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Replicating biological patterns is promising for designing materials with multifaceted properties. Twisted cholesteric liquid crystal patterns are found in the iridescent tessellated cuticles of many insects and a few fruits. Their accurate replication is extremely difficult since discontinuous patterns and colors must coexist in a single layer without discontinuity of the structures. Here, a solution is demonstrated by addressing striped insect cuticles with a complex twisted organization. Geometric constraints are met by controlling the thermal diffusion in a cholesteric oligomer bilayer subjected to local changes in the molecular anchoring conditions. A multicriterion comparison reveals a very high level of biomimicry. Proof-of-concept prototypes of anti-counterfeiting tags are presented. The present design involves an economy of resources and a high versatility of chiral patterns unreached by the current manufacturing techniques such as metallic layer vacuum deposition, template embossing and various forms of lithography which are limited and often prohibitively expensive. Replicating biological patterns is promising for designing materials with multifaceted properties but replication of twisted cholesteric liquid crystal patterns found in insects is extremely difficult. Here, the authors use liquid crystal oligomers to reproduce the textural, structural and color properties of biological liquid crystals.

Cholesteric liquid-crystalline states of matter are abundant in nature: atherosclerosis 1 , arthropod cuticles 2 , 3 , condensed phases of DNA 4 , plant cell walls 2 , 5 , human compact bone osteon 6 , and chiral biopolymers 7 , 8 , 9 , 10 . The self-organized helical structure produces unique optical properties 11 . Light is reflected when the wavelength matches the pitch (twice periodicity); cholesteric liquid crystals are not only coloured filters, but also reflectors and polarizers. But, in theory, the reflectance is limited to 50% of the ambient (unpolarized) light because circularly polarized light of the same handedness as the helix is reflected. Here we give details of a cholesteric medium for which the reflectance limit is exceeded. Photopolymerizable monomers are introduced into a cholesteric medium exhibiting a thermally induced helicity inversion, and the blend is then cured with ultraviolet light when the helix is right-handed. Because of memory effects attributable to the polymer network, the reflectance exceeds 50% when measured at the temperature assigned for a cholesteric helix with the same pitch but a left-handed sense before the reaction. As cholesteric materials are used as tunable bandpass filters, reflectors or polarizers and temperature or pressure sensors 12 , novel opportunities to modulate the reflection over the whole light flux range, instead of only 50%, are offered.

The saga of liquid crystal research began in 1888 when Friedrich Reinitzer, a botanist working at the Institute of Plant Physiology in Prague, lent credence to the unusual colour changes of crystals extracted from carrots that were subjected to a temperature cycle. In 2025, liquid crystals returned to their roots for the 17 th European conference, which brought together 200 senior and junior researchers from 30 countries.The conference highlighted the vitality of liquid crystal research and its growing importance in academic and practical applications. The program included four plenary lectures. Maria H. Godinho (NOVA University Lisbon, Portugal) (Figure 1(a)) opened the event with a presentation on cellulose and chitin liquid crystalline phases that emphasised sustainable and bio-derived mesophases. Ivan. I. Smalyukh (University of Colorado Boulder, USA) (Figure 1(b)) presented on nanocellulose-based aerogels for smart window applications, combining photonics with green materials science. Damian Pociecha (University of Warsaw, Poland) (Figure 1(c)) introduced novel strategies for symmetry breaking in polar and smectic phases. Kristiaan Neyts (SKL of Advanced Displays and Optoelectronic Technologies, Hong Kong University of Science and Technology) (Figure 1(d)) reviewed photoalignment techniques in liquid crystal design.The program included over 20 invited talks, numerous oral and short oral contributions, and two very well attended, large poster sessions on Monday and Tuesday.The conference paid special attention to areas such as ferroelectric nematics, which emerged as a dominant theme, as well as to photonic systems, theory and simulations, polymers, elastomers, colloids and gels, biological and bio-inspired materials, and applications.There were over 180 poster presentations, and the topics ranged from novel mesogens and synthetic routes to liquid crystal -based sensors, smart windows, and photonic devices (Figure 2).In tribute to our dear colleague who passed away earlier this year, Rebecca Walker (University of Aberdeen, UK) retraced the personal and scientific journey of Corrie T. Imrie (Figure 3).The conference was attended by a large number of early career and student researchers. Many of their outstanding contributions were recognised by the presentation of awards.

Patterning nano-objects is an exciting interdisciplinary research area in current materials science, arising from new optical and optoelectronic properties and the need to miniaturize electronic components. Many techniques have been developed for assembling nanoparticles into two- and three-dimensional arrays. Most studies involving liquid crystals as templates have dealt with colloidal particles and nematic and smectic phases. Here, we demonstrate the long-range ordering of nanoparticle assemblies that adopt the helical configuration of the cholesteric liquid crystalline phase. Because we used glass-forming cholesterics, the nanostructures could be examined by transmission electron microscopy. The platinum nanoparticles form periodic ribbons that mimic the well-known 'fingerprint' cholesteric texture. Surprisingly, the nanoparticles do not decorate the original cholesteric texture but create a novel helical structure with a larger helical pitch. By varying the molar fraction of cholesterol-containing mesogen in the liquid crystal host, we show that the distance between the ribbons is directly correlated to the pitch. Therefore this inherent lengthscale becomes a simple control parameter to tune the structuring of nanoparticles. These results demonstrate how such an assembly process could be modulated, providing a versatile route to new materials systems.

The problem of imaging materials with circular polarization properties is discussed within the framework of vectorial ptychography. We demonstrate, both theoretically and numerically, that using linear polarizations to investigate such materials compromises the unicity of the solution provided by this computational method. To overcome this limitation, an improved measurement approach is proposed, which involves specific combinations of elliptical polarizations. The effectiveness of this strategy is demonstrated by numerical simulations and experimental measurements on cholesteric liquid crystals films, which possess unique polarization properties. With the help of Pauli matrices algebra, our results highlight the technique's ability to discern between different types of circular polarizers, uniform vs. non-uniform, and determine their handedness.