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Where can the low dielectric constant go in dense inorganic materials?

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Journal of Materiomics 2023年第5期9卷 980-983页

作者： Lei li xiao li zhu Xiang Ming Chen Lab of Dielectric Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou310058China

In order to meet the requirements of future development in microelectronics and mobile communication,low-dielectricconstant(low-εr)materials have been receiving the increasing attention[1,2].The low-εr(εrlications in the future microwave communication towards millimeter wave band[1],and the semiconductor industry has been showing the increasing needs for ultralow-εr(limit of dielectric constant.

关键词： ceramics dielectric inorganic

Polarization Mechanism in Filled Tungsten Bronze Ba4Eu2Ti4Nb6O30 with Pinched P-E Hysteresis Loops

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Chinese Physics Letters 2021年第4期38卷 129-134页

作者： Lang zhu xiao-li zhu xiao-Qiang liu Xiang-Ming Chen School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China

Pinched P-E hysteresis loops have been observed in filled tungsten bronze Ba_(4)Eu_(2)Ti_(4)Nb_(6)O_(30),indicating the presence of novel polarization *** investigate the evolution of polar order in filled tungsten bronze Ba_(4)Eu_(2)Ti_(4)Nb_(6)O_(30),together with its dielectric properties over a wide temperature range,from 50 K to 773 *** temperature dependences of the dielectric properties exhibit two low-temperature dielectric relaxations,at around 300 K(P1),and 100 K(P2),and a high temperature peak at 588 K with no frequency dispersion,indicating the ferroelectric transition temperature T_(c).Pinched P-E loops are observed in the temperature range between the low temperature relaxation at P1,and the ferroelectric *** cooling,the pinched P-E hysteresis loops open gradually,with increasing remnant polarization(P_(r)).Two pairs of reversal electric fields indicate two types of polar reversal mechanisms,with an activated energy of 1.41 eV(E_(1)),and 0.94 eV(E_(2)),*** corresponds to the field-induced transition from a nonpolar to a polar state,which dominates at a high temperature close to T_(c),while the other relates to the reversal of ferroelectric domains which stabilize gradually on *** temperatures below 300 K,the polarization exhibits an evident decrease,probably related to the disruption of the polar order due to the dielectric relaxation at P1.

关键词： ferroelectric relaxation polarization

Unconventional Fluorescent and Multi-responsive Polyethyleneimine with LCST and UCST Behavior:Synthesis,Characterization and Biological Applications

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Chinese Journal of Polymer Science 2024年第6期42卷 826-837页

作者： Feng-Ming Yin li-li Wu Shu-Sheng li xiao-Na Pan xiao-li zhu Xu-Bao Jiang Xiang Zheng Kong College of Chemistry and Chemical Engineering University of JinanJinan250022China Shandong Institute for Product Quality Inspection Jinan250102China College of Chemical Engineering Tianjin UniversityTianjin300072China

Non-aromatic fluorescent and multi-responsive materials,exhibiting inherent fluorescence emission and controlled phase change,have garnered significant attention in recent ***,the underlying interaction between their fluorescent properties and phase transition remains *** this study,we synthesized a series of catalyst-free aza-Michael addition-based polyethyleneimine(RFPEI)materials by reacting polyethyleneimine(PEI)with N-isopropyl acrylamide(NIPAM).The resulting RFPEI was comprehensively characterized,and demonstrated dual-phase transition behavior(LCST and UCST)in water,which could be finely tuned by adjusting its composition or external factors such as ***,upon UV irradiation(365 nm),RFPEI exhibited strong fluorescence *** further investigated the effects of NIPAM grafting percentage to PEI,polymer concentration,and pH on the LCST/UCST and fluorescent properties of RFPEI aqueous ***,we showcased the great potential of RFPEI as a versatile tool for physiological cell imaging,trace detection,and controlled release of *** study presents a novel class of stimuli-responsive fluorescent materials with promising applications in the field of biomedicine.

