Surface properties of styrene–ethylene oxide block copolymers

Abstract

Hydrophobic–hydrophilic block copolymers were prepared by “living” anionic polymerization. They consist of polystyrene and poly(ethylene oxide) blocks, and are soluble in water. Their interfacial properties were investigated, employing aqueous solutions. The block copolymers lowered the surface tension of water in analogy with the low molecular weight surfactants such as sodium lauryl sulfate and heptaethylene oxide n‐dodecyl ether. Their aqueous solutions exhibited solubilization properties differing from those of polyethylene glycol. Therefore, it is thought that the polystyrene blocks produce solubilization phenomena. In samples of the same styrene content, the precipitation temperature of a high molecular weight copolymer in water was lower than that of a low molecular weight copolymer at the same concentration in the same solvent. The surface tension and precipitation temperature of aqueous solutions seem to be influenced by molecular weight and composition.

Photo-responsive shell cross-linked micelles based on carboxymethyl chitosan and their application in controlled release of pesticide

“…When the polymer concentration falls below the critical micellization concentration (CMC) because of high dilution, polymeric micelles will dissociate accompanied with undesirable release of encapsulated pesticides before reaching the targeted sites (Nakamura, Ryuichi, & Takeda, 1976;Dubey, Jhelum, & Patanjali, 2011;Jiang, Liu, & Narain, 2009). Moreover, the physical encapsulation of pesticides within polymeric micelles will lead to premature pesticide release during storage and reduce the effectiveness of pesticides.…”

High density polyethylene/acrylonitrile butadiene rubber blends: Morphology, mechanical properties, and compatibilization

“…For the optimization of mixing parameters, blending was carried out over a temperature range from 150 to 180°C, mixing time from 6 to 15 min, and rotor speeds from 40 to 70 rpm. In order to optimize each parameter, that parameter was varied over a range while maintaining the other two parameters constant.…”

Block‐Selective Solvent Influence on Morphology of the Micelles Self‐Assembled by PS38‐b‐P(AA190‐co‐MA20)

“…Depending on the composition of the block copolymers, two types of micelles can be distinguished: star and crew-cut, although there is no sharp boundary between these two classes of aggregates. [2][3][4][5] The star micelles are usually made from block copolymers in which the shell-forming blocks are much longer than the coreforming blocks, while the latter are made from copolymers in which the core-forming blocks are much longer. Crewcut aggregates are usually prepared by method of water addition because the fraction of insoluble blocks in the copolymers is large.…”

“…[5][6][7][8] In addition of the water addition method, star micelles can also be prepared by direct dissolution of block polymers in a block-selective solvent. [4,5] The formation of crew-cuts and star micelles is controlled by a force balance principally involving three factors, i.e., the stretching of the core-forming blocks in the core, the surface tension between the micelle core and the solvent outside of the core, and the interactions between the shell-forming polymer chains. [5,9] One of the noteworthy phenomena associated with crew-cut aggregates is the accessibility of a wide range of morphologies such as spheres, rods, vesicles, lamellae, large compound vesicles, a hexagonally packed hollow hoop structure, large compound micelles and nanotubes.…”