao Geckeler, 2011). 

Vinyl addition polymerizations, being chain reactions, are more complex than condensation polymerizations and they are generally more likely to include minor side reactions leading to branching or cross-linking. The structures of the pol3oneric products are consequently more difficult to establish with certainty. 

The process utilizing supramolecular organization involves pore expansion in silicas. A schematic view of such micelles built from the pure surfactant and those involving in addition n-alkane is shown in Figure 4.9. Another example of pore creation provides a cross-linking polymerization of monomers within the surfactant bilayer [30]. As a result vesicle-templated hollow spheres are created. Dendrimers like that shown in Figure 4.10 exhibit some similarity to micellar structures and can host smaller molecules inside themselves [2c]. Divers functionalized dendrimers that are thought to present numerous prospective applications will be presented in Section 7.6. 

T ignin is one of the most abundant natural products constituting about one-fourth of the woody tissue in plants. Nature has chosen a unique synthetic technique to prepare this cross-linked polymeric material from coniferyl alcohol and related substances. The mechanism of lignin formation is not completely known yet, and the structural characterization of lignin has been only partially successful despite considerable research. 

Phenol-formaldehyde adhesives are produced by a condensation polymerization reaction between phenol and formaldehyde. The phenolics used for exterior particleboard are made at a formalde-hyde/phenol ratio greater than 1.0 i.e., they are classified as resoles and additional formaldehyde is not required to complete the curing reaction to a highly cross-linked network structure. Many characteristics can be incorporated into the adhesives by changes in the F/P ratio, condensation pH, and condensation time. The reactive solids content is normally between kO and 50 percent since the stability and viscosity are adversely affected at higher solids. 

Molecules that differ in size can be separated by passing the sample solution through a stationary phase consisting of a porous cross-linked polymeric gel. The pores of the gel exclude molecules greater than a certain critical size whilst smaller molecules can permeate the gel structure by diffusion. The process is described as gel pern eation, gel-filtration or exclusion chromato-... 

Mei, W. Me Cormick, A.V. Scriven, L.E. Kinetic gelation modeling structural inhomogeneity during cross-linking polymerization. Macromolecules 2003, 36, 4140. 

The columnar structure can be fixed by the cross-linking reaction. After the cross-linking polymerization was completed, the samples were removed from the moulds [77,78]. 

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