title: Calorimetric study of octylcyanobiphenyl liquid crystal confined to a controlled-pore glass.
abstract: We present a calorimetric study of the phase behavior of octylcyanobiphenyl (8CB) liquid crystal confined to a controlled-pore glass (CPG). We used CPG matrices with characteristic void diameters ranging from 400 to 20 nm. In bulk we obtain weakly first-order isotropic to nematic (I-N) phase transition and nearly continuous character of the nematic to smectic-A (N-SmA) phase transition. In all CPG matrices the I-N transition remains weakly first order, while the N-SmA one becomes progressively suppressed with decreasing CPG pore radius. With decreased pore diameters both phase transition temperatures monotonously decrease following similar trends, but increasing the stability range of the N phase. The heat-capacity response at the weakly first order I-N and continuous N-SmA phase transitions gradually approaches the tricritical-like and three-dimensional XY behavior, respectively. The main observed features were explained using a bicomponent single pore type phenomenological model.
authors.affiliation: Jozef Stefan Institute, P.O. Box 3000, 1001 Ljubljana, Slovenia.
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Kutnjak
authors.forename: Samo
authors.initials: S
authors.lastname: Kralj
authors.forename: Gojmir
authors.initials: G
authors.lastname: Lahajnar
authors.forename: Slobodan
authors.initials: S
authors.lastname: Zumer