The outstanding electrical, mechanical and chemical properties of graphene make it attractive for applications in flexible electronics. However, efforts to make transparent conducting films from graphene have been hampered by the lack of efficient methods for the synthesis, transfer and doping of graphene at the scale and quality required for applications. Here, we report the roll-to-roll production and wet-chemical doping of predominantly monolayer 30-inch graphene films grown by chemical vapour deposition onto flexible copper substrates. The films have sheet resistances as low as approximately 125 ohms square(-1) with 97.4% optical transmittance, and exhibit the half-integer quantum Hall effect, indicating their high quality. We further use layer-by-layer stacking to fabricate a doped four-layer film and measure its sheet resistance at values as low as approximately 30 ohms square(-1) at approximately 90% transparency, which is superior to commercial transparent electrodes such as indium tin oxides. Graphene electrodes were incorporated into a fully functional touch-screen panel device capable of withstanding high strain.
Multiresponsive elastic poly(methyl methacrylate-butyl acrylate) (P(MMA-BA)) copolymer nanoparticles with controlled sizes are fabricated through a onestep method, which further serve as building blocks for the construction of multiresponsive films via self-assembly. Taking advantage of the relatively low glass transition temperature and the core-shell structure of the copoly mer nanoparticles, they possess the capacity to partially deform and fuse at room temperature under dry status, eventually resulting in the enhancement of the mechanical properties as well as the control of optical properties in the assembled ordered structures. The generated elastic films not only can control the concealment or exhibition of the designed color information, but also can rapidly respond to external stimuli such as the solvent, pH, and tensile force in a reversible fashion. These functional elastic copolymer nanoparticles have potential applications in dynamic color display, optical sensing, and anticounterfeiting.
Bacteriophages are essentially bionanoparticles with a protein coat, the composition of which can be controlled with atomic precision via genetic engineering, a property that makes them superior to synthetic nanoparticles as building blocks for bottom-up synthesis of multifunctional materials with advanced properties. We report hierarchically structured hydrogels of self-organized M13 bacteriophage bundles, composed of hundreds of M13 nanofilaments, which exhibit both longrange and micron-scale order, are visible in electron micrographs of the cross-linked state, and can adsorb up to 16× their weight in water. We further demonstrate that these hierarchical hydrogels of M13 exhibit advanced properties at room temperature, namely, self-healing under biological conditions, autofluorescence in three channels, which decays through biodegradation, potentiating non-destructive imaging capability, and bioactivity in the cross-linked state toward the host bacteria. The latter is, in particular, a powerful property, allowing the development of hydrogels with tunable bioactivity when combined with the phage display and/or recombinant DNA technology. Filamentous phage M13 has garnered significant attention in the past decade for the development of functional materials, ranging from tissue engineering scaffolds to batteries. Our investigation reveals the ability of these nanofilaments to self-organize into hierarchically structured soft matter, highlighting the power of self-organized M13 structures as building blocks for bottom-up synthesis.
In this work, we demonstrate the fabrication of photonic crystal patterns with controllable morphologies and structural colors utilizing electrohydrodynamic jet (E-jet) printing with colloidal crystal inks. The final shape of photonic crystal units is controlled by the applied voltage signal and wettability of the substrate. Optical properties of the structural color patterns are tuned by the self-assembly of the silica nanoparticle building blocks. Using this direct printing technique, it is feasible to print customized functional patterns composed of photonic crystal dots or photonic crystal lines according to relevant printing mode and predesigned tracks. This is the first report for E-jet printing with colloidal crystal inks. Our results exhibit promising applications in displays, biosensors, and other functional devices.
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