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Engineering or mimicking living materials found in nature has the potential to transform the use of materials. Unlike classic synthetic materials which are typically optimized for static properties, economics, and recently also for sustainability, materials of life are dynamic, feedback‐controlled, evolving, and adaptive. Although synthetic materials do not typically exhibit such complicated functionalities, researchers are increasingly challenging this viewpoint and expanding material concepts toward dynamic systems inspired by selected life‐like functions. Herein, it is suggested that such materials can be approached from two perspectives: through engineering of biological organisms and their functions to provide the basis for new materials, or by producing synthetic materials with selected rudimentary life‐inspired functions. Current advances are discussed from the perspectives of (i) new material features based on built‐in memory and associative learning, (ii) emergent structures and self‐regulated designs using non‐equilibrium systems, and (iii) interfacing living and non‐living systems in the form of cellular community control and growth to open new routes for material fabrication. Strategies combining (i)–(iii) provide materials with increasingly life‐inspired responses and potential for applications in interactive autonomous devices, helping to realize next‐generation sensors, autonomous and interactive soft robots, and external control over the bioproduction of self‐organizing structural materials. [ABSTRACT FROM AUTHOR]

Supramolecular complexation between photoresponsive azobenzene chromophores andaphotopassive polymer host offers synthetic and design advantages compared with conventional covalent azo-containing polymers. In this context, it is important to understand the impact of the strength of the supramolecular interaction on the optical response. Herein, we study the effect of hydrogen-bonding strength between a photopassive polymer host [poly(4-vinylpyridine), or P4VP] and three azobenzene analogues capable of forming weaker (hydroxyl), stronger (carboxylic acid), or no H-bonding with P4VP. The hydroxyl-functionalized azo forms complete H-bonding complexation up to equimolar ratio with VP, whereas the COOH-functionalized azo reaches only up to 30% H-bond complexation due to competing acid dimerization that leads to partial phase separation and azo crystallization. We show that the stronger azo-polymer H-bonding nevertheless provides higher photoin-duced orientation and better performance during optical surface patterning, in terms of grating depth and diffraction efficiency, when phase separation is either avoided altogether or is limited by using relatively low azo contents. These results demonstrate the importance of the H-bonding strength on the photoresponse of azopolymer complexes, as well as the need to consider the interplay between different intermolecular interactions that can affect complexation. Key words: supramolecular complexes, azo-containing materials, photo-orientation, surface relief gratings. La complexation supramoleculaire entre des chromophores azobenzeniques photosensibles et un hote polymerique photopassif offre des avantages sur le plan de la synthese et de la conception par rapport aux polymeres azoiques covalents classiques. Dans ce contexte, il importe de comprendre les effets de la force des interactions supramoleculaires sur la reponse optique. Dans le cadre des presents travaux, nous avons etudie l'effet de la force des liaisons hydrogene entre un hote polymerique photopassif--la poly(4-vinylpyridine), ou P4VP - et trois analogues azobenzeniques capables de former des liaisons hydrogene faibles (hydroxyle) ou fortes (acide carboxylique) avec la P4VP, ou de ne former aucune liaison hydrogene. Les composes azoiques hydroxyles se complexent entierement par liaisons hydrogene avec la VP, la complexation atteignant un rapport equimolaire, tandis que les composes azoiques carboxyles n'atteignent qu'un taux de complexation par liaisons hy-drogene de 30%. Ce dernier resultat est attribuable a la dimerisation de l'acide, qui entre en competition, entrainant une separation de phases partielle et la cristallisation du compose azoique. Nous demontrons que les liaisons hydrogene plus fortes avec le polymere azoique permettent neanmoins une orientation photo-induite plus importante et une meilleure performance durant le modelage optique de la surface, notamment en ce qui concerne la profondeur du reseau et l'efficacite de diffraction, lorsque la separation de phases est evitee completement ou limitee par l'utilisation de quantites relativement faibles de compose azoique. Ces resultats demontrent l'influence de la force des liaisons hydrogene sur la photosensibilite des complexes de polymeres azoiques de meme que la necessite de prendre en compte l'interrelation entre les differentes interactions inter-moleculaires qui peuvent intervenir dans la complexation. [Traduit par la Redaction] Mots-cles : complexes supramoleculaires, composes azoiques, photo-orientation, reseaux de surface., Introduction Supramolecular chemistry, basedon specific noncovalent interactions between complementary molecules, is an excellent tool for building libraries of functional materials, because one structural material element at a time can be [...]

