Abstract
Aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO 109-PPO 41-PEO 109) copolymers are nonionic surfactants that self-organize to form aggregate structures with increasing temperature or concentration. We have studied two concentrations over a range of temperatures so that the copolymers are in one of three microphases: unimers, micelles, or hydrogels formed from body centered cubic aggregates of micelles. Three different coumarin dyes were chosen based on their hydrophobicity so that different aggregate regions could be probed independently - water insoluble coumarin 153 (C153), hydrophobic coumarin 102 (C102), and the hydrophilic sodium carboxylate form of coumarin 343 (C343 -). Fluorescence anisotropy experiments provide detailed information on the local microviscosity. C153 experiences a fourfold increase in reorientation time and hence microviscosity with increasing temperature through the microphase transition from unimers to micelles. C102 also shows an increase in microviscosity with temperature but smaller in magnitude and with the microphase transition shifted to higher temperature relative to C153. C343 - shows only a slight sensitivity to the microphase transition. For any of the three coumarin probes, fluorescence anisotropies do not show any correlation with the microphase transition to form cubic hydrogels.
| Original language | English |
|---|---|
| Pages (from-to) | 22273-22284 |
| Number of pages | 12 |
| Journal | Journal of Physical Chemistry B |
| Volume | 109 |
| Issue number | 47 |
| DOIs | |
| Publication status | Published - Dec 1 2005 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
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Microviscosity in multiple regions of complex aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide). / Grant, Christian D.; Steege, Karen E.; Bunagan, Michelle R.; Castner, Ed.
In: Journal of Physical Chemistry B, Vol. 109, No. 47, 01.12.2005, p. 22273-22284.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Microviscosity in multiple regions of complex aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)
AU - Grant, Christian D.
AU - Steege, Karen E.
AU - Bunagan, Michelle R.
AU - Castner, Ed
PY - 2005/12/1
Y1 - 2005/12/1
N2 - Aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO 109-PPO 41-PEO 109) copolymers are nonionic surfactants that self-organize to form aggregate structures with increasing temperature or concentration. We have studied two concentrations over a range of temperatures so that the copolymers are in one of three microphases: unimers, micelles, or hydrogels formed from body centered cubic aggregates of micelles. Three different coumarin dyes were chosen based on their hydrophobicity so that different aggregate regions could be probed independently - water insoluble coumarin 153 (C153), hydrophobic coumarin 102 (C102), and the hydrophilic sodium carboxylate form of coumarin 343 (C343 -). Fluorescence anisotropy experiments provide detailed information on the local microviscosity. C153 experiences a fourfold increase in reorientation time and hence microviscosity with increasing temperature through the microphase transition from unimers to micelles. C102 also shows an increase in microviscosity with temperature but smaller in magnitude and with the microphase transition shifted to higher temperature relative to C153. C343 - shows only a slight sensitivity to the microphase transition. For any of the three coumarin probes, fluorescence anisotropies do not show any correlation with the microphase transition to form cubic hydrogels.
AB - Aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO 109-PPO 41-PEO 109) copolymers are nonionic surfactants that self-organize to form aggregate structures with increasing temperature or concentration. We have studied two concentrations over a range of temperatures so that the copolymers are in one of three microphases: unimers, micelles, or hydrogels formed from body centered cubic aggregates of micelles. Three different coumarin dyes were chosen based on their hydrophobicity so that different aggregate regions could be probed independently - water insoluble coumarin 153 (C153), hydrophobic coumarin 102 (C102), and the hydrophilic sodium carboxylate form of coumarin 343 (C343 -). Fluorescence anisotropy experiments provide detailed information on the local microviscosity. C153 experiences a fourfold increase in reorientation time and hence microviscosity with increasing temperature through the microphase transition from unimers to micelles. C102 also shows an increase in microviscosity with temperature but smaller in magnitude and with the microphase transition shifted to higher temperature relative to C153. C343 - shows only a slight sensitivity to the microphase transition. For any of the three coumarin probes, fluorescence anisotropies do not show any correlation with the microphase transition to form cubic hydrogels.
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U2 - 10.1021/jp053929k
DO - 10.1021/jp053929k
M3 - Article
VL - 109
SP - 22273
EP - 22284
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 47
ER -