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An evaporation-induced method for aggregation of polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelles to unusual polymeric microcubic particles is reported. PS-b-PAA self-assembles into spherical nanomicelles in the block-selective solvent water. After addition of butanone, 1-propanol, acetic acid, N,N-dimethylformamide (DMF), or n-butylamine, evaporation of the solvent mixture induces aggregation of the nanomicelles into microcubic particles on the substrate a glass slide. The concentration of the additive, temperature, and substrate affect the morphology of the aggregation of the nanomicelles. Vaporizing the additive/water mixture at 120 °C results in the formation of highly symmetrical microcubic particles on a glass slide. The size of microcubic particles is in range from 200 × 200 × 200 nm3 to 600 × 600 × 600 nm3. Microcubic particles can also form on a silicon and gold wafer with a size similar to that of those formed on a glass slide. The morphology of the microcubic particles almost remains unchanged at temperatures lower than 150 °C, while it is destroyed above 200 °C.

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The fluorescence of pyrenyl labelled polystyrene has been investigated. The ratio of excimer to monomer intensities (Ie/Im) is found to vary tortuously with increasing concentration (C) and displays two critical concentration points, C+ at about 3.2 × 10−2 g ml−1 and Cm at about 0.32 g ml−1. In the region C+ < C < Cm, an abrupt increase of Ie/Im is revealed because of intermolecular interaction. At C > Cm, the sharp decrease of Ie/Im is ascribed to entanglements of polymer chains. © 1999 Society of Chemical Industry

No abstract