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Temperature-responsive inclusion complex of cationic PNIPAAM diblock copolymer and gamma-cyclodextrin

Lazzara, Giuseppe LU ; Olofsson, Gerd LU ; Alfredsson, Viveka LU ; Zhu, Kaizheng; Nystrom, Bo and Schillén, Karin LU (2012) In Soft Matter 8(18). p.5043-5054
Abstract
Aqueous mixtures of gamma-cyclodextrin (gamma-CD) and the thermosensitive cationic diblock copolymer poly(N-isopropylacrylamide)-b-poly(3-acrylamidopropyl)trimethylammonium chloride (PNIPAAM(24)-b-PAMPTAM(+)(9)) or the PNIPAAM homopolymer PNIPAAM(47) have been investigated using various experimental methods. Solid g-CD-polymer inclusion complexes (pseudopolyrotaxanes) form at ambient temperatures in fairly concentrated CD solutions. The NMR measurements showed that the stoichiometry of the inclusion complexes is close to two NIPAAM units per CD molecule. The cationic block of the copolymer is not incorporated into the CD cavity. Synchrotron radiation X-ray diffraction spectra of the solid inclusion complexes indicate a compact columnar... (More)
Aqueous mixtures of gamma-cyclodextrin (gamma-CD) and the thermosensitive cationic diblock copolymer poly(N-isopropylacrylamide)-b-poly(3-acrylamidopropyl)trimethylammonium chloride (PNIPAAM(24)-b-PAMPTAM(+)(9)) or the PNIPAAM homopolymer PNIPAAM(47) have been investigated using various experimental methods. Solid g-CD-polymer inclusion complexes (pseudopolyrotaxanes) form at ambient temperatures in fairly concentrated CD solutions. The NMR measurements showed that the stoichiometry of the inclusion complexes is close to two NIPAAM units per CD molecule. The cationic block of the copolymer is not incorporated into the CD cavity. Synchrotron radiation X-ray diffraction spectra of the solid inclusion complexes indicate a compact columnar structure of CD molecules threaded onto the PNIPAAM chains. In water, square-shaped cyclodextrin aggregates were found to co-exist with single cyclodextrin molecules. In mixed solutions of gamma-CD and PNIPAAM(24)-b-PAMPTAM(+)(9) these aggregates disintegrate with time as inclusion complexes are formed and the kinetics was studied using time-resolved static and dynamic light scattering and cryo-TEM. Steady-state fluorescence spectroscopy measurements reveal that the CD molecules dethread from the PNIPAAM chains upon increasing the temperature to 40 degrees C, which is above the lower critical solution temperature of PNIPAAM. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
8
issue
18
pages
5043 - 5054
publisher
Royal Society of Chemistry
external identifiers
  • wos:000302636700027
  • scopus:84859813977
ISSN
1744-6848
DOI
10.1039/c2sm07252a
language
English
LU publication?
yes
id
47aa04d3-8ce3-4ac3-94c1-269bb9c79997 (old id 2587348)
date added to LUP
2012-06-04 12:55:59
date last changed
2017-08-27 04:37:05
@article{47aa04d3-8ce3-4ac3-94c1-269bb9c79997,
  abstract     = {Aqueous mixtures of gamma-cyclodextrin (gamma-CD) and the thermosensitive cationic diblock copolymer poly(N-isopropylacrylamide)-b-poly(3-acrylamidopropyl)trimethylammonium chloride (PNIPAAM(24)-b-PAMPTAM(+)(9)) or the PNIPAAM homopolymer PNIPAAM(47) have been investigated using various experimental methods. Solid g-CD-polymer inclusion complexes (pseudopolyrotaxanes) form at ambient temperatures in fairly concentrated CD solutions. The NMR measurements showed that the stoichiometry of the inclusion complexes is close to two NIPAAM units per CD molecule. The cationic block of the copolymer is not incorporated into the CD cavity. Synchrotron radiation X-ray diffraction spectra of the solid inclusion complexes indicate a compact columnar structure of CD molecules threaded onto the PNIPAAM chains. In water, square-shaped cyclodextrin aggregates were found to co-exist with single cyclodextrin molecules. In mixed solutions of gamma-CD and PNIPAAM(24)-b-PAMPTAM(+)(9) these aggregates disintegrate with time as inclusion complexes are formed and the kinetics was studied using time-resolved static and dynamic light scattering and cryo-TEM. Steady-state fluorescence spectroscopy measurements reveal that the CD molecules dethread from the PNIPAAM chains upon increasing the temperature to 40 degrees C, which is above the lower critical solution temperature of PNIPAAM.},
  author       = {Lazzara, Giuseppe and Olofsson, Gerd and Alfredsson, Viveka and Zhu, Kaizheng and Nystrom, Bo and Schillén, Karin},
  issn         = {1744-6848},
  language     = {eng},
  number       = {18},
  pages        = {5043--5054},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Temperature-responsive inclusion complex of cationic PNIPAAM diblock copolymer and gamma-cyclodextrin},
  url          = {http://dx.doi.org/10.1039/c2sm07252a},
  volume       = {8},
  year         = {2012},
}