Institute of Chemistry
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Hexafluorophosphate intercalation into graphite electrode from gamma-butyrolactone solutions in activated carbon/graphite capacitors
No full textIn our recent work, the solvent of ethylene carbonate (EC) has been found to retard the intercalation of anions into graphite electrodes. Here we demonstrate that gamma-butyrolactone (GBL) also exhibits suppressive effect on the intercalation of PF6- into the interlayer space between the graphene planes. The intercalation process of PF6- into graphite electrode from GBL has been investigated by in situ XRD, in situ Raman and EQCM. Furthermore, the effect of GBL has been compared with those of EC and propylene carbonate (PC). (C) 2015 Elsevier B.V. All rights reserved
Al/C/MnO2 sandwich nanowalls with highly porous surface for electrochemical energy storage
No full textHierarchical materials supported on metal substrates present promising applications in flexible energy storage and conversion devices. Compared to Au, Ag, Cu, Ni, Ti, Wand their alloys, Al, the most abundant metal in the crust has been less used in supercapacitors due to its high activity which makes it unstable in acid and base electrolytes. In this paper, we explore a novel Al/C/MnO2 sandwich structured material for the first time for supercapacitor. Owing to the highly porous and open surface structure and the highly conductive Al/C double core current collector on nanoscale, the Al/C/MnO2 sandwich nanowall arrays supported on Al foil show excellent capacitance performance with a maximum area specific capacitance of 1008.3 mF cm(-2) and a high energy density of 35.2 mu Wh cm(-2) at 2 mA cm(-2). Moreover, a supercapacitor device with 4 supercapacitors connected in series can power a LED lamp. The present study demonstrates a novel electrode architecture based on Al foil with remarkably high area specific capacitance and stability for promising supercapacitor applications. Our strategy provides a new approach to the fabrication of hierarchical electrode materials from Al metal (could also be extend to other metal substrates) for supercapacitors and other energy storage and conversion devices. (C) 2015 Elsevier B.V. All rights reserved
Use of asymmetric multilayer polylactide nanofiber mats in controlled release of drugs and prevention of liver cancer recurrence after surgery in mice
No full textLocal tumor recurrence remains a major clinical problem following surgical treatment for most cancers such as hepatocellular carcinoma (HCC). An implantable local drug delivery system may be suitable for addressing this unmet clinical need. In this study, asymmetric multilayer polylactide nanofiber (AMPN) mats were prepared and a one-sided and prolonged release profile of hydrophilic dye or oxaliplatin was observed after they were sandwiched between two liver lobes in mice. Covering the surgery site by drug-loaded AMPN mat after tumor resection, in both subcutaneous and orthotopic HCC model in mice, the recurrence of HCC was significantly retarded and the survival time of mice was markedly prolonged. In conclusion, post-surgical therapy at tumor resection margins by drug-loaded AMPN mats may represent a suitable application of nanofiber-based local chemotherapy
miRNA oligonucleotide and sponge for miRNA-21 inhibition mediated by PEI-PLL in breast cancer therapy
No full textThe metastasis of breast cancer is the leading cause of cancer death in women. In this work, an attempt to simultaneously inhibit the primary tumor growth and organ-specific metastasis by the cisplatin-loaded LHRH-modified dextran nanoparticles (Dex-SA-CDDP-LHRH) was performed in the 4T1 orthotopic mammary tumor metastasis model. With the rationally designed conjugation site of the LHRH ligand, the Dex-SA-CDDP-LHRH nanoparticles maintained the targeting function of LHRH and specifically bound to the LHRH-receptors overexpressed on the surface of 4T1 breast cancer cells. Therefore, the Dex-SA-CDDP-LHRH nanoparticles exhibited improved cellular uptake and promoted cytotoxicity, when compared with the non-targeted Dex-SA-CDDP nanoparticles. Moreover, both the non-targeted and targeted nanoparticles significantly decreased the systemic toxicity of CDDP and increased the maximum tolerated dose of CDDP from 4 to 30 mg kg(-1). Importantly, Dex-SA-CDDP-LHRH markedly enhanced the accumulation of CDDP in the injected primary tumor and metastasis-containing organs, and meanwhile significantly reduced the nephrotoxicity of CDDP. Dose-dependent therapeutic effects further demonstrated that the CDDP-loaded LHRH-decorated polysaccharide nanoparticles significantly enhanced the antitumor and antimetastasis efficacy, as compared to the non-targeted nanoparticles. These results suggest that Dex-SA-CDDP-LHRH nanoparticles show great potential for targeted chemotherapy of metastatic breast cancer. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Nanostructure and Linear Rheological Response of Comb-like Copolymer PSVS-g-PE Melts: Influences of Branching Densities and Branching Chain Length
