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Single‐Line EPR Spectra from Radicals Encapsulated in Aggregates of Amphiphilic Block Copolymers with Hydrophobic Dendritic Pendants in Water
Author(s) -
Tamano Kana,
Tanaka Toshiyuki,
Awaga Kunio,
Imae Toyoko,
Yusa Shinichi,
Shimada Yoshihiko
Publication year - 2006
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200600499
Subject(s) - dpph , electron paramagnetic resonance , radical , amphiphile , aqueous solution , chemistry , absorption spectroscopy , copolymer , polymer , photochemistry , polymer chemistry , organic chemistry , nuclear magnetic resonance , antioxidant , optics , physics
Summary: A water‐insoluble organic 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical is solubilized in aqueous solutions of aggregates of amphiphilic block copolymers with hydrophobic dendritic pendants. The number (100–200) of DPPH molecules solubilized in an aggregate, which is evaluated from UV‐visible absorption spectra, is in agreement with that of the DPPH radicals determined from electron paramagnetic resonance (EPR) spectroscopy. The DPPH radicals are stably solubilized without decomposition in the polymer aggregates. The radicals exhibit a single‐line EPR absorption, which is narrowed by the interspin interaction, and indicates the assembly formation of DPPH radicals in polymer aggregates. These results suggest the effective utilization of the DPPH radical as a spin‐probe indicator in aqueous solutions.When DPPH is solubilized in aqueous solutions of NaAMPS‐ b ‐G2(n3), the polymer solutions become purple colored, which is characteristic of the DPPH radical.