X-ray diffraction study of poly-p-phenylene doped with SbF5 and SbCl5

X-ray diffraction experiments have been performed on SbF₅ and SbCl₅ doped PPP prepared by the Kovacic method. Results are discussed in terms of two structural models which account for the regular intercalation of dopants within the polymer crystal lattice.     

EPR study of polyaniline highly doped by p-toluenesulfonic acid

Magnetic, relaxation and electronic dynamic parameters of paramagnetic centers in crystalline domains of polyaniline highly doped by p-toluenesulfonic acid (PANI-PTSA) as well as PANI-PTSA dispersed in poly(methyl methacrylate) (PANI-PTSA/PMMA) were studied by the 3-cm (9.7 GHz) and 2-mm (140 GHz) wavebands EPR. At both wavebands these polymers demonstrate the Lorentzian single line with the Dysonian contribution indicating intrinsic conductivity of metal-like domains ca. 1500-4000 S/cm at room temperature. Effective conductivity of the polymer is defined by Q3D delocalization of charge carriers within such domains and their Mott variable range hopping between the domains dominating its micro- and macroscopic conductivity. It was shown that the interaction of the charge carriers with the lattice phonons governs the intradomain charge transfer at high temperatures. Dimensionality of the system increases with the polymer dispersion in an insulating matrix. Dipole-dipole interaction of polarons with oxygen biradicals reversibly changes the relaxation of the spins in the initial and dispersed polymers. These paramagnetic centers strongly interact below and weakly above critical temperature T_c of the phase transition that leads to an extremal temperature dependence of the polymer linewidth. The dependence of T_c on electron precession frequency and/or on the PANI-PTSA dispersion in an insulating matrix was revealed. Spin relaxation and dynamics were analyzed to be non-correlated with charge transfer in PANI-PTSA that contradicts the “single conducting chain” model and justifies the formation of Q3D metal-like domains.     

有机酸掺杂聚苯胺的研究进展

聚苯胺是一种非常有前途的导电聚合物。掺杂能提高聚苯胺的导电性、稳定性及其他性能,聚苯胺的掺杂受到了人们的广泛关注,尤其是有机酸的掺杂。有机酸种类众多且性能各异,能够使聚苯胺很多性质发生变化。本文重点综述了分别以单一有机酸、有机酸和金属氧化物、有机酸和无机酸、有机酸和其他无机物为掺杂剂合成聚苯胺的研究现状,详细介绍了各种掺杂态聚苯胺的性能及应用,简要介绍了影响聚苯胺性能的因素,并比较了不同掺杂态聚苯胺的优缺点。分析结果表明：与单一有机酸掺杂的聚苯胺相比,采用两种类型的掺杂剂共掺杂合成的聚苯胺具有更突出的性能及更大的应用前景。提出了采用两种或两种以上不同类型的掺杂剂共掺杂将是聚苯胺今后的主要研究方向。     

X-ray diffraction study of solvent-induced crystallization in polyester filaments

The present paper attempts to characterize the solvent—fibre interactions in oriented poly(ethylene terephthalate) filaments from measurements of the degree of crystallinity using wide-angle X-ray diffraction. It is shown that the solvent-induced crystallinity is dependent on the solubility parameter of the solvent. An increase in temperature has a favourable effect on the solvent-induced crystallization for most solvents. The degree of solvent-induced crystallinity is linearly related to the shrinkage of filaments. However, the crystallization of PET molecules can occur even if the shrinkage of filaments has been prevented.     

An instrument for the X-ray diffraction study of electrodes

An easily constructed reciprocating device for the X-ray examination of working electrodes is described, and an example is given of its application to the study of electrodeposited layers.     

Effect of water on inorganic acids doped polyaniline

Based on gravimetric measurements, the effect of water on thin films of inorganic acids doped polyaniline (PANI) was developed. The starting point was the fact that PANI coating on the electrode of quartz crystal microbalances (QCM) showed significant frequency shifts under exposure to liquid water. The changes in the frequency as a function of treatment time in water were quantitatively measured. These changes suggested that the mass decreases under water exposure were due to dopant ions release. The data have been collected using doped PANI films with HCl, H₂SO₄, and H₃PO₄. For PANI‐HCl upon immersion in water showed rapid mass loss followed by slow kinetically dopant ions release with time. However, PANI‐H₃PO₄ and PANI‐H₂SO₄ showed a slow kinetically release out of the film immediately upon immersion in water. The release process was well described by Fickian diffusion process. The diffusion coefficients (D) were determined and found to be dependent on the acid dopant utilized. They varied within the range of (1.68–14.7) × 10^‐14 cm²/s. This work presented an attempt to find a simple method based on the QCM for investigating the diffusion of dopant ions out of thin PANI films upon immersion in water and determining D. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

X-ray diffraction study of the structure of thin polyfluorene films

The molecular arrangement in thin films of poly(9,9-dioctylfluorene) and poly(9,9-dihexylfluorene) deposited on silicon substrates has been investigated with grazing incidence X-ray diffraction. In particular, the effect of the interface on the molecular orientation is highlighted. Both materials display a periodicity normal to the surface arising from stacked sheets of fluorene chains in both the crystalline and liquid crystalline phases. For the crystalline phase, a periodicity in the plane of the surface of 4.15 Å is observed corresponding to half the fluorene ring repeat distance along the backbone, consistent with interdigitating side-chains. For crystalline films deposited onto rubbed polyimide films, strong orientation effects are observed. In the liquid-crystalline phase, this strong in-plane ordering of backbones is lost. Poly(9,9-dihexylfluorene) exhibits an additional degree of ordering in the plane of the interface, which is likely to arise from hexagonal ordering of the backbone chains.     

