Poly(phenylene oxide) copolymer anion exchange membranes

Poly(phenylene oxide) block and random copolymers are synthesized by oxidative polymerization of 2,6-dimethylphenol and 2,6-diphenylphenol for potential alkaline exchange membrane application. The copolymers are functionalized on the methyl substituted repeat units through a two-step process to produce pendent quaternary ammonium cationic groups. The amount of quaternary ammonium cations and the ion exchange capacity are quantified through titration measurements. Ionic conductivity of the copolymer membranes is measured by electrochemical impedance spectroscopy. Block copolymers show increased bromide conductivity at higher ion exchange capacities compared with the random copolymer analogs. The bromide conductivity for a block copolymer film with an ion exchange capacity of 1.27 mequiv/g reaches 26 mS/cm at 90 °C and 95% relative humidity. The hydroxide conductivity for the same film was measured to be 84 mS/cm at 80 °C and 95% relative humidity. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1770–1778, 2013     

Easy and effective method to produce functionalized particles for cellular uptake

In this contribution, a versatile approach for the synthesis of functionalized particles for drug delivery is presented, using two nonaggressive standardized procedures. The first procedure considered is the functionalization of an azido‐terminated α‐norbornenyl poly(ethylene oxide) (PEO) macromonomer with an alkyne‐containing active molecule via the copper catalyzed azide alkyne cycloaddition, click type reaction. The functionalized macromonomer is then polymerized by Ring‐Opening Metathesis Polymerization (ROMP) in dispersion to form functionalized particles. The second procedure consists in synthesizing particles by ROMP in dispersed media of norbornene with azido‐terminated α‐norbornenyl PEO macromonomer. The ROMP was initiated by the first generation Grubbs catalyst. Such functionalized core‐shell particles have stealthy properties due to their PEO shell and can be viewed as universal nanocarriers on which any alkyne‐modified active molecule can be grafted by click chemistry. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

(Mg(BH_4)_2)_n团簇结构与性质的密度泛函理论研究

采用了密度泛函理论中的杂化密度泛函B3LYP方法,在6-31G*基组水平上对[Mg(BH_4)_2]_n(n=1-3)团簇的结构进行了优化,几何结构优化时自旋多重度取了1、3、5等多种情况进行计算.最后对最稳定结构的振动特性、成键特性、电荷特性和稳定性等进行了研究.结论表明:团簇最稳定结构易形成链状结构,其中Mg-B键长为0.210～0.253 nm,-BH_4基中靠近Mg原子处的B-H键长约为0.125 nm、远离Mg原子处的B-H键长为0.119 nm.对比团簇和晶体的光谱结构表明,-BH_4基在团簇和晶体中结构基本一致. Mg原子的自然电荷在1.687～1.757e之间,B原子的自然电荷在-0.702～-0.788e之间,H原子基本不参与电荷转移,其自然电荷在-0.094～0.070e之间.团簇中Mg原子和-BH_4基之间相互作用呈现较强的离子性,Mg(BH_4)_2团簇具有相对较高的动力学稳定性.     

Pico-second photoelectric characteristic in manganite oxide La0.67Ca0.33MnO3 films

Ultrafast photoelectric characteristic has been observed in La_0.67Ca_0.33MnO₃ films on tilted SrTiO₃ substrates. A pico-second (ps) open-circuit photovoltage of the perovskite manganese oxide films has been obtained when the films were irradiated by a 1.064μm laser pulse of 25 ps duration. The rise time and full width at half-maximum of the photovoltage pulse are ～300 ps and ～700 ps, respectively. The photovoltaic sensitivity was as large as ～500 mV/mJ.     

Au_nAg_m~-(n+m=2～4)负离子团簇光脱附电子谱计算

利用密度泛函理论,通过几何优化和态密度计算了Au_nAg_m^-（n+m=2～4）团簇的光电子光谱,结果显示只有Au₂Ag₂^-团簇的第一个峰发生了0.5eV的红移,而其它团簇的峰位置符合的很好,因此理论计算给出的团簇结构是合理的.     

