Reports

Multiple Morphologies of "Crew-Cut" Aggregates of Polystyrene-b-poly(acrylic acid) Block Copolymers

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Science  23 Jun 1995:
Vol. 268, Issue 5218, pp. 1728-1731
DOI: 10.1126/science.268.5218.1728

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.