PI表面改性对PANI/PI复合膜性能的影响

采用分散聚合体系,在聚酰亚胺(PI)薄膜表面原位沉积聚苯胺(PANI)制得高导电性PANI/PI复合膜。用不同物理、化学方法对PI薄膜表面进行改性。结果表明,通过等离子体处理、超声波处理以及不同溶液浸泡处理的PI基体均改善了复合膜表面质量,提高复合膜电导率,其中过硫酸胺(APS)水溶液处理制得复合膜的电导率相对最高。紫外光谱和红外光谱分析证实基体表面为质子酸掺杂的PANI膜层,膜中不含有空间稳定剂聚乙烯吡咯烷酮。

颗粒模板法制备大孔Al_2O_3材料

采用颗粒模板法制备了大孔氧化铝(Al2O3)材料.扫描电子显微镜(SEM)结果显示,大孔Al2O3结构中的大孔呈“囊泡状”且孔道的贯通性较差.Zeta电位测量表明,共沉积条件下聚苯乙烯(PS)和Al2O3两种胶体颗粒带有相反的电荷,在静电引力作用下先发生了吸附,再沉积在一起.吸附在PS微球表面的Al2O3纳米颗粒形成的吸附层是导致大孔呈“囊泡状”和孔道不贯通的主要原因.采用聚二烯丙基二甲基氯化铵(PD)溶液对PS胶体微球带电性质进行了改性,PS微球的Zeta电位由-44.36mV变成了+37.41mV,进而消除了沉积过程中二元颗粒间的吸附现象.扫描电子显微镜显示,大孔样品中“囊泡状”大孔消失,同时孔道贯通性得到改善.

Haemocompatibility of Ti-3Zr-2Sn-3Mo-25Nb biomedical alloy with surface heparinization using electrostatic self assembly technology

The haemocompatibility of Ti-3Zr-2Sn-3Mo-25Nb biomedical alloy was studied after surface heparinization. A layer of sol-gel TiO2 films was applied on the alloy samples followed by active treatment in the bio-functionalized solution for introducing the OH- and groups, and then the heparin was immobilized on the active TiO2 films through the electrostatic self assembly technology. It is shown that the heparinized films are mainly composed of anatase and rutile with smooth and dense surface. In vitro blood compatibility was evaluated by haemolysis test, clotting time and platelet adhesion behavior tests. The results show that the haemocompatibility of the alloy could be significantly improved by surface heparinization.

Carbon Foam Anode Modified by Urea and Its Higher Electrochemical Performance in Marine Benthic Microbial Fuel Cell

Electrode materials have an important effect on the property of microbial fuel cell(MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel cell(BMFC) with higher voltage and output power. The electrochemical properties of plain carbon foam(PC) and urea-modified carbon foam(UC) are measured respectively. Results show that the UC obtains better wettability after its modification and higher anti-polarization ability than the PC. A novel phenomenon has been found that the electrical potential of the modified UC anode is nearly 100 m V lower than that of the PC, reaching-570 ±10 m V(vs. SCE), and that it also has a much higher electron transfer kinetic activity, reaching 9399.4 m W m-2, which is 566.2-fold higher than that from plain graphite anode(PG). The fuel cell containing the UC anode has the maximum power density(256.0 m W m-2) among the three different BMFCs. Urea would enhance the bacteria biofilm formation with a more diverse microbial community and maintain more electrons, leading to a lower anodic redox potential and higher power output. The paper primarily analyzes why the electrical potential of the modified anode becomes much lower than that of others after urea modification. These results can be utilized to construct a novel BMFC with higher output power and to design the conditioner of voltage booster with a higher conversion ratio. Finally, the carbon foam with a bigger pore size would be a potential anodic material in conventional MFC.

