Abstract:Electric field induced dynamic reorientation phenomenon of graphene/graphitic flakes in homogeneously aligned nematic liquid crystal (NLC) medium has been demonstrated by optical microscopy. The flakes reorient from parallel to perpendicular configuration with respect to boundary plates of confining cells for an applied field strength of as low as tens of millivolt per micrometer. After field removal the reoriented flakes recover to their initial state with the help of relaxation of NLC. Considering flake reor… Show more
“…Improvement in display properties of LCs has been demonstrated on incorporation of CNTs [12] and graphene. [29,30] In the present study, integration of GQDs with FLC has also shown two significant changes -first an enhancement in the PL intensity and subsequently a lowering of the response time of the FLC on the formation of the GQDs/FLC composite. Varied concentrations (5-15 μl) of GQDs were added into the FLC material stepwise, and their effect on PL intensity, physical parameters and the alignment of FLCs was observed.…”
We present a pioneer study depicting a significant improvement in the photoluminescence (PL) intensity and display of an expeditious electro-optic response of ferroelectric liquid crystal (FLC) when doped with graphene quantum dots (GQDs). Significant threefold enhancement in PL intensity of GQDs/FLC composite material can be ascribed to the additive combination of emissions from GQDs and FLCs. Furthermore, promptness in electrooptical response by a factor of 34% can be attributed to the lowering of rotational viscosity of the FLC material due to the incorporation of GQDs. These results would certainly be helpful in realisation of highly luminescent and faster generation of LC systems.
“…Improvement in display properties of LCs has been demonstrated on incorporation of CNTs [12] and graphene. [29,30] In the present study, integration of GQDs with FLC has also shown two significant changes -first an enhancement in the PL intensity and subsequently a lowering of the response time of the FLC on the formation of the GQDs/FLC composite. Varied concentrations (5-15 μl) of GQDs were added into the FLC material stepwise, and their effect on PL intensity, physical parameters and the alignment of FLCs was observed.…”
We present a pioneer study depicting a significant improvement in the photoluminescence (PL) intensity and display of an expeditious electro-optic response of ferroelectric liquid crystal (FLC) when doped with graphene quantum dots (GQDs). Significant threefold enhancement in PL intensity of GQDs/FLC composite material can be ascribed to the additive combination of emissions from GQDs and FLCs. Furthermore, promptness in electrooptical response by a factor of 34% can be attributed to the lowering of rotational viscosity of the FLC material due to the incorporation of GQDs. These results would certainly be helpful in realisation of highly luminescent and faster generation of LC systems.
“…This is different from the classic linear law of mixture 23 . In fact, the orientation of anisotropic particles affects many other properties such as flow permeability 29 , optical 30 , and others 31 , 32 . Figure 3 Property changes during the rotation of ellipsoidal particle.…”
This work reveals a torque from electric field to electrically neutral flakes that are suspended in a higher electrical conductive matrix. The torque tends to rotate the particles toward an orientation with its long axis parallel to the electric current flow. The alignment enables the anisotropic properties of tiny particles to integrate together and generate desirable macroscale anisotropic properties. The torque was obtained from thermodynamic calculation of electric current free energy at various microstructure configurations. It is significant even when the electrical potential gradient becomes as low as 100 v/m. The changes of electrical, electroplastic and thermal properties during particles alignment were discussed.
“…Polarized light imaging measures the local orientation order by imaging the slow axis of alignment of the graphene sheets in the plane of the membrane, while X-ray diffraction measures the crystalline order of the interlayer spacing. Polarized light imaging technique has been widely used for order parameter characterization of molecules and particles 56 57 as well as GO sheets in liquids 16 18 58 or solid state films 33 . We have compared the optical anisotropy of SAM with those synthesized by vacuum filtration 2 12 13 14 .…”
Graphene-based membranes demonstrating ultrafast water transport, precise molecular sieving of gas and solvated molecules shows great promise as novel separation platforms; however, scale-up of these membranes to large-areas remains an unresolved problem. Here we demonstrate that the discotic nematic phase of graphene oxide (GO) can be shear aligned to form highly ordered, continuous, thin films of multi-layered GO on a support membrane by an industrially adaptable method to produce large-area membranes (13 × 14 cm2) in <5 s. Pressure driven transport data demonstrate high retention (>90%) for charged and uncharged organic probe molecules with a hydrated radius above 5 Å as well as modest (30–40%) retention of monovalent and divalent salts. The highly ordered graphene sheets in the plane of the membrane make organized channels and enhance the permeability (71±5 l m−2 hr−1 bar−1 for 150±15 nm thick membranes).
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