Differential scanning calorimetry ͑DSC͒ has been used to evaluate the average enthalpy of desorption of the water of primary hydration bound to wet-spun films of potassium hyaluronate ͑KHA͒ and CsDNA. The enthalpies were measured to be 0.24Ϯ0.08 eV/H 2 O molecule for KHA and 0.32Ϯ0.10 eV/H 2 O molecule for CsDNA. A Kissinger analysis was used to extract the net activation energy (0.61Ϯ0.04 eV͒ for the desorption of this water from KHA by analyzing DSC data acquired at different heating rates. The average effective force constants at 295 K of this water bound to KHA (63Ϯ3 dyn/Å͒ and NaDNA (17Ϯ4 dyn/Å͒ are determined from Rayleigh scattering of Mossbauer radiation data ͓G. Albanese, A. Deriu, F. Cavatorta, and A. Rupprecht, Hyperfine Interact. 95, 97 ͑1995͔͒ via a harmonic approximation.

Differential scanning calorimetry has been used to study the thermal properties of hydrated films of calf-thymus Na-, K- and CsDNA between 20 and 320 degrees C. A broad endothermic transition near 75 degrees C and a sharp exothermic transition near 240 degrees C are observed. The broad transition is due to the dehydration of the DNA, while the exothermic transition is due to pyrolysis of the sample. the peak temperatures of both transitions increase as the scan rate is increased. Based on a Kissinger analysis, the net activation energy for the desorption of the primary water of hydration is about 0.6 eV while that for the pyrolysis is about 1.9 eV. X-ray diffraction patterns suggest that heating the DNA films to 180 degrees C once does not, but thrice does, destroy their structural ordering.