Department of Physics, University of Ioannina, 451 10 Ioannina, Greece.
ACS Nano. 2011 Nov 22;5(11):9208-15. doi: 10.1021/nn203448c. Epub 2011 Oct 11.
The nematic-to-isotropic, crystal-to-nematic, and supercooled liquid-to-glass temperatures are studied in the liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) confined in self-ordered nanoporous alumina. The nematic-to-isotropic and the crystal-to-nematic transition temperatures are reduced linearly with the inverse pore diameter. The finding that the crystalline phase is completely suppressed in pores having diameters of 35 nm and below yields an estimate of the critical nucleus size. The liquid-to-glass temperature is reduced in confinement as anticipated by the model of rotational diffusion within a cavity. These results provide the pertinent phase diagram for a confined liquid crystal and are of technological relevance for the design of liquid crystal-based devices with tunable optical, thermal, and dielectric properties.
研究了液晶 4-戊基-4'-氰基联苯（5CB）在自有序纳米多孔氧化铝中受限的向列-各向同性、晶-向列和过冷液体-玻璃化转变温度。向列-各向同性和晶-向列转变温度随孔径的倒数线性降低。发现直径为 35nm 及以下的孔中完全抑制了结晶相，这给出了临界核大小的估计。正如腔内旋转扩散模型所预期的那样，受限液体的玻璃化转变温度降低。这些结果为受限液晶提供了相关的相图，对于设计具有可调光学、热学和介电性能的基于液晶的器件具有技术意义。
