Loudet JC, Barois P, Poulin P
Centre de Recherche Paul Pascal/CNRS, Pessac, France.
Nature. 2000 Oct 5;407(6804):611-3. doi: 10.1038/35036539.
Some binary mixtures exist as a single phase at high temperatures and as two phases at lower temperatures; rapid cooling therefore induces phase separation that proceeds through the initial formation of small particles and subsequent growth and coarsening. In solid and liquid media, this process leads to growing particles with a range of sizes, which eventually separate to form a macroscopically distinct phase. Such behaviour is of particular interest in systems composed of an isotropic fluid and a liquid crystal, where the random distribution of liquid-crystal droplets in an isotropic polymer matrix may give rise to interesting electro-optical properties. Here we report that a binary mixture consisting of an isotropic fluid and a liquid crystal forming the continuous phase does not fully separate into two phases, but self-organizes into highly ordered arrays of monodisperse colloidal droplet chains. We find that the size and spatial organization of the droplets are controlled by the orientational elasticity of the liquid-crystal phase and the defects caused by droplets exceeding a critical size. We expect that our approach to forming monodisperse, spatially ordered droplets in liquid crystals will allow the controlled design of ordered composites that may have useful rheological and optical properties.
一些二元混合物在高温下以单相存在，而在低温下以两相存在；因此，快速冷却会引发相分离，该过程通过小颗粒的初始形成以及随后的生长和粗化来进行。在固体和液体介质中，这一过程会导致形成一系列尺寸的生长颗粒，这些颗粒最终会分离形成宏观上不同的相。这种行为在由各向同性流体和液晶组成的系统中尤为有趣，其中液晶液滴在各向同性聚合物基质中的随机分布可能会产生有趣的电光特性。在此，我们报告由形成连续相的各向同性流体和液晶组成的二元混合物不会完全分离成两相，而是自组织成高度有序的单分散胶体液滴链阵列。我们发现液滴的尺寸和空间组织由液晶相的取向弹性以及超过临界尺寸的液滴所导致的缺陷控制。我们预计，我们在液晶中形成单分散、空间有序液滴的方法将允许对可能具有有用流变学和光学特性的有序复合材料进行可控设计。