X-ray diffraction study of phase transformation in hydrolyzed zirconia nanoparticles

The occurrence of metastable tetragonal (t′) phase and its transformation into monoclinic (m) in nanocrystalline ZrO₂ were systematically studied by using X-ray diffraction with respect to the grain size and processing conditions. The zirconia particles in the average size range 7–20 nm were prepared by hydrolyzis of zirconium oxy-chloride solution for different hydrolyzing periods. Drastic changes in grain size and the phase formation with the hydrolyzing time were observed. The amorphous ZrO₂ crystallizes in the t′ phase around 718 to 753 K on heating. However, if the crystallization occurs during the hydrolyzis itself, the monoclinic phase is formed even the grain size is less than 10 nm. The microstructural defects seem to dominate the grain size effect causing the reduction in crystal symmetry in the nanocrystalline zirconia obtained after 72 h of hydrolyzis. ©     

A study of branching in ethylene copolymers by X-ray diffraction

By slow cooling and annealing polyethylene a semiequilibrium crystallisation state is obtained. Under such crystallisation conditions changes in unit cell dimensions and crystallinities, as measured by X-ray diffraction, may be related to the size and number of branch groups in polyethylene copolymers. Thus methyl and ethyl groups may be accommodated within the crystalline lattice whereas butyl groups are not. The method may be used to determine the type and extent of branching in unknown ethylene copolymers.     

Structural study of cokes using optical microscopy and X-ray diffraction

Cokes exhibiting a range of optical texture from isotropie to anisotropic domains > 60 μm diameter were examined by X-ray diffraction. The variation of an optical texture index (OTI) with crystallite height and interlayer spacing was studied. The OTI varies little with the X-ray parameters for cokes whose optical texture is larger than medium-grained (1.5–5.0 μm) mosaic anisotropy. For cokes of smaller optical texture there is a sharp decrease in crystallite height and an increase in interlayer spacing. These results are discussed in terms of fluid mesophase removing defects in cokes of optical texture of size of coarsegrained mosaics and larger. The cokes of smaller optical texture are formed from less fluid mesophase which does not coalesce. Defects therefore remain in this anisotropic carbon of the coke so reducing crystallographic order.     

Proton NMR study on the molecular motion and conformation of polyaniline doped with HCl

Summary Proton NMR spectra and spin-lattice relaxation time (T₁) for polyaniline doped with HCl were measured at 90MHz over a temperature range of 110–430K. A narrow line with a width of about 1–2KHz superimposed on broad NMR peak was observed above 210K, and it was tentatively assigned to the protons in dopant and absorbed water. The analysis of linewidths and second moments for the broad lines reveal two distinct relaxation processes with activation energies of 1.9 and 7.8Kcal./mole,respectively. The former may be associated with the motion of the dopant and water absorbed and the latter with the rotation of benzoid ring about C-N bond axis. The second moment data suggest that the twist angle between the adjacent rings decreases with rising the doping ratio. Proton NMR relaxation rate was fitted with a theoretical equation containing the contributions from nuclear dipolar interaction and from electron-proton interaction, R_d and R_p, respectively.R_d is negligible below room temperature and R_p has little change above 100K. The total relaxation rate is dominated by R_p near room temperature.     

Studies on Cu+2 ion doped polyaniline

Cu⁺² ion doped polyanilines (PANI) were synthesized by oxidative polymerization of aniline using ammonium persulphate in presence of copper sulphate solution having varying Cu⁺² ion concentration. Products were characterized by UV?CVis and FTIR spectroscopy. Morphology of the products was observed by SEM. Morphology of the emeraldine-base form of PANI (EB-PANI) changed when doped with Cu⁺² ion and its concentration had also shown influence on the morphology. Thermal stability of the Cu⁺² doped PANI was found to be less than that of EB-PANI. Experimental results showed that Cu⁺² ions were successfully incorporated into the polymer and there was a strong interaction between the Cu⁺² ions and PANI chains. Formation of semiquinone segments (polaron species) upon coordination with Cu⁺² ions was undoubtedly demonstrated by UV?CVis and FTIR spectroscopic results. FTIR spectroscopy showed shifts towards the lower wavenumbers for the Cu⁺² ion doped PANI as compared to EB-PANI. An increase in intensity of the band at 1,130?cm^?1 was observed which corresponds to the electronic like absorption confirming the doping of EB-PANI. Crystallinity was studied by powder XRD analysis and it was found that Cu⁺² ion doped PANI has developed a crystalline structure while EB-PANI is amorphous. Conductivity was found to be dependent on the concentration of the Cu⁺² ions and there was an optimum concentration of Cu⁺² ions for getting the highest conductivity.     

