Gelation of micellar solutions of diblock‐copoly (oxyethylene/oxybutylene) in aqueous K₂SO₄. An investigation of excluded volume effects

Abstract

The micellization and gelation properties of oxyethylene/oxybutylene diblock copolymers E40B10 and E41B8 in aqueous K2SO4 solutions were investigated. The thermodynamic and hydrodynamic volumes of the micelles in salt solutions of various concentrations up to 0.4 mol dm−3 were determined by static and dynamic light scattering, respectively. The related changes in the gelation behavior of concentrated micellar solutions of the copolymers were explained as thermodynamic (excluded) volume effects. The thermodynamic volumes of micelles measured in moderately concentrated solution were used successfully to predict the critical gel concentrations of concentrated solutions. ©1995 John Wiley & Sons, Inc.

Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

“…Detailed static and dynamic light scattering experiments reveal that this results in a contraction of the coronal layer accompanied by an increase in the core radius due to an increased aggregation number. 56 Consequently, the intermicellar interactions become more short-ranged, and the structure adopts a fcc lattice. Although this illustrates the effect of a changing solvent quality on the micellar structure, our system differs in the sense that the PS coronal chains are wellsolvated over the entire temperature range, and it is mainly the degree of selectivity toward core PI chains that influences the micellar packing.…”

Effects of block architecture and composition on the association properties of poly(oxyalkylene) copolymers in aqueous solution

“…Effects on micelle properties are illustrated for copolymer E 40 B 10 in Fig. 28 a (SLS) and 28b (DLS) 151) . The underlying cause of the effect on the concentration dependence of the scattering quantities is a reduction in the excluded volume of the micelles as the solvent quality is decreased on addition of salt.…”

Phase-transition characteristics of amphiphilic poly(2-ethyl-2-oxazoline)/poly(?-caprolactone) block copolymers in aqueous solutions

“…[1][2][3][4][5][6][7][8][9] In particular, phase-transition behaviors of triblock copolymers consisting of poly(ethylene oxide) and poly(propylene oxide) (PEO-PPO-PEO; Pluronics) have been intensively investigated. [1][2][3][4][5] They exhibit low-temperature-boundary sol-gel and high-temperature-boundary gel-sol transitions, where gel regions appear at high concentrations and intermediate temperature ranges.…”

“…In recent reports, studies on thermoreversible gel-sol transition have been expanded to structurally varied block copolymer systems including PEO-aliphatic polyesters. 9,13,14 In this study, we describe the phase-transition behavior of concentrated aqueous solutions of amphiphilic block copolymers based on hydrophilic poly(2-ethyl-2-oxazoline) (PEtOz) and hydrophobic poly(-caprolactone) (PCL). The micelle formation of these block copolymers in aqueous media was confirmed recently by our group.…”