Infrared spectroscopic investigation of poly(2-methoxyethyl vinyl ether) during thermosensitive phase separation in water.
Hydration changes of poly(2-methoxyethyl vinyl ether) (PMOVE) synthesized via living cationic polymerization have been investigated during a temperature-responsive phase separation in water by using infrared spectroscopy. An aqueous PMOVE solution has lower critical solution temperatures (LCSTs) of 66 degrees C in H2O and 65 degrees C in D2O at approximately 15 wt %. During phase separation, the C-H stretching (nu(C-H)) bands of PMOVE shift downward (red shift). In particular, the IR band assigned to the antisymmetric stretching vibration of the terminal methyl groups exhibits a remarkably large red shift by 16 cm-1. The band also exhibits a red shift with increasing polymer concentration at T < Tp. Density functional theory (DFT) calculations of the models of hydrated PMOVE indicate that the shift is due mainly to the breaking of hydrogen bonds (H-bonds) between the oxygen of the methoxy groups and water and partially to the breaking of the CH...O H-bond to them.
Maeda
Yasushi
Y
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, Fukui 910-8507, Japan. y_maeda@acbio2.acbio.fukui-u.ac.jp
Yamauchi
Hideo
H
Fujisawa
Mie
M
Sugihara
Shinji
S
Ikeda
Isao
I
Aoshima
Sadahito
S