Large-area bi-component processing of organic semiconductors by spray deposition and spin coating with orthogonal solvents

Micrometre-thick uniform layers of a polymeric semiconductor (poly(3-hexylthiophene), P3HT) have been fabricated from solution by spray deposition making use of a commercial airbrush. Multi-scale characterization by optical microscopy and atomic force microscopy revealed the formation of smooth layers featuring reproducible patterns of spatially correlated micron-sized holes. This morphology was found to be uniform over the whole sample surface, on millimetre scale. On this micro-patterned P3HT layer an orthogonal solvent (i.e. a solvent which does not dissolve the P3HT) has been employed to deposit either by spin coating or by drop casting a second organic semiconductor. While spin-coated films exhibited nano-crystals of an alkylated perylene tetracarboxy diimide (PDI) preferentially grown into the micro-fabricated holes, drop-cast films displayed crystalline PDI fibres adsorbed on the patterned surface in random positions. This work was supported by the ESF-SONS2-SUPRAMATES project, the German Science Foundation (Mu 334/28-1), the Regione Emilia-Romagna PRIITT Nanofaber Net-Lab as well as the EU through the projects Marie Curie EST—SUPER (MEST-CT-2004-008128) and the RTN PRAIRIES (MRTN-CT-2006-035810).     

Magnetic {Mo72Fe30}-embedded hybrid nanocapsules

Magnetic nanocapsules were constructed by fabricating nanometer scaled C₆₀-like “Keplerate” type {Mo₇₂Fe₃₀} with molecular formula [Mo₇₂^VIFe₃₀^IIIO₂₅₂(CH₃COO)₁₂{Mo₂O₇(H₂O)}₂{H₂Mo₂O₈(H₂O)}(H₂O)₉₁]ca.150H₂O into nanocapsule shells using the LbL technique. The morphology of the obtained hybrid nanocapsules was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Shell thickness of the {Mo₇₂Fe₃₀}-embedded nanocapsules can be tailored at the nanometer level more precisely than other nanoparticle-embedded capsules due to the homogeneous diameter and surface charges of {Mo₇₂Fe₃₀}. Interestingly, the {Mo₇₂Fe₃₀}-embedded nanocapsules could be separated and aligned under a circumstance of magnetic field, though {Mo₇₂Fe₃₀} is a paramagnetic molecule. This is the first time to fabricate hybrid magnetic materials containing {Mo₇₂Fe₃₀} using LbL technique. The obtained nanocapsules can be a good candidate for bioseparation as well as targeted delivery.     

原位凝聚法制备聚电解质微胶囊——模板中掺杂聚电解质量对微胶囊结构与性能的影响

通过在CaCO3制备过程中加入不同浓度聚苯乙烯磺酸钠(PSS)的方法来控制掺杂进CaCO3粒子中的PSS含量,得到了PSS掺杂量为4%～11%,尺寸均匀的CaCO3球形微粒.在微粒表面仅吸附一层聚烯丙基胺盐酸盐(PAH)后,用乙二胺四乙酸二钠(EDTA)使碳酸钙溶解;释放出的PSS与PAH原位凝聚制备得到了分散良好且完整的聚电解质复合物微胶囊.在所研究的范围内,模板微粒中PSS的含量对微胶囊的形态结构和性能没有明显影响.与传统的层层组装微胶囊相比,聚电解质复合物微胶囊有较好的热稳定性,但在高盐浓度下尺寸收缩程度较大.由于和层层组装微胶囊相比缺乏结合紧密的有序结构,原位凝聚法制备的微胶囊囊壁的截留分子量较大.     

A model for the Gibbs energy of aqueous solutions of polyelectrolytes

A new model for the excess Gibbs energy of aqueous solutions of polyelectrolytes is presented and applied for the correlation of the activity of water in aqueous solutions of polyelectrolytes without as well as with an added (single) salt. The model considers the phenomenon of counterion condensation, i.e., the partial dissociation of highly charged polyelectrolytes in water. Three parameters (a binary interaction parameter between polymer segments, the equilibrium constant of the dissociation reaction and a parameter which accounts for the polymer configuration) were fitted to the experimental results. The model allows for a reliable correlation of experimental results for the osmotic coefficient of aqueous solutions of a single polyelectrolyte (without as well as with an added salt).     

Correlation effects,image charge effects and finite size in the macro-ion-electrolyte system: A field-theoretic approach

