Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

Cao, Min; Liu, Senping; Zhu, Qingli; Wang, Ya; Ma, Jian; Li, Zeshen; Chang, Dan; Zhu, Enhui; Ming, Xin; Liu, Yingjun; Jiang, Yanqiu; Xu, Zhen; Gao, Chao

doi:10.1007/s40820-022-00925-2

Cited by 6 publications

(2 citation statements)

References 41 publications

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“…Graphene macroscopic materials were fabricated according to the previous works after optimizations 55 . Briefly, GF 16 was fabricated by casting debris-free and giant GO dispersions (concentration of 6 mg mL −1 ), followed by thermal annealing at 1300 °C for 2 h and 2800 °C for 2 h. For hydrophilic treatment, air plasma (Harrick Plasma, PlasmaFlo PDC-FMG−2) was applied to the surface of GF.…”

Section: Methodsmentioning

confidence: 99%

Sub-second ultrafast yet programmable wet-chemical synthesis

Zhang,

Peng,

et al. 2023

Nat Commun

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Wet-chemical synthesis via heating bulk solution is powerful to obtain nanomaterials. However, it still suffers from limited reaction rate, controllability, and massive consumption of energy/reactants, particularly for the synthesis on specific substrates. Herein, we present an innovative wet-interfacial Joule heating (WIJH) approach to synthesize various nanomaterials in a sub-second ultrafast, programmable, and energy/reactant-saving manner. In the WIJH, Joule heat generated by the graphene film (GF) is confined at the substrate-solution interface. Accompanied by instantaneous evaporation of the solvent, the temperature is steeply improved and the precursors are concentrated, thereby synergistically accelerating and controlling the nucleation and growth of nanomaterials on the substrate. WIJH leads to a record high crystallization rate of HKUST-1 (~1.97 μm s−1), an ultralow energy cost (9.55 × 10−6 kWh cm−2) and low precursor concentrations, which are up to 5 orders of magnitude faster, −6 and −2 orders of magnitude lower than traditional methods, respectively. Moreover, WIJH could handily customize the products’ amount, size, and morphology via programming the electrified procedures. The as-prepared HKUST-1/GF enables the Joule-heating-controllable and low-energy-required capture and liberation towards CO2. This study opens up a new methodology towards the superefficient synthesis of nanomaterials and solvent-involved Joule heating.

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Section: Methodsmentioning

confidence: 99%

Sub-second ultrafast yet programmable wet-chemical synthesis

Zhang,

Peng,

et al. 2023

Nat Commun

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“…Direct ink writing (DIW), as an extrusion-based 3D printing technique, has been widely used to locally direct the material properties during 3D printing [ 9 – 12 ]. The flow inside the DIW's nozzle guides the self-assembly of anisotropic materials that has been widely used to enhance mechanical properties or induce anisotropic stimuli response in 3D printed constructs [ 13 – 17 ]. To analyze flow-induced self-assemblies, rheological measurements are commonly combined with other techniques, such as numerical simulations [ 18 ], in situ characterization [ 19 ], microfluidics [ 20 ], optical rheology [ 21 ], small angle light scattering [ 22 , 23 ], and light spectroscopy [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

Engineering Nano/Microscale Chiral Self-Assembly in 3D Printed Constructs

Esmaeili,

Akbari,

George

et al. 2023

Nano-Micro Lett.

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Helical hierarchy found in biomolecules like cellulose, chitin, and collagen underpins the remarkable mechanical strength and vibrant colors observed in living organisms. This study advances the integration of helical/chiral assembly and 3D printing technology, providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate geometries. We designed reactive chiral inks based on cellulose nanocrystal (CNC) suspensions and acrylamide monomers, enabling the chiral assembly at nano/microscale, beyond the resolution seen in printed materials. We employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate conditions. These techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks, and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates, as well as their post-flow relaxation. Furthermore, we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting bath. These insights into the interplay between the chiral inks self-assembly dynamics, 3D printing flow kinematics and photo-polymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments, ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length, as well as random orientation of chiral domains. Our biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs.

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Vertical Array of Graphite Oxide Liquid Crystal by Microwire Shearing for Highly Thermally Conductive Composites

Cao

et al. 2023

Advanced Materials

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10 W m −1 K −1 even at a high filler content (≈50 vol%). [3] Modulating vertical orientation of anisotropic nanofillers is a pronounced way for high throughplane thermal conductive composites. 2D nanosheets, such as graphene oxide and multilayer graphene, have been used as building blocks to form structurally anisotropic skeletons. [4] The highest throughplane thermal conductivity of such TIMs reaches 62.4 W m −1 K −1 with a graphene loading of 13.3 vol%. [5] However, achieving the higher through-plane thermal conductivity of TIMs under low filler contents remains challenging.Achieving high thermal conductivity of TIMs request high crystallite orientation, large crystallite size, and high density of skeleton. [6] Such perfect crystalline pathway of skeleton ensures high thermal conductivity of composites. [7] As a result, accurate control of vertical sheet alignment, high sheet content, and lower interface phonon scattering are three indispensable factors for producing advanced TIMs. 2D nanosheets typically have lateral dimensions less than 50 µm and a few atomic layer thicknesses. [8] The atom-thin and small-sized sheets render discontinuous crystalline domains and massive polymer/sheet interfaces when oriented vertically. In addition, the content of nanosheet liquid crystals is commonly below 30 mg g −1 because of strong steric and electrostatic repulsion. Low content of liquid crystals causes limited heat flux of skeleton, which rules out highly thermally conductive composites. Compared with colloidal nanosheets, giant sheets typically have much larger lateral dimensions of hundreds of microns and thicknesses of microns. [9] Selecting giant sheets as building blocks is promising, which provides a Excellent through-plane thermally conductive composites are highly demanded for efficient heat dissipation. Giant sheets have large crystalline domain and significantly reduce interface phonon scattering, making them promising to build highly thermally conductive composites. However, realizing vertical orientation of giant sheets remains challenging due to their enormous mass and huge hydrodynamic drag force. Here, we achieve highly vertically ordered liquid crystals of giant graphite oxide (more than 100 µm in lateral dimension) by microwire shearing, which endows the composite with a recorded through-plane thermal conductivity of 94 W m −1 K −1 . Microscale shearing fields induced by vertical motion of microwires conquer huge hydrodynamic energy barrier and vertically reorient giant sheets. The resulting liquid crystals exhibit extremely retarded relaxation and impart large-scale vertical array with bidirectional ordering degree as high as 0.82. The graphite array-based composites demonstrate an ultrahigh thermal enhancement efficiency of over 35 times per unit volume. Furthermore, the composites improve cooling efficiency by 93% for thermal management tests compared to commercial thermal interface materials. This work offers a novel methodology to precisely manipulate the orientation of giant particles and promo...

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Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

Cited by 6 publications

References 41 publications

Sub-second ultrafast yet programmable wet-chemical synthesis

Sub-second ultrafast yet programmable wet-chemical synthesis

Engineering Nano/Microscale Chiral Self-Assembly in 3D Printed Constructs

Vertical Array of Graphite Oxide Liquid Crystal by Microwire Shearing for Highly Thermally Conductive Composites

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