直接甲醇燃料电池新型聚合物膜的研究

通过溶液共混方法，制备了聚偏氟乙烯与聚苯乙烯磺酸（PVDF－PSSA）、聚偏氟乙烯与Nafion(PVDF-Nafion)两种共混膜。研究了膜组成对膜电导率和甲醇透过率的影响。与NafionR117膜相比，PVDF－Nafion共混膜在Nafion含量为25wt%时，电导率σ下降2个数量级，而甲醇透过率P却降低3个数量级，若以（σ／P）为综合指标，则PVDF－Nafion共混膜和PVDF－PSSA共混膜的综合性能分别比NafionR117膜高约40倍、16倍。     

聚偏氟乙烯基含氟聚合物介电和储能研究进展

聚偏氟乙烯（PVDF）和偏氟乙烯（VDF）／三氟乙烯（TrFE）二元共聚物以其优异的铁电、压电性能而备受关注。近年来,该类聚合物经物理／化学改性后表现出非常优异的介电、储能性能,尤其在高储能放电电容器领域被寄予厚望。经分子组成优化和挤出拉伸处理的PVDF基含氟聚合物在室温下具有高介电常数（12～60）,高击穿电场强度,...     

改性聚偏氟乙烯接枝磺化聚(苯乙烯-co-丙烯酸)膜的研制

以过氧化苯甲酰(BPO)作引发剂,通过溶液接枝聚合法把苯乙烯/丙烯酸同时接枝到原硅酸钠改性的聚偏氟乙烯(PVDF)膜上,磺化后得到聚偏氟乙烯接枝磺化聚(苯乙烯-co-丙烯酸)膜(PVDF-g-P(SSA-co-AA)).研究了苯乙烯和丙烯酸的不同比例对膜的接枝反应及其相对湿度对膜电导率和含水量的影响.用傅立叶变换红外光谱(FTIR)检测原硅酸钠改性的PVDF膜经过接枝和磺化后所发生的结构变化,并用扫描电镜(SEM)观察PVDF膜接枝前后的形貌以及接枝磺化后产物PVDF-g-P(SSA-co-AA)膜的形貌及硫和硅分布.结果表明,原硅酸钠改性的PVDF膜与苯乙烯/丙烯酸同时发生接枝聚合反应,环境的相对湿度在20%～80%范围,对添加10wt%Na4SiO4的PVDF-g-P(SSA-co-AA)膜的电导率的影响基本不变,并达到0.0198S·cm-1.原硅酸钠改性的PVDF膜结构在接枝前后和磺化前后发生变化,确认磺化反应不只是在膜表面,同时渗入膜中进行.     

聚偏氟乙烯-稀释剂间介电常数差异对热致相分离法制膜微观结构的影响

采用1,4-丁内酯、邻苯二甲酸二甲酯、水杨酸甲酯、邻苯二甲酸二丁酯、三醋酸甘油酯和卡必醇醋酸酯作为稀释剂, 研究了在以热致相分离(TIPS)法制备聚偏氟乙烯(PVDF)微孔膜过程中, 聚偏氟乙烯-稀释剂间介电差异对PVDF膜微观结构的影响. 实验发现, PVDF-稀释剂间介电常数的差异与PVDF膜微观结构有一定关联. 当PVDF介电常数大于稀释剂的介电常数时, PVDF的分子间作用以引力为主导, PVDF分子易于聚集结晶, 形成松散球粒结构. 当PVDF介电常数与稀释剂的介电常数相近时, PVDF的分子间引力作用与斥力作用相均衡, 在淬冷条件下可形成近似双连续结构. 当PVDF介电常数小于稀释剂的介电常数时, PVDF分子间有一定的斥力效应, PVDF分子结晶困难.     

聚偏氟乙烯溶液法接枝苯乙烯磺酸膜的结构与形貌研究

以过氧化苯甲酰(BPO)作引发剂，通过溶液接枝聚合法把苯乙烯接枝到碱处理过的聚偏氟乙烯(PVDF)膜上，磺化后得到聚偏氟乙烯接枝苯乙烯磺酸(PVDF-g-PSSA)电解质膜。研究发现碱处理过的PVDF膜更容易与苯乙烯发生接枝聚合反应，且接枝率与碱处理时间呈线性变化关系。用红外光谱、差示扫描量热法检测PVDF膜经过接枝以及随后的磺化所发生的膜结构变化，并用SEM观察PVDF膜接枝前后以及接枝磺化后产物PVDF-g-PSSA膜的形貌及硫分布。研究表明，用KOH碱处理过的PVDF膜与苯乙烯进行接枝共聚反应时，PVDF膜结构在接枝前后和磺化前后发生变化，说明苯乙烯确实接枝到PVDF膜上。     

