Multiple Morphologies and Characteristics of “Crew-Cut” Micelle-like Aggregates of Polystyrene-b-poly(acrylic acid) Diblock Copolymers in Aqueous Solutions
03 Apr 1996-Journal of the American Chemical Society (American Chemical Society)-Vol. 118, Iss: 13, pp 3168-3181
TL;DR: In this paper, the insoluble block (PS) contents in the copolymers ranged from 80 to 98 wt % and the micelle cores, formed by aggregation of the PS blocks, were generally monodisperse.
Abstract: Crew-cut micelle-like aggregates of various morphologies prepared from polystyrene-b-poly(acrylic acid), PS-b-PAA, diblock copolymers under near-equilibrium conditions, were studied by transmission electron microscopy (TEM). The insoluble block (PS) contents in the copolymers ranged from 80 to 98 wt %. In spherical micelles, the micelle cores, formed by aggregation of the PS blocks, were generally monodisperse. A comparison between star and crew-cut micelles showed that the latter are distinguished by a low density of corona chains on the core surface and a low degree of stretching of the PS blocks in the cores. As the PAA content in block copolymer decreased, the morphology of the aggregates changed progressively from spheres to cylinders, to bilayers (both vesicles and lamellae), and eventually to compound micelles consisting of an assembly of inverted micelles surrounded by a hydrophilic surface. The compound micelles are believed to be a new morphology for block copolymers. The addition of homopolysty...
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TL;DR: A needle-like solid is obtained on drying of aqueous solutions of the spherical micelles of the highly asymmetric polystyrene-poly-(acrylic acid) block copolymers prepared in a low molecular weight solvent system.
Abstract: The observation by transmission electron microscopy of six different stable aggregate morphologies is reported for the same family of highly asymmetric polystyrene-poly-(acrylic acid) block copolymers prepared in a low molecular weight solvent system. Four of the morphologies consist of spheres, rods, lamellae, and vesicles in aqueous solution, whereas the fifth consists of simple reverse micelle-like aggregates. The sixth consists of up to micrometer-size spheres in aqueous solution that have hydrophilic surfaces and are filled with the reverse micelle-like aggregates. In addition, a needle-like solid, which is highly birefringent, is obtained on drying of aqueous solutions of the spherical micelles. This range of morphologies is believed to be unprecedented for a block copolymer system.
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TL;DR: In this article, the concentration du copolymere de la variation des proprietes spectroscopiques du pyrene provoquee par son partage entre les phases micellaires et aqueuses permet de determiner les concentrations of critiques micellaire and les coefficients de partage.
Abstract: L'etude en fonction de la concentration du copolymere de la variation des proprietes spectroscopiques du pyrene provoquee par son partage entre les phases micellaires et aqueuses permet de determiner les concentrations critiques micellaires et les coefficients de partage
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