Developments in anionic polymerization — A critical review

“…Micellization plays an important role in polymerization reaction kinetics, because only dissociated free living anions are believed to be active species for the propagation reaction. [33][34][35][36][37] Thus the precise aggregation number m, the association constant (or the free energy of micellar formation), and the structure of the reversed micelle formed by polymer living anions are prerequisite to the profound understanding of the anionic polymerization.…”

Section: Polymer Living Anions In a Non-polar Solventmentioning

confidence: 99%

Macromolecular Assemblies in Solution: Characterization by Light Scattering

Sato

Matsuda

2009

Polym. J.

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This review article demonstrates that the light scattering technique provides important structural information of the following macromolecular assemblies, polymer living anions in a non-polar solvent, amphiphilic telechelic polymer and block copolymers in aqueous solution, and a thermally denatured double-helical polysaccharide aggregated during renaturation. To get accurate information from light scattering data, however, we have to analyze the data using proper theoretical tools, which are briefly explained in this article. The structural information of these macromolecular assemblies assists us in understanding, e.g., the kinetics of living anionic polymerization and gelation. 1 There are many types of architecture of macromolecular assemblies (cf. Figure 1). For associating polymers with a single attractive moiety per chain (e.g., diblock copolymers, polymer living anions, water-soluble polymers hydrophobically modified at one end), the architecture may be spherical (star-like), cylindrical, bilayer or vesiclar.2-7 On the other hand, if the chain possesses a number of attractive moieties, its assembly may be a uni-core or multicore flower micelle. [8][9][10][11][12][13] Multi-stranded helical polymers may form assemblies of their unique architecture by the hydrogenbonding.14 The macromolecular assemblies formed by associating polymers in solution can be characterized in terms of the architecture, the size (i.e., the radius of gyration, hydrodynamic radius, or intrinsic viscosity), the average and distribution of the aggregation number, and inter-assembly interaction. However, the determination of these characteristics is not necessarily an easy task in comparison with molecularly dispersed polymers.The difficulty comes from (1) the concentration dependence of the degree of aggregation, (2) the variety and complexity of the architecture, and (3) the dispersity in the assembly structure in the case of open association systems. 15 Because of (1), the standard procedure of infinite dilution and also size exclusion chromatography does not necessarily provide right information of the assemblies at a given finite concentration. To make proper characterization, we have to take into account the association-dissociation equilibrium and inter-assembly interaction of associating polymers in solution of the finite concentration. To overcome the difficulties (2) and (3), we have to formulate characteristic parameters using models suitable for each architectures considering the dispersity effect if necessary.The present article reviews recent light scattering studies on various macromolecular assemblies in dilute solution. Light scattering is one of the most suitable techniques to characterize macromolecular assemblies in solution. Its measurements are made on assemblies in solution without any perturbations, and nanometer to sub-micrometer structures can be investigated. However, analyses of light scattering data are accompanied with the above mentioned difficulties. In what follows, we will explain the method for each sy...

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“…4 (m, 9H, aromatic C{H chain-end functionalized polystyrene ( 3). All polymerizations were carried out in all-glass, sealed reactors using standard high-vacuum techCharacterization niques and breakseals to add reagents.…”

Section: Nn-diisopropyl-4-(1-phenylethenyl)benzamide (1)mentioning

confidence: 99%

“…The product was extracted with tion of the diethyl ether gave crude product as dichloromethane (2 1 200 mL) and dried with anwhite crystals. Recrystallization from benzene/pehydrous MgSO 4 . Evaporation of the dichloromethtroleum ether afforded 21.62 g (71%) of pure N,Nane produced crude product as a light yellow visdiisopropyl-4-benzoylbenzamide as white needles.…”

Section: Nn-diisopropyl-4-(1-phenylethenyl)benzamide (1)mentioning

confidence: 99%