Solubility Behavior of Amphiphilic Block and Random Copolymers Based on 2-Ethyl-2-oxazoline and 2-Nonyl-2-oxazoline in Binary Water–Ethanol Mixtures
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Lambermont-Thijs, Hanneke M. L.; Hoogenboom, Richard; Fustin, Charles-André; Bomal-D', Cécile; Haese, ; Gohy, Jean-Francois; Schubert, Ulrich S.
- Abstract:
- The solution properties of random and block copolymers based on 2-
ethyl-2-oxazoline (EtOx) and 2-nonyl-2-oxazoline (NonOx) were investigated in
binary solvent mixtures ranging from pure water to pure ethanol. The solubility
phase diagrams for the random and block copolymers revealed solubility (after heating),
insolubility, dispersions, micellization as well as lower critical solution temperature
(LCST) and upper critical solution temperature behavior. The random and block
copolymers containing over 60 mol % pNonOx were found to be solubilized in ethanol
upon heating, whereas the dissolution temperature of the block copolymers was
found to be much higher than for the random copolymers due to the higher extent of
crystallinity. Furthermore, the block copolymer containing 10 mol % pNonOx exhibited
a LCST in aqueous solution at 68.7 C, whereas the LCST for the random
copolymer was found to be only 20.8 C based on the formation of hydrophobic microdomains
in the block copolymer. The random copolymer displayed a small increase in
LCST up to a solvent mixture of 9 wt % EtOH, whereas further increase of ethanol
led to a decrease in LCST, which is probably due to the ‘‘water-breaking’’ effect
causing an increased attraction between ethanol and the hydrophobic part of the
copolymer. In addition, the EtOx-NonOx block copolymers revealed the formation of
micelles and dynamic light scattering demonstrated that the micellar size is increasing
with increasing the ethanol content due to the enhanced solubility of EtOx.
- Year:
- 2009
- Type of Publication:
- Article
- Journal:
- Journal of Polymer Science: Part A: Polymer Chemistry
- Volume:
- 47
- Pages:
- 515–522