Electrokinetic and Flotation Investigations of Surface Properties Modification of Magnesite and Serpentinite Using Biosurfactants and Surfactants

This paper presents some results of zeta potential measurements performed into biosurfactant adsorption onto magnesite and serpentinite surface. Zeta potential and isoelectric point measurement of magnesite and serpentinite particles before and after interaction with biosurfactant broth solution and activator （nickel（II） ion solution） were carried out. The zeta potential results show that presence of biosurfactants changes both magnesite and serpentinite surface potential by physical adsorption which increases the hydrophobicity of mineral particles. Measurements of particles zeta potential in the presence of biosurfactant broth are relevant to the minerals flotation. Hallimod flotation response of magnesite and serpentinite as a function of collector concentration was investigated. Bioflotation test results show that at the presence of broth, the flotation separation of magnesite from serpentinite is possible.

Influence of nitrogen hetero-substitution on the electrochemical performance of coal-based activated carbons measured in non-aqueous electrolyte

Nitrogen-containing carbons were prepared by modification of activated carbons.The modified carbons were used as electrode materials with improved electrochemical performance.Precursor anthracite was activated by KOH(KOH:anthracite= 1:1), modified by melamine or urea and then treated at 1173 K to obtain the modified carbons.The porous structure, the chemical composition and the electrochemical characteristics of the carbons were investigated by nitrogen sorption, XPS and electrochemical methods respectively.Electrochemical experiments were performed in an organic electrolytic solution of 1 M(C2H5)4NBF4/PC.The samples modified by the different methods showed differences in chemical composition that introduced varying degrees of electrochemical performance enhancement.The presence of nitrogen enhanced the electron donor properties and the surface wettability of the activated carbons:this ensured a sufficient utilization of the exposed surface for charge storage.

Enhancing Structural Stability and Pervaporation Performance of Composite Membranes by Coating Gelatin onto Hydrophilically Modified Support Layer

The interfacial compatibility of composite membrane is an important factor to its structural stability, andseparation performance. In this study, poly （ether sulfone） （PES） support layer was first hydrophilically modified with poly（vinyl alcohol） （PVA） via surface segregation during the phase inversion process. Gelatin （GE） was then cast on the PVA-modified PES support layer as the active layer followed by crosslinking to fabricate composite membranes for ethanol dehydration. The enrichment of PVA on the surface of support layer improved interfacial compatibility of the as-prepared GE/PVA-PES composite membrane. The water contact angle measurement and X-ray photoelectron spectroscopy （XPS） data confirmed the surface segregation of PVA with a surface coverage density of -80%. T-peel test showed that the maxima/force to separate the support layer and the active layer was enhanced by 3 times compared with the GE/PES membrane. The effects of PVA content in the support layer, crosslinking of GE active layer and operating parameters on the pervaporative dehydration performance were investigated. The operational stability of the composite membrane was tested by immersing the membrane in ethanol aqueous solution for a period of time. Stable pervaporation performance for dehydration of 90% ethanol solution was obtained for GE/PVA-PES membrane with a separation factor of -60 and a permeation flux of -1910 g.m^-2.h1 without peeling over 28 days immersion.

Tradeoffbetween Narrowing Optical Band Gap and Enhancing Electrical Conductivity of the Metal Nanoparticles-Modified Titanium Oxide Films

The n-type semiconducting titanium oxide thin films are well-known as electron transporting interlayer in photovoltaic cells. The favorable characteristics of interlayers in photovoltaics are high optical transmittance （T%）, wide band gap energy （Eg） and high electrical conductivity （σ）. Modifying titanium oxide films with metal nanoparticles would increase electrical conductivity but reduce optical band gap energy. We developed the sol-gel derived titanium suboxide （TiOx） films modified with silver （Ag） or gold （Au） or copper （Cu） nanoparticles （NPs）. This study explores a tradeoff between narrowing optical band gap and enhancing electrical conductivity of nanostructured TiOx films by controlling the Au- or Ag- or Cu-NPs loading concentrations （mol%） in titania. The Au- and Cu-NPs loading concentration of 4 mol% should meet a tradeoff which yields the higher T%, wider Eg and higher compared to those of pure TiOx films. In addition, since the pure Cu is not thermodynamically stable in ambience as compared to Au and Ag, the stability of as-obtained colloidal CuNPs is also examined. A careful examination of the time evolution of surface plasmon resonance （SPR） bands of CuNPs indicates that their stability is only up to 4 h.

