Effect of core-shell micelle formation on the redox properties of phenothiazine-labeled poly(ethyl glycidy ether)-block-poly(ethylene oxide).
Redox properties of phenothiazine-labeled poly(ethyl glycidy ether)-block-poly(ethylene oxide) (PT-EGE(n)-b-EO(m)) are reversibly changed by core-shell micelle formation. In the temperature range higher than the critical micellization temperature (cmt), the anodic potential of PT group positively shifts and concomitantly its anodic current decrease, or levels off compared to those of the reference polymer PT-EO(m) without the thermo-responsive EGE(n) segment. The former alteration is caused by incorporation of hydrophobic PT groups into a core of the micelle and the latter by the decrease in the diffusion coefficient of PT groups due to formation of the core-shell micelles. The cmt value and the temperature-dependent alteration in the redox properties strongly depend on the polymer structure, especially the length of thermo-responsive EGE(n) segment. The electrochemically determined hydrodynamic radii of the polymer aggregates seem to be overestimated, compared to the values reported for the aggregates of other thermo-responsive polymers with similar molecular weights, implying the presence of electrochemically inactive PT groups in the copolymers having longer thermo-responsive segments.
Tsuda
Ryohei
R
Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Kaino
Sayaka
S
Kokubo
Hisashi
H
Imabayashi
Shin-Ichiro
S
Watanabe
Masayoshi
M
D004058:Diffusion; D004563:Electrochemistry / Q000379:methods; D004852:Epoxy Compounds / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D015394:Molecular Structure; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010640:Phenothiazines / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D014867:Water / Q000737:chemistry
D004852:Epoxy Compounds; D008823:Micelles; D010640:Phenothiazines; D011108:Polymers; C020344:glycidyl ethers; D014867:Water; D011092:Polyethylene Glycols; D011189:Potassium Chloride; C031637:phenothiazine