Fast Analog Electrooptic Liquid Crystal Materials

科罗拉多大学博尔德分校的实验和计算机模拟小组，瑞典查尔默斯理工大学的实验小组，德国斯图加特大学和加拿大女王大学的实验小组，以及英国斯特拉斯克莱德大学的理论小组，提出了一个显示快速模拟电光的手性/极性液晶研究的联合计划。虽然在过去几年里，合作伙伴的各种组合一直在单独合作，所有合作伙伴都有联合出版物，但拟议的网络将创建一个独特而强大的团队，用于手性液晶的前沿研究。这项建议集中于新型近晶液晶材料的合成、表征和理论模拟，它将比现有材料具有许多优点，包括更快的开关速度、更低的能耗以及在电光和所有光学器件中更广泛的应用。一些奇异的手性近晶液晶材料将被研究，包括具有最快模拟液晶电光效应的V型开关铁电近晶材料；在近晶C*相中倾斜而没有层收缩的DeVries材料，密切相关的正圆锥高倾斜反铁电材料；以及最近发现的具有极性近晶A相的弯芯液晶家族，它只提供相位电光调制。De Vries类近晶材料的特征是反常的弱层收缩，这使得人们能够避免近晶层在倾斜转变时发生屈曲，从而导致所谓的Z字形缺陷的形成，这严重降低了史密晶材料的光学质量。所有这些近晶材料都将通过偏光显微镜、偏振和倾角测量、X射线散射技术和折射率测量进行实验研究，并将在实验指导、分子理论和原子计算机模拟的指导下合成具有先进性能的新材料。这项拟议的研究突出了这些新型液晶系统的性质与软材料科学各个领域的分支之间关系的基础研究。相应的材料开发将使各种新的应用成为可能，包括全息数据存储和投影、光束转向和手性检测。整个提议的理论部分(工作包Strathclyde)专注于发展德弗里斯类型铁电材料的先进分子理论，考虑了分子间的短程取向和位置关联，并解释了其他团队获得的实验结果。利用实验研究和计算机模拟的结果，将建立具有纳米分离基团的模拟德夫里斯近晶材料的分子模型，数值计算这些材料的有序参数，并与实验数据进行比较。研究了不同的分子模型参数对Devries类材料自发极化的大小和温度变化的影响，包括分子形状和柔性、偶极分布和纳米隔离基团的影响。

A joint program of research in chiral/polar liquid crystals showing fast analog electrooptics is proposed between experimental and computer simulation group at the University of Colorado, Boulder, experimental groups at Chalmers University of Technology, Sweden, the University of Stuttgart, Germany and Queen's University, Canada, and the theoretical group at the University of Strathclyde, UK. While various combinations of the partners have been collaborating separately over the past several years, all with joint publications, the proposed Network will create a uniquely powerful team for forefront research on chiral liquid crystals. The proposal is focused into synthesis, characterization and theoretical modelling of novel smectic liquid crystal materials, which will have a number of advantages over the existing materials including much faster switching, lower energy consumption and a broader range of applications in electrooptic and all optical devices. A number of exotic chiral smectic liquid crystal materials will be investigated including the V-shaped switching ferroelectric smectics with the most rapid analog liquid crystal electro-optic effects; the deVries materials which tilt without layer contraction in the Smectic C* phase, the closely related orthoconic high-tilt antiferroelectrics; and the recently discovered family of bent-core liquid crystals with a polar smectic A phase that give phase-only electrooptic modulation The de Vries type smectic materials are characterized by anomalously weak layer contraction which enables one to avoid buckling of smectic layers at the tilting transition leading to the formation of the so-called zig-zag defects which seriously degrade the optical quality of smectic materials.. All of these smectic materials will be studied experimentally using polarized microscopy, polarization and tilt angle measurements, x-ray scattering technique and refractometry, and new materials with advanced characteristics will be synthesized using guidance from experiment, molecular theory and atomistic computer simulations. The proposed research highlights fundamental studies of the relationships of the properties of these novel liquid crystal systems with ramifications for a variety of areas in soft materials science. The corresponding materials development will enable a variety of novelapplications, including holographic data storage and projection, beam steering, and chirality detection. The theoretical part of the whole proposal (Work package Strathclyde) is focused into the development of the advance molecular theory of de Vries type ferroelectric materials, taking into account short-range orientational and positional intermolecular correlations, and interpretation of the experimental results obtained by other teams. Using the results of experimental studies and computer simulations, molecular models of analog de Vries smectic materials with nano-segregating groups will be developed, order parameters of these materials will be calculated numerically and compared with experimental data. Effect of various molecular model parameters on the value and temperature variation of the spontaneous polarization in de Vries type materials will be investigated including the effects of molecular shape and flexibility, dipole distribution and nano-segregating groups.