热处理对聚偏氟乙烯-酰胺类溶剂所制薄膜结晶行为的影响

使用红外光谱和偏光显微镜对PVDF(聚偏氟乙烯)-DMF(N,N-二甲基甲酰胺)和PVDF-DMAc(N,N-二甲基乙酰胺)体系结晶行为的研究表明,PVDF薄膜的结晶受制备溶剂,后期热处理温度和膜厚度等因素的影响;升高温度,β相含量减小;当温度低于90℃时,PVDF-DMF体系的F(β)值较DMAc体系大,在90~160℃之间则相反,且两种体系的F(β)值分别在约90℃和80℃发生“突变”;同时,结晶还明显受到薄膜厚度的影响,厚度大,结晶较完善.     

碱处理PVDF膜对制备高电导率质子交换膜的作用

燃料电池是一种高能量密度、低污染的新型能源. 质子交换膜是燃料电池的核心组件之一. 在对聚偏氟乙烯(PVDF)膜进行了碱处理改性的基础上制备了高电导率的聚偏氟乙烯接枝聚苯乙烯磺酸(PVDF-g-PSSA)质子交换膜, 对碱处理后的PVDF膜进行了傅立叶变换红外光谱(FTIR)、傅立叶变换拉曼光谱(FT-Raman)及电子自旋共振(ESR)分析. 振动光谱显示在处理后的膜中存在共轭碳碳双键. 首次用ESR检测到碱处理后的PVDF膜中形成了自由基, 其浓度在10¹⁶ spin/g. 研究表明碱处理引起的膜结构变化有利于接枝反应的进行, 对提高所合成的质子交换膜的电导率有重要作用, 电导率提高一个数量级, 至6.40×10^－2 S/cm.     

PMMA/PVDF共混对PVDF的β相构型影响的研究

采用溶液法制备了不同含量的聚甲基丙烯酸甲酯/聚偏二氟乙烯(PMMA/PVDF)共混薄膜,利用傅立叶变换红外光谱(FTIR)、X射线衍射谱(XRD)、和差热分析法(DSC)对共混薄膜的结晶行为进行了分析。结果表明,共混物中PMMA的含量对PVDF的β相构型有明显影响:PMMA/PVDF=30/70共混物中β相含量最高。为提高PVDF薄膜的铁电性能提供了新的研究方法。     

马钱子碱分子结构和振动光谱的密度泛函理论研究

用密度泛函理论B3LYP/6-31G*方法对天然药材马钱子中的生物碱马钱子碱的几何构型进行了优化,得到马钱子碱分子的平衡结构参数,并同实验结构进行了比较.计算了上述分子在平衡构型下的振动谐力场和振动基频.针对不同的振动模式,提出了相应的校正因子,并据此对计算频率进行了校正.理论计算和实验测定频率的平均误差为19.0cm-1.根据DFT计算的振动模式和IR光谱强度值对目标分子的实验振动基频进行了完善的和合理的指认和解释.     

纳米Fe3O4/PVDF磁性复合膜的原位制备及表征

通过膜相渗透原位化学沉积法制备了聚合物基Fe3O4/聚偏氟乙烯（PVDF）磁性纳米复合膜，研究了复合膜制备的适宜条件，采用红外光谱（FT-IR）、差热分析（DSC）、X射线衍射、扫描电镜（SEM）等手段对复合膜的组成、结构进行了表征和分析，通过气体渗透法测定了复合膜的孔径随制备条件的变化情况. FT-IR和XRD图谱结果表明，在基膜中原位生成Fe3O4后不影响基膜PVDF的分子结构；复合膜中的Fe3O4粒子尺寸为68 nm左右，复合膜的磁化率达0.044 cm3•g－1；复合膜的磁化率、平均孔径、最大孔径及孔径分布范围随反应条件的改变而有明显变化.     

亚碘酰苯低聚物的结构与振动光谱18O-同位素效应的理论研究

应用LDA-PWC方法对亚碘酰苯低聚物HO-(PhIO)n-H (n＝1～10)(链末端以羟基结束)共10个模型分子进行了理论研究. 计算结果表明PhIO分子链大致呈“T”形, I—O链的两个I—O键键长非常接近, 同时发现I—O链产生扭转, 整个亚碘酰苯低聚物呈螺旋状结构. 应用B3LYP法得到HO-(PhIO)6-H更为精确的亚碘酰苯低聚物稳定构型, 平均I—O键长为0.2089 nm, 标准偏差为0.0007 nm. 理论计算表明在600～400 cm－1段, PhI18O的吸收峰向低波数方向移动, 与实验观测结果一致. 振动模式分析发现该段吸收峰均涉及氧原子, 18O同位素效应将降低各振动峰值的频率. 峰值移动最大的吸收峰为591/566 cm－1 (16O/18O), 与之对应的理论计算值为590.409/557.788 cm－1 (16O/18O), 属于对称伸缩振动ν(I—O—I). 吸收峰(443/436 cm－1)对应的理论计算值为460.627/439.158 cm－1 (16O/18O), 归属于不对称伸缩振动ν(I—O—I).     

