The thermodynamics of polyrotaxane based on dibenzo-24-crown-8 and polyurea in the range 0-500 K

The temperature dependence of the heat capacity of polyrotaxane and its constituents dibenzo-24-crown-8 and polyurea prepared from 2,3,5,6-tetrafluorophenylene diisocyanate-1,4 and 1,4-xylenylenediamine was studied, using the techniques of adiabatic vacuum and dynamic calorimetry, in the range of 6-500 K with a precision of about 0.2%. The physical transformations of these compounds upon their heating and cooling in this temperature range were revealed and characterized. From the experimental data obtained, the thermodynamic functions C(p)degrees (T), Hdegrees (T) - Hdegrees(O), Sdegrees(T) - Sdegrees(O), and Gdegrees(T) - Hdegrees(O) over the range from T --> 0 to T = 500 K; the standard entropy of formation DeltaS(f)degrees at T = 298.15 K; and the thermodynamic characteristics of the hypothetical direct process of preparation of polyrotaxane from dibenzo-24-crown-8 and the polyurea in the range from of T --> 0 to T = 500 K were calculated. The temperature functions of heat capacity of polyrotaxane and the corresponding additive mixture of compounds composing the polyrotaxane in the interval 6-340 K were compared. The fractal dimensionality D in the heat capacity function of the multifractal version of the Debye heat capacity theory, which characterizes the heterodynamics of the examined compounds, were determined.