关键词： Polyethyleneimine Multi-responsiveness Intrinsic fluorescence emission Cell imaging Controlled drug release

Characterization and photocatalytic properties of silver and silver chloride doped TiO_2 hollow nanoparticles

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Chinese Chemical Letters 2012年第12期23卷 1399-1402页

作者： Ping li Ji Xiang Zheng Kong Jin Gang Wang xiao li zhu College of Chemistry and Chemical Engineering University of Jinan

Using polystyrene （PSt） particles as template, PSt/TiO2 composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO3 and NaCl. AgCl doped TiO2 hollow particles were successfully prepared with the PSt/TiO2 composite microspheres pretreated at 180 ℃ followed by calcination. The morphology of PSt/TiO2 particles and the crystal structures of the AgCl doped TiO2 hollow particles were characterized. The photocatalytic activity of the doped TiO2 hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO2 particles. The results showed that TiO2 hollow particles, either doped with Ag or AgCl, demonstrated higher photocatalytic activity than the pure TiO2 particles. This enhancement in photocatalytic activity was more significant with AgCl doped TiO2 than that with Ag doped, and more distinct when the degradation was done under visible light than that under UV light.

关键词： TiO2 hollow particles AgCl doping Photocatalysis light absorption shifting Rhodamine B degradation

A novel and simple pathway to synthesis of porous polyurea absorbent and its tests on dye adsorption and desorption

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Chinese Chemical Letters 2013年第4期24卷 287-290页

作者： Shu-Sheng li Xiang-Zheng Kong Xu-Bao Jiang xiao-li zhu College of Chemistry and Chemical Engineering University of Jinan

A novel one-step protocol for the preparation of porous polyurea material （PPU） through precipitation polymerization of toluene diisocynate （TDI） is presented. The process is based on step polymerization of one single monomer, TDI, with water in water-acetone mixed solvent. PPU is obtained without need for any porogen or additives, and no any chemical modification on the outcome polymer is necessary. The morphology, pore size and size distribution of PPU are characterized by scanning electron microscope and BET nitrogen adsorption. Taking acid fuchsine （AF） and Congo Red as dye examples in wastewaters, their adsorption on, desorption from PPU and the reusability of PPU were tested. Experimental conditions for AF adsorption were optimized with regard to pH, adsorption time, AF concentration and amount of PPU. Results demonstrate that the as-prepared PPU is of high performance in dyes adsorption and recycled use. This work presents therefore a novel and attractive candidate for removal of anionic dyes from wastewaters.

关键词： Precipitation polymerizationPorous polyureaDye removalisothermal adsorption

Microencapsulation of dodecyl acetate by complex coacervation of whey protein with acacia gum and its release behavior

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Chinese Chemical Letters 2012年第7期23卷 847-850页

作者： You Tong Yu li Na liu xiao li zhu Xiang Zheng Kong College of Chemistry and Chemical Engineering University of JinanJinan 250022China

Complex coacervation of whey protein（WP） with acacia gum（AG） was carried out in water with the presence of dodecyl acetate （DA）,a component of insect sex pheromones,in order to obtain microcapsules with DA as the core material and WP-AG coacervate as the wall *** variations in wall/core ratios,concentrations of the wall materials in capsule preparations,DA encapsulation was optimized,which showed a high DA encapsulation was achieved when coacervation was conducted at pH 3.5 with wall/core mass ratio at 3 combined with concentration of wall materials at 1.0 wt%.Morphology and the structure of DA loaded microcapsules were examined by scanning electron microscope,which showed the microcapsules were of core/shell structure with DA encapsulated in the inner of the *** release was examined and the behavior of the release was discussed.