No full textComb-like poly(styrene-co-4-(vinylphenyl)-1-butene)-g-polyethylene copolymers (PSVS-g-PE) with various branching parameters were synthesized to study the influence of branch chains on morphology (at melt state) and linear rheological response of the copolymers. The results showed that both the branching density and branch chain length of PSVS-g-PE copolymers strongly affected linear rheological behavior of the copolymers, resulting from the formation of different microphase separation structure in the melt state. PSVS-g-PE copolymers with low branching density (2.3-3.5 branch chains per 100 repeating units of the backbone) showed a microphase-separated structure at the melt state, and a typical rheological characteristic for network-like structure was observed. Furthermore, the type of microphase-separated structure at the melt state strongly influences the applicability of the time temperature superposition (TTS) principle. As a result, the TTS failure was observed in the modulus curves for PSVS52.7-3.5-PE4.9 (poor-order lamellar structure) and PSVS54.4-2.7-PE10.7 (long tubular structure). In contrast, the PSVS-g-PE sample with high branching density (16.6-24.5 branch chains per 100 repeating units of the backbone) showed homogeneous phase structure and normal rheological behavior, similar to linear or comb-like homopolymers. The gel-like state appeared in a limited frequency regime (a plateau regime of tan delta versus omega) during decreasing the frequency from the high frequency regime in these comb-like copolymers
Enhancement of the Carbon Dots/K2S2O8 Chemiluminescence System Induced by Triethylamine
No full textTriethylamine (TEA), a common coreactant for electrochemiluminescence (ECL), is first utilized as a coreactant for chemiluminescence (CL). The CL intensity of carbon dots/K2S2O8 could be increased by similar to 20 times in the presence of TEA. On the basis of this fascinating phenomenon, a room temperature operated senor is constructed for the fast, selective, and sensitive determination of TEA. A wide linear relationship between CL intensity and TEA concentration from 1 mu M to 1000 mu M (R-2 = 0.9995) was found with the detection limit down to 1 mu M. The enhancement mechanism of TEA to this CL system is carefully investigated. Experimental results reveal that the forming of TEA free radical is what indeed induced the enhancement of the CL efficiency of CDs
Kumada catalyst transfer polycondensation for controlled synthesis of polyfluorenes using 1,3-bis(diarylphosphino)propanes as ligands
No full textThree new bis(diphenylphosphino) propane (dppp) derivatives, i.e., 1,3-bis(di(4-methylphenyl)phosphino)propane (L1), 1,3-bis(di(3-methylphenyl)phosphino)propane (L2) and 1,3-bis(di(2-methylphenyl)phosphino)propane (L3), were synthesized for studying the effect of the ligand on the Kumada catalyst transfer polycondensation (KCTP) of 7-bromo-9,9-dialkylfluorenylmagnesium chloride (M1) using Ni(acac)(2)/L (L = dppp, L1, L2 or L3) as the catalyst. Ni(acac)(2)/L1 exhibited a polymerization performance comparable to Ni(acac)(2)/dppp, and the polymerization could be well-controlled with >= 1 mol% catalyst. When the most hindered ligand L3 was used, the polymerization was out-of-control and only poly(9,9-dioctylfluorene)s (PF8s) with relatively low number-average molecular weights (M-n) and large polydispersity indices (PDIs) could be obtained. In contrast, the moderately hindered catalyst Ni(acac)(2)/L2 outperformed Ni(acac)(2)/dppp. The polymerization was well-controlled with a catalyst of >= 0.5 mol%, as confirmed by the linear correlation of M-n versus [monomer]/[Ni], and PF8s with M-n up to 91.1 kDa and fluorene-thiophene block copolymers (PF8-b-P3HTs) with M-n up to 78.4 kDa could be prepared in a controlled manner. Density functional theory (DFT) calculations, P-31 NMR spectroscopy studies and block copolymerizations revealed that the great performance of L2 can be attributed to the stronger affinity of the L2Ni(0)-polymer p-complex and the higher stability of active chain ends. The active chain ends of the high molecular weight polymers were unstable, probably owing to unknown side reactions assisted by chain aggregation or entanglement, which may be responsible for the out-of-control nature of the polymerization at low catalyst loadings
过氧化物引发聚(3-羟基丁酸酯-co-4-羟基丁酸酯)交联及增容共混体系结构与性能的研究
No full text来源于可再生资源的聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]和聚乳酸（PLA）作为生物基高分子材料这一大家族中的优秀代表，因其具有良好的生物降解性和生物相容性而成为具有巨大发展潜力的环境友好型高分子材料，越来越受到人们的重视。然而，作为脂肪族聚酯，P(3HB-co-4HB)和PLA自身存在以下缺陷：热稳定性差，结晶缓慢，尺寸稳定性差，熔体强度低，力学性能差等等，极大地限制了它们的广泛应用。 本论文针对P(3HB-co-4HB)和PLA的不足，提出了利用过氧化物引发交联的方法改变P(3HB-co-4HB)的分子链结构和凝聚态结构，旨在提高其熔体强度和改变其结晶行为；以及将此方法应用到P(3HB-co-4HB)和PLA共混体系，期望两组分间发生交联反应、增强两组分相容性、提高材料力学性能，开发出性能优良的生物可降解材料。由此发展出一种新的生物可降解脂肪族聚酯的改性...Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] and poly(L- lactide) (PLA) derived from renewable resources have received considerable attentions due to their good biocompatibility and biodegradability. However, as aliphatic polyesters, the inherent deficiencies of P(3HB-co-4HB) and PLA, such as the limited thermal stability, slow crystallization rate, limited dimensional stability, low melt strength, and poor mechanical properties, etc. have limited their wide applications. In the present dissertation, considering the disadvantages of P(3HB-co-4HB) and PLA, branched/crosslinked P(3HB-co-4HB) was prepared by peroxide to enhance the rheological properties and tailor the crystallization behavior through changing the structure of polymer chain firstly. Secondly, this method was i..