Aspects of the conducting properties of nafion doped polyaniline

The Nafion doped polyaniline blends are prepared by a one-step method based on the codis-solution of a proton exchanged Nafion powder and polyemeraldine base in NMP. As determined by elemental analysis, the doping level of PAni is dependent on the number of sulphonate groups per aniline unit and reaches a maximum value of 0.4. TEM pictures reveal the electronic conducting polymer dispersion in the Nafion matrix. Ionic conduction and electronic transfers are examined by ac impedance spectroscopy. The dependence of the electronic conductivity of the material on the composition, the swelling rate and the temperature leads us to suggest the contribution to the bulk conductivity of transverse polarons and bipolarons stabilised by sulphonate groups.     

功能酸二次掺杂聚苯胺的防腐蚀性能

聚苯胺具有独特的掺杂脱掺杂特性,能在特定的反应条件下合成出形貌较好的纳米纤维,使得通过脱掺杂和二次掺杂能制备出拥有特殊防腐官能团的新型纳米材料。将硫酸体系中合成的聚苯胺纳米纤维经氨水脱掺杂,再用磷酸、对甲苯磺酸和酒石酸等功能酸在脱掺杂态聚苯胺基础上制备出二次掺杂态聚苯胺,测试了聚苯胺/环氧树脂复合涂层的防腐蚀性能,并与功能酸一次掺杂态聚苯胺进行了对比。结果表明,功能酸掺杂的聚苯胺都有一定的防腐蚀效果;功能酸二次掺杂态聚苯胺比一次掺杂态聚苯胺有更好的防腐蚀性能,二次掺杂态聚苯胺涂层拥有更高的阻抗,其中酒石酸二次掺杂态聚苯胺涂层的阻抗最高,浸泡120 d后为3.48×10⁷ Ω·cm²,较其一次掺杂态聚苯胺涂层高出一个数量级。     

X-ray diffraction study of some normal alkyl esters of long-chain acids

X-ray powder diffraction data are reported for 15 normal long-chain esters. The compounds represent all combinations of acid and alcohol where the acid portion is n-tetradecanoic, n-hexadecanoic, or n-octadecanoic acid, and the alcohol portion is n-tetradecanol, n-pentadecanol, n-hexadecanol, n-heptadecanol, or n-octadecanol. The individual compounds can be identified and distinguished by the diffraction data. Several of the esters have long spacings that are a linear function of the number of carbon atoms in the molecule and are consistent with a similar function for ethyl esters of long-chain acids. The remainder of the compounds crystallize in other polymorphic forms and therefore do not follow this function. Presented at AOCS Meeting, Philadelphia, October 1966. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Stress study of HFCVD boron-doped diamond films by X-ray diffraction measurements

Stress analysis on chemical vapor deposition (CVD) diamond films has demonstrated an apparent disagreement among various researchers in recent works even for similar deposition conditions. The type and the value of stress have shown a strong dependence on film thickness, which can be attributed to columnar growth and grain size and boundaries. X-Ray diffraction techniques appeared to be more suitable to study these effects and permit the evaluation of the average stress in larger sample areas when compared with micro-Raman spectroscopy, which feels a local strain inside the grains. In the case of boron-doped diamond films, boron incorporation on substitucional or interstitial sites can produce stresses according to the doping level. In order to investigate these effects, a series of diamond films were deposited on silicon (001) substrate in a hot filament (HF)-assisted CVD reactor at 800°C. The CH₄ flow is kept at 0.5 sccm for all experiments and the H₂ and B₂O₃/CH₃OH/H₂ flows are controlled in order to obtain the desired B/C ratios. Stress behavior in HFCVD boron-doped diamond films has been investigated by X-ray diffraction measurements using the sin² ψ technique. Tensile and compressive stresses have been observed and the thermal and intrinsic components have been calculated. The diamond films were characterized by scanning electron microscopy and Raman spectroscopy.     

X-ray diffraction study of the effect of microwave treatment of zeolite Na-A

The effect of microwave irradiation on zeolite Na-A has been studied in comparison with classical heat treatment. The thermal behavior and the structural transformations of the zeolite were investigated by X-ray powder diffraction. The structure of zeolite Na-A changed concurrently with microwave treatment. The longer the irradiation period, the larger was the amount of zeolite transformed into another crystalline phase (low-carnegieite), while a decreasing zeolite content remained detectable. On the other hand, during classical heat treatment at 400–800°C, zeolite Na-A went through subsequent structural changes; at about 800°C nepheline (NaAlSiO₄) crystallized as a stable phase along with a considerable amount of amorphous material.     

X-ray diffraction by aluminum soaps

Journal of the American Oil Chemists' Society -