A New Order of Liquids: Polar and ferroelectric orientationally modulated soft materials

液晶（LC）结合了类液体的流动性和晶体材料的一些光学特性（如双折射）。向列型液晶是那些组成分子（或粒子）有取向顺序（即它们大致平行或反平行排列）但缺乏位置顺序的液晶。向列型液晶是现代液晶显示（LCD）技术的基础，这种技术现在在我们的日常生活中无处不在，几乎看不见，你可能正在阅读这篇文章。其他类型的向列液晶一直是人们激烈猜测的主题，但却没有得到实验发现：值得注意的是，铁电向列是由诺贝尔奖获得者彼得·德拜和马克斯·伯恩在20世纪初独立预测的。铁电性，即材料在外加电场作用下表现出强度变化的永久电极化（PS），在有机和/或流体材料中通常较弱，只有在陶瓷中才能达到应用水平，而陶瓷易碎、难以制造且成本高昂。新的向列基态的发现是罕见的；2011年扭弯向列相（NTB）的发现是一个多世纪以来第一个新的向列态。NTB相具有周期性振荡的向列分子序，因此，它被称为调制向列。最近，我发现了第二种已知的调制向列相，即斜向列相（NS）；这个阶段是在楔形分子组织成一种结构时形成的，这种结构让人联想到一排首尾相连的日本扇子。这种正反顺序使得NS相成为第一个——也是迄今为止唯一的——铁电向列的真正例子。NS材料的PS值可与固体材料相媲美，但保留了液体的流动性，具有两个主要优点；材料加工被简化，并且由于活性介质的流动性，对机械力（自我修复）的容忍度大大增加。NS相的显著电场响应有可能重新改造基于向列的技术，使利用这些软材料的变革性应用成为可能：潜在的受益领域包括通过电热效应进行温度调节，以及通过铁电随机存取存储器和场效应晶体管进行计算。NS材料的一个关键优势是，它们可以使用为现有LCD技术开发的现有加工/对准技术，大大降低了未来应用的障碍。NS相是最近才发现的，为了实现其无与伦比的潜力，需要进行新的研究来设计具有该相的材料的特性：降低其高工作温度，增加其短工作温度范围，并提高其稳定性（化学和热）。满足这些要求的新材料的设计是不平凡的，并且由于需要发展我们对物质的这些相的发生率和分子结构之间关系的理解而变得复杂。该奖学金将为我们对调制向列式的基础化学和物理的理解带来范式转变。将分子设计（化学）与分子建模（化学/物理）和材料表征（物理）联系起来，所需知识的增长将会出现。作为NS阶段的发现者，在这两门科学的背景下，我处于独特的地位，可以将这项研究从科学好奇心转向现实应用。我将开发具有优异性能的材料，并加深我们对驱动这一阶段发生的分子特征的理解。我的研究将为现实世界的应用提供材料，同时也为液晶的规则手册增加了全新的章节，并将在未来几十年里为液晶和软物质设定研究议程

Liquid crystals (LC) combine liquid-like fluidity with some of the optical properties of crystalline materials (such as birefringence). Nematic liquid crystals are those in which the constituent molecules (or particles) have orientational order, (i.e. they align roughly parallel or antiparallel) but lack positional order. It is nematic LCs that underpin modern liquid crystal display (LCD) technology which is now ubiquitous to the point of being invisible in our daily lives, and via which you are perhaps reading this document. Other types of nematic liquid crystal had been the subject of intense speculation but eluded experimental discovery: notably, ferroelectric nematics were predicted independently by Peter Debye and Max Born, both Nobel laureates, in the early 20th century. Ferroelectricity, in which a material exhibits a permanent electric polarization (PS) which varies in strength under an applied electric field, is typically weak in organic and/or fluid materials and only approaches application-ready levels in ceramics, which can be brittle, difficult to fabricate, and costly.The discovery of new nematic ground states is rare; the discovery of the twist-bend nematic phase (NTB) in 2011 was the first new nematic state in over a century. The NTB phase features nematic molecular ordering which oscillates periodically, hence, it is known as a modulated nematic. Recently I discovered the second known modulated nematic phases, the splay-nematic (NS); this phase is formed when wedge shaped molecules organise themselves into a structure reminiscent of an array of Japanese fans arranged head-to-tail. This head-tail ordering makes the NS phase is the first - and to date only - bona fide example of a ferroelectric nematic. The values of PS of NS materials rival those of solid materials but retain the fluidity of a liquid, conferring two principal advantages; materials processing is simplified, and there is much increased tolerance to mechanical force (self-healing) due to the fluidity of the active medium. The remarkable electric-field response of the NS phase has the potential to remake nematic based technology anew, enabling transformative applications utilising these soft materials: potential areas of benefit include temperature regulation via the electrocaloric effect, and computing via ferroelectric random-access memory and field effect transistors. One key advantage of NS materials is that they can use existing processing/alignment technologies developed for existing LCD technology, significantly lowering the barrier to future applications. The NS phase is such a recent discovery that new research is required to engineer the properties of materials that exhibit this phase in order to realise their unrivalled potential by: reducing their high operating temperatures, increasing their short working temperature ranges, and improving their stability (chemical and thermal). The design of new materials to satisfy these requirements is non-trivial, and complicated by a need to develop our understanding of the relationship between the incidence of these phases of matter and molecular structure. This Fellowship will deliver a paradigm shift in our understanding of the chemistry and physics that underpins modulated nematics. The growth in knowledge required will arise from linking molecular design (chemistry) with molecular modelling (chemistry/physics), and material characterisation (physics). As the discoverer of the NS phase with a background in both sciences I am uniquely placed to lead this research from scientific curiosity towards real-world application. I will develop materials with superior properties and growing our understanding of the molecular features that drive the incidence of this phase. My research will deliver materials for real world applications while also adding entirely new chapters to the rulebook on liquid crystals, and will set the research agenda in liquid crystals and soft matter in the decades to come