ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The shear viscosity of a moderately concentrated solution of the triblock copolymer polystyrene-block-polybutadiene-block-polystyrene is studied in a common solvent (1,4-dioxane) and in so-called selective solvents (mixtures of 1,4-dioxane with different alcohols). In the latter, which dissolve only the styrene blocks and precipitate the butadiene blocks, the block copolymer molecules aggregate and form micelles with the precipitated blocks as the core and the dissolved blocks as the cilia. The micelle solutions exhibit non-Newtonian behaviour over certain concentration ranges. The viscosity of the micellar solutions in the dilute regime is found to be lower than that of their unimer solutions (i. e., the viscosity measured in 1,4-dioxane) at the same concentration, whereas at higher concentrations the situation is opposite. The viscosity of micellar solutions is first increasing and then decreasing with temperature for all selective solvents used. These variations with concentration and temperature are explained in terms of micelle structure, intermicellar entanglement, swelling of the inner core and coiling of the micelle cilia.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1988.021890706
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