Institute of Chemistry
Changchun Institute of Applied Chemistry, Chinese Academy Of SciencesNot a member yet
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Biomimetic glycopolymers tethered gold nanoparticles: Preparation, self-assembly and lectin recognition properties
No full textBiomimetic glycopolymers poly(gluconamidoethylmethacrylate)-b-poly(epsilon-caprolactone)-b-poly (gluconamidoethylmethacrylate) with degradable disulfide groups in the backbone (PGAMA-PCL-SS-PCL-PGAMA) were synthesized by the combination of ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The internal disulfide bonds were cleaved by reduction with DL-dithiothreitol to yield the corresponding thiol terminated glycopolymers. The thiol terminated glycopolymers were effectively anchored on the surface of gold nanoparticles to prepare the biomimetic glycopolymers modified gold nanoparticles (Gly@Au NPs). Moreover, the properties of the Gly@Au NPs in aqueous solution were investigated. Transmission electron microscopy (TEM) analysis revealed that the self-assembly morphology of the Gly@Au NPs can be fine-tuned, from irregular clusters to spherical aggregates, by changing the weight fraction of the hydrophobic PCL block. Furthermore, the Gly@Au NPs had specific recognition with Concanavalin A (Con A). (C) 2014 Elsevier B.V. All rights reserved
An amperometric sensor for detection of tryptophan based on a pristine multi-walled carbon nanotube/graphene oxide hybrid
No full textWe report the fabrication of a novel amperometric sensor for tryptophan (Trp) based on a pristine multi-walled carbon nanotube/graphene oxide (pMWCNT/GO) hybrid obtained through the sonication of pMWCNTs in an aqueous solution of GO. The results of transmission electron microscopy and electrochemical impedance spectroscopy demonstrate the successful formation and the excellent charge transfer ability of the resulting hybrid. Compared with the commonly used acid-treated MWCNTs and GO, the resulting hybrid exhibits better electrocatalytic activity towards the oxidation of Trp, which is attributed to the synergistic effect of MWCNTs and GO. The current-time curve reveals that the catalytic oxidation current is linearly dependent on Trp concentration in the range of 50 nM to 4.25 mu M with a detection limit of 8 nM (S/N = 3). In addition, the proposed sensor is successfully employed to detect Trp in the real samples with satisfactory results
Facile template-based high-yield-transformation synthesis and electrocatalytic properties of PdTe nanowires
No full textPdTe nanowires with well-defined morphology are prepared by a simple Te nanowire-template-based pathway. The as-prepared PdTe nanowires present a small diameter (about 12 nm) and long length (several tens of microns). After the electrochemical activation process, the prepared PdTe nanowire catalyst reveals a better catalytic ability for ethylene glycol electrooxidation in alkaline conditions when compared with a commercial Pd/C catalyst
Hemi-salen aluminum catalysts bearing N, N, O-tridentate type binaphthyl-Schiff-base ligands for the living ring-opening polymerisation of lactide
No full textFour hemi-salen aluminum complexes based on tridentate N, N, O-type binaphthyl-Schiff-base derivatives (1: R = Pr-i; R-1 = H; 2: R = Pr-i; R-1 = Cl; 3: R = 2-adamantyl; R-1 = H; 4: R = 2-adamantyl; R-1 = Bu-t) were prepared. These complexes were characterized by H-1, C-13 NMR spectroscopy and elemental analysis, these four complexes were employed for ring-opening polymerisation of L-lactide and rac-lactide. Complex 2, which was based on pro-ligand L-2 with smaller steric hindrance and electron-withdrawing substituents, displayed the highest activity for ROP of L-lactide among these complexes, and complex 4, which was supported by pro-ligand L-4 with the biggest steric hindrance, showed the highest stereoselectivity for the ROP of rac-lactide with partially isotactic polylactide with a P-m of 0.65. Kinetic studies revealed the ROP of L-lactide initiated by complex 3 had first-order dependency on [LA] as well as [Al]
Luminescence properties of a novel reddish orange long-lasting phosphorescence phosphor Zn2P2O7:Sm3+, Li+
No full textIn this article we synthesized a series of new reddish orange long-lasting phosphorescence phosphors by co-doping Li+ ions into Sm3+ activated alpha-Zn2P2O7, characterized their luminescence properties, and evaluated the effect of Li+ co-doping on both photoluminescence and Phosphorescence. The results showed that both the photoluminescence and Phosphorescence originated from characteristic reddish orange emissions of Sm3+ from its 4f-4f transitions of (4)G(5/2)-H-6(5/2), (4)G(5/2)-H-6(7/2) (4)G(5/2)-H-6(9/2) and (4)G(5/2)-H-6(11/2). Besides markedly enhancing the photoluminescence intensity of Sm3+, the Li+ entering into the crystal lattice also promoted the long lasting phosphorescence performance via modifying the defect levels in the phosphors. The optimal long afterglow material was achieved when the Li+ concentration is 2 mol%. This phosphor shows bright reddish orange phosphorescence which could last for more than 3 hours in the dark. Four peaks appeared in its thermoluminescence curve, and the one at around 350 K was proved to be responsible for the occurrence of long lasting phosphorescence. The release of the captured electrons in the defect levels corresponding to this TL peak in room temperature to emission centers of Sm3+ underwent a tunneling process
Suppressed charge recombination in polymer solar cells based on perylene diimide derivative acceptors via solvent vapor annealing
