Dresden 2014 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 54: Poster Session 3
CPP 54.38: Poster
Thursday, April 3, 2014, 15:00–19:00, P2
Structure and Phase Transitions in a Series of Triphenylene-Based Discotic Liquid Crystals in the Nanoconfined State — •Christina Krause, Franziska Emmerling, and Andreas Schönhals — BAM Federal Institute for Materials Research and Testing, Berlin, Germany
The structure and phase behavior of a series of discotic liquid crystal based on the triphenylene core (Hexakis [nalkyloxy] triphenylene, HATn; n=5, 6, 10, 12) is studied by means of X-ray Scattering and Differential Scanning Calorimetry (DSC) in the bulk and when confined to self-ordered alumina oxide membranes with different pore sizes. The influence of chain length and confinement on the phase transition is discussed in more detail: In confinement the two phase transitions between plastic crystalline and hexagonal ordered phase at lower and from the latter to an isotropic state at higher temperatures are also observed, but different phase structures close to the wall and in the pore center are evidenced by additional peaks in the heat flow for smaller pore sizes. While the former peaks are independent of the pore size, the depression of the phase transition temperatures of the latter ones can be described by the Gibbs-Thomson-equation. With decreasing pore size for both phase transitions the transition enthalpies decrease. The critical pore size dcri estimated for phase transformation from the pore size dependence of the transition enthalpies for each material increases with increasing chain length.