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Complex Formation between a Fluorescently-Labeled Polyelectrolyte and a Triblock Copolymer

Costa, Telma; Seixas de Melo, J. Sergio; Miguel, Maria; Lindman, Björn LU and Schillén, Karin LU (2009) In The Journal of Physical Chemistry Part B 113(18). p.6205-6214
Abstract
The association between a randomly pyrene labeled PAA polymer (PAAMePy55) and a PEO-PPO-PEO

triblock copolymer (P123) in aqueous solutions of different NaCl concentrations and pHs has been studied

by means of dynamic light scattering (DLS) and steady-state fluorescence spectroscopy at 40 °C. At acidic

pH values, in the low P123/PAAMePy55 molar ratio regime (i.e., at low P123 concentrations), the relaxation

time distributions retrieved from the DLS data analysis were monomodal and very similar to those obtained

for the pure PAAMePy55 solution. The apparent hydrodynamic radius of PAAMePy55 at low pH is 18 nm.

At higher molar ratios (i.e., at high P123 concentrations), still in the acidic... (More)
The association between a randomly pyrene labeled PAA polymer (PAAMePy55) and a PEO-PPO-PEO

triblock copolymer (P123) in aqueous solutions of different NaCl concentrations and pHs has been studied

by means of dynamic light scattering (DLS) and steady-state fluorescence spectroscopy at 40 °C. At acidic

pH values, in the low P123/PAAMePy55 molar ratio regime (i.e., at low P123 concentrations), the relaxation

time distributions retrieved from the DLS data analysis were monomodal and very similar to those obtained

for the pure PAAMePy55 solution. The apparent hydrodynamic radius of PAAMePy55 at low pH is 18 nm.

At higher molar ratios (i.e., at high P123 concentrations), still in the acidic pH regime, bimodal relaxation

time distributions were obtained, where the fast relaxation mode is connected to the translational diffusion of

free P123 micelles with a hydrodynamic radius obtained at infinite P123 dilution (RH,P123)0) of 10-11 nm.

This value coincides perfectly with the hydrodynamic radius of the pure P123 micelles at 40 °C, which was

found to be ca. 10 nm at all pH values. The second mode corresponds to a complex consisting of one

PAAMePy55 polymer chain and about 42 P123 micelles and with a RH,P123)0 between 35 and 36 nm depending

on pH. At pH 9, the mixed system also presented bimodal relaxation time distributions. At this high pH, the

intermolecular association between PAAMePy55 and P123 is less strong than at acidic pH according to the

steady-state fluorescence measurements. The fast mode is also in this case attributed to free P123 micelles

whereas the second mode is related to the so-called “slow mode” commonly observed for polyelectrolyte

solutions. In this system, it is related to the formation of multichain domains, that is, large domains formed

by several PAAMePy55 chains that move in a common electrostatic field (i.e., a structure factor effect). The

presence of P123 micelles does not lead to the total disruption of these domains. They may either contain

entrapped P123 micelles or hydrophilic diblock impurities (originating from the P123 sample) that associate

with the PAAMePy55 chains. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
113
issue
18
pages
6205 - 6214
publisher
The American Chemical Society
external identifiers
  • pmid:19354271
  • wos:000265687500005
  • scopus:66349083237
ISSN
1520-5207
DOI
10.1021/jp8093885
language
English
LU publication?
yes
id
2f769dfd-458b-4273-bca1-46f38e53b758 (old id 1367263)
date added to LUP
2009-04-22 12:40:40
date last changed
2017-01-01 06:33:08
@article{2f769dfd-458b-4273-bca1-46f38e53b758,
  abstract     = {The association between a randomly pyrene labeled PAA polymer (PAAMePy55) and a PEO-PPO-PEO<br/><br>
triblock copolymer (P123) in aqueous solutions of different NaCl concentrations and pHs has been studied<br/><br>
by means of dynamic light scattering (DLS) and steady-state fluorescence spectroscopy at 40 °C. At acidic<br/><br>
pH values, in the low P123/PAAMePy55 molar ratio regime (i.e., at low P123 concentrations), the relaxation<br/><br>
time distributions retrieved from the DLS data analysis were monomodal and very similar to those obtained<br/><br>
for the pure PAAMePy55 solution. The apparent hydrodynamic radius of PAAMePy55 at low pH is 18 nm.<br/><br>
At higher molar ratios (i.e., at high P123 concentrations), still in the acidic pH regime, bimodal relaxation<br/><br>
time distributions were obtained, where the fast relaxation mode is connected to the translational diffusion of<br/><br>
free P123 micelles with a hydrodynamic radius obtained at infinite P123 dilution (RH,P123)0) of 10-11 nm.<br/><br>
This value coincides perfectly with the hydrodynamic radius of the pure P123 micelles at 40 °C, which was<br/><br>
found to be ca. 10 nm at all pH values. The second mode corresponds to a complex consisting of one<br/><br>
PAAMePy55 polymer chain and about 42 P123 micelles and with a RH,P123)0 between 35 and 36 nm depending<br/><br>
on pH. At pH 9, the mixed system also presented bimodal relaxation time distributions. At this high pH, the<br/><br>
intermolecular association between PAAMePy55 and P123 is less strong than at acidic pH according to the<br/><br>
steady-state fluorescence measurements. The fast mode is also in this case attributed to free P123 micelles<br/><br>
whereas the second mode is related to the so-called “slow mode” commonly observed for polyelectrolyte<br/><br>
solutions. In this system, it is related to the formation of multichain domains, that is, large domains formed<br/><br>
by several PAAMePy55 chains that move in a common electrostatic field (i.e., a structure factor effect). The<br/><br>
presence of P123 micelles does not lead to the total disruption of these domains. They may either contain<br/><br>
entrapped P123 micelles or hydrophilic diblock impurities (originating from the P123 sample) that associate<br/><br>
with the PAAMePy55 chains.},
  author       = {Costa, Telma and Seixas de Melo, J. Sergio and Miguel, Maria and Lindman, Björn and Schillén, Karin},
  issn         = {1520-5207},
  language     = {eng},
  number       = {18},
  pages        = {6205--6214},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Complex Formation between a Fluorescently-Labeled Polyelectrolyte and a Triblock Copolymer},
  url          = {http://dx.doi.org/10.1021/jp8093885},
  volume       = {113},
  year         = {2009},
}