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Dae-shik Seo - One of the best experts on this subject based on the ideXlab platform.
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Ion-beam-spurted Dimethyl-Sulfate-doped PEDOT:PSS composite-layer-aligning liquid crystal with low residual direct-current voltage
Applied Physics Letters, 2016Co-Authors: Yang Liu, Ju Hwan Lee, Dae-shik SeoAbstract:Thin ion-beam (IB)-spurted Dimethyl Sulfate/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (DMS/PEDOT:PSS) layers with improved electro-optic performance are presented for aligning liquid crystals. IB spurting is effective for enhancing the conductivity of such layers, as well as the anchoring energy of the liquid crystals sandwiched between them. Compared with a commercial twisted-nematic cell assembled with polyimide alignment layers, the same cell assembled with 3.0-keV IB-spurted DMS/PEDOT:PSS alignment layers shows a 38% faster switching and a 93% lower residual direct current. The improved electro-optic performance here is likely due to the enhanced electric field effect and the charge-releasing ability of thin IB-spurted DMS/PEDOT:PSS layers.
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Super-fast switching of liquid crystals sandwiched between highly conductive graphene oxide/Dimethyl Sulfate doped PEDOT:PSS composite layers
Journal of Applied Physics, 2016Co-Authors: Yang Liu, Yifan Zhang, Dae-shik SeoAbstract:Graphene oxide (GO)-doped Dimethyl Sulfate (DMS)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) superconductive alignment layer, aligning liquid crystals (LCs) with super switching and non-residual direct current (non-residual DC) performance, is presented in this manuscript. Doping of GO increased the pristine polar energy of a thin composite layer as well as the corresponding anchoring energy of the LCs sandwiched between these thin layers but only slightly affected the thin layers' morphology. When rubbed GO/DMS/PEDOT:PSS composite layers were used as alignment layers, a homogeneous alignment of nematic LCs was observed with competitive optoelectrical switching properties and non-residual DC performance because of the enhanced field effect and charge transport induced by the doped GO.
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super fast switching of liquid crystals sandwiched between highly conductive graphene oxide Dimethyl Sulfate doped pedot pss composite layers
Journal of Applied Physics, 2016Co-Authors: Yang Liu, Yifan Zhang, Dae-shik SeoAbstract:Graphene oxide (GO)-doped Dimethyl Sulfate (DMS)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) superconductive alignment layer, aligning liquid crystals (LCs) with super switching and non-residual direct current (non-residual DC) performance, is presented in this manuscript. Doping of GO increased the pristine polar energy of a thin composite layer as well as the corresponding anchoring energy of the LCs sandwiched between these thin layers but only slightly affected the thin layers' morphology. When rubbed GO/DMS/PEDOT:PSS composite layers were used as alignment layers, a homogeneous alignment of nematic LCs was observed with competitive optoelectrical switching properties and non-residual DC performance because of the enhanced field effect and charge transport induced by the doped GO.
Yang Liu - One of the best experts on this subject based on the ideXlab platform.
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Determination of Dimethyl Sulfate in the air of workplace by GC-MS
Zhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational di, 2017Co-Authors: Changmei Zhou, Baoli Zhu, Yang LiuAbstract:Objective: To establish a method to detect the concentrations of Dimethyl Sulfate in the air of workplace by GC-MS. Methods: DMS in the air of workplace adsorpted by Silicone tube, then desorped by acetone, add 1.0 ml of acetone, shake 1 min, placed after 30 min, the desorption solution qualitative and quantitative determination by gas chromatography-mass. Results: The calibration curves were liner in the range of 0.1-200.0 μg/ml. The within-run and between-run precisions were 2.6%-4.7% and 4.0%-9.0% respectively. The method detection limit is 0.1 μg/ml, the minimum detectable concentration is 0.02 mg/m(3) (in terms of sampling 4.5 L) . Add 1 ml of desorption liquid, place 30 min, the average desorption efficiency of more than 90%. Conclusion: This method has simple pretreatment, short analysis period, and optimized linear rage and limit of detection, and is suitable for the determination of DMS in workplace air.