No full textA singly-linked perylene bisimide dimer (di-PBI) and a low band gap polymer based on dithienocarbazole and isoindigo moieties (P(IID-DTC)) are selected as electron acceptor and donor respectively to fabricate non-fullerene based polymer solar cells. The combination of di-PBI acceptor and P(IID-DTC) donor provides well overlapped absorption profile with solar light in the visible region. The P(IID-DTC):di-PBI blend morphology and its effect on charge transport and recombination have been investigated in detail. The dominant bimolecular recombination in commonly processed P(IID-DTC):di-PBI blend results in a low power conversion efficiency of merely 1%. We find that CH2Cl2 vapor annealing can effectively improve bi-continuous phase separation and boost the electron transport by more than two orders of magnitude due to the detrap of di-PBI molecules from amorphous P(IID-DTC) matrix. More importantly, the dominant bimolecular recombination in the P(IID-DTC): di-PBI blend films is strongly suppressed. Finally, the power conversion efficiency of non-fullerene P(IID-DTC):di-PBI blend solar cell is dramatically improved to 2.95%. (C) 2015 Elsevier B.V. All rights reserved
Synthesis and linear rheological property of comb-like styrene-based polymers with a high degree of branch chain
Get PDFA series of model comb-like polymers (PSVS-g-PS) with high branching degree were synthesized by nucleophilic substitution reaction between iodinated copolymer of styrene (St) with 4-(vinylphenyl)-1-butene (VSt) (PSVSI, backbone) and living polystyrene lithium (PSLi, side chain). This method is a facile way for modular synthesis of graft copolymers based on living anionic polymerization and hydrozirconation reaction. The branching density of PSVS-g-PS (the number of branch chain per 100 repeat backbone units) ranged from 2.4 to 20.7%. The backbone length of PSVS-g-PS was larger than the entanglement molecular weight (M-e) of PS, while the molecular weight of branch chain was designed to be below or above the M-e of PS. The results from the linear rheological properties of the PSVS-g-PS showed hierarchical relaxation process. One appeared in the intermediate angular frequency region, corresponding to the relaxation of the side chain. The other is in the terminal region, which is related to the movement of the whole comb polymer. From scaling law of zero shear viscosity (eta(0)) of PSVS-g-PS with versus molecular weight, it could be seen that the dynamical behavior of PSVS-g-PS was different from those of both poly(macromonomers) and entangled linear polymer chains, indicating that there is certain entanglement for PSVS-g-PS with long branch chain. (C) 2015 Elsevier Ltd. All rights reserved
Morphology of melt-crystallized beta ' phase crystals of monodisperse poly(9,9-dioctylfluorene)
Get PDFA novel beta' phase crystal with lamellar structure of monodisperse poly(9,9-dioctylfluorene) (PFO) has been prepared by means of melt crystallization, demonstrating similar optical properties with beta phase crystals. A preliminary determination of unit cell dimensions and molecular packing (orthorhombic, a = 1.30 nm, b = 2.22 nm, c = 3.36 nm, 4 chains, with space group Pmc2(1) and density 1.06 g/cm(3)) was made by combined analysis of the selected-area electron diffraction (SAED) and X-ray diffraction (XRD) patterns. In the lamellar crystals, the molecular backbone chains are parallel to the lamellar plane with the alkyl side chains interdigitation in the thickness of lamella. (C) 2015 Elsevier Ltd. All rights reserved
A Monte Carlo study on LCCC characterization of graft copolymers at the critical condition of side chains
Get PDFLiquid chromatography at the critical condition (LCCC) has been used to characterize graft copolymers based on the assumption that one of the copolymer blocks becomes chromatographically "invisible" at the critical condition of the corresponding homopolymer. We investigate the validity of this assumption with lattice Monte Carlo simulations of A-g-B graft copolymers modeled as either random walk (RW) or self-avoiding walk (SAW) chains composed of multiple invisible B blocks grafted to an A backbone that is either in size-exclusion chromatography (SEC) or liquid adsorption chromatography (LAC) mode. The simulations show that, in agreement with recent experimental results, the B blocks have a small, but noticeable, impact on the overall elution of the graft copolymer. This influence exists even when the chains are modeled as RWs, indicating that its fundamental origin is due to chain connectivity, not excluded volume interactions. In general, both models show that grafting B blocks to an A backbone in SEC mode tends to increase copolymer retention, while grafting B blocks to an A backbone in LAC mode tends to decrease copolymer retention. When the copolymer is modeled as a SAW, the excluded volume interaction increases the entropic penalty associated with the addition of a B block and, therefore, the addition of B blocks in SAW chains is more likely to result in a decrease in the retention time of the copolymer when the A backbone is in LAC mode. (C) 2015 Elsevier Ltd. All rights reserved
A fluorescence turn-on detection of copper(II) based on the template-dependent click ligation of oligonucleotides
Get PDFIn this work, a fluorescence turn-on method for copper(II) detection is reported. A molecular beacon (MB) was designed as a template. Cu2+ was reduced to Cu+ in the presence of a reductant (ascorbic acid). Two short single-stranded oligonucleotides one was labeled with a 5'-alkyne and the other with 3'-azide group, proceeded a template-dependent chemical ligation through the Cu(I)-catalyzed azide-alkyne cycloaddition. The newly generated click-ligated long chain oligonucleotide, which was complementary to the MB, opened the MB hairpin structure and resulted in a turn on fluorescence. The increase in fluorescence intensity is directly proportional to the amount of Cu2+ added to the assay solution. The present assay is quite sensitive and allows the detection of 2 nM Cu2+. The described assay also exhibits high selectivity over other metal ions. (C) 2014 Elsevier B.V. All rights reserved