| Abstract
| - Hydration changes of poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMoEoEMa) during thermosensitive phaseseparation in water have been investigated by infrared spectroscopy. The CO stretching band can be separated intothree components assigned to non-hydrated carbonyl groups and singly and doubly hydrogen-bonded carbonyl groups(1728, 1709, and 1685 cm-1, respectively). Relatively large parts of the carbonyl groups (50% in 30 wt % solution)do not form hydrogen bonds even below the transition temperature (Tp) probably because they possess crowdedpositions near the backbone. The fraction of hydrogen-bonding carbonyl groups decreased during phase separationby ∼0.2. Among five ν(C−H) bands, the highest- and the lowest-frequency bands (ν(C−H)A and ν(C−H)E) exhibitedrelatively large red shifts of 8 and 11 cm-1, respectively. DFT calculations indicate that the formation of a H-bondbetween the ether oxygen and water leads to blue shifts of ν(C−H) of adjacent alkyl groups and has a larger effectthan a direct H-bond to the alkyl groups, namely, C−H···O H-bonds. The fraction of hydrogen-bonding methoxyoxygens estimated from the position of the ν(C−H)A is 1 at <Tp and zero at >Tp. This result indicates that the methoxyoxygens and the carbonyl are more favorably hydrated than the other at <Tp and >Tp, respectively.
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