Role of the thermoresponsive segment in determining the redox properties of phenothiazine-labeled poly(ethoxyethyl glycidyl ether)-block-poly(ethylene oxide)

Naotaka Nakadan, Shinichiro Imabayashi, Masayoshi Watanabe

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This study demonstrates that the position of the phenothiazine (PT) group relative to the poly(ethoxyethyl glycidyl ether) (PEEGE) segment is an important factor in determining the phase transition behavior and redox properties of diblock copolymers consisting of the thermoresponsive PEEGE segment, a poly(ethylene oxide) (PEO) segment, and a redox-active hydrophobic PT group attached to the chain-end of the copolymer. In the case of PT-PEEGE-b-PEO, where PT is adjacent to the PEEGE segment, water-soluble core-shell micelles are formed at temperatures higher than the coil-globule transition temperature of the PEEGE segment (Tc). However, in the case of PT-PEO-b-PEEGE, where PT is not adjacent to the PEEGE segment, insoluble aggregates are formed in an aqueous solution in the temperature range from 40 to 50 °C. The oxidation potential of PT in PT-PEEGE-b-PEO is more positive than that of PT in PT-PEO-b-PEEGE at temperatures lower than Tc; this suggests that the PT group of the former is incorporated in a hydrophobic atmosphere formed by the PEEGE segment even at temperatures lower than Tc. When the temperature increases, the rate of the temperature-dependent shift in the oxidation potential of PT increases significantly and the anodic current starts to decrease around Tc; this result shows that the microscopic atmosphere around PT groups changes into a hydrophobic atmosphere, accompanying the formation and growth of core-shell micelles. In the case of PT-PEO-b-PEEGE, a PT group remains in a hydrophilic atmosphere even at temperatures higher than Tc where aggregates are formed, as indicated by the constant rate of the potential shift in the temperatures around Tc.

Original languageEnglish
Pages (from-to)59-63
Number of pages5
JournalJournal of Electroanalytical Chemistry
Volume632
Issue number1-2
DOIs
Publication statusPublished - 2009 Jul 1
Externally publishedYes

Fingerprint

Polyethylene oxides
Ethers
Temperature
Micelles
Oxidation-Reduction
poly(ethoxyethyl glycidyl ether)
phenothiazine
Oxidation
Superconducting transition temperature
Block copolymers
Copolymers
Phase transitions

Keywords

  • Core-shell micelle
  • Phase transition
  • Redox response of phenothiazine
  • Thermoresponsive diblock copolymer

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Analytical Chemistry
  • Electrochemistry

Cite this

@article{5209d83527f14a4d8e4474f472f97812,
title = "Role of the thermoresponsive segment in determining the redox properties of phenothiazine-labeled poly(ethoxyethyl glycidyl ether)-block-poly(ethylene oxide)",
abstract = "This study demonstrates that the position of the phenothiazine (PT) group relative to the poly(ethoxyethyl glycidyl ether) (PEEGE) segment is an important factor in determining the phase transition behavior and redox properties of diblock copolymers consisting of the thermoresponsive PEEGE segment, a poly(ethylene oxide) (PEO) segment, and a redox-active hydrophobic PT group attached to the chain-end of the copolymer. In the case of PT-PEEGE-b-PEO, where PT is adjacent to the PEEGE segment, water-soluble core-shell micelles are formed at temperatures higher than the coil-globule transition temperature of the PEEGE segment (Tc). However, in the case of PT-PEO-b-PEEGE, where PT is not adjacent to the PEEGE segment, insoluble aggregates are formed in an aqueous solution in the temperature range from 40 to 50 °C. The oxidation potential of PT in PT-PEEGE-b-PEO is more positive than that of PT in PT-PEO-b-PEEGE at temperatures lower than Tc; this suggests that the PT group of the former is incorporated in a hydrophobic atmosphere formed by the PEEGE segment even at temperatures lower than Tc. When the temperature increases, the rate of the temperature-dependent shift in the oxidation potential of PT increases significantly and the anodic current starts to decrease around Tc; this result shows that the microscopic atmosphere around PT groups changes into a hydrophobic atmosphere, accompanying the formation and growth of core-shell micelles. In the case of PT-PEO-b-PEEGE, a PT group remains in a hydrophilic atmosphere even at temperatures higher than Tc where aggregates are formed, as indicated by the constant rate of the potential shift in the temperatures around Tc.",
keywords = "Core-shell micelle, Phase transition, Redox response of phenothiazine, Thermoresponsive diblock copolymer",
author = "Naotaka Nakadan and Shinichiro Imabayashi and Masayoshi Watanabe",
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TY - JOUR

