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International Journal of Polymer Science
Volume 2010, Article ID 294790, 6 pages
Research Article

Diblock/Triblock Structural Transition and Sol-Gel Transition of Peptide/PEG Diblock Copolymer Having a Terminal Terpyridine Group Induced by Complexation with Metal Ion

Department of Materials Science, The University of Shiga Prefecture, Hassaka, Hikone 522-8533, Japan

Received 26 January 2010; Accepted 21 June 2010

Academic Editor: Harald W. Ade

Copyright © 2010 Satoshi Tanimoto et al. 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.


Terpyridine-polyethyleneglycol-block-polyleucine block copolymer (tpy-PEG-PLeu) was synthesized by a ring-opening polymerization of L-leucine 𝑁 -carboxyanhydride. The copolymer complexed with F e 2 + ion and its aqueous solution showed a purple color as a result of the complexation. This complexation caused the diblock/triblock structural transition of the copolymer. The change of the aggregation behavior caused by the structural transition was observed by a dynamic light scattering apparatus. The diblock tpy-PEG-PLeu copolymer formed a micelle in the aqueous solution. On the other hand, the triblock-type copolymer, after the complexation, formed the micelle structures and huge aggregates, which is considered to be a network structure. The complexation of the diblock tpy-PEG-PLeu copolymer with Fe ion is consequently considered to be a trigger of the gelation.