Jul 3 – 6, 2017
Europe/Warsaw timezone

Reentrant phenomenon and odd-even effect in homologous binary system of 4‑alkyl-4’-cyanobiphenyl ($n$CB)

Jul 4, 2017, 12:00 PM
oral presentation Soft matter and glass formers Soft Matter


Dr Yasuhisa Yamamura (University of Tsukuba)


`A family of 4-alkyl-4’-cyanobiphenyl ($n$CB, $n$ is the number of carbon atoms in the alkyl chain) is one of the most famous mesogenic series of calamitic molecules. The $n$CBs exhibit liquid crystalline phases, nematic (N) and smectic A$_\mathrm{d}$ (SmA$_\mathrm{d}$, d means dimer) phases, below the isotropic liquid (IL) depending on the length $n$ of the alkyl chain. Although a huge number of studies on both the $n$CBs and their mixtures ($n$CB/$m$CB) have been done, only the normal sequence of long-range molecular order (IL-N-SmA$_\mathrm{d}$ on cooling) has been reported, in contrast to a structurally similar mesogenic series, 4-alkyloxy-4’-cyanobiphenyl ($n$OCB). 6OCB/8OCB mixture, for example, shows the reentrant phenomenon with the sequence of IL-N-SmA$_\mathrm{d}$-reentrant N (RN) on cooling.` `Recently, we found the reentrant phenomenon showing the IL-N-SmA$_\mathrm{d}$-RN sequence on cooling in $n$CB/$m$CB ($n$ = 0-6; $m$ = 8,9) binary mixtures for the first time [1,2]. Interestingly, their phase diagram against an averaged length of alkyl-chain ($n^\ast$) showed four N(RN)-SmA$_\mathrm{d}$ phase boundary curves corresponding to four combinations of odd and even chains in $n$CB/$m$CB systems: even/even, odd/even, even/odd, and odd/odd [2]. We successfully clarified the odd-even effect based on their molecular packing structure of the SmA$_\mathrm{d}$ phase. The reentrant phenomenon and the odd/even effect will be discussed.` References [1] S. Fujimura, Y. Yamamura, M. Hishida, S. Nagatomo, K. Saito, `$\textit{Liq. Cryst.}$` `$\textbf{41}$, 927 (2014). [2] Y. Yamamura, R. Tsuchiya, S. Fujimura, M. Hishida, K. Saito, `$\textit{J. Phys. Chem. B}$` `$\textbf{121}$`, 1438 (2017).

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Dr Yasuhisa Yamamura (University of Tsukuba)

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