Investigation of thermodynamic properties of liquid-crystalline carbosilane dendrimers with methoxyphenylbenzoate terminal groups

Abstract

The temperature dependences of the heat capacity of liquid-crystalline carbosilane dendrimers of the first to the fourth generations with methoxyphenylbenzoate terminal groups have been measured by the method of adiabatic vacuum calorimetry over the range from T=(6 to 370)K in the present investigation. The phase transformations have been detected and their thermodynamic characteristics have been estimated and analyzed in the above temperature range. The standard thermodynamic functions, namely, the heat capacity Cp°(T), enthalpy H°(T)−H°(0), entropy S°(T)−S°(0) and potential Φm°, for the range from T→(0 to 370)K and the standard entropy of formation of dendrimers in different physical states at T=298.15K have been calculated based on the experimental values. The standard entropies of hypothetic synthesis of studied compounds were estimated. The linear dependences of changing the corresponding thermodynamic properties of the dendrimers on their molecular weight and the number of mesogenic groups on the outer layer have been obtained.