T1 - Role of the thermoresponsive segment in determining the redox properties of phenothiazine-labeled poly(ethoxyethyl glycidyl ether)-block-poly(ethylene oxide)

AU - Nakadan, Naotaka

AU - Imabayashi, Shinichiro

AU - Watanabe, Masayoshi

PY - 2009/7/1

Y1 - 2009/7/1

N2 - This study demonstrates that the position of the phenothiazine (PT) group relative to the poly(ethoxyethyl glycidyl ether) (PEEGE) segment is an important factor in determining the phase transition behavior and redox properties of diblock copolymers consisting of the thermoresponsive PEEGE segment, a poly(ethylene oxide) (PEO) segment, and a redox-active hydrophobic PT group attached to the chain-end of the copolymer. In the case of PT-PEEGE-b-PEO, where PT is adjacent to the PEEGE segment, water-soluble core-shell micelles are formed at temperatures higher than the coil-globule transition temperature of the PEEGE segment (Tc). However, in the case of PT-PEO-b-PEEGE, where PT is not adjacent to the PEEGE segment, insoluble aggregates are formed in an aqueous solution in the temperature range from 40 to 50 °C. The oxidation potential of PT in PT-PEEGE-b-PEO is more positive than that of PT in PT-PEO-b-PEEGE at temperatures lower than Tc; this suggests that the PT group of the former is incorporated in a hydrophobic atmosphere formed by the PEEGE segment even at temperatures lower than Tc. When the temperature increases, the rate of the temperature-dependent shift in the oxidation potential of PT increases significantly and the anodic current starts to decrease around Tc; this result shows that the microscopic atmosphere around PT groups changes into a hydrophobic atmosphere, accompanying the formation and growth of core-shell micelles. In the case of PT-PEO-b-PEEGE, a PT group remains in a hydrophilic atmosphere even at temperatures higher than Tc where aggregates are formed, as indicated by the constant rate of the potential shift in the temperatures around Tc.

AB - This study demonstrates that the position of the phenothiazine (PT) group relative to the poly(ethoxyethyl glycidyl ether) (PEEGE) segment is an important factor in determining the phase transition behavior and redox properties of diblock copolymers consisting of the thermoresponsive PEEGE segment, a poly(ethylene oxide) (PEO) segment, and a redox-active hydrophobic PT group attached to the chain-end of the copolymer. In the case of PT-PEEGE-b-PEO, where PT is adjacent to the PEEGE segment, water-soluble core-shell micelles are formed at temperatures higher than the coil-globule transition temperature of the PEEGE segment (Tc). However, in the case of PT-PEO-b-PEEGE, where PT is not adjacent to the PEEGE segment, insoluble aggregates are formed in an aqueous solution in the temperature range from 40 to 50 °C. The oxidation potential of PT in PT-PEEGE-b-PEO is more positive than that of PT in PT-PEO-b-PEEGE at temperatures lower than Tc; this suggests that the PT group of the former is incorporated in a hydrophobic atmosphere formed by the PEEGE segment even at temperatures lower than Tc. When the temperature increases, the rate of the temperature-dependent shift in the oxidation potential of PT increases significantly and the anodic current starts to decrease around Tc; this result shows that the microscopic atmosphere around PT groups changes into a hydrophobic atmosphere, accompanying the formation and growth of core-shell micelles. In the case of PT-PEO-b-PEEGE, a PT group remains in a hydrophilic atmosphere even at temperatures higher than Tc where aggregates are formed, as indicated by the constant rate of the potential shift in the temperatures around Tc.

KW - Core-shell micelle

KW - Phase transition

KW - Redox response of phenothiazine

KW - Thermoresponsive diblock copolymer

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U2 - 10.1016/j.jelechem.2009.03.016

DO - 10.1016/j.jelechem.2009.03.016

M3 - Article

VL - 632

SP - 59

EP - 63

JO - Journal of Electroanalytical Chemistry

JF - Journal of Electroanalytical Chemistry

SN - 0022-0728

IS - 1-2

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