关键词： Whey protein Acacia gum Complex coacervation Insect pheromone encapsulation Controlled release

Highly Sensitive and Selective Amperometric Sensor for Iodate Based on 9,10-Phenanthrenequinone Derived Graphene

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Chemical Research in Chinese Universities 2013年第1期29卷 132-138页

作者： WANG Hong-juan CHENG Na-na YANG xiao-yang li xiao-meng zhu lian-de Faculty of Chemistry Northeast Normal University Changchun 130024 P. R. China

We reported on a new amperometric sensor for the sensitive and selective determination of iodate in table salt. The iodate sensor was constructed by the integration of a novel nanocomposite which was made from 9,10-phenanthrenequinone（PQ） and graphene（GP） with a glassy carbon electrode（GCE）. The synthesized graphene and the nanocomposite were well characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM）, Fourier transform infrared（FTIR） spectroscopy and Raman spectroscopy. We fully studied the electrochemical beha- vior and kinetic characteristics of the PQ/GP nanocomposite at GCE. The PQ/GP electrode shows a good electrochemical catalytic activity towards the reduction of iodate, which makes itself a sensitive and selective electrochemical sensor for iodate. The iodate sensor displays a high sensitivity（1.04 ***.L-1）, a low detection limit（1.0X 10-8 mol/L）, a rapid response（less than 2 s）, and a broad linear range（from 5.0X 10-8 mol/L to 6.0X 10-3 mol/L ）. In addition, the sensor is interference free. The practical application of the proposed sensor was tested by the detection of iodate in table salt.

关键词： 9,10-Phenanthrenequinone Graphene Amperometric sensor Iodate

Dielectric and ferroelectric characteristics of Ba(Ti_(0.25)Zr_(0.25)Hf_(0.25)Sn_(0.25))O_(3)high-entropy ceramics

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Journal of Materiomics 2023年第4期9卷 634-641页

作者： Rui Hu Mi Bu Hang Chen xiao li zhu Xiang Ming Chen School of Materials Science and Engineering Zhejiang UniversityHangzhou310027China

Ba(Ti_(0.25)Zr_(0.25)Hf_(0.25)Sn_(0.25))O_(3)high-entropy ceramics were prepared by a standard solid state reaction process,and the dielectric and ferroelectric characteristics were investigated together with the *** X-ray diffraction(XRD)and energy dispersive spectroscopy(EDS)analysis demonstrated a single-phase perovskite structure in the present ceramics.A broad dielectric peak with strong frequency dispersion feature was determined,which indicated the typical relaxor nature originating from the nanoscale ferroelectric domain *** resulted from the structural distortion and chemical disorder due to high-entropy,where the long-range order of ferroelectric domains was *** homogeneous microstructure led to the reduced leakage current density and significantly improved dielectric strength,which was desired for the practical *** with the similar systems of Ba(Ti_(1-x)Zr_(x))O_(3)&Ba(Ti_(1-x)Sn_(x))O_(3),the present high-entropy ceramics indicated better relaxor ferroelectric characteristics.

关键词： High-entropy ceramic Microstructure Perovskite Relaxor ferroelectric

A novel associative latex thickener using ethoxylated behenyl methacrylate as functional monomer

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Chinese Chemical Letters 2010年第5期21卷 616-619页

作者： Xiang Zheng Kong Chen Wang Xu Bao Jiang xiao li zhu College of Chemistry and Chemical Engineering University of JinanJinan 250022China

Alkali-soluble associative latex thickeners modified with hydrophobic long chain alkyl groups were prepared using common acrylics and varying amount of a functional monomer,ethoxylated behenyl methacrylate(BEM),through emulsion *** was found that the size of the emulsion particle became larger with addition of *** light transmittance of the thickener latex sharply increased with pH varied from 6 to *** associative latex thickener manifested a higher viscosity when solids in the latex thickeners were kept at 0.5 wt%or higher,and the optimal amount of BEM was found to be around 2.5 wt%,or 0.16 mol%.All thickener latexes modified with BEM have better shearing resistance than the BEM-free thickener.

关键词： Associative thickener Functional monomer Ethoxylated behenyl methacrylate Viscosity