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Characterization of Polyisoprene-b-Poly(methyl methacrylate) Diblock Copolymer Micelles in Acetonitrile

Schillén, Karin LU ; Yekta, Ahmad; Ni, Shaoru; Farinha, Jose Paulo S. and Winnik, Mitchell A. (1999) In The Journal of Physical Chemistry Part B 103(43). p.9090-9103
Abstract
In acetonitrile, polyisoprene-b-poly(methyl methacrylate) (PI−PMMA) diblock copolymers form starlike micelles with a dense core of the insoluble PI blocks and a soft solvent-swollen corona of the soluble PMMA blocks. Static and dynamic light scattering experiments in combination with viscosity measurements show that these micelles behave hydrodynamically as hard spheres. The block copolymers are labeled at the block junction, with a single fluorescent dye, either a donor chromophore (phenanthrene) or an acceptor chromophore (anthracene). These dyes are confined to the interface during self-assembly. Fluorescence energy-transfer experiments on molecularly mixed micelles of donor- and acceptor-labeled copolymers provide a core radius of 7.6... (More)
In acetonitrile, polyisoprene-b-poly(methyl methacrylate) (PI−PMMA) diblock copolymers form starlike micelles with a dense core of the insoluble PI blocks and a soft solvent-swollen corona of the soluble PMMA blocks. Static and dynamic light scattering experiments in combination with viscosity measurements show that these micelles behave hydrodynamically as hard spheres. The block copolymers are labeled at the block junction, with a single fluorescent dye, either a donor chromophore (phenanthrene) or an acceptor chromophore (anthracene). These dyes are confined to the interface during self-assembly. Fluorescence energy-transfer experiments on molecularly mixed micelles of donor- and acceptor-labeled copolymers provide a core radius of 7.6 ± 0.8 nm and a number-average aggregation number ( ) of 98 ± 22 under the assumption that the energy transfer takes place on a surface of a sphere. Simulations in terms of a Helfand−Tagami junction distribution profile confirm that the core−corona interface of the PI−PMMA micelles is thin (ca. 0.9 nm) and that almost all of the energy transfer occurs within a narrow interfacial region. From the static light scattering measurements of the mixed micelles a weight-average aggregation number ( ) of 127 ± 6 is obtained. The ratio / = 1.3 agrees with size polydispersity of the micelles obtained from the analysis of dynamic light scattering data. The experimental corona thicknesses are in good agreement with those calculated from expressions describing starlike block copolymer micelles. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
103
issue
43
pages
9090 - 9103
publisher
The American Chemical Society
external identifiers
  • scopus:0000786269
ISSN
1520-5207
DOI
10.1021/jp990251y
language
English
LU publication?
yes
id
c9239175-54e0-4b34-a63b-4304b2cddddd (old id 1736882)
date added to LUP
2010-12-09 18:01:06
date last changed
2017-01-01 06:42:35
@article{c9239175-54e0-4b34-a63b-4304b2cddddd,
  abstract     = {In acetonitrile, polyisoprene-b-poly(methyl methacrylate) (PI−PMMA) diblock copolymers form starlike micelles with a dense core of the insoluble PI blocks and a soft solvent-swollen corona of the soluble PMMA blocks. Static and dynamic light scattering experiments in combination with viscosity measurements show that these micelles behave hydrodynamically as hard spheres. The block copolymers are labeled at the block junction, with a single fluorescent dye, either a donor chromophore (phenanthrene) or an acceptor chromophore (anthracene). These dyes are confined to the interface during self-assembly. Fluorescence energy-transfer experiments on molecularly mixed micelles of donor- and acceptor-labeled copolymers provide a core radius of 7.6 ± 0.8 nm and a number-average aggregation number ( ) of 98 ± 22 under the assumption that the energy transfer takes place on a surface of a sphere. Simulations in terms of a Helfand−Tagami junction distribution profile confirm that the core−corona interface of the PI−PMMA micelles is thin (ca. 0.9 nm) and that almost all of the energy transfer occurs within a narrow interfacial region. From the static light scattering measurements of the mixed micelles a weight-average aggregation number ( ) of 127 ± 6 is obtained. The ratio / = 1.3 agrees with size polydispersity of the micelles obtained from the analysis of dynamic light scattering data. The experimental corona thicknesses are in good agreement with those calculated from expressions describing starlike block copolymer micelles.},
  author       = {Schillén, Karin and Yekta, Ahmad and Ni, Shaoru and Farinha, Jose Paulo S. and Winnik, Mitchell A.},
  issn         = {1520-5207},
  language     = {eng},
  number       = {43},
  pages        = {9090--9103},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Characterization of Polyisoprene-b-Poly(methyl methacrylate) Diblock Copolymer Micelles in Acetonitrile},
  url          = {http://dx.doi.org/10.1021/jp990251y},
  volume       = {103},
  year         = {1999},
}