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Ion-beam-spurted Dimethyl-Sulfate-doped PEDOT:PSS composite-layer-aligning liquid crystal with low residual direct-current voltage
Applied Physics Letters, 2016Co-Authors: Yang Liu, Ju Hwan Lee, Dae-shik SeoAbstract:Thin ion-beam (IB)-spurted Dimethyl Sulfate/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (DMS/PEDOT:PSS) layers with improved electro-optic performance are presented for aligning liquid crystals. IB spurting is effective for enhancing the conductivity of such layers, as well as the anchoring energy of the liquid crystals sandwiched between them. Compared with a commercial twisted-nematic cell assembled with polyimide alignment layers, the same cell assembled with 3.0-keV IB-spurted DMS/PEDOT:PSS alignment layers shows a 38% faster switching and a 93% lower residual direct current. The improved electro-optic performance here is likely due to the enhanced electric field effect and the charge-releasing ability of thin IB-spurted DMS/PEDOT:PSS layers.
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Super-fast switching of liquid crystals sandwiched between highly conductive graphene oxide/Dimethyl Sulfate doped PEDOT:PSS composite layers
Journal of Applied Physics, 2016Co-Authors: Yang Liu, Yifan Zhang, Dae-shik SeoAbstract:Graphene oxide (GO)-doped Dimethyl Sulfate (DMS)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) superconductive alignment layer, aligning liquid crystals (LCs) with super switching and non-residual direct current (non-residual DC) performance, is presented in this manuscript. Doping of GO increased the pristine polar energy of a thin composite layer as well as the corresponding anchoring energy of the LCs sandwiched between these thin layers but only slightly affected the thin layers' morphology. When rubbed GO/DMS/PEDOT:PSS composite layers were used as alignment layers, a homogeneous alignment of nematic LCs was observed with competitive optoelectrical switching properties and non-residual DC performance because of the enhanced field effect and charge transport induced by the doped GO.
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super fast switching of liquid crystals sandwiched between highly conductive graphene oxide Dimethyl Sulfate doped pedot pss composite layers
Journal of Applied Physics, 2016Co-Authors: Yang Liu, Yifan Zhang, Dae-shik SeoAbstract:Graphene oxide (GO)-doped Dimethyl Sulfate (DMS)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) superconductive alignment layer, aligning liquid crystals (LCs) with super switching and non-residual direct current (non-residual DC) performance, is presented in this manuscript. Doping of GO increased the pristine polar energy of a thin composite layer as well as the corresponding anchoring energy of the LCs sandwiched between these thin layers but only slightly affected the thin layers' morphology. When rubbed GO/DMS/PEDOT:PSS composite layers were used as alignment layers, a homogeneous alignment of nematic LCs was observed with competitive optoelectrical switching properties and non-residual DC performance because of the enhanced field effect and charge transport induced by the doped GO.
Der-jang Liaw - One of the best experts on this subject based on the ideXlab platform.
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Photophysical and rheological properties of naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer)
Journal of Polymer Science Part B: Polymer Physics, 1998Co-Authors: Der-jang Liaw, Ching-cheng Huang, En-tang KangAbstract:The synthesis, rheological, and fluorescence properties of cationic watersoluble copolymer, naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer), poly(DSQADMAPM)/ NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the cationic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. The salt and pH responsiveness inherent to the cationic copolymer systems is a function of ionic group type. Experimental results indicate that I E /I M increases steadily with increases in polymer concentration and I E / I M values for a given polymer concentration are higher in salt. At low pH values, I E / I M is high and excimer emission increases as the quaternary amino groups (R 4 N + ) are screened out. Dynamic light scattering (QELS) measurements indicate that diffusion coefficients of the cationic copolymer increase and the hydrodynamic diameters decrease with increasing salt concentration. Viscosity studies reveal that the polymer coil shrinks as salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of thallium (Tl + ) with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty in reacting with bound naphthalenes located in the shrunk polymer coil. The cationic copolymer is depicted as an expanded polymer coil in deionized water because of intra-and interchain repulsions. Consequently, salt addition breaks down the repulsions and enhances intrapolymer micellization.
