Sadati Monirosadat, Martinez-Gonzalez Jose A, Cohen Alexander, Norouzi Sepideh, Guzmán Orlando, de Pablo Juan J
Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
Department of Chemical Engineering, Swearingen Engineering Center, University of South Carolina, Columbia, South Carolina 29208, United States.
ACS Nano. 2021 Oct 26;15(10):15972-15981. doi: 10.1021/acsnano.1c04231. Epub 2021 Oct 1.
Liquid crystals are important components of optical technologies. Cuboidal crystals consisting of chiral liquid crystals-the so-called blue phases (BPs), are of particular interest due to their crystalline structures and fast response times, but it is critical that control be gained over their phase behavior as well as the underlying dislocations and grain boundaries that arise in such systems. Blue phases exhibit cubic crystalline symmetries with lattice parameters in the 100 nm range and a network of disclination lines that can be polymerized to widen the range of temperatures over which they occur. Here, we introduce the concept of strain-controlled polymerization of BPs under confinement, which enables formation of strain-correlated stabilized morphologies that, under some circumstances, can adopt perfect single-crystal monodomain structures and undergo reversible crystal-to-crystal transformations, even if their disclination lines are polymerized. We have used super-resolution laser confocal microscopy to reveal the periodic structure and the lattice planes of the strain and polymerization stabilized BPs in 3D real space. Our experimental observations are supported and interpreted by relying on theory and computational simulations in terms of a free energy functional for a tensorial order parameter. Simulations are used to determine the orientation of the lattice planes unambiguously. The findings presented here offer opportunities for engineering optical devices based on single-crystal, polymer-stabilized BPs whose inherent liquid nature, fast dynamics, and long-range crystalline order can be fully exploited.
液晶是光学技术的重要组成部分。由手性液晶构成的立方晶体——即所谓的蓝相（BPs），因其晶体结构和快速响应时间而备受关注，但关键是要控制其相行为以及此类系统中出现的潜在位错和晶界。蓝相呈现立方晶体对称性，晶格参数在100纳米范围内，且有一个旋错线网络，该网络可被聚合以拓宽其出现的温度范围。在此，我们引入了受限条件下蓝相的应变控制聚合概念，这使得能够形成与应变相关的稳定形态，在某些情况下，即使其旋错线已聚合，这些形态也能采用完美的单晶单畴结构并经历可逆的晶体到晶体的转变。我们使用超分辨率激光共聚焦显微镜在三维真实空间中揭示了应变和聚合稳定的蓝相的周期性结构和晶格平面。我们依靠理论和计算模拟，根据张量序参量的自由能泛函，对实验观察结果进行了支持和解释。模拟用于明确确定晶格平面的取向。此处呈现的研究结果为基于单晶、聚合物稳定的蓝相设计光学器件提供了机会，其固有的液体性质、快速动力学和长程晶体有序性能够得到充分利用。