FT-IR, FT-Raman, NMR and UV-vis spectra, vibrational assignments and DFT calculations of 4-butyl benzoic acid

The solid phase FTIR and FT-Raman spectra of 4-butyl benzoic acid (4-BBA) have been recorded in the regions 400-4000 and 50-4000cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for monomer and dimer by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities. (13)C and (1)H NMR spectra were recorded and (13)C and (1)H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was recorded in the region 200-400nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities, chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule.     

Experimental and theoretical investigation of the molecular and electronic structure of anticancer drug camptothecin

The Fourier Transform Infrared spectrum of (S)-4 ethyl-4-hydroxy-1H-pyrano [3',4':6,7]-indolizino-[1,2-b-quinoline-3,14-(4H,12H)-dione] [camptothecin] was recorded in the region 4000-400 cm(-1). The Fourier Transform Raman spectrum of camptothecin (CPT) was also recorded in the region 3500-50 cm(-1). Quantum chemical calculations of geometrical structural parameters and vibrational frequencies of CPT were carried out by MP2/6-31G(d,p) and density functional theory DFT/B3LYP/6-311++G(d,p) methods. The assignment of each normal mode has been made using the observed and calculated frequencies, their IR and Raman intensities. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. Most of the computed frequencies were found to be in good agreement with the experimental observations. The isotropic chemical shifts computed by (13)C and (1)H NMR analysis also show good agreement with experimental observations. Comparison of calculated spectra with the experimental spectra provides important information about the ability of computational method to describe the vibrational modes of large sized organic molecule.     

NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of nicotinic acid N-oxide: A combined experimental and theoretical study

In this work, the experimental and theoretical UV, NMR, and vibrational features of nicotinic acid N-oxide (abbreviated as NANO, C(6)H(5)NO(3)) were studied. The ultraviolet (UV) absorption spectrum of studied compound that dissolved in water was examined in the range of 200-800nm. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400cm(-1) and 3500-50cm(-1), respectively. The (1)H and (13)C NMR spectra in DMSO were recorded. The geometrical parameters, energies and the spectroscopic properties of NANO were obtained for all four conformers from density functional theory (DFT) B3LYP/6-311++G(d,p) basis set calculations. There are four conformers, C(n), n=1-4 for this molecule. The computational results identified the most stable conformer of title molecule as the C1 form. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. (13)C and (1)H nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies, were performed by CIS approach. Finally the calculation results were applied to simulate infrared, Raman, and UV spectra of the title compound which show good agreement with observed spectra.     

CO2二聚体分子弱结合作用的DFT计算

用密度泛函理论(DFT)的Becke 3LYP方法,在不同基集合（6 31G和6 311G系列）下对平行结构（C 2h）和T形结构(C2v)的CO2二聚体进行ab initio计算.通过计算,得到了CO2二聚体C2h和C2v两种构型的结构参数和离解能,并给出了CO2二聚体相对稳定构型C2h的12个正则振动分析图.结果表明,CO2二聚体的离解能为2 kJ•mol－1,CO2分子之间振动频率很小,从而说明CO2二聚体是弱结合分子.     

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular geometry of butylated hydroxy toluene

The FT-IR spectrum of 2,6-di-tert-butyl-4-methylphenol [butylated hydroxy toluene] was recorded in the region 4000-400 cm(-1). The FT-Raman spectrum of butylated hydroxy toluene was also recorded in the region 3500-50 cm(-1). The molecular structure and vibrational frequencies of butylated hydroxy toluene (BHT) have been investigated with combined experimental and theoretical study. Two stable conformers of the title compound were obtained from the result of geometry optimizations of these possible conformers. The conformer 1 is (approximately 2.6 kcal/mol) more stable than conformer 2. Geometry optimizations and vibrational frequency calculations were performed by BLYP and B3LYP methods using 6-31G(d), 6-31G(d,p) and 6-31+G(d,p) as basis sets. The scaled frequencies were compared with experimental spectrum and on the basis of this comparison; assignments of fundamental vibrational modes were examined. Comparison of the experimental spectra with harmonic vibrational wavenumbers indicates that B3LYP/6-31G(d) results are more accurate. Predicted electronic absorption spectra of BHT from TD-DFT calculation have been analyzed and compared with the experimental UV-vis spectrum. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule.     

