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Research Letters in Physical Chemistry
Volume 2009 (2009), Article ID 146849, 5 pages
http://dx.doi.org/10.1155/2009/146849
Research Letter

Reversible Control of Primary and Secondary Self-Assembly of Poly(4-allyloxystyrene)-Block-Polystyrene

Department of Materials Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan

Received 17 February 2009; Accepted 18 May 2009

Academic Editor: Alaa Abd-El-Aziz

Copyright © 2009 Eri Yoshida and Satoshi Kuwayama. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The reversible control of primary and secondary self-assemblies was attained using a poly(4-allyloxystyrene)-block-polystyrene diblock copolymer (PASt- 𝑏 -PSt) through variations in temperature. The copolymer showed no self-assembly in cyclohexane over 3 5 C and existed as a unimer with a 37.1 nm hydrodynamic diameter. When the temperature was lowered to 3 0 C , the copolymer formed micelles with 269.9 nm by the primary self-assembly. As the result of further lowering the temperature to 2 0 C , the secondary self-assembly of the micelles occurred to produce ca. 2975.9 nm aggregates. The aggregates were dissociated into unimers by increasing the temperature up to 4 0 C . The light scattering studies demonstrated that the thermoresponsivity of the copolymer showed good hysteresis throughout the variation in the temperature in the range between 20 and 4 0 C , based on the Marquadt analysis of the hydrodynamic diameter distribution. It was found that the primary and secondary self-assemblies of the copolymer were perfectly controlled by the temperature.