HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
Philos Trans A Math Phys Eng Sci. 2013 Mar 4;371(1988):20120257. doi: 10.1098/rsta.2012.0257. Print 2013 Apr 13.
The response of anisotropic pigment particle suspensions to externally applied electric fields has been explored for possible application in reflective display technologies. Three different types of pigment particle were suspended in dodecane, using a polymeric stabilizer, and showed Schlieren textures between crossed polarizers at high concentrations (greater than 25-30 wt%), indicating the formation of colloidal nematic phases. Orientational order parameters were determined by X-ray scattering, and the influence of polydispersity on the values is discussed. X-ray scattering measurements also demonstrated a change in the structure factor consistent with the onset of a colloidal nematic phase. In addition, the pigment particles were dispersed into various liquid crystal hosts at low concentrations (less than 5 wt%) with and without the presence of mesogenic mimic stabilizers. However, the influence of these stabilizers on orientational ordering could not be confirmed. The electro-induced ordering determined via scattering was related to the electro-optical response of each suspension using a simple model. The particles in nematic hosts not only showed a high degree of orientational ordering at lower electric field strengths, but also showed a reduction in stability. Although these systems have shown strong orientational ordering, the optical response has been limited by the intrinsic shape of the pigment particles and the distribution of the transition dipoles moments within them. Nevertheless, the feasibility of developing materials for display applications has been demonstrated.
各向异性颜料粒子悬浮液对外加电场的响应，因其可能应用于反射式显示技术而受到研究。三种不同类型的颜料粒子使用聚合物稳定剂悬浮于十二烷中，在高浓度（大于 25-30wt%）下于正交偏振器之间显示出丝纹织构，表明形成了胶体向列相。取向有序参数通过 X 射线散射确定，并讨论了多分散性对其值的影响。X 射线散射测量还表明，结构因子发生了变化，与胶体向列相的出现一致。此外，将颜料粒子在低浓度（小于 5wt%）下分散到各种液晶主体中，无论是否存在介晶模拟稳定剂。然而，这些稳定剂对取向有序性的影响无法得到证实。通过散射确定的电诱导有序性与每种悬浮液的电光响应使用简单模型相关联。各向异性主体中的粒子不仅在较低的电场强度下表现出高度的取向有序性，而且还表现出稳定性降低。尽管这些系统表现出强烈的取向有序性，但光学响应受到颜料粒子的固有形状和其中的跃迁偶极矩分布的限制。然而，已经证明了开发用于显示应用的材料的可行性。
