scholarly journals Azobenzene-Containing Liquid Crystalline Composites for Robust Ultraviolet Detectors Based on Conversion of Illuminance-Mechanical Stress-Electric Signals

2021 ◽  
Author(s):  
Xiaoxiong Zheng ◽  
Yining Jia ◽  
Aihua Chen
Keyword(s):  
Response Time ◽  
Mechanical Stress ◽  
Electrostatic Interactions ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Fast Response ◽  
Electric Signal ◽  
Wearable Electronics ◽  
Uv Detectors ◽  
Ultraviolet Detectors

Abstract Wearable ultraviolet (UV) detectors have attracted considerable interest in the military and civilian realms. However, semiconductor-based UV detectors are easily interfered by elongation due to the elastic modulus incompatibility between rigid semiconductors and polymer matrix. Polymer detectors containing UV responsive moieties seriously suffer from slow response time. Herein, a novel UV illuminance-mechanical stress-electric signal conversion has been proposed based on well-defined ionic liquid (IL)-containing liquid crystalline polymer (ILCP) and highly elastic polyurethane (TPU) composite fabrics, to achieve a robust UV monitoring and shielding device with a fast response time of 5 s. Due to the electrostatic interactions and hydrogen bonds between ILs and LC networks, the ILCP-based device can effectively prevent the exudation of ILs and maintain stable performance upon stretching, bending, washing and 1000 testing cycles upon 365 nm UV irradiation. This work provides a generalizable approach toward the development of full polymer-based wearable electronics and soft robots.

scholarly journals Azobenzene-containing liquid crystalline composites for robust ultraviolet detectors based on conversion of illuminance-mechanical stress-electric signals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoxiong Zheng ◽  
Yining Jia ◽  
Aihua Chen
Keyword(s):  
Response Time ◽  
Mechanical Stress ◽  
Electrostatic Interactions ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Fast Response ◽  
Electric Signal ◽  
Wearable Electronics ◽  
Uv Detectors ◽  
Ultraviolet Detectors

AbstractWearable ultraviolet (UV) detectors have attracted considerable interest in the military and civilian realms. However, semiconductor-based UV detectors are easily interfered by elongation due to the elastic modulus incompatibility between rigid semiconductors and polymer matrix. Polymer detectors containing UV responsive moieties seriously suffer from slow response time. Herein, a UV illuminance–mechanical stress–electric signal conversion has been proposed based on well-defined ionic liquid (IL)-containing liquid crystalline polymer (ILCP) and highly elastic polyurethane (TPU) composite fabrics, to achieve a robust UV monitoring and shielding device with a fast response time of 5 s. Due to the electrostatic interactions and hydrogen bonds between ILs and LC networks, the ILCP-based device can effectively prevent the exudation of ILs and maintain stable performance upon stretching, bending, washing and 1000 testing cycles upon 365 nm UV irradiation. This work provides a generalizable approach toward the development of full polymer-based wearable electronics and soft robots.

scholarly journals Solar-Blind Photodetector Based on NaTaO3/TiO2 Composite Film with Enhanced Photoelectric Performance

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1178
Author(s):  
Min Zhang ◽  
Zhenjiang Li ◽  
Yunfei Zhao ◽  
Zhaofeng Wu ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Response Time ◽  
Dark Current ◽  
High Performance ◽  
Uv Light ◽  
Fast Response ◽  
Current Ratio ◽  
Coated Glass Substrate ◽  
Ultraviolet Detectors ◽  
Photoelectric Performance ◽  
Solar Blind

In this study, ultraviolet detectors based on NaTaO3/TiO2 were fabricated with enhanced detection performance towards solar-blind (200–280 nm) light. A TiO2 seed layer was introduced and served as a buffer layer between the fluorine tin oxide (FTO)-coated glass substrate and the TiO2 film, which increased the adhesion between them. The periodic stability and photoelectric characteristics of the detectors were studied and analyzed. The detectors showed a high performance when illuminated by 265 nm and 254 nm UV light. At −15 V bias, the dark current of the detector was only 70 pA. Under the bias of −15 V and the illumination of 254 nm, the maximum photo-to-dark current ratio reached 20, and the response time was less than 300 ms. Moreover, the detector exhibited a fast response time and remained very stable after numerous testing cycles. These results demonstrate the potential application of NaTaO3/TiO2 composites in UV detection.

Structure-property relations of liquid crystalline polymers

1987 ◽  
Vol 45 ◽  
pp. 460-463
Author(s):  
Linda C. Sawyer
Keyword(s):  
Solid State ◽  
Liquid Crystalline ◽  
Structural Model ◽  
Crystalline Polymer ◽  
Liquid Crystalline Polymers ◽  
Mechanical Anisotropy ◽  
Structure Property ◽  
Preparation Methods ◽  
Crystalline Polymers ◽  
Extended Chain

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

Phase Separation in Liquid-Crystalline Copolymer/Poly(methyl methacrylate) Blends

1995 ◽  
Vol 60 (11) ◽  
pp. 1869-1874 ◽  
Author(s):  
Anatoly E. Nesterov ◽  
Yuri S. Lipatov ◽  
Vitaly V. Horichko
Keyword(s):  
Phase Separation ◽  
Methyl Methacrylate ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Ethylene Terephthalate ◽  
Crystalline Polymer ◽  
Scattering Method ◽  
Thermally Induced ◽  
Poly Methyl Methacrylate ◽  
Copolymer Poly

The phase separation in the blends of poly(methyl methacrylate) and liquid-crystalline polymer (copolymer of ethylene terephthalate and p-hydroxybenzoic acid) has been studied by the light scattering method and the cloud point curves have been obtained. Simultaneously some morphological features of the blends have been observed. It was found that the initial blends are in the state of forced compatibility and that thermally induced phase separation occurs by the mechanism of spinodal decomposition but presumably in the non-linear regime.

