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Amphiphilic molecules such as cetyl trimethylammonium bromide (CTAB) and minerals such as graphene oxide (GO) self-assemble to form lyotropic liquid crystal (LLC) systems in water. Here we describe the preparation, structures and mechanical properties of the hybrid CTAB and GO LLC system. We present a series of phase diagrams for the CTAB/GO/water ternary system with independently varying CTAB and GO loadings, covering various combinations of the isotropic and the different lyotropic phases of each that occur as a function of concentration and temperature. The corresponding LLC microstructures are identified through polarised optical microscopy (POM) in a confined environment. We find that GO either promotes or suppresses the formation of the different LLC phases of CTAB depending on the concentration of GO and whether the GO itself is in its isotropic or lyotropic phase, resulting in the formation of a complex hybrid system. GO also significantly depresses the melting point of CTAB at moderate loadings, but the melting point recovers for higher GO loading. Rheology of the CTAB/GO/water system reveals a reinforcement effect of the GO sheets through the formation of CTAB/GO complexes that alter the hexagonal phase nanostructure. Our work reveals the diverse effects on molecular LC phases by an interpenetrating mineral LC phase, and the potential to design a wide range of novel nanostructured hybrid LLC materials. Image 1 [ABSTRACT FROM AUTHOR]

• Electrodynamic vortex ring effect can shape core-shell graphene oxide hydrogel particles. • There shapes can be produced – sphere, donut and jellyfish. • The shapes are controlled by 3 process parameters – the GO concentration, the CTAB concentration and the impact velocity. • The shapes are determined by 3 dimensionless parameters – the Reynolds, Weber and Ohnesorge numbers. • The particles can be used for highly efficient adsorptive purification of water. The vortex ring (VR) effect occurs when fluid droplets impact on another fluid, leading to toroidal flow within the impacting droplet due to viscous friction, resulting in a wide variety of flow-induced morphologies. When applied to dispersions of 2-dimensional materials, such as graphene oxide (GO) in water, the VR effect can be used to generate 3-dimensional assemblies of GO flakes. Here, we have taken advantage of the surface charge on GO flakes in water, interacting with cationic aqueous surfactant systems, to generate an electrohydrodynamic VR effect. This yields GO hydrogel and aerogel microparticles with complex axially symmetric shapes, with a core-shell structure featuring a shell of aligned GO flakes. Using high frame-rate optical imaging, we have captured the real-time self-assembly of GO core-shell hydrogel microparticles shaped like spheres, donuts and jellyfish. We describe, both qualitatively and quantitatively, the electrohydrodynamics that drive the formation of such shapes. We also demonstrate how the underlying processes can be tuned by varying parameters such as GO concentration, flake size and drop velocity, and surfactant chemistry and concentration to produce a wide variety of controllable exterior and interior morphologies. Indeed, we show that the formation regimes of the different shapes are determined by dimensionless Weber and Ohnesorge numbers. Lastly, we demonstrate how these microparticles can be used for the efficient adsorption and removal of anionic contaminants in water, with tuneable adsorption capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] Electromagnetic wave absorbers constructed by reduced graphene oxide (rGO) and magnetic nanoparticles are extremely desirable for enhancing electromagnetic wave absorption performance due to the effective integration of the properties of dielectric and magnetic materials. However, the arrangement of graphene sheets and the growth of magnetic nanoparticles have always been challenging. Herein, an in-situ growth process has been used to successfully prepare accordion-like graphene with homogeneously distributed Fe nanoparticles in the confined structure via ion absorption and pyrolysis. The as-prepared Fe/layered rGO composites show excellent electromagnetic wave absorption performance with thin thickness, low filler loading, and broad effective absorption bandwidth (EAB). The minimum reflection loss of the composites achieves −54.6 dB with 20 wt% filler loading, and the tunable EAB reach 6.8 GHz (2.2 mm with 10 wt% filler loading) and 4.6 GHz (2.8 mm with 30 wt% filler loading), which can cover the entire Ku-band and X-band. The mechanism analysis indicates that the superior absorption performance is attributed to the multi-component loss mechanism, enhanced impedance matching degree and attenuation ability caused by the synergistic effect of layered rGO sheets and magnetic nanoparticles. This work opens up a new avenue for constructing accordion-like graphene-based composites as highly efficient electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

[Display omitted] Electromagnetic wave absorbers constructed by reduced graphene oxide (rGO) and magnetic nanoparticles are extremely desirable for enhancing electromagnetic wave absorption performance due to the effective integration of the properties of dielectric and magnetic materials. However, the arrangement of graphene sheets and the growth of magnetic nanoparticles have always been challenging. Herein, an in-situ growth process has been used to successfully prepare accordion-like graphene with homogeneously distributed Fe nanoparticles in the confined structure via ion absorption and pyrolysis. The as-prepared Fe/layered rGO composites show excellent electromagnetic wave absorption performance with thin thickness, low filler loading, and broad effective absorption bandwidth (EAB). The minimum reflection loss of the composites achieves −54.6 dB with 20 wt% filler loading, and the tunable EAB reach 6.8 GHz (2.2 mm with 10 wt% filler loading) and 4.6 GHz (2.8 mm with 30 wt% filler loading), which can cover the entire Ku-band and X-band. The mechanism analysis indicates that the superior absorption performance is attributed to the multi-component loss mechanism, enhanced impedance matching degree and attenuation ability caused by the synergistic effect of layered rGO sheets and magnetic nanoparticles. This work opens up a new avenue for constructing accordion-like graphene-based composites as highly efficient electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]