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3D printed concrete is being applied in an increasing amount worldwide. While in theory, there are environmental and economic benefits associated with using this technology, in practice, the amount of cement in printable concrete is much higher than in a conventional one, leading to increased environmental and economic costs. Furthermore, cement's performance relies heavily on climate variables, specifically temperature. One way to solve this issue is to include local alternative low‐CO2 materials, such as processed mine tailings, as cement replacement. This paper presents an experimental approach to assess the use of copper tailings as cement replacement in printable concrete under different ambient temperatures. Three levels of cement volume replacement have been researched. The copper tailings' rheological effect has been measured using standard printability tests and a rheometer. Four mixtures have been printed in a controlled‐climate chamber to evaluate print‐ability, buildability and extrudability. The mechanical effect has been assessed with compressive and flexural strength tests of samples collected from the printed specimens. The results show that copper tailings are a promising alternative to cement in printable concrete in countries where this by‐product is abundant. [ABSTRACT FROM AUTHOR]

Fluorescent photochromic molecules that exhibit distinct light‐triggered changes in their emission colors are highly desirable for the fabrication of smart soft materials and advanced photonic devices. α‐Cyanodiarylethenes, that is, α‐cyano‐functionalized diarylethenes, as alternative "non‐azo" Z/E photochromic molecular switches, are popular choices due to their unique characteristics such as their aggregation‐induced emission or aggregation‐induced‐enhanced emission behavior in their self‐assembled states, and visible changes in fluorescence colors during Z/E photoisomerization. In recent years, the development of fluorescent photochromic α‐cyanodiarylethene‐based compounds including α‐cyanostilbenes, dicyanodistyrylbenzenes, and diaryldicyanoethenes, has mainly focused on molecular design, photochemical and photophysical behavior in solution, and smart soft matter technologies. In this review, recent significant achievements in light‐responsive systems based on the Z/E photoisomerization of fluorescent photochromic α‐cyanodiarylethene switches that span the range from liquid crystals to gels and finally to self‐assembled nanostructures, are highlighted. The smart soft materials constructed from α‐cyanodiarylethene molecular switches find use in a plethora of areas, including display, sensing, encrypting, actuating, and biomedical imaging applications, among others. The review concludes with a brief perspective on some major challenges and opportunities for the future development of light‐responsive smart soft photonic materials. [ABSTRACT FROM AUTHOR]

Adding colloidal nanoparticles into liquid-crystal media has become a promising pathway either to enhance or to introduce novel properties for improved device performance. Here we designed and synthesized new colloidal hybrid silica nanoparticles passivated with a mesogenic monolayer on the surface to facilitate their organo-solubility and compatibility in a liquid-crystal host. The resulting nanoparticles were identified by 1H NMR spectroscopy, TEM, TGA, and UV/Vis techniques, and the hybrid nanoparticles were doped into a dual-frequency cholesteric liquid-crystal host to appraise both their compatibility with the host and the effect of the doping concentration on their electro-optical properties. Interestingly, the silica-nanoparticle-doped liquid-crystalline nanocomposites were found to be able to dynamically self-organize into a helical configuration and exhibit multi-stability, that is, homeotropic (transparent), focal conic (opaque), and planar states (partially transparent), depending on the frequency applied at sustained low voltage. Significantly, a higher contrast ratio between the transparent state and scattering state was accomplished in the nanoparticle-embedded liquid-crystal systems. [ABSTRACT FROM AUTHOR]

Self-organized 3D photonic superstructures loaded with plasmonic hybrid nanorods were found to undergo structural transformation from body-centered cubic to simple cubic upon NIR-light irradiation resulting from the “photothermal effect” of gold nanorods. Furthermore, dynamic NIR light-directed red, green and blue reflections of the nanocomposites were demonstrated. [ABSTRACT FROM AUTHOR]

Light-driven phase transition in liquid crystals is a fascinating endeavour from both scientific and technological points of view. Here we demonstrate the proof-of-principle that the photothermal effect of organo-soluble plasmonic gold nanorods can introduce the phase transition of thermotropic liquid crystals upon near infrared laser irradiation. Interestingly, the reverse process occurs when the laser is switched off. [ABSTRACT FROM AUTHOR]

In this article, we report on the synthesis and thermotropic behaviour of methacrylic polymers containing 4′-(4-alkyloxyphenyl)azobenzene mesogens attached to the backbone throughn-alkyloxy spacers of 6 or 10 methylene groups. Polymerisations were carried out via free radicals using azobisisobutyronitrile (AIBN) as initiator. Chemical structures of polymers and their precursors were characterised by1H NMR spectroscopy. Thermogravimetric analysis showed that azopolymers are thermally stable up to temperatures around 300°C. The thermotropic liquid-crystalline (LC) behaviour was studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD). Results indicate that all synthesised mesogens, monomers and polymers developed two or more orthogonal LC phases in wide temperature ranges. Mesogens and monomers developed nematic and smectic phases, whereas polymers exhibited only smectic phase. In polymers, the arrangement of mesogens depends on the relative length of the spacer and the terminal flexible chain; two distinct structural models were proposed based on chemical interactions and steric constrains. Thetrans–cisphotoisomerisation of monomers and polymers in solution was also studied. Highcis-isomer contents (>80%) were reached in relative short irradiation times despite the steric constrains imposed by the polymer backbone. [ABSTRACT FROM AUTHOR]