含齐聚苯连接单元的有机磷光与荧光材料的合成与性能
No full text鉴于齐聚苯的刚性、共轭结构以及长度易调等优势，本论文采用齐聚苯作为桥联单元，通过改变苯环数目来分别调控磷光材料的浓度淬灭效应、蓝光荧光材料的荧光量子效率以及双极型蓝光材料的D-A相互作用，发展了一系列含齐聚苯连接单元的有机磷光与荧光材料。主要创新点如下： 1）采用绿光铱配合物Ir(pbi)3作为中心核和一代咔唑作为树枝，设计合成了含有不同长度齐聚苯连接单元的树枝状铱配合物（2P-G1、3P-G1、4P-G1和5P-G1），其分子尺寸由2P-G1的1.8 nm增加到5P-G1的3.0 nm。随着中心核和树枝之间距离的增加，浓度淬灭效应逐渐减弱，光致发光量子效率增加；同时，当苯环的数目超过3个时，齐聚苯连接单元的三线态能级会低于绿光中心核（2.45 eV），导致三线态激子的损失。因此，2P-G1表现出最优的非掺杂器件性能，最大发光效率达到36.9 cd/A，比参比化合物1P-G1（28.4 c...In view of their rigid conjugated structures and tuable length, oligophenylenes have been used as linking units for the design of solution-processed light-emitting molecules, aiming at suppressing the concentration quenching effect for phosphorescent emitters, improving the photoluminescent (PL) quantum efficiency for blue fluorescent emitters as well as adjusting the D-A interaction for bipolor fluorescent emitters. With this design strategy, a series of phosphorescent emitters and fluorescent ones containing oligophenylenes are obtained with high device performance in this dissertation. (1) Ir dendrimers (2P-G1, 3P-G1, 4P-G1, 5P-G1) with various length of oligophenylenes inserted between the Ir(pbi)3 core and the carbazole dendrons are designed and synthesized. The diameter of the molecu..
活性炭/LiNi0.5Mn1.5O4混合型电化学电容器的研究
No full text近年来，能源危机与环境污染日趋严重，寻找新型能量存储装置已成为当今研究的重点。电化学电容器作为一种新型的储能器件，具有功率密度高、充放电速度快、循环寿命长、使用温度范围宽、免维护、安全环保等优点，受到世界研究者的广泛关注。目前商用的有机系双电层电容器采用两个对称的活性炭电极，能量密度较低，限制了其广泛应用。因此，提高电化学电容器的能量密度成为亟待解决的“瓶颈问题”。根据能量密度E=1/2CV2这一基本公式，提升电容器能量密度的有效的方式是提高工作电压和增大电极材料的比容量，而前者的效果更显著，这个目的可通过使用有机系电解液和组装锂离子电池高压正极材料与炭材料的混合型电容器来实现。 本论文的主要的研究内容和结果如下： 1. 制备锂离子电池高电压正极材料LiNi0.5Mn1.5O4(LNMO)。采用了喷雾干燥法、共沉淀法、乙二醇辅助共沉淀法等多种方法进行合成，详细讨论了不同制备方法对材料LiN...Recently, energy crisis and environmental pollution has become increasingly serious. Searching for new energy storage devices has become the focal point of current research. As a new kind of energy storage devices, electrochemical capacitor has attracted the attention of researchers all over the world. It has a lot of advantages, such as high power density, fast rate capability, long cycle life, wide working temperature range, free of maintenance, safety and environmental benignity. Commercial electric double layer capacitors consisting two symmetrical activated carbon electrodes and organic electrolyte solutions possess low energy density, which limits its wide application. Therefore, improving energy density of electrochemical capacitor becomes an urgent issue. According to the energy de..