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Associative phase behaviour and disintegration of copolymer aggregates on adding poly(acrylic acid) to aqueous solutions of a PEO-PPO-PEO triblock copolymer

Santos, Salome LU ; Luigjes, Bob LU and Piculell, Lennart LU (2010) In Soft Matter 6(19). p.4756-4767
Abstract
The influence of adding poly(acrylic acids) of two different chain lengths (PAA(25) and PAA(6000)) on the phase behaviour of the amphiphilic triblock copolymer Pluronic (R) P104 (P104 = (EO)(27)(PO)(61)(EO)(27), where EO = ethylene oxide, PO = propylene oxide) in H2O was investigated. The resulting phase equilibria and structures were investigated by visual inspection, using crossed polarizers, and small angle X-ray scattering (SAXS). At low and intermediate P104 concentrations an associative phase separation was found, where a concentrated phase separated out from a dilute one on adding PAA. The corresponding phase separation region appeared in the phase diagram as a closed, droplet-shaped miscibility gap that was significantly larger for... (More)
The influence of adding poly(acrylic acids) of two different chain lengths (PAA(25) and PAA(6000)) on the phase behaviour of the amphiphilic triblock copolymer Pluronic (R) P104 (P104 = (EO)(27)(PO)(61)(EO)(27), where EO = ethylene oxide, PO = propylene oxide) in H2O was investigated. The resulting phase equilibria and structures were investigated by visual inspection, using crossed polarizers, and small angle X-ray scattering (SAXS). At low and intermediate P104 concentrations an associative phase separation was found, where a concentrated phase separated out from a dilute one on adding PAA. The corresponding phase separation region appeared in the phase diagram as a closed, droplet-shaped miscibility gap that was significantly larger for the longer PAA. Neither of the coexisting phases contained any long-range ordered structures. At higher concentrations of P104 (above ca. 25 wt%) no miscibility gap appeared but, remarkably, the various ordered liquid crystalline phases observed in binary P104/H2O mixtures were eventually destroyed upon the replacement of H2O by PAA. A similar effect was found when propionic acid (PrA), corresponding to the repeating unit of the PAA chain, was added to aqueous P104. A decrease in the PAA length, in the series PAA(6000) - PAA(25) - PrA, increased the efficiency to destroy the structured phases. NMR self-diffusion measurements showed that the self-assembled P104 aggregates dissolved on replacing water with PrA. The same mechanism was found to be responsible for the effect of added PAA, that is, PAA (or PrA) acts as less selective "solvent'' for the PEO and PPO blocks compared to water. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
6
issue
19
pages
4756 - 4767
publisher
Royal Society of Chemistry
external identifiers
  • wos:000282008300019
  • scopus:77956900246
ISSN
1744-6848
DOI
10.1039/c0sm00052c
language
English
LU publication?
yes
id
7ced99de-dba8-4675-ba61-f6182e52fa5e (old id 1695790)
date added to LUP
2010-10-25 15:31:54
date last changed
2018-05-29 09:42:40
@article{7ced99de-dba8-4675-ba61-f6182e52fa5e,
  abstract     = {The influence of adding poly(acrylic acids) of two different chain lengths (PAA(25) and PAA(6000)) on the phase behaviour of the amphiphilic triblock copolymer Pluronic (R) P104 (P104 = (EO)(27)(PO)(61)(EO)(27), where EO = ethylene oxide, PO = propylene oxide) in H2O was investigated. The resulting phase equilibria and structures were investigated by visual inspection, using crossed polarizers, and small angle X-ray scattering (SAXS). At low and intermediate P104 concentrations an associative phase separation was found, where a concentrated phase separated out from a dilute one on adding PAA. The corresponding phase separation region appeared in the phase diagram as a closed, droplet-shaped miscibility gap that was significantly larger for the longer PAA. Neither of the coexisting phases contained any long-range ordered structures. At higher concentrations of P104 (above ca. 25 wt%) no miscibility gap appeared but, remarkably, the various ordered liquid crystalline phases observed in binary P104/H2O mixtures were eventually destroyed upon the replacement of H2O by PAA. A similar effect was found when propionic acid (PrA), corresponding to the repeating unit of the PAA chain, was added to aqueous P104. A decrease in the PAA length, in the series PAA(6000) - PAA(25) - PrA, increased the efficiency to destroy the structured phases. NMR self-diffusion measurements showed that the self-assembled P104 aggregates dissolved on replacing water with PrA. The same mechanism was found to be responsible for the effect of added PAA, that is, PAA (or PrA) acts as less selective "solvent'' for the PEO and PPO blocks compared to water.},
  author       = {Santos, Salome and Luigjes, Bob and Piculell, Lennart},
  issn         = {1744-6848},
  language     = {eng},
  number       = {19},
  pages        = {4756--4767},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Associative phase behaviour and disintegration of copolymer aggregates on adding poly(acrylic acid) to aqueous solutions of a PEO-PPO-PEO triblock copolymer},
  url          = {http://dx.doi.org/10.1039/c0sm00052c},
  volume       = {6},
  year         = {2010},
}