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A rheological investigation of the complex formation between hydrophobically modified ethyl (hydroxy ethyl) cellulose and cyclodextrin

Karlson, L; Thuresson, Krister LU and Lindman, Björn LU (2002) In Carbohydrate Polymers 50(3). p.219-226
Abstract
The thickening effect of a hydrophobically modified polymer in an aqueous solution is dependent on intermolecular hydrophobic associations, and if the polymer concentration is significantly above the overlap concentration also on chain entanglements. In this investigation we have added different cyclodextrins (CD) in order to decouple hydrophobic polymer-polymer associations via inclusion complex formation with the polymer hydrophobic tails. Both size and hydrophobicity of the cavity of the CD-molecules were found to have an effect on the process. In addition, the influence of chemical structure of the polymer hydrophobic tails was investigated. Either a linear C-14-chain or a more bulky nonylphenol group was used. The viscosity as a... (More)
The thickening effect of a hydrophobically modified polymer in an aqueous solution is dependent on intermolecular hydrophobic associations, and if the polymer concentration is significantly above the overlap concentration also on chain entanglements. In this investigation we have added different cyclodextrins (CD) in order to decouple hydrophobic polymer-polymer associations via inclusion complex formation with the polymer hydrophobic tails. Both size and hydrophobicity of the cavity of the CD-molecules were found to have an effect on the process. In addition, the influence of chemical structure of the polymer hydrophobic tails was investigated. Either a linear C-14-chain or a more bulky nonylphenol group was used. The viscosity as a function of CD-concentration first decreased strongly, and then attained a constant value. At excess CD the viscosity became virtually the same as in a solution of the unmodified parent polymer, provided that complex formation was not sterically bindered. This suggests that all hydrophobic links, originating from the hydrophobic modification process, which influence the theology could be deactivated. On the other hand, with combinations where the complex formation was hindered to a certain degree the initial decrease was less accentuated, and also, the viscosity leveled out at a significantly higher value. In an attempt to rationalize the data a simple model based on the assumption that each complex formed deactivates one theologically active link was used. In combination with the Langmuir adsorption model the number of complexes as a function of CD concentration could be obtained. This model also gave a value of the complex formation constant. Furthermore, in solutions where all hydrophobic links could be deactivated the results from the model suggested that all polymer hydrophobic tails were originally active in forming the network. (C) 2002 Elsevier Science Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
hydrophobically modified, cyclodextrin, ethyl (hydroxy ethyl) cellulose, polymers
in
Carbohydrate Polymers
volume
50
issue
3
pages
219 - 226
publisher
Elsevier
external identifiers
  • wos:000177137100001
  • scopus:0037112799
ISSN
0144-8617
DOI
10.1016/S0144-8617(02)00036-X
language
English
LU publication?
yes
id
0f55d48c-6744-4fed-8c52-9bc57e9a4281 (old id 332418)
date added to LUP
2007-10-29 14:37:27
date last changed
2017-04-02 03:25:01
@article{0f55d48c-6744-4fed-8c52-9bc57e9a4281,
  abstract     = {The thickening effect of a hydrophobically modified polymer in an aqueous solution is dependent on intermolecular hydrophobic associations, and if the polymer concentration is significantly above the overlap concentration also on chain entanglements. In this investigation we have added different cyclodextrins (CD) in order to decouple hydrophobic polymer-polymer associations via inclusion complex formation with the polymer hydrophobic tails. Both size and hydrophobicity of the cavity of the CD-molecules were found to have an effect on the process. In addition, the influence of chemical structure of the polymer hydrophobic tails was investigated. Either a linear C-14-chain or a more bulky nonylphenol group was used. The viscosity as a function of CD-concentration first decreased strongly, and then attained a constant value. At excess CD the viscosity became virtually the same as in a solution of the unmodified parent polymer, provided that complex formation was not sterically bindered. This suggests that all hydrophobic links, originating from the hydrophobic modification process, which influence the theology could be deactivated. On the other hand, with combinations where the complex formation was hindered to a certain degree the initial decrease was less accentuated, and also, the viscosity leveled out at a significantly higher value. In an attempt to rationalize the data a simple model based on the assumption that each complex formed deactivates one theologically active link was used. In combination with the Langmuir adsorption model the number of complexes as a function of CD concentration could be obtained. This model also gave a value of the complex formation constant. Furthermore, in solutions where all hydrophobic links could be deactivated the results from the model suggested that all polymer hydrophobic tails were originally active in forming the network. (C) 2002 Elsevier Science Ltd. All rights reserved.},
  author       = {Karlson, L and Thuresson, Krister and Lindman, Björn},
  issn         = {0144-8617},
  keyword      = {hydrophobically modified,cyclodextrin,ethyl (hydroxy ethyl) cellulose,polymers},
  language     = {eng},
  number       = {3},
  pages        = {219--226},
  publisher    = {Elsevier},
  series       = {Carbohydrate Polymers},
  title        = {A rheological investigation of the complex formation between hydrophobically modified ethyl (hydroxy ethyl) cellulose and cyclodextrin},
  url          = {http://dx.doi.org/10.1016/S0144-8617(02)00036-X},
  volume       = {50},
  year         = {2002},
}