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Effect of solute hydrophobicity on phase behaviour in solutions of thermoseparating polymers

Johansson, Hans-Olof LU ; Karlström, Gunnar LU and Tjerneld, Folke LU (1997) In Colloid and Polymer Science 275(5). p.458-466
Abstract
Abstract (1/2-em) Two-phase systems consisting of a polymer rich phase and polymer depleted phase, where the polymer is either ethyl(hydroxy ethyl)cellulose (EHEC) or Ucon (a random copolymer of ethylene oxide and propylene oxide), have been studied. Both of these polymers can be separated from an aqueous solution by either temperature increase or addition of cosolutes. The polymers are thermoseparating and phase separate in water solutions at the cloud point temperature. Two types of EHEC have been studied: one with a cloud point at 60 degreesC and the other at 37 degreesC. The Ucon polymer used in this study has a cloud point at 50 degreesC. Ternary phase diagrams of polymer/water/cosolute systems have been investigated. When a strongly... (More)
Abstract (1/2-em) Two-phase systems consisting of a polymer rich phase and polymer depleted phase, where the polymer is either ethyl(hydroxy ethyl)cellulose (EHEC) or Ucon (a random copolymer of ethylene oxide and propylene oxide), have been studied. Both of these polymers can be separated from an aqueous solution by either temperature increase or addition of cosolutes. The polymers are thermoseparating and phase separate in water solutions at the cloud point temperature. Two types of EHEC have been studied: one with a cloud point at 60 degreesC and the other at 37 degreesC. The Ucon polymer used in this study has a cloud point at 50 degreesC. Ternary phase diagrams of polymer/water/cosolute systems have been investigated. When a strongly hydrophilic or hydrophobic cosolute is added to an EHEC- or Ucon-water solution, a phase separation occurs already at, or below, room temperature. As cosolutes, hydrophobic molecules like phenol, butyric and propionic acid, and hydrophilic molecules like glycine, ammonium acetate, sodium carboxylates (acetate to valerate), were studied. The polymer rich phase formed when mixing polymer, water and cosolute was strongly enriched or depleted with hydrophobic or hydrophilic cosolutes, respectively. The two phase region increased for propionic acid, butyric acid and phenol as a result of increased cosolute hydrophobicity. The opposite occurred in the series sodium acetate, sodium butyrate and sodium valerate. The effect of temperature on the phase behaviour has also been investigated. Model calculations based on Flory-Huggins theory of polymer solutions are presented, in form of a phase diagram, which semiquantitatively reproduce some experimental results. (Less)
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organization
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Contribution to journal
publication status
published
subject
keywords
Key words (1/2-em) Polymer . thermoseparation . aqueous two-phase systems . temperature-induced phase separation
in
Colloid and Polymer Science
volume
275
issue
5
pages
458 - 466
publisher
Springer
external identifiers
  • scopus:0001291729
ISSN
0303-402X
DOI
10.1007/s003960050104
language
English
LU publication?
yes
id
be6b5205-9a78-41d3-9f48-973eb2d329db (old id 126176)
date added to LUP
2007-07-05 16:29:17
date last changed
2017-01-01 04:44:16
@article{be6b5205-9a78-41d3-9f48-973eb2d329db,
  abstract     = {Abstract (1/2-em) Two-phase systems consisting of a polymer rich phase and polymer depleted phase, where the polymer is either ethyl(hydroxy ethyl)cellulose (EHEC) or Ucon (a random copolymer of ethylene oxide and propylene oxide), have been studied. Both of these polymers can be separated from an aqueous solution by either temperature increase or addition of cosolutes. The polymers are thermoseparating and phase separate in water solutions at the cloud point temperature. Two types of EHEC have been studied: one with a cloud point at 60 degreesC and the other at 37 degreesC. The Ucon polymer used in this study has a cloud point at 50 degreesC. Ternary phase diagrams of polymer/water/cosolute systems have been investigated. When a strongly hydrophilic or hydrophobic cosolute is added to an EHEC- or Ucon-water solution, a phase separation occurs already at, or below, room temperature. As cosolutes, hydrophobic molecules like phenol, butyric and propionic acid, and hydrophilic molecules like glycine, ammonium acetate, sodium carboxylates (acetate to valerate), were studied. The polymer rich phase formed when mixing polymer, water and cosolute was strongly enriched or depleted with hydrophobic or hydrophilic cosolutes, respectively. The two phase region increased for propionic acid, butyric acid and phenol as a result of increased cosolute hydrophobicity. The opposite occurred in the series sodium acetate, sodium butyrate and sodium valerate. The effect of temperature on the phase behaviour has also been investigated. Model calculations based on Flory-Huggins theory of polymer solutions are presented, in form of a phase diagram, which semiquantitatively reproduce some experimental results.},
  author       = {Johansson, Hans-Olof and Karlström, Gunnar and Tjerneld, Folke},
  issn         = {0303-402X},
  keyword      = {Key words (1/2-em) Polymer . thermoseparation . aqueous two-phase systems . temperature-induced phase separation},
  language     = {eng},
  number       = {5},
  pages        = {458--466},
  publisher    = {Springer},
  series       = {Colloid and Polymer Science},
  title        = {Effect of solute hydrophobicity on phase behaviour in solutions of thermoseparating polymers},
  url          = {http://dx.doi.org/10.1007/s003960050104},
  volume       = {275},
  year         = {1997},
}