Programming of liquid crystalline elastomers (LCEs) for stimuli-responsive shape change relies on an intricate balance of polymer network and liquid crystalline properties. Fundamental insight into how responsive behavior can be manipulated at the molecular and polymer network level enables targeted design of complex macroscopic actuators. Here, these synergistic properties are explored across length scales spanning the molecular design of liquid crystalline components and functional monomers to the patterning and reprogramming of alignment and network topology. These aspects are highlighted in the context of pioneering discoveries in the field alongside recent innovations, including examples from our work, illustrating the potential for advancing the design of LCEs and their impact in modern applications based on methodical use of fundamental knowledge.
Liquid crystals are fascinating materials with peculiar chemical and physical properties and widespread technological applications. However, from the educational point of view, this topic presents a certain level of complexity, and it is usually viewed as challenging by high school teachers. The experiences gained in the last 10 years with high school students during educational laboratories and outreach activities carried out at the University of Pisa were extremely positive in terms of students' engagement and knowledge achievements. Based on those experiences, a modular and flexible didactic path to introduce liquid crystals was recently proposed to high school teachers covering several themes with a multidisciplinary approach by combining STEM and 'kitchen chemistry' laboratories.
Chromonic liquid crystals (CLCs) are lyotropic materials which are attracting growing interest for their adaptability to living systems. This paper reviews some of the contributions concerning their theoretical modelling, aimed at rationalising experiments. The elastic theory of CLCs is not completely established. Their ground state in $3D$3D space, as revealed by a number of recent experiments, is twisted instead of uniform, differently form ordinary nematics. The common explanation provided for this state within the classical Frank elastic theory demands that one Ericksen's inequality is violated, thus making the Frank stored-energy density unbounded below; the legitimacy of these theoretical treatments is threatened by mathematical issues. To overcome these difficulties, a novel elastic theory has been proposed and tested for CLCs; it extends the Frank energy by incorporating a quartic twist term. CLCs exhibit broad biphasic regions, and mathematical models inspired by experimental settings have been developed for CLC droplets in 2D dimensions; they address the morphogenesis of nuclei and topological defects during phase transitions, topological shape transformations, and the prediction of shape bistability. General methods have been applied to experimental data to extract estimates of isotropic-surface tension and chromonics' anchoring strength.