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photophysical and rheological properties of naphthalene labeled cationic poly Dimethyl Sulfate quaternized acrylamide n n Dimethylaminopropylmaleimide copolymer
Journal of Polymer Science Part B, 1998Co-Authors: Der-jang Liaw, Ching-cheng Huang, En-tang KangAbstract:The synthesis, rheological, and fluorescence properties of cationic watersoluble copolymer, naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer), poly(DSQADMAPM)/ NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the cationic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. The salt and pH responsiveness inherent to the cationic copolymer systems is a function of ionic group type. Experimental results indicate that I E /I M increases steadily with increases in polymer concentration and I E / I M values for a given polymer concentration are higher in salt. At low pH values, I E / I M is high and excimer emission increases as the quaternary amino groups (R 4 N + ) are screened out. Dynamic light scattering (QELS) measurements indicate that diffusion coefficients of the cationic copolymer increase and the hydrodynamic diameters decrease with increasing salt concentration. Viscosity studies reveal that the polymer coil shrinks as salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of thallium (Tl + ) with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty in reacting with bound naphthalenes located in the shrunk polymer coil. The cationic copolymer is depicted as an expanded polymer coil in deionized water because of intra-and interchain repulsions. Consequently, salt addition breaks down the repulsions and enhances intrapolymer micellization.
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Dilute solution properties of naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer)
Journal of Polymer Research, 1997Co-Authors: Der-jang Liaw, Ching-cheng HuangAbstract:The properties of a novel cationic, naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer), poly-(DSQADMAPM)/NA in aqueous solution are examined in this study, measuring intrinsic viscosity, reduced viscosity, and ionic strength. This cationic poly(DSQADMAPM)/NA’s intrinsic viscosity is dependent on the type and concentration of salt added to the aqueous solution. The intrinsic viscosity behavior of the cationic poly(DSQADMAPM)/NA resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. Smaller anions such as F− with a common cation (K+) are found to be the most difficult to be bound to the end group, indicating that a higher intrinsic viscosity of the poly(DSQADMAPM)/NA would be in KF salt aqueous solution. Smaller cations such as Li+ with a common anion (Cl−) are found to be the most difficult to be bound to the quaternary ammonium group, indicating that a higher intrinsic viscosity of the poly(DSQADMAPM)/NA would also be in LiCI salt aqueous solution. Models are proposed to account for the poly(DSQADMAPM)/NA solution viscometrics.
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Dilute solution properties of cationic poly(Dimethyl Sulfate quaternized Dimethylaminoethyl methacrylate)
Journal of Applied Polymer Science, 1992Co-Authors: Der-jang Liaw, Saa-jen Shiau, Kueir-rarn LeeAbstract:The dilute solution properties of a cationic polyelectrolyte, poly(Dimethyl Sulfate quaternized Dimethylaminoethyl methacrylate) [poly(DMAEM · C2H6SO4)], are studied by measurements of intrinsic viscosity, degree of binding, and flocculation application. The intrinsic viscosity of this polyelectrolyte is related to the type and concentration of added salt. The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. The polyelectrolyte in the presence of KCl has a lower degree of binding, indicating that the proton ion (H+) is relatively difficult to bind to the CH3SO4− at the polymer end. The polymerization of DMAEM · C2H6SO4 in 0.5M KCl aqueous solution proceeded more easily than that of DMAEM · C2H6SO4 in pure water. The polymerization rate of DMAEM · C2H6SO4 is found to pass through an extreme value as a function of pH. Optimum flocculation, corresponding to the complete removal of turbidity in the supernatant, is achieved. Beyond the optimum flocculation, high polymer dosages redisperse the bentonite suspensions.
Simon Parsons - One of the best experts on this subject based on the ideXlab platform.
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Structure determination and phase transition behaviour of Dimethyl Sulfate
Acta Crystallographica Section B Structural Science, 2006Co-Authors: Richard M. Ibberson, Mark T. F. Telling, Simon ParsonsAbstract:The crystal structures of phase I and phase II of Dimethyl Sulfate, (CH3O)2SO2, have been determined using complementary high-resolution neutron powder and single-crystal X-ray diffraction techniques. Below its melting point of 241 K Dimethyl Sulfate crystallizes in an orthorhombic structure (I) in the space group Fdd2. On cooling below ∼175 K the crystal transforms to a monoclinic structure (II) in the space group I2/a. The molecule is located on a twofold axis (Z′ = 1/2) in both structures. The phase transition is of first order with strong hysteresis. The phase transition results in changes to both the intra- and the intermolecular coordination environment.
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Structure determination and phase transition behaviour of Dimethyl Sulfate.
