Thermally induced aging in bicyclohexane compounds and its influence on the N-SmB phase transition and interface morphology

Although the alkyl-bicyclohexyl-carbonitrile compounds supposed to be chemi cally stable, an aging behaviour was observed which strongly influences the growth of smectic B germs in the undercooled nematic phase. The aging also results in a broadening of the phase coexistence temperature ranges and in a saturating shift of phase transition temperatures with a temperature dep endent dynamics. The phenomenon has been characterized by polarizing micros copy and DSC, and an experimental evidence has been given that the air atmo sphere is responsible for the thermally induced ageing.