Bright white color is often achieved in nature by the combination of polydisperse scattering structures and high refractive index contrast between the scatterer and the surrounding medium. Similarly, synthetic systems have commonly utilized inorganic materials as the scattering centers to achieve white color, which, however, lacks the ability to switch the optical properties. While hydrogels capable of scattering light are utilized in applications such as smart windows, their reflection properties have remained limited due to the low refractive index contrast between the polymer and water. As a result, thick layers in the millimeter range are often required to achieve reasonable whiteness. Here a hydrogel consisting of a temperature‐responsive poly(N‐isopropylacrylamide) (PNIPAm) and chemically modified agarose used as a chemical macro‐crosslinker is presented. The hydrogel exhibits high whiteness at temperatures above the phase transition (≈31 °C). The reflectance at 800 nm is four times as high as for standard PNIPAm, and a change in transmittance can be induced by laser pulses as short as 30 ms. The macro‐crosslinked structure of this hydrogel provides superior reflectance at a lower thickness compared to reported hydrogel systems, enabling a variety of potential applications including smart windows, responsive displays, optical switches, and camouflage. [ABSTRACT FROM AUTHOR]

Materials that undergo shape morphing in response to external stimuli have numerous applications, e.g., in soft robotics and biomedical devices. Shape memory polymers utilize kinetically trapped states to, typically irreversibly, transfer between a programmed morphed shape and an equilibrium shape. Liquid crystal elastomers (LCEs), in turn, can undergo reversible actuation in response to several stimuli. This study combines the irreversible and reversible shape morphing processes to obtain LCEs that undergo shape‐programming via the shape memory effect and subsequent reversible actuation of the programmed shape. This is enabled by an LCE crosslinked via dynamic hydrogen bonds that break at high temperatures and reform upon cooling, endowing the shape memory effect, while mild thermal or photothermal stimulation yields the reversible actuation. Through this combination, proof‐of‐concept robotic application scenarios such as grippers that can adjust their shape for grabbing different‐sized objects and crawling robots that can morph their shape to adapt to constrained spaces, are demonstrated. It is anticipated that this work adds new diversity to shape‐programmable soft microrobotics. [ABSTRACT FROM AUTHOR]

Light‐fueled self‐oscillators based on stimuli‐responsive soft materials have been explored toward the realization of a myriad of nonequilibrium robotic functions, such as adaptation, autonomous locomotion, and energy conversion. However, the high energy density and unidirectionality of the light field, together with the unscalable design of the existing demonstrations, hinder their further implementation. Herein, a light‐responsive lampshade‐like smart material assembly as a new self‐oscillator model that is unfettered by the abovementioned challenges, is introduced. Liquid crystal elastomer with low phase transition temperature is used as the photomechanical component to provide twisting movement under low‐intensity incoherent light field. A spiral lampshade frame ensures an equal amount of light being shadowed as negative feedback to sustain the oscillation upon constant light field from omnidirectional excitation (0°–360° azimuth and 20°–90° zenith). Different‐sized oscillators with 6, 15, and 50 mm in diameter are fabricated to prove the possibility of scaling up and down the concept. The results provide a viewpoint on the fast‐growing topic of self‐oscillation in soft matter and new implications for self‐sustained soft robots. [ABSTRACT FROM AUTHOR]

Diffractive optical elements (DOE) are integral components for lightweight and ultra‐thin optical elements due to their ability to manipulate light efficiently and accurately. However, conventional DOEs are static and cannot be altered after fabrication, which hinders their adaptability to changing requirements. To overcome this limitation, the potential of surface patterning on azobenzene thin films to fabricate reconfigurable DOEs is investigated. Using holographic lithography, surface topographies with sinusoidal surface relief gratings (SRG) are created and the superposition of up to 80 SRGs with high accuracy and minimal information loss in subsequent inscriptions is demonstrated. This is enabled by a surface patterning tool combining holographic lithography and digital holographic microscopy. Reconfigurable and adaptive optical elements can improve the efficiency of optical coupling and increase the sensitivity and selectivity of sensors, especially in applications such as near‐eye displays and plasmonic sensors. These results demonstrate the ability to create complex azobenzene‐based DOEs for advanced photonic applications, where the ability to alter optical elements is of high importance. [ABSTRACT FROM AUTHOR]

Supramolecular host–guest complexes are dynamic systems composed of typically macrocyclic host molecules encapsulating smaller guest molecules. One of their applications is the selective encapsulation of fluorescent dye molecules to tackle quenching and photobleaching in solution. When extended to solid matrices, the efficiency of dyes can be especially poor, limiting their use in fluorescence‐based applications. Here it is demonstrated that supramolecular host–guest complexation in a hydrogel network allows readily tunable hydrogel‐based lasers. Poly(N‐isopropylacrylamide)‐based copolymer hydrogel is used with covalently linked Rhodamine B molecules. By controlled doping of cucurbit[7]uril as a host molecule in the hydrogel, it is shown that the fluorescent quantum yield increases from 17% to 51%, accompanied by 15‐fold enhancement in photostability. As proof of concept, a thin‐film distributed feedback hydrogel laser with wavelength tunability is fabricated. The results reveal a 30% increase in slope efficiency in the presence of host molecules. These results, combined with the inherent stimuli‐response of hydrogels, enable new possibilities for affordable and small‐scale photonic devices capable of safely interacting with the environment in, for example, sensing applications. [ABSTRACT FROM AUTHOR]