The effect of modified layers on the performance of inverted ZnO nanorods/MEH-PPV solar cells

We fabricate inverted organic/inorganic hybrid solar cells based on vertically oriented ZnO nanorods and polymer MEH-PPV. The morphology of ZnO nanorods and ZnO nanorods/MEH-PPV hybrid structure is depicted by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscope (AFM), respectively. It is observed that ZnO nanorods array grows primarily aligned along the perpendicular direction of the ITO substrate. The MEH-PPV molecule does not enter the interspace between ZnO nanorods completely according to SEM picture. It results in the small and bad contact area between ZnO nanorods and MEH-PPV. To improve the photovoltaic performance, we also fabricate another kind of photovoltaic (PV) device modified by N719 dye, and exploit the effect of N719. After the modification of ZnO nanorods by N719, not only Jsc increases from 0.257 mA/cm2 to 0.42 mA/cm2, but also Voc enhances from 0.37 V to 0.42 V. Insert LiF buffer layer between MEH-PPV and anode, Jsc of 1.05 mA/cm2 is obtained, and it is 2.5 times that the device without LiF.

High efficiency bulk heterojunction organic solar cell by using high conductivity modified PEDOT:PSS as a buffer layer

In this paper,bulk heterojunction solar cells with poly-(3-hexylthiophene)(P3HT):[6,6]-phenyl-C61-butyric-acid-methylester(PCBM) as an active layer and modified poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) as a buffer layer are fabricated.The buffer layer is modified by adding 1% to 5% dimethyl sulfoxide(DMSO) into PEDOT:PSS solution before spin-coating.The conductivity of modified PEDOT:PSS and the performance of solar cells with modified PEDOT:PSS are measured.The highest conductivity of modified PEDOT:PSS with 4% DMSO can achieve 89.693 S/cm.The performance of organic solar cell with PEDOT:PSS modified by 4% DMSO is the best.The 4% DMSOmodified-PEDOT:PSS cell has a power conversion efficiency of 3.34%,V oc of 5.7 V,J sc of 14.56 mA/cm 2 and filling factor(FF) of 40.34%.

Phosphoester modified poly(ethylenimine) as efficient and low cytotoxic genevectors

Cyclic phosphoester monomer ethyl ethylene phosphate (EEP) modified poly(ethylenimine) (PEI),denoted as PEI-EEP,was developed for gene delivery.Three PEI-EEP polymers were synthesized and their structures were characterized by 1H and 31P NMR methods.All the PEI-EEP polymers could condense DNA efficiently at N/P ratios higher than 0.5/1.The physiochemical characteristics of PEI-EEP/DNA complexes were analyzed by particle size and zeta potential measurements.The particle sizes of complexes were around 160–250 nm,and their zeta potentials were around 30–45 mV at the N/P ratios ranging from 10/1 to 50/1.In vitro cell viability and transfection ability were evaluated in HEK293 and HeLa cells using PEI as the control.The cytotoxicity of PEI-EEP and PEI-EEP/DNA complexes was lower than that of PEI and its complexes with DNA.The transfection efficiency of PEI-EEP/DNA complexes was correlated to modification degrees with phosphoester.When the modification of phosphoester to PEI was moderate,the PEI-EEP1/DNA and PEI-EEP2/DNA complexes exhibited comparable or even higher transfection ability than PEI/DNA complex at its optimal N/P ratio in the absence of serum.However,transfection efficiency of PEI-EEP3 reduced dramatically.More importantly,the PEI-EEP exhibited higher transfection efficiency in the presence of 10% serum than that without serum.Therefore,PEI-EEP polymers may be attractive vectors for non-viral gene therapy.