We have studied properties of novel thermotropic mesogenic materials that exhibit both an achiral double gyroid (Ia3[combining macron]d symmetry) and chiral cubic phase (previously assigned the Im3[combining macron]m symmetry). We argue that in the chiral cubic phase molecules form micelles and channels arranged into continuously interconnected hexagons. From the X-ray diffraction experiment supported by modelling, exact positions of hexagons and their connections were deduced and showed to be embedded on a WP (degenerated Neovius) minimal primitive surface. The elastic energy of such a structure is close to the one of the double gyroid phase, which is in agreement with a very low enthalpy change observed at the phase transition. We also argue that the chirality of the phase is related to the lack of mirror symmetry of non-flat hexagons accompanied by an alternating inclination of molecules in the neighbouring segments of hexagon; the chirality of individual hexagon is amplified on the whole hexagon network by steric effects.
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Article Synopsis
- The text examines phase transitions, specifically martensitic transformations, which involve the movement of atoms in a coherent way to shift from one crystalline structure to another, and highlights recent experimental observations in soft materials.
- The study utilizes direct simulations of a liquid crystalline blue phase (BP II) to analyze the dynamic transition to another phase (BP I) through a machine-learning approach to identify local structures and defects.
- Findings reveal that this transformation can be triggered by the breakup of line defect junctions and can be reversed by changing temperature, shedding light on complex structural changes in ordered materials more broadly.
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