Hierarchical ordering in light-triggered additive manufacturing

Additive manufacturing (AM) emerged, in the last decades, as a promising manufacturing technique for the low-cost fabrication of personalised 3D objects. Recently, this technology has been increasingly utilised, both in everyday life and in industry. Among the numerous AM techniques available, light-triggered AM allows for great shape resolution and a smooth surface, while being a relatively fast process. The increasing interest given to AM naturally motivated the development of novel 3D printable materials in order to keep on widening the possibilities of the techniques. Herein, we present an overview of the materials having been recently reported in the field, for which the incorporation of hierarchical ordering was essential to access novel functionalities and properties. In particular, hybrid materials such as fibre- and nanocrystal-reinforced polymeric networks, liquid crystalline materials and metal–organic framework embedded printable materials along with their future prospects will be discussed

Multi‐Photon 4D Printing of Complex Liquid Crystalline Microstructures by In Situ Alignment Using Electric Fields

An approach is presented to align the direction of liquid crystal networks or elastomers in situ during multi-photon laser printing for each voxel in three dimensions by applying a quasi-static electric field with variable orientation. This approach enables the making of 3D micro-heterostructures operating under ambient conditions that show large-amplitude elastic actuation, with temperature serving as the stimulus (“4D microstructures”). The approach involves two novelties. First, a dedicated sample cell with a variable height suitable for laser printing is introduced. It is based on optically transparent electrodes and allows to apply arbitrary electric field vectors in three dimensions, for example, parallel or normal to the substrate plane. Second, a variable optical phase plate combined with a pivotable half-wave plate warrants a single well-defined laser focus for nearly all possible quasi-static electric field vectors. Without the latter, one generally obtains two spatially separated laser foci, an ordinary and an extraordinary one, due to the optical birefringence of the medium induced by the alignment of the liquid crystal director via the applied quasi-static electric field. The versatility of the approach is illustrated by manufacturing and characterizing several exemplary architectures

Material‐Independent 3D Patterning Via Two‐Photon Lithography and Discontinuous Wetting

The fabrication of complex 3D structures composed of micrometer-sized features made of different functional materials is an immensely important and yet highly challenging task. Here, a method is developed to fabricate multimaterial 3D structures with micrometer precision by combining macroscopic 3D printing (digital light processing), with two-photon lithography (2PL) and material-independent discontinuous dewetting. Specifically, 3D inherently superhydrophobic objects are first printed by DLP, followed by creating hydrophilic micropatterns on their surface using 2PL. By exploiting the effect of discontinuous wetting, the selective deposition of solutions of functional materials into microscopic hydrophilic regions on the surface of 3D structures, with high resolution and great design flexibility is demonstrated. Importantly, the method is material-independent and enables the micropatterning of a variety of functional materials dispersed in aqueous solutions including polydopamine, silica, or Ag nanoparticles. As an exemplary application, it is shown that conductive Ag electrodes can be created on the curved surface of 3D-printed objects to construct structural electronics. The flexibility, high resolution, and material diversity in designing multimaterial 3D structures open exciting new functionalities and possibilities in a variety of applications including advanced electronics, soft robotics, and chemical or bioengineering

Two-Photon Laser Microprinting of Highly Ordered Nanoporous Materials Based on Hexagonal Columnar Liquid Crystals

Nanoporous materials relying on supramolecular liquid crystals (LCs) are excellent candidates for size- and charge-selective membranes. However, whether they can be manufactured using printing technologies remained unexplored so far. In this work, we develop a new approach for the fabrication of ordered nanoporous microstructures based on supramolecular LCs using two-photon laser printing. In particular, we employ photo-cross-linkable hydrogen-bonded complexes, that self-assemble into columnar hexagonal (Colh) mesophases, as the base of our printable photoresist. The presence of photopolymerizable groups in the periphery of the molecules enables the printability using a laser. We demonstrate the conservation of the Colh arrangement and of the adsorptive properties of the materials after laser microprinting, which highlights the potential of the approach for the fabrication of functional nanoporous structures with a defined geometry. This first example of printable Colh LC should open new opportunities for the fabrication of functional porous microdevices with potential application in catalysis, filtration, separation, or molecular recognition

Dissociation in Problematic Gaming: a Systematic Review

Purpose of Review The present article consists of a systematic review of recent (2007–2018) empirical studies addressing the relationship between problematic gaming and dissociation. Nineteen peer-reviewed empirical studies that examined the relationship between problematic gaming and dissociation were identified. Recent Findings The findings suggest that excessive video game use is linked to a variety of dissociative phenomena (e.g. depersonalisation experiences, escapism, psychotic-like experiences, game transfer phenomena). Summary Dissociative experiences are associated with problematic gaming. The findings support the hypothesis that problematic video game use can represent a maladaptive coping strategy onwhich people can rely to escape from disturbing mental states, adverse emotions or real-life problems. In these circumstances, dissociative symptoms might represent the side effects of an alteration in consciousness that is generated by excessive video game use. However, further research (especially experimental and longitudinal) is required in order to establish a potential causal link between problematic gaming patterns and dissociation

Atelier transport et énergie

Cours - 86 pages, figures, tableauxLe choix du groupe s'est porté sur un sujet ayant trait au transport, bien qu'aucun d'entre nous n'ait de compétences particulières dans ce domaine. Néanmoins, le thème du transport nous est apparu intéressant, dans la mesure où il nous concerne tous dans notre vie quotidienne. De fait, nous avons décidé de porter notre attention sur un sujet touchant le transport à Paris et après discussion, nous nous sommes accordés sur l'intitulé du sujet suivant : "Quelles alternatives, d'ici 2020, à l'usage individuel de l'automobile à Paris et ses communes limitrophes ?" La définition du sujet étant acquise, nous avons commencé à travailler sur les différentes étapes de l'atelier, énoncées sur notre feuille de route. Nous présenterons, dans ce dossier, les résultats de ces étapes successives, qui ont conduit notre réflexion