Divergence of Cholesteric Pitch Near the Smectic-A Transition in Some Cholesteryl Nonanoate Binary Mixtures

Abstract

The cholesteryl nonanoate-propionate and nonanoate-butyrate binary mixtures were studied at different component ratio. The detailed temperature dependence of the pitch of the cholesteric mesophase was measured. The intrinsic pitch was calculated. The divergence of the pitch near the smectic-A transition shows a power-law behavior. For the cholesteryl nonanoate-propionate mixtures with weight ratios (90: 10), (85: 15), (80: 20) and (75: 25) the corresponding values of the critical exponent v of the power-law are 0.683, 0.675, 0.681 and 0.693 respectively. And those for the cholesteryl nonanoate-butyrate mixtures with weight ratios (90:10), (85:15), (80:20), (75:25) and (70:30) the corresponding values of v are 0.678, 0.679, 0.668, 0.672 and 0.662. These values agree with de Gennes' prediction.