Kassapidou K, Lekkerkerker HN
Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, The Netherlands.
Nature. 2000 Aug 24;406(6798):868-71. doi: 10.1038/35022535.
Colloidal suspensions that form periodic self-assembling structures on sub-micrometre scales are of potential technological interest; for example, three-dimensional arrangements of spheres in colloidal crystals might serve as photonic materials, intended to manipulate light. Colloidal particles with non-spherical shapes (such as rods and plates) are of particular interest because of their ability to form liquid crystals. Nematic liquid crystals possess orientational order; smectic and columnar liquid crystals additionally exhibit positional order (in one or two dimensions respectively). However, such positional ordering may be inhibited in polydisperse colloidal suspensions. Here we describe a suspension of plate-like colloids that shows isotropic, nematic and columnar phases on increasing the particle concentration. We find that the columnar two-dimensional crystal persists for a polydispersity of up to 25%, with a cross-over to smectic-like ordering at very high particle concentrations. Our results imply that liquid crystalline order in synthetic mesoscopic materials may be easier to achieve than previously thought.
能在亚微米尺度上形成周期性自组装结构的胶体悬浮液具有潜在的技术应用价值；例如，胶体晶体中球体的三维排列可作为光子材料用于操控光。具有非球形形状（如棒状和板状）的胶体颗粒因其形成液晶的能力而备受关注。向列型液晶具有取向有序性；近晶型和柱状液晶还分别在一维或二维上表现出位置有序性。然而，这种位置有序性在多分散胶体悬浮液中可能会受到抑制。在此，我们描述了一种板状胶体悬浮液，随着颗粒浓度的增加，它呈现出各向同性、向列型和柱状相。我们发现，柱状二维晶体在多分散度高达25%时仍能持续存在，在非常高的颗粒浓度下会转变为类似近晶型的有序排列。我们的结果表明，合成介观材料中的液晶有序性可能比之前认为的更容易实现。
