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Name (Title):<br />
Jan Labuta (JSPS Fellow, Supermolecules group)<br />
Affiliation:<br />
Supermolecules Group, WPI Research Center for Materials<br />
Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS)<br />
Address:<br />
1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan<br />
Email: LABUTA.Jan@nims.go.jp<br />
Home Page: http://www.nims.go.jp/super/HP/Jan/Jan.htm<br />
Presentation Title:<br />
Morphological Aspects of Phase Separation in Poly(Vinyl Methyl Ether)/Water/Ethanol Solutions<br />
<strong>Abstract</strong>:<br />
Poly(vinyl methyl ether) (PVME) exhibits phase separation in<br />
water above 308 K as a consequence of a lower critical solution<br />
temperature phenomenon (LCST). Such separation is<br />
manifestation of a coil-globule transition associated with<br />
competition between hydrogen bonding and hydrophobic<br />
interactions [1]. We investigated the phase separation of linear<br />
PVME in water/ethanol (D2O/EtOH) mixtures in a broad<br />
concentrations range of polymer and ethanol, respectively. The<br />
addition of ethanol to aqueous solutions of PVME induces the<br />
increase of the LCST. This supports the positive role of ethanol<br />
in stabilization of the hydrogen bonds between solvent molecules<br />
and PVME.<br />
The effect of the polymer and ethanol concentration on<br />
appearance and extent of the phase separation was determined<br />
from temperature dependences of 1 H NMR spectra [2]. Methods<br />
of differential scanning calorimetry (DSC), optical microscopy<br />
(OM) and dynamic light scattering (DLS) were chosen in order<br />
to obtain information regarding reversibility, microscopic<br />
morphology and the size of globules during phase separation<br />
events. The distribution of the globules’ radii at defined<br />
temperature was estimated independently by OM (Fig. 1) and<br />
DLS measurements.<br />
Fig. 1. Stack of OM images<br />
during phase sepration and<br />
their analysis which resulted<br />
in globule size distributions<br />
(in bottom picture curves are<br />
vertically shifter for clarity).<br />
References :<br />
[1] Molyneux P., Water-Soluble Synthetic Polymers: Properties and Behavior, Vol. I., Boca<br />
Raton (Florida): CRC Press, 1983, 58-61<br />
[2] Hanykova L., Labuta J., Spevacek J., Polymer 47, 2006, 6107-6116<br />
52<br />
Poster Session PM-10
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