Ab initio-based all-mode two-dimensional infrared spectroscopy of a sugar molecule

To construct two-dimensional infrared (2D IR) spectra having all vibrational modes of a molecule included is still quite challenging, both experimentally and theoretically. Here we report an ab initio-based all-mode 2D IR spectra simulation approach. Using deuterated glycolaldehyde (CH2OHCDO), the smallest sugar as a model molecule, we have calculated correlation 2D IR spectrum of its entire 3N-6 (N=8) normal modes in the mid-to-far-IR region (4000-0 cm(-1)), using quantum chemical anharmonic frequency and anharmonicity computations in conjunction with time-domain third-order nonlinear response functions. The calculated 2D IR spectra were found to contain a network of structural and dynamical parameters of the molecule. It is found that certain spectral regions, once enlarged, show features that are in reasonable agreement with limited but already available single- and dual-frequency 2D IR experimental results. The extension of narrow-band 2D IR spectroscopy into the full mid-to-far-IR regime would allow us to characterize the structural distributions and dynamics of molecular complexes in condensed phases with sufficient number of parameters.     

Communication: Probing non-equilibrium vibrational relaxation pathways of highly excited C≡N stretching modes following ultrafast back-electron transfer

Fifth-order nonlinear visible-infrared spectroscopy is used to probe coherent and incoherent vibrational energy relaxation dynamics of highly excited vibrational modes indirectly populated via ultrafast photoinduced back-electron transfer in a trinuclear cyano-bridged mixed-valence complex. The flow of excess energy deposited into four C≡N stretching (ν(CN)) modes of the molecule is monitored by performing an IR pump-probe experiment as a function of the photochemical reaction (τ(vis)). Our results provide experimental evidence that the nuclear motions of the molecule are both coherently and incoherently coupled to the electronic charge transfer process. We observe that intramolecular vibrational relaxation dynamics among the highly excited ν(CN) modes change significantly en route to equilibrium. The experiment also measures a 7 cm(-1) shift in the frequency of a ～57 cm(-1) oscillation reflecting a modulation of the coupling between the probed high-frequency ν(CN) modes for τ(vis) < 500 fs.     

Spectroscopic (NMR, UV, FT-IR and FT-Raman) analysis and theoretical investigation of nicotinamide N-oxide with density functional theory

The spectroscopic properties of the nicotinamide N-oxide (abbreviated as NANO, C(6)H(6)N(2)O(2)) were examined by FT-IR, FT-Raman, NMR and UV techniques. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. The (1)H and (13)C NMR spectra were recorded in DMSO. The UV absorption spectrum of the compound that dissolved in water was recorded in the range of 200-800 nm. The structural and spectroscopic data of the molecule in the ground state were calculated by using Density Functional Theory (DFT) employing B3LYP methods with the 6-311++G(d,p) basis set. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The optimized structure of compound was interpreted and compared with the reported experimental values. The observed vibrational wavenumbers, absorption wavelengths and chemical shifts were compared with calculated values. As a result, the optimized geometry and calculated spectroscopic data show a good agreement with the experimental results.     

Infrared and ab initio studies of conducting molecules: 2,5-diamino-3,6-dichloro-1,4-benzoquinone

2,5-Diamino-3,6-dichloro-1,4-benzoquinone has been synthesized by modifying the procedure reported in literature. Its IR spectrum has been recorded in the solid phase in the range 4000-400cm(-1). Ab initio calculations have been performed using Gaussian '03 program to compute optimized geometry, harmonic vibrational frequencies along with intensities in IR and Raman spectra and atomic charges at RHF/6-31+G*, B3LYP/6-31+G* and B3LYP/6-311++G** levels. To make vibrational analysis Gaussian View software was used. The optimized molecular structure is found to possess C2h point group symmetry. The observed IR frequencies have been assigned to different modes taking C2h molecular symmetry with the help of pictorial view of normal modes. From the magnitude of the observed frequencies corresponding to the NH2 stretching motions an indication of H-bonding is noticed. From geometrical parameters of the molecule it appears that two parallel sets of conjugated strands are formed in this molecule providing a route to conduct charges. The N-H bonds facing towards chlorine atoms are found to be shorter than those facing towards oxygen atoms indicating the presence of H-bonding between hydrogen atom of an NH2 group and carbonyl (quinoid) oxygen atom.