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

• Published in: International Journal of Polymer Science Vol. 2010; no. 2010; pp. 72 - 77
• Main Authors: Hirokawa, Yoshitsugu, Yamaoka, Hitoshi, Nakamura, Yasushi, Tanimoto, Satoshi
• Format: Journal Article
• Language: English
• Published: Cairo, Egypt Hindawi Limiteds 01.01.2010; Hindawi Puplishing Corporation; Hindawi Publishing Corporation; John Wiley & Sons, Inc; Wiley
• Subjects: Agglomeration; Aggregates; Aqueous solutions; Color; Complexation; Copolymers; Fourier transforms; Iron; Micelles; Molecular weight; Peptides; Polymerization; Spectrum analysis; Terminals
• ISSN: 1687-9422; 1687-9430
• DOI: 10.1155/2010/294790

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 Fe2+ 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.