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      • KCI등재

        Synthesis and Characterization of Poly(N-arylenebenzimidazole ketone ketone)s

        Yewei Xu,Jie Tang,Guanjun Chang,Fanghua Zhu,Xuan Luo,Lin Zhang 한국고분자학회 2013 Macromolecular Research Vol.21 No.6

        Poly(N-arylenebenzimidazole ketone ketone)s (PNABIKKs) consisting of m- and p-phenylene linkages have been synthesized by nucleophilic aromatic substitution from bis(benzimidazolyl) derivatives containing sulfonyl,carbonyl, and ether groups with activated aromatic difluorides in sulfolane at 210 oC in the presence of anhydrous potassium carbonate. The structures of the polymers were characterized by means of Fourier tramsfom infrared (FTIR), proton nuclear magnetic resonance (1H NMR) spectroscopy, and elemental analysis, and the results were largely consistent with the proposed structure. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) measurements demonstrated that polymers had high glass transition temperatures (Tg>220 oC) and good thermal stability with high decomposition temperatures (TD>480 oC). These novel polymers also showed good solubility.

      • KCI등재

        Conjugated Polymers Based on Modified Benzo[1,2-b:4,5-b']Dithiophene and Perylene Diimide Derivatives: Good Optical Properties and Tunable Electrochemical Performance

        Kun Fang,Xu Ye,Yawen Huang,Guanjun Chang,Junxiao Yang,Yueqin Shen 한국고분자학회 2015 Macromolecular Research Vol.23 No.6

        Three original conjugated polymers were devised and synthesized via the alternating conjugated polymerization of the electron-donating monomer of the modified benzo[1,2-b:4,5-b']dithiophene (BDT) and electronaccepting monomers of perylene diimide (PDI), dithienyl-perylene diimide (DTPDI) and dithienocoronene diimide (DTCDI), respectively. The synthesized conjugated polymers presented excellent thermal stability (Td >400 oC) as well as broad absorption in visible region and narrow gap of energy level (1.80 to 2.01 eV). Moreover, P(BDT-DTCDI) exhibited strong fluorescence properties ( =736 nm with excitation at 680 nm). According to the theoretical calculations, P(BDT-PDI) and P(BDT-DTPDI) displayed significant polymer backbone torsion (41.44o and 39.64o), and P(BDT-DTCDI) had highly coplanar backbone with negligible angle between BDT and DTCDI. The results indicated that P(BDT-DTCDI) had potential applications in the fields of organic thin-film transistors (OTFTs) and fluorescence materials, and P(BDT-PDI) and P(BDT-DTPDI) could be used as a stable n-type semiconductor for polymer solar cells.

      • KCI등재

        pH and Redox Dual Stimuli-Responsive Injectable Hydrogels Based on Carboxymethyl Cellulose Derivatives

        Yueqin Shen,Xian Li,Yawen Huang,Guanjun Chang,Ke Cao,Junxiao Yang,Renyi Zhang,Xueying Sheng,Xu Ye 한국고분자학회 2016 Macromolecular Research Vol.24 No.7

        pH and redox dual stimuli-responsive injectable hydrogels were prepared by cross-linking oxidized carboxymethyl cellulose (oxi-CMC) with 3,3'-dithiobis (propionohydrazide) (DTP) via Schiff base reaction under physiological condition. The hydrogels showed good performance such as tunable gelling time, appropriate rheology properties, high swelling ratio and low degradation rate. In vitro release studies confirmed that bovine serum albumin (BSA) as a model drug exhibited a sustainable release at pH 7.4 and an accelerated release under a lower pH 5.0 and/or reducing environments. The results signified that oxi-CMC/DTP hydrogels could be an attractive candidate for drug delivery system, tissue engineering or cell scaffold materials.

      • Nonradiative energy transfer between colloidal quantum dot-phosphors and nanopillar nitride LEDs.

        Zhang, Fan,Liu, Jie,You, Guanjun,Zhang, Chunfeng,Mohney, Suzanne E,Park, Min Joo,Kwak, Joon Seop,Wang, Yongqiang,Koleske, Daniel D,Xu, Jian Optical Society of America 2012 Optics express Vol.20 No.2

        <P>We present in this communication our study of the nonradiative energy transfer between colloidal quantum dot (QD) phosphors and nitride nanopillar light emitting diodes (LEDs). An epitaxial p-i-n InGaN/GaN multiple quantum-well (QW) heterostructure was patterned and dry-etched to form dense arrays of nanopillars using a novel etch mask consisting of self-assembled In3Sn clusters. Colloidal QD phosphors have been deposited into the gaps between the nanopillars, leading to sidewall coupling between the QDs and InGaN QW emitters. In this approach, close QW-QD contact and a low-resistance design of the LED contact layer were achieved simultaneously. Strong non-radiative energy transfer was observed from the InGaN QW to the colloidal QD phosphors, which led to a 263% enhancement in effective internal quantum efficiency for the QDs incorporated in the nanopillar LEDs, as compared to those deposited over planar LED structures. Time-resolved photoluminescence was used to characterize the energy transfer process between the QW and QDs. The measured rate of non-radiative QD-QW energy-transfer agrees well with the value calculated from the quantum efficiency data for the QDs in the nanopillar LED.</P>

      • KCI등재

        A Fiber Spool’s Vibration Sensitivity Optimization Based on Orthogonal Experimental Design

        Jing Gao,Linbo Zhang,Dongdong Jiao,Guanjun Xu,Xue Deng,Qi Zang,Honglei Yang,Ruifang Dong,Tao Liu,Shougang Zhang 한국광학회 2024 Current Optics and Photonics Vol.8 No.1

        A fiber spool with ultra-low vibration sensitivity has been demonstrated for the ultra-narrowlinewidth fiber-stabilized laser by the multi-object orthogonal experimental design method, which can achieve the optimization object and analysis of influence levels without extensive computation. According to a test of 4 levels and 4 factors, an L 16 (4 4 ) orthogonal table is established to design orthogonal experiments. The vibration sensitivities along the axial and radial directions and the normalized sums of the vibration sensitivities are determined as single objects and comprehensive objects, respectively. We adopt the range analysis of object values to obtain the influence levels of the four design parameters on the single objects and the comprehensive object. The optimal parameter combinations are determined by both methods of comprehensive balance and evaluation. Based on the corresponding fractional frequency stability of ultra-narrow-linewidth fiber-stabilized lasers, we obtain the final optimal parameter combination A3B1C2D1, which can achieve the fiber spool with vibration sensitivities of 10 −12 /g magnitude. This work is the first time to use an orthogonal experimental design method to optimize the vibration sensitivities of fiber spools, providing an approach to design the fiber spool with ultra-low vibration sensitivity.

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