AunLa(n=1~8)团簇的密度泛函研究简

采用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法,在LANL2DZ基组水平上研究了Aun La(n=1~8)团簇的几何结构.计算并讨论了基态结构稳定性及电子性质.结果表明,当n=3-8时,基态结构均为三维结构且La原子趋向与更多的Au原子结合.团簇二阶能量差分,能隙和化学硬度计算结果显示除了AuLa外,具有偶数数目的团簇比奇数数目的团簇具有更好的稳定性,其中,Au3La团簇的稳定性相对较好.     

机械抛光铜金属表面对罗丹明的荧光增强效应

应用激光光谱学方法,研究了铜表面Rh6G分子的荧光增强效应对于金属衬底表面所形成的氧化层的依赖关系,探索了由于空气氧化而形成的氧化层在表面荧光增强效应中的重要意义和作用机理.实验采用罗丹明6G荧光探针分子,在532 nm连续光激发下,研究机械抛光铜金属衬底在经历不同氧化时间,对吸附其表面的Rh6G分子的荧光增强效果.研究结果表明,适当控制金属样品表面的氧化时间,金属铜表面对若丹明分子的荧光发射表现出猝灭和增强效应.金属氧化层起到了隔离荧光分子与金属表面的作用,减弱了由于激发态荧光分子向金属转移非辐射能量和在金属表面诱导反向偶极子而产生的荧光猝灭效应,从而提高了纯金属铜表面荧光增强辐射行为.因此在微纳金属衬底的荧光增强效应研究中,采用适当的实验手段,精确控制隔离层间距,是表面增强光谱获取的重要途径之一.     

Density functional theory study on Ni-doped MgnNi (n=1-7) clusters

The possible geometrical and the electronic structures of small MgnNi(n = 1-7) clusters are optimised by the density functional theory with a LANL2DZ basis set.The binding energy,the energy gap,the electron affinity,the dissociation energy and the second difference in energy are calculated and discussed.The properties of Mg n Ni clusters are also discussed when the number of Mg atom increases.     

高压下固相硝基甲烷分解的分子动力学计算

基于ReaxFF, 采用NVT系综和Berendsen方法对0–7 GPa时和2500 K时固相硝基甲烷的 分解过程进行分子动力学计算, 通过分析硝基甲烷发生分解反应生成的碎片数量随时间的变化, 对不同压强下硝基甲烷的分解机理进行研究. 计算结果表明在0–3 GPa时, 初始分解路径为C–N键断裂和硝基甲烷的异构化; 在4–7 GPa 时, 初始分解路径为分子间质子转移和C–N, N–O键的断裂; 在硝基甲烷的第二阶段反应中存在H₂O, NO, NO₂, HONO, 硝基甲烷分子自身的催化反应. 硝基甲烷在高温高压下发生热分解反应生成碳团簇, 且团簇中碳原子的数量和碳团簇的空间构型随着压强的变化而变化. 关键词： ReaxFF 分子动力学 热分解 压强效应 碳团簇     

Synthesis of Acrylamide Molecularly Imprinted Polymers Immobilized on Graphite Oxide through Surface-Initiated Atom Transfer Radical Polymerization

A novel acrylamide (AA) molecularly imprinted polymer was synthesized by atom transfer radical polymerization (ATRP) on graphite oxide (GO) particles. Propionamide (PAM) was used as a dummy template molecule, hydroxy ethyl acrylate (HEA) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a crosslinking agent, and acetonitrile as both solvent and dispersion medium. Scanning electron microscopy (SEM) images and infrared spectroscopy (IR) confirmed that the molecularly imprinted polymers (MIP) were successfully grafted onto the surface of the GO particles. The corresponding adsorption kinetic curves and adsorption isotherms showed that the AA adsorption reached equilibrium after 5 h, with large amounts of AA being adsorped in the first 100 min. The maximum AA adsorption capacity was 123.48 µmol g^?1 according to Scatchard analysis, which indicated that the MIP possesses good AA adsorption capacity. This MIP-GO material was used to selectively determine AA in fried food samples.