![]() ![]() Such a material has wide application prospects in camouflage materials, control devices and biomimetic devices. Relying on a combination of photo-chromic effect, thermochromic effect, pigment blending effect, photothermal conversion effect, and gradient stress effect, this flower mimic material can furl or open it “petals” under the on/off stimulation of near-infrared light, meanwhile possess a tri-stable showy color switch system which is tunable through varying the wavelength band (365 nm, 520 nm, 808 nm) of light stimuli. ![]() In-spired by this fascinating natural phenomenon, here we report a two-spiropyran-unit-functionalized, monodomain/polydomain bilayer-structured liquid crystal elastomer strategy to fabricate an ultraviolet, green and near-infrared tri-light-modulated tri-color-changing flower mimic soft actuator. In nature, many flowers can open their petals into blooming flowers or furl them into buds, and simultaneously alter the petal colors under the precise control of light, temperature, pH, humidity or other environmental stimuli. Additionally, Janus particle with two chemically different and incompatible facets can interact to each other in response to changes in their environment, i.e., changes in solvent and heating conditions, and undergo hierarchical self-assembly to create complex superstructures with novel applications (Choi et al. 2016), building blocks for directed selfassembly (Xing et al. 2017), drug delivery vehicles (Xu and Sun 2013), biomedicine enhancers (Cao et al. The coexistence of different attributes within a single particle not only renders the ability of directional interaction or side selective reactivity in the Janus particles but also endows the Janus nanomaterials with promising applications in a diverse areas such as surfactants/emulsion stabilizers (Kim et al. Janus particles are colloidal patchy building blocks consisting of at least two surface regions, which exhibit different chemistry, functionality, and directionality derived from the anisotropy or asymmetry within a single set of particles (Poggi and Gohy 2017 Walther and Muller 2013). Additionally, the prepared materials possess high specific surface areas, low bulk densities, and porosities of up to 84%. The contact angle of a water droplet on the monolithic surface can be altered from 146 to 100° by irradiation of the monolith with UV light for 3 min. A strong dependence of the surface polarity and water wettability on the prevalent isomer was observed. ![]() The transformation can be triggered simply by irradiation of the spiropyran-containing silsesquioxane monolith with UV or visible light or by the pH value of the chemical environment. UV-vis measurements prove the conversion of the colorless closed-ring form of the spiropyran molecule into its highly colored purple isomer or the yellow colored protonated structure thereof. We demonstrate that a silylated spiropyran derivative can be covalently incorporated into ultralight silsesquioxane-based bulk materials by a two-step co-condensation sol-gel approach without restricting its conformational freedom and thus its stimulus-responsive properties. Spiropyrans are often embedded in polymer matrices their covalent attachment into porous monolithic silsesquioxane frameworks, however, is virtually unexplored. Interestingly and despite all of these effects, we find that solvent sorption in the brush is described rather well with a simple mean-field Flory–Huggins model that incorporates an entropic penalty for stretching of the brush polymers, provided that parameters such as the polymer–solvent interaction parameter, grafting density, and relative vapor pressure are varied individually.ĭynamic materials comprising spiropyrans have emerged as one of the most interesting and promising class of stimulus-responsive materials. Moreover, adsorption layers of enhanced solvent density are formed at the brush–vapor interface. Polymer density profiles for vapor-solvated brushes decay more sharply than for liquid-solvated brushes. Here, we use molecular dynamics simulations to show that solvent and polymer density distributions for brushes exposed to vapors are qualitatively different from those of brushes exposed to liquids. While polymer brushes in contact with liquids have been researched intensively, the characteristics of brushes in equilibrium with vapors have been largely unexplored, despite their relevance for many applications, including sensors and smart adhesives.
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