Introduction Hydrogen bonding (abbreviated as H bonding, hereafter) between water molecules is induced by the electrostatic interaction between the partially positive hydrogen atom on the water molecule and the partially negative oxygen atom of the neighboring water molecule.1,2 The H bonding and nonlinear bent structure of water molecules induce a fluctuated H-bonded network in the liquid state and give anomalous physical properties of liquid water among ordinary liquids (heat capacity, heat of solidification, heat of vaporization, thermal conductivity, etc.). These results suggest that the phospholipid analogue monomer residues with a zwitterionic structure do not significantly disturb the hydrogen bonding between water molecules in either the aqueous solution or the thin film systems. At an early stage of sorption of water into the Poly(MPC-r-BMA) film, the O-H stretching band of the IR spectra for the water incorporated in the film was similar to that for free water, which is in contrast with the drastic change in the O-H stretching band of water incorporated in polymer films such as poly(2-hydroxyethyl methacrylate), poly(methyl methacrylate), and poly(n-butyl methacrylate). 10 µm) on a ZnSe crystal for the ATR-IR spectroscopy. Furthermore, water-insoluble Poly(MPC-r-BMA) with a large molecular weight (4.2 × 105) could be cast as a thin film (thickness, ca. The number of hydrogen bonds collapsed by the presence of one monomer residue (Ncorr value) of Poly(MPC-r-BMA) (Mw 1.3 × 104, 3.0 × 104, and 9.3 × 104) was much smaller than those for ordinary polyelectrolytes and close to those for neutral polymers such as poly(ethylene glycol) and poly(N-vinylpyrrolidone). The relative intensity of the collective band (C value) corresponding to a long-range coupling of O-H stretchings of the Raman spectra for the aqueous solution of Poly(MPC-r-BMA) was very close to that for pure water, which is in contrast with the smaller C value in the aqueous solution of ordinary polyelectrolytes. In Final Form: SeptemThe structure and hydrogen bonding of water in the vicinity of phospholipid analogue random copolymers with various molecular weights were analyzed in their aqueous solutions and thin films with contours of O-H stretching of Raman and attenuated total reflection infrared (ATR-IR) spectra, respectively. Structure of Water in the Vicinity of Phospholipid Analogue Copolymers As Studied by Vibrational Spectroscopy† Hiromi Kitano,*,‡ Makoto Imai,‡ Takayuki Mori,‡ Makoto Gemmei-Ide,‡ Yoshiyuki Yokoyama,§ and Kazuhiko Ishihara| Department of Chemical and Biochemical Engineering, Toyama University, Toyama 930-8555, Japan, Central Research Institute, Toyama Industrial Technology Center, Takaoka 933-0981, Japan, and Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656, Japan Received June 3, 2003.
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