Calorimetric study of phase transitions for octylphenylthiolpentyloxybenzoate in silica aerogels

An a.c. calorimetric study has been carried out on octylphenylthiolpentyloxybenzoate (<(8)over bar S5>) in three silica aerogels with mass densities rho = 0.08, 0.17 and 0.36 g cm(-3). Results for the least porous aerogel (rho = 0.36) are completely consistent with those reported previously for 8CB in the same aerogel. Freezing of <(8)over bar S5> damaged the more porous rho = 0.08 and 0.17 aerogels by creating internal voids and cracks that are large compared with the intrinsic gore size. As a result, overlapping sharp bulk-like C-p features and rounded features due to <(8)over bar S5> in residual aerogel pores were observed, and no quantitative separation of these features could be achieved.