Acta crystallographica. Section B Structural science, 2006Co-Authors: Richard M. Ibberson, Mark T. F. Telling, Simon ParsonsAbstract:The crystal structures of phase I and phase II of Dimethyl Sulfate, (CH3O)2SO2, have been determined using complementary high-resolution neutron powder and single-crystal X-ray diffraction techniques. Below its melting point of 241 K Dimethyl Sulfate crystallizes in an orthorhombic structure (I) in the space group Fdd2. On cooling below approximately 175 K the crystal transforms to a monoclinic structure (II) in the space group I2/a. The molecule is located on a twofold axis (Z' = 1/2) in both structures. The phase transition is of first order with strong hysteresis. The phase transition results in changes to both the intra- and the intermolecular coordination environment.
Ching-cheng Huang - One of the best experts on this subject based on the ideXlab platform.
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photophysical and rheological properties of naphthalene labeled cationic poly Dimethyl Sulfate quaternized acrylamide n n Dimethylaminopropylmaleimide copolymer
Journal of Polymer Science Part B, 1998Co-Authors: Der-jang Liaw, Ching-cheng Huang, En-tang KangAbstract:The synthesis, rheological, and fluorescence properties of cationic watersoluble copolymer, naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer), poly(DSQADMAPM)/ NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the cationic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. The salt and pH responsiveness inherent to the cationic copolymer systems is a function of ionic group type. Experimental results indicate that I E /I M increases steadily with increases in polymer concentration and I E / I M values for a given polymer concentration are higher in salt. At low pH values, I E / I M is high and excimer emission increases as the quaternary amino groups (R 4 N + ) are screened out. Dynamic light scattering (QELS) measurements indicate that diffusion coefficients of the cationic copolymer increase and the hydrodynamic diameters decrease with increasing salt concentration. Viscosity studies reveal that the polymer coil shrinks as salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of thallium (Tl + ) with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty in reacting with bound naphthalenes located in the shrunk polymer coil. The cationic copolymer is depicted as an expanded polymer coil in deionized water because of intra-and interchain repulsions. Consequently, salt addition breaks down the repulsions and enhances intrapolymer micellization.
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Photophysical and rheological properties of naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer)
Journal of Polymer Science Part B: Polymer Physics, 1998Co-Authors: Der-jang Liaw, Ching-cheng Huang, En-tang KangAbstract:The synthesis, rheological, and fluorescence properties of cationic watersoluble copolymer, naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer), poly(DSQADMAPM)/ NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the cationic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. The salt and pH responsiveness inherent to the cationic copolymer systems is a function of ionic group type. Experimental results indicate that I E /I M increases steadily with increases in polymer concentration and I E / I M values for a given polymer concentration are higher in salt. At low pH values, I E / I M is high and excimer emission increases as the quaternary amino groups (R 4 N + ) are screened out. Dynamic light scattering (QELS) measurements indicate that diffusion coefficients of the cationic copolymer increase and the hydrodynamic diameters decrease with increasing salt concentration. Viscosity studies reveal that the polymer coil shrinks as salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of thallium (Tl + ) with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty in reacting with bound naphthalenes located in the shrunk polymer coil. The cationic copolymer is depicted as an expanded polymer coil in deionized water because of intra-and interchain repulsions. Consequently, salt addition breaks down the repulsions and enhances intrapolymer micellization.
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Dilute solution properties of naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer)
Journal of Polymer Research, 1997Co-Authors: Der-jang Liaw, Ching-cheng HuangAbstract:The properties of a novel cationic, naphthalene-labeled cationic poly(Dimethyl Sulfate quaternized acrylamide/N,N-Dimethylaminopropylmaleimide copolymer), poly-(DSQADMAPM)/NA in aqueous solution are examined in this study, measuring intrinsic viscosity, reduced viscosity, and ionic strength. This cationic poly(DSQADMAPM)/NA’s intrinsic viscosity is dependent on the type and concentration of salt added to the aqueous solution. The intrinsic viscosity behavior of the cationic poly(DSQADMAPM)/NA resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. Smaller anions such as F− with a common cation (K+) are found to be the most difficult to be bound to the end group, indicating that a higher intrinsic viscosity of the poly(DSQADMAPM)/NA would be in KF salt aqueous solution. Smaller cations such as Li+ with a common anion (Cl−) are found to be the most difficult to be bound to the quaternary ammonium group, indicating that a higher intrinsic viscosity of the poly(DSQADMAPM)/NA would also be in LiCI salt aqueous solution. Models are proposed to account for the poly(DSQADMAPM)/NA solution viscometrics.