Dielectric investigations on carbon nanotubes doped polymer dispersed liquid crystal films

Ganea, Constantin Paul; Mănăilă-Maximean, Doina; Cı̂rcu, Viorel

doi:10.1140/epjp/s13360-020-00795-w

Cited by 28 publications

(8 citation statements)

References 35 publications

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“…LC‐CNT shows endothermic peaks at 35.5 °C and 46.5 °C, which is attributed to the above‐mentioned liquid crystal phase transition of 7CB assembled on its surface. The phase transition temperature is slightly increased, attributed to the fact that CNT hinders the thermal motion of 7CB molecules to a certain extent [36,37] . Figure 1f shows the X‐ray diffraction (XRD) spectra of 7CB, CNT and LC‐CNT.…”

Section: Resultsmentioning

confidence: 99%

“…The phase transition temperature is slightly increased, attributed to the fact that CNT hinders the thermal motion of 7CB molecules to a certain extent. [36,37] Figure 1f shows the X-ray diffraction (XRD) spectra of 7CB, CNT and LC-CNT. 7CB shows diffraction peaks at 22°, 24°, 29°, 44°and 49°, corresponding to the (001), ( 100), ( 101), ( 110) and ( 201) crystal planes, respectively.…”

Section: Characterizations Of 7cb Cnt and Lc-cntmentioning

confidence: 99%

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Electric‐Field‐Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films

Ruan,

Shi,

Zhang

et al. 2023

Angew Chem Int Ed

118

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The positive liquid crystals, 4'‐heptyl‐4‐biphenylcarbonitrile (7CB), are used to functionalize carbon nanotubes (LC‐CNT), which can be aligned in the liquid crystalline polyimide (LC‐PI) matrix under an alternating electric field to fabricate the thermally conductive LC‐CNT/LC‐PI composite films. The efficient establishment of thermal conduction pathways in thermally conductive LC‐CNT/LC‐PI composite films with a low amount of LC‐CNT is achieved through the oriented alignment of LC‐CNT within the LC‐PI matrix. When the mass fraction of LC‐CNT is 15 wt%, the in‐plane thermal conductivity coefficient (λ∥) and the through‐plane thermal conductivity coefficient (λ⊥) of the LC‐CNT/LC‐PI composite films reach 4.02 W/(m·K) and 0.55 W/(m·K), which are 90.5% and 71.9% higher than those of the intrinsically thermally conductive LC‐PI films respectively, also 28.8% and 5.8% higher than those of the CNT/LC‐PI composite films respectively. Meanwhile, the thermally conductive LC‐CNT/LC‐PI composite films also possess excellent mechanical and heat resistance properties. The Young’s modulus and the heat resistance index are 2.3 GPa and 297.7oC, respectively, which are higher than the intrinsically thermally conductive LC‐PI films and the thermally conductive CNT/LC‐PI composite films under the same amount of CNT.

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Section: Resultsmentioning

confidence: 99%

Section: Characterizations Of 7cb Cnt and Lc-cntmentioning

confidence: 99%

Electric‐Field‐Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films

Ruan,

Shi,

Zhang

et al. 2023

Angew Chem Int Ed

118

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“…The authors have explained this shift in the N-I phase transition temperature by taking into the account the anchoring energy and π-π interactions between the guest CNTs and the host NLC. Usually, the shift in the N-I transition temperature originates from the anchoring of CNTs around the In another study, Ganea et al [145] investigated the phase behavior of CNT-doped polymer dispersed LC (PDLC) films. They performed three heating/cooling cycles of DSC from room temperature to 413 K with a scanning rate of 10 K min −1 and observed that a broad peak corresponding to the N-Is transition of the LC mixture was only visible during the heating run (figure 15).…”

Section: Phase Transitions In Cnm/lc Compositesmentioning

confidence: 99%

Recent progress and future perspectives on carbon-nanomaterial-dispersed liquid crystal composites

Kumar¹,

Singh²,

Singh³

2021

J. Phys. D: Appl. Phys.

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The realm of liquid crystals (LCs) has significantly benefited when amalgamated with the exciting features of nanotechnology. Various nanomaterials (NMs) have shown their potentiality in tailoring the display and non-display characteristics of LC materials. Carbon-based nanomaterials (CNMs) such as carbon nanotubes, graphene oxide, graphene flakes, graphene and carbon dots are found to exhibit synergistic interaction with LCs to provide interesting properties such as low switching threshold voltage, faster switching response, reduced ionic conductivity and the formation of localized pseudonematic domains, etc. The network of benzene rings in the CNMs is found to offer π–π stacking of electrons with a benzene-based core of LC molecules which could provide a susceptible pathway for the strong interaction between the LCs and the CNMs. However, the uniform and stable dispersion of CNMs in the LC matrix has been found to be a challenging step in preparation of CNM/LC composites. Herein, we present a detailed review on the recent research work based on CNM-dispersed LC composites with an emphasis on the methods to obtain uniform CNM/LC dispersion and the dielectric, electro-optical, orientation, photophysical properties, etc, of the composites. Moreover, we have critically discussed the pros and cons of these composites and proposed the future scope of research in this exciting field.

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“…These nanostructured materials are now very suitable for use as additives in PDLC systems to improve the characteristics of the latter [ 22 , 23 ]. In recent years, a large number of reports have witnessed the effectiveness of metal nanoparticles, inorganic oxide nanoparticles, and ferroelectric nanoparticles in changing the physical and electro-optical properties of PDLC [ 24 , 25 , 26 , 27 , 28 , 29 ]. For example, Martin U et al [ 30 ] studied the impact of functionalized gold nanoparticles on the impedance response of nematic nanoparticle/liquid crystal dispersions in the frequency range of 0.1 Hz~100 kHz.…”

Section: Introductionmentioning

confidence: 99%

Electro-Optical Characteristics of Polymer Dispersed Liquid Crystal Doped with MgO Nanoparticles

Zhao

et al. 2022

Molecules

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In this paper, inorganic oxide MgO nanoparticles-doped polymer dispersed liquid crystal (PDLC) films were made from a mixture of the prepolymer, SLC1717 liquid crystal, and MgO nanoparticles by the polymerization induced phase separation (PIPS) process. To observe the effect of MgO concentration, PDLC was dispersed with 0.2, 0.4, 0.6, and 0.8 wt.% MgO. Electro-optical properties of the films have been investigated using LCD parameter meter and Scanning Electron Microscope (SEM) at room temperature. It is established that MgO nanoparticles affect the microstructure of PDLC films significantly because of the formed agglomerates of MgO nanoparticles. Results show an improvement in the electro-optical properties and a decrease in the driving voltage for doped systems with MgO nanoparticles. When the doping amount of MgO is 0.8 wt.%, the threshold voltage (Vth) is reduced to about 7.5 V. Therefore, MgO-doped PDLC is expected to become an excellent choice in the field of energy-saving.

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Dielectric investigations on carbon nanotubes doped polymer dispersed liquid crystal films

Cited by 28 publications

References 35 publications

Electric‐Field‐Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films

Electric‐Field‐Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films

Recent progress and future perspectives on carbon-nanomaterial-dispersed liquid crystal composites

Electro-Optical Characteristics of Polymer Dispersed Liquid Crystal Doped with MgO Nanoparticles

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