Thermodynamic properties of liquid-crystalline carbosilane dendrimers of the second and the fourth generation with methoxyphenylbenzoate terminal groups

In the present work temperature dependences of heat capacity of liquid-crystalline carbosilane dendrimers with terminal methoxyphenylbenzoate groups of the second and the fourth generations have been determined in the range from 6 to 370 K by the precision adiabatic vacuum calorimetry. In the above temperature range the phase transformations have been detected and their thermodynamic characteristics have been determined and analyzed. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity C-p degrees(T), enthalpy H degrees(T) - H degrees(0), entropy S degrees(T) - S degrees(0) and Gibbs energy G degrees(T) - Ho (0), for the range from T -> 0 to 370 K. The standard entropies of formation of dendrimers in liquid-crystalline state at T = 298.15K and the standard entropies of hypothetic synthesis at the same temperature were estimated. It was shown that thermodynamic properties dendrimers under study do not depend on generation number and are defined by nature of terminal groups. (C) 2015 Elsevier B.V. All rights reserved.