Discotic columnar liquid-crystalline polymer semiconducting materials with high charge-carrier mobility via rational macromolecular engineering

2017 ◽  
Vol 8 (21) ◽  
pp. 3286-3293 ◽  
Author(s):  
Bin Mu ◽  
Xingtian Hao ◽  
Jian Chen ◽  
Qian Li ◽  
Chunxiu Zhang ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Cost Effective ◽  
Crystalline Polymer ◽  
Charge Carrier Mobility ◽  
Optoelectronic Device ◽  
Side Chain ◽  
Liquid Crystal Polymers ◽  
Semiconducting Materials ◽  
Organic Semiconducting Materials ◽  
Device Applications

Well-prepared side-chain discotic liquid crystal polymers with shorter spacers in ordered columnar phases are fascinating and promising cost-effective, solution-processable organic semiconducting materials for various potential optoelectronic device applications.

scholarly journals Fiber Formation and Structural Development of HBA/HNA Thermotropic Liquid Crystalline Polymer in High-Speed Melt Spinning

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1134
Author(s):  
Bo Seok Song ◽  
Jun Young Lee ◽  
Sun Hwa Jang ◽  
Wan-Gyu Hahm
Keyword(s):  
Mechanical Properties ◽  
Shear Rate ◽  
High Speed ◽  
Melt Spinning ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Fiber Formation ◽  
Structural Development ◽  
Thermotropic Liquid Crystalline Polymer

High-speed melt spinning of thermotropic liquid crystalline polymer (TLCP) resin composed of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-napthoic acid (HNA) monomers in a molar ratio of 73/27 was conducted to investigate the characteristic structure development of the fibers under industrial spinning conditions, and the obtained as-spun TLCP fibers were analyzed in detail. The tensile strength and modulus of the fibers increased with shear rate in nozzle hole, draft in spin-line and spinning temperature and exhibited the high values of approximately 1.1 and 63 GPa, respectively, comparable to those of industrial as-spun TLCP fibers, at a shear rate of 70,000 s−1 and a draft of 25. X-ray diffraction demonstrated that the mechanical properties of the fibers increased with the crystalline orientation factor (fc) and the fractions of highly oriented crystalline and non-crystalline anisotropic phases. The results of structure analysis indicated that a characteristic skin–core structure developed at high drafts (i.e., spinning velocity) and low spinning temperatures, which contributed to weakening the mechanical properties of the TLCP fibers. It is supposed that this heterogeneous structure in the cross-section of the fibers was induced by differences in the cooling rates of the skin and core of the fiber in the spin-line.

scholarly journals Dual-Cation Electrolytes Crosslinked with MXene for High-Performance Electrochromic Devices

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 874
Author(s):  
Soyoung Bae ◽  
Youngno Kim ◽  
Jeong Min Kim ◽  
Jung Hyun Kim
Keyword(s):  
Ionic Conductivity ◽  
Response Time ◽  
Indium Tin Oxide ◽  
High Performance ◽  
Fast Response ◽  
High Ionic Conductivity ◽  
Electrochromic Device ◽  
Fast Response Time ◽  
Coloration Efficiency ◽  
Conduction Pathway

MXene, a 2D material, is used as a filler to manufacture polymer electrolytes with high ionic conductivity because of its unique sheet shape, large specific surface area and high aspect ratio. Because MXene has numerous -OH groups on its surface, it can cause dehydration and condensation reactions with poly(4-styrenesulfonic acid) (PSSA) and consequently create pathways for the conduction of cations. The movement of Grotthuss-type hydrogen ions along the cation-conduction pathway is promoted and a high ionic conductivity can be obtained. In addition, when electrolytes composed of a conventional acid or metal salt alone is applied to an electrochromic device (ECD), it does not bring out fast response time, high coloration efficiency and transmittance contrast simultaneously. Therefore, dual-cation electrolytes are designed for high-performance ECDs. Bis(trifluoromethylsulfonyl)amine lithium salt (LiTFSI) was used as a source of lithium ions and PSSA crosslinked with MXene was used as a source of protons. Dual-Cation electrolytes crosslinked with MXene was applied to an indium tin oxide-free, all-solution-processable ECD. The effect of applying the electrolyte to the device was verified in terms of response time, coloration efficiency and transmittance contrast. The ECD with a size of 5 × 5 cm2 showed a high transmittance contrast of 66.7%, fast response time (8 s/15 s) and high coloration efficiency of 340.6 cm2/C.

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