Mediation of a phase transition in hyaluronate films by the counterions Li, Cs, Mg and Ca as observed by infrared spectroscopy, optical microscopy and optical birefringence |
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Authors: | Marlowe R L Hoppe A Rupprecht A Lee S A |
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Institution: | Dept. of Physics, Geology and Astronomy, The University of Tennessee at Chattanooga, 37403, USA. |
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Abstract: | Infrared (IR) spectroscopy and optical microscopy have been performed as a function of relative humidity (rh) on wet-spun oriented films of hyaluronate (HA) prepared with various counterions. Complete swelling measurements have been obtained through optical microscopy for films of Cs-, Mg-, and CaHA. IR spectroscopy of Cs-, Mg-, Ca-, and LiHA films was performed for skeletal vibrations (800-1000 cm(-1)) and for vibrational modes (1150-1300 cm(-1)) attributed to C-C and C-O stretching modes and C-C-H and C-O-H bending modes. These techniques reveal evidence of a counterion-dependent phase transition occuring at high relative humidities. Optical birefringence measurements on the polycrystalline samples showed order before and disorder after the transition from lower to higher humidity. |
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