Insights into Chirality in Curved Rod Nematics
Recent research has revealed significant insights into the behavior of polar uniaxial nematics, particularly focusing on their chiral structures. The paper titled "Entropy stabilized form chirality in curved rod nematics: structure and symmetries" by Alexandros G. Vanakaras, Edward T. Samulski, and Demetri J. Photinos discusses findings from Monte Carlo molecular simulations of curve-shaped rods. These simulations indicate that such shapes exhibit polymorphism, leading to both smectic and nematic phases.
The study highlights that the nematic phase displays a nanoscale modulated local structure characterized by a unique polar, C2-symmetry axis. This structure spirals tightly, resulting in a mirror-symmetry-breaking organization of achiral rods, which forms chirality. The researchers confirm that this nanoscale modulation violates conventional splay- and twist-bend continuum elasticity, suggesting a need for revised models in understanding these materials.
Moreover, the research indicates that entropy plays a crucial role in stabilizing the polar director in the polar-twisted nematic phase, akin to the isotropic-to-nematic transition. This work clarifies the relationship between macroscale form chirality in ferroelectric nematics and the twist-bend nematic phase, addressing previous misattributions regarding the nanoscale modulation found in lower temperature nematic phases.
These findings could have implications for the development of advanced materials and applications in soft condensed matter physics, particularly in the design of new liquid crystal technologies. The full paper can be accessed here.