Calorimetric study of nonyloxybenzoyloxy-cyanoazobenzene (90BCAB)

Abstract

Calorimetric studies of 90BCAB have been made using DSC and high-resolution ac techniques. A small heat capacity peak associated with the smectic-Ad(SmAd)-reentrant nematic (Nr) second-order transition has been observed. Analysis in terms of the critical exponent agr suggests the possibility of Fisher renormalization at this SmAd-Nr transition. DSC measurements have shown the presence of two metastable crystal phases (denoted CrX and CrY) as well as the equilibrium CrK crystal phase. The latent heats for first-order transitions among these crystal phases and for the Nr-CrX and Nr-CrK melting/freezing transitions have been determined. The transition from Nt into the monotropic mon-olayer smectic-A phase was preempted in our experiments by Nr rarr CrX freezing.