Linear cross-linked

C NMR of linear cross-linked PS. The proton decoupled 13C NMR spectra of linear and 1% cross-linked PS at 75 MHz in chloroform are illustrated in Figure 3. These spectra are similar to those for linear and cross-linked chloromethylated PS previously reported at lower field (14), although we have been able to resolve more structure in tHe" aliphatic and aromatic regions here. The quarternary and methylene carbon resonances at about 146 ppm and between 40 and 50 ppm respectively, are the most strongly affected by stereochemistry (20). The ortho and meta resonances at 128.4 ppm show partially resolved structure in the linear PS, as does the para carbon at 126.1 ppm. The methine resonance at... 

Generally speaking, the physical properties of polymers depend on crystallinity, molecular weight, molecular weight distribution, linearity/ cross-linking, and chemical composition/structure. 

In general, three major macromolecular classes, namely linear, cross-linked, and branched architectures, are produced by statistical polymerization processes. Therefore their architectures are not structurally-controlled as in many biological systems [37]. However, the discovery of dendrimers has changed this paradigm. 

Synthetic polymers in general can be classified (1) by thermal behavior, i.e., thermoplastic and thermosetting (2) by chemical nature, i.e., amino, alkyd, acrylic, vinyl, phenolic, cellulosic, epoxy, urethane, siloxane, etc. and (3) by molecular structure, i.e., atactic, stereospecific, linear, cross-linked, block, graft, ladder, etc. Copolymers are products made by combining two or more polymers in one reaction (styrene-butadiene). See cross-linking block polymer epitaxy homopolymer plastics. 

Organic polymers or macromolecules contain only carbon in the main chain or network. Examples are polyolefines, polystju-ene (linear cross-linked), polyacetylenes, etc. 

The Michael addition is a very efficient reaction that has been widely applied for dendrimer synthesis due to a small amount of side reactions and mild reaction conditions, poly (amido amine) (PAMAM) or poly(propylene imine) (PPI) dendrimers are two well-known examples that rely on the Michael addition. Long et al. reviewed the synthetic approaches to linear, cross-linked, and branched polymers via step-growth Michael polyaddition.Thermally stable, high-Tg poly... 

Classically polymers may be linear, cross-linked, block or graft copolymers, and so on, as delineated throughout this text. However, there are a host of novel structures now synthesized, with some beginning to play important roles in polymer science and engineering. Many fall under the category called selfassembling polymers. 

The architectures of polymers synthesized using ROMP generally fall under four broad categories linear, cross-linked, branched, and dendritic. Linear polymers, as the name implies, possess chains that extend in one dimension, and encompass flexible coils, rigid rods, cycles, and polyrotaxanes, which can all be related to a string. Flexible coils may be imagined as a... 

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