Blog
I'm thrilled to delve into the intricate world of cholesteric liquid crystals, a subject at the heart of our recent research. Collaborating with a team of distinguished scientists, we've unveiled new insights into the transition pathways within these captivating materials, specifically focusing on splay mediation and maximally biaxial defect points.
Cholesteric liquid crystals, known for their unique helical structure and optical properties, exhibit a complex dance of molecular alignment and reorientation. Our study reveals two primary ways these crystals transform, each pathway offering a glimpse into the adaptive nature of cholesterics.
The first process, splay mediation, involves a gradual and continuous realignment of molecules. Imagine a slowly twisting ribbon, where each turn represents a subtle shift in the molecular orientation. This process is both elegant and intricate, reflecting the delicate balance in the liquid crystal's structure.
In contrast, the emergence of maximally biaxial defect points is more abrupt, akin to a rapid flick of the ribbon, leading to a noticeable and distinct change. This pathway highlights the dynamic capabilities of cholesterics to respond swiftly to environmental changes.
Our journey to these discoveries was as fascinating as the findings themselves. Utilising advanced, novel analytical techniques and computational modelling, we were able to observe and analyse these transitions in unprecedented detail. Furthermore, we used advanced algorithms to predict the typical optical motifs that would be measured through methods such as polarised light microscopy. This enabled us to provide the expected experimental signatures that would be measured. We proposed both dynamical time evolution signatures and static signatures of the metastable energy minimising states.
The methods employed were not only cutting-edge but also accessible to researchers in the field. By combining numerical techniques with theoretical models, we developed a comprehensive understanding of the cholesteric configuration along the transition pathway of least action. This approach underscores the power of interdisciplinary research in uncovering the secrets of complex materials.
These insights are not just academically intriguing; they have practical implications too. Understanding the mechanisms behind these transitions opens up new possibilities in the design of optical devices, displays, and sensors. Cholesteric liquid crystals, with their unique optical properties, could lead to the development of more efficient and adaptable technologies.
As we continue to explore the fascinating properties of cholesteric liquid crystals, we are constantly reminded of the beauty and complexity of the material world. Our research is a testament to the endless possibilities that emerge when we combine scientific curiosity with collaborative exploration.
To dive deeper into our research and explore the intricate world of cholesteric liquid crystals, I invite you to read our full paper published in the open access journal Physical Review Research, which provides a more detailed account of our methods and findings.
Discover more by accessing the complete paper at the following link.
Uniaxial versus biaxial pathways in one-dimensional cholesteric liquid crystals; Phys. Rev. Research, 4, L032018I am delighted to have been part of a very interesting multi-author research project, collaborating with colleagues from Emory University (USA) and Roskilde University (Denmark), investigating the quasi-universality of higher order structural correlations in various Lennard-Jones systems.
The idea of quasi-universality in liquids has been shown to be evident in a variety of so called ‘Roskilde-Simple’ liquid systems. These are liquids in which there is a notable direct correlation between the instantaneous virial and potential energy of the system. Quasi-universality is evidenced via a collapse of a range of structural and dynamical properties of the system when scaled between statepoints of constant excess entropy, ie; the configurational contributions to the entropy. The existence of quasi-universality has led to such statepoints being referred to as ‘Thermodynamic Wormholes’. These specially density-scaled liquids are however more commonly known as Isomorphs.
Despite much evidence of the collapse of two-point structural correlation functions (RDF) at multiple statepoints relevant to this so-called Isomorph Scaling, an interesting investigation conducted by A. Malins and C. P. Royall et al (2014) seemed to suggest that despite the success of Isomorphic description of the collapse of the RDF, higher-order correlations were not subject the same rules of quasi-universality.
This apparently anomalous behaviour of the Locally Favoured Structure in the Kob-Andersen (KA) system became even more interesting when higher-order correlations were shown to successfully scale in KA systems subjected to high levels of confinement (down to 6 particles in width), albeit at higher temperatures, by BMGD Carter and T. Ingebrigtsen et al (2021).
In order to test this apparent disagreement even further, a project was devised to test the limits of Isomorph Theory and further consider the deviation from the collapse of higher-order (up to twelve-point) correlation functions. It was shown that these structures indeed collapsed when systems were scaled in the appropriate manner. However; we also showed that the 11A (bi-capped square antiprism) structure, which has been deemed to be the Locally Favoured Structure for the supercooled KA system, did indeed not successfully collapse as was determined in 2014.
In order to figure out the interesting devious behaviour, further work will be carried out in an attempt to determine the origin of the discrepancy between two of the wonderful theories describing supercooled liquids.
For more information, read the full open-source manuscript published in the journal ‘Molecules’ at the link below.
Read More