We consider a model of a macro-ion surrounded by small ions of an electrolyte solution. The finite size of ionic charge distributions of ions, and image charge effects are considered. From such a model it is possible to construct a statistical field theory with a single fluctuating field and derive physical interpretations for both the mean field and two-point correlation function. For point-like charges, at the level of a Gaussian (or saddle point) approximation, we recover the standard Poisson-Boltzmann equation. However, to include ionic correlation effects, as well as image charge effects of individual ions, we must go beyond this. From the field theory considered, it is possible to construct self-consistent approximations. We consider the simplest of these, namely the Hartree approximation. The Hartree equations take the form of two coupled equations. One is a modified Poisson-Boltzmann equation; the other describes both image charge effects on the individual ions, as well as correlations. Such equations are difficult to solve numerically, so we develop an (a WKB-like) approximation for obtaining approximate solutions. This, we apply to a uniformly charged rod in univalent electrolyte solution, for point like ions, as well as for extended spherically symmetric distributions of ionic charge on electrolyte ions. The solutions show how correlation effects and image charge effects modify the Poisson-Boltzmann result. Finite-size charge distributions of the ions reduce both the effects of correlations and image charge effects. For point charges, we test the WKB approximation by calculating a leading-order correction from the exact Hartree result, showing that the WKB-like approximation works reasonably well in describing the full solution to the Hartree equations. From these solutions, we also calculate an effective charge compensation parameter in an analytical formula for the interaction of two charged cylinders. Electronic supplementary material  Supplementary material in the form of a doc file available from the journal web page at and are accessible for authorised users.     

The mechanism of the attracting acoustic radiation force on a polymer-coated gold sphere in plane progressive waves

Acoustic plane progressive waves incident on a sphere immersed in a nonviscous fluid exert a steady force acting along the direction of wave motion. It is shown here that when an elastic gold sphere is coated with a polymer-type (polyethylene) viscoelastic layer, this force becomes a force of attraction in the long wavelength limit. Kinetic, potential and Reynolds stress energy densities are defined and evaluated with and in the absence of absorption in the layer. Without absorption, the mechanical energy density counteracts the Reynolds stress energy density, which causes a repulsive force. However, in the case of absorption, the attractive force is predicted to be a physical consequence of a mutual contribution of both the mechanical and the Reynolds stress energy densities. This condition provides an impetus for further designing acoustic tweezers operating with plane progressive waves as well as fabricating polymer-coated gold particles for specific biophysical and biomedical applications.     

Can a difference in molecular weights cause an eruption in a driven flow of self-organizing immiscible system?

Driven flow of a non-equilibrium non-conservative (NENC) system with a mixture of immiscible particles (A,B of molecular weight M_A, M_B) exhibits self-organizing patterns (segregation, phase-separation, etc.) in steady-state. The flow response (v) of mass flux density (j) to bias (H), in steady-state is found to be sensitive to molecular weight ratio (α = M_B/M_A). While the flux density (j) responds linearly to bias for both components (A, B) at α = 1, onset of eruptive response occurs at extreme bias (H ↦ 1) at α > 1 where v ↦∞ for heavier (B) and v ↦- ∞ for lighter (A) constituents. Difference in molecular weights (M_A, M_B) is not only critical to eruptive flow but also in controlling the flow response prior to this crossover.     

Strain-induced grain growth in non-oriented electrical steels

The present work considers a method of columnar microstructure development in vacuum-degassed non-oriented electrical steels. Samples after temper rolling were annealed under special heat treatment conditions. The influence of the applied thermo-mechanical treatments on microstructure progress in the investigated non-oriented steels is studied. Columnar microstructure is obtained after combining the temper rolling and appropriate annealing conditions. The dependence of texture on the applied conditions was studied by EBSD facilities in the investigated material. It was confirmed that the obtained columnar microstructure possesses pronounced cube texture components.     

The amplification effect of functionalized gold nanoparticles on the binding of anticancer drug dacarbazine to DNA and DNA bases

The promising application of functionalized gold nanoparticles to amplify the performance of biosensors and relevant biomolecular recognition processes has been explored in this paper. Our observations illustrate the apparent enhancement effect of the gold nanoparticles on the electrochemical response of the anticancer drug dacarbazine (DTIC) binding to DNA and DNA bases, indicating that these functionalized gold nanoparticles could readily facilitate the specific interactions between DTIC and DNA/DNA bases. This raises the potential valuable applications of these biocompatible nanoparticles in the promising biosensors and biomedical engineering.     

Properties of NiO thin films deposited by chemical spray pyrolysis using different precursor solutions

NiO thin films have been deposited by chemical spray pyrolysis using a perfume atomizer to grow the aerosol. The influence of the precursor, nickel chloride hexahydrate (NiCl₂·6H₂O), nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O), nickel hydroxide hexahydrate (Ni(OH)₂·6H₂O), nickel sulfate tetrahydrate (NiSO₄·4H₂O), on the thin films properties has been studied. In the experimental conditions used (substrate temperature 350 °C, precursor concentration 0.2-0.3 M, etc.), pure NiO thin films crystallized in the cubic phase can be achieved only with NiCl₂ and Ni(NO₃)₂ precursors. These films have been post-annealed at 425 °C for 3 h either in room atmosphere or under vacuum. If all the films are p-type, it is shown that the NiO films conductivity and optical transmittance depend on annealing process. The properties of the NiO thin films annealed under room atmosphere are not significantly modified, which is attributed to the fact that the temperature and the environment of this annealing is not very different from the experimental conditions during spray deposition. The annealing under vacuum is more efficient. This annealing being proceeded in a vacuum no better than 10⁻² Pa, it is supposed that the modifications of the NiO thin film properties, mainly the conductivity and optical transmission, are related to some interaction between residual oxygen and the films.