From superhydrophobic‐ to superhydrophilic‐patterned poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) architectures as a novel platform for biotechnological applications

The manufacture of three‐dimensional patterned electroactive poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) microstructures with tailored architecture, morphology, and wettability is presented. The patterned microstructures are fabricated using a simple, effective, low cost, and reproducible technique based on microfluidic technology. These novel structures can represent innovative platforms for advanced strategies in a wide range of biotechnological applications, including tissue engineering, drug delivery, microfluidic, and sensors and actuators devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1802–1810     

水热法制备二氧化钛微球的形貌控制及机理研究

以钛粉、Na OH和H2O2为原料,采用水热法成功制备出二氧化钛微球。利用X-射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和场发射扫描电镜(FESEM)对产物的结构、形貌和尺度进行了表征。结果表明,产物为金红石型Ti O2,微球的直径约为1~2μm,微球由许多纳米管组成。根据实验结果,讨论了二氧化钛纳米管的生长机理,初步研究了双氧水用量,水热温度以及煅烧温度等对产物形貌形成的影响。     

Synthesis,spectroscopic studies,thermal analyses,biological activity of tridentate-coordinated transition-metal complexes [M(L)X2] and crystal structure of [ZnBr2(2,6-bis(tert-butylthiomethyl)pyridine)]

A new terdentate acyclic pincer ligand, 2,6-bis(tert-butylthiomethyl)pyridine (tbtmp), was synthesized and reacted with several complexes of iron, zinc, nickel, cobalt, and copper. The ligand and its coordination compounds were characterized using elemental analysis, infrared, ¹H- and ¹³C-NMR-spectroscopy, thermal analyses, plus—for the Zn complex—single-crystal X-ray diffractometry. The structure of [Zn(L)Br₂] was solved in the tetragonal crystal system, chiral space groups P4₁2₁2 and P4₃2₁2 (No. 92 and No. 96, a = 947.2(1) pm, c = 2265.2(5) pm), revealing five-fold coordination of the metal atoms. According to spectroscopy, all complexes share the same coordination environment around the metal atoms, consisting of two halide anions and a sulfur-methylene-pyridine-methylene-sulfur entity; tbtmp acts as a tridentate ligand with the pyridine N atom and both tert-butylthio S atoms coordinating to the metal ions (NS2). The analysis results indicate that the metal ions are coordinated as distorted pseudo-bipyramids, LMX₂, with the chelate ligand meridionally arranged. One of the complexes contains ethanol as an additional ligand, resulting in a pseudo-octahedral coordination sphere [Ni(L)Cl₂EtOH]. The latter was obtained in the form of green crystals, which turn into a red powder with loss of the ethanol molecule. Fe (III), Co(II), Ni(II) and Cu(II) metal complexes [M(L)Cl₂] were screened for their antibacterial activity against B. subtilis G(+) and Escherichia coli G(−) bacteria, and fungus (Candida albicans and Aspergillus flavus).     

Morphology and microphase separation of star copolymers

Star copolymers have attracted significant interest due to their different characteristics compared with diblock copolymers, including higher critical micelle concentration, lower viscosity, unique spatial shape, or morphologies. Development of synthetic skills such as anionic polymerization and controlled radical polymerization have made it possible to make diverse architectures of polymers. Depending on the molecular architecture of the copolymer, numerous morphologies are possible, for instance, Archimedean tiling patterns and cylindrical microdomains at symmetric volume fraction for miktoarm star copolymers as well as asymmetric lamellar microdomains for star‐shaped copolymers, which have not been reported for linear block copolymers. In this review, we focus on morphologies and microphase separations of miktoarm (A_mB_n and ABC miktoarm) star copolymers and star‐shaped [(A‐b‐B)_n] copolymers with nonlinear architecture. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1–21     

Structural and Dielectric Properties of Polythiophene/Chrom(III) Acetylacetonate Composites

The dielectric and morphological properties of polythiophene (PT) filled with various mass fractions of chrom(III) acetylacetonate (Cr(acac)₃), synthesized via chemical oxidative polymerization, are described. Significant shifts of the absorption peak of the C-S bond in the Fourier transform infrared (FT-IR) spectra indicated that the metal cations mostly interacted with sulfur atoms. Thermal analyses performed by differential scanning calorimetry (DSC) indicated that the cold crystallization temperature (T_cc) of PT decreased with increasing doping level. Microstructural differences were observed between PT and its composites in scanning electron microscopy (SEM) images. Dielectric measurements showed that the conductivity of the PT significantly increased with increasing doping level, from ?10^?7 S/m to ?10^?4 S/m at 10 kHz and 300 K.     

Universal power law behavior of the AC conductivity versus frequency of agglomerate morphologies in conductive carbon nanotube‐reinforced epoxy networks

The Jonscher universal power law for ac conductivity versus frequency (f = ω/2π) in the dispersion region was tested for a multiwall carbon nanotube/epoxy nanocomposite. The effect of changes in agglomerate morphology on the fitting parameters A and n in the equation σ_{ac =} Aωⁿ was investigated. Changing nanotube agglomerate morphology was tracked by optical microscopy through curing. Evolving morphology was compared alongside ac conductivity obtained via a broadband dielectric spectrometer to elucidate possible physical meaning of the universal power law in the context of this system. The ?logA/n was unaffected by changes in agglomerate morphology affected during cure, yet connected with each other in their dependence on temperature. For this system, the relationship between the fitting parameters in the universal dynamic response equation remains empirical at this stage with regard to biphasic “texture” or morphology within such a network. Electrical conductivity σ versus frequency ω for a composite consisting of agglomerated multiwalled carbon nanotubes dispersed throughout a cured epoxy matrix was discovered to follow the empirical universal dynamic response equation of Jonscher. The frequency behavior of the exponent n is discussed in terms of underlying morphology throughout which charge carriers migrate. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1918–1923     

On standardization of low symmetry crystal fields

Standardization methods of low symmetry – orthorhombic, monoclinic and triclinic – crystal fields are formulated and discussed. Two alternative approaches are presented, the conventional one, based on the second-rank parameters and the standardization based on the fourth-rank parameters. Mainly f-electron systems are considered but some guidelines for d-electron systems and the spin Hamiltonian describing the zero-field splitting are given. The discussion focuses on premises for choosing the most suitable method, in particular on inadequacy of the conventional one. Few examples from the literature illustrate this situation.     

Charge transport properties of MDMO PPV thin films cast in different solvents

Charge transport properties in thin films of Poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylenevinylene) (MDMO PPV) cast using either chloroform (CF), toluene (TOL), or chlorobenzene (CB) as solvent were investigated. Hole mobility (μ) in these thin films measured using time‐of‐flight transient photoconductivity showed an increasing trend with respect to the solvent used in the same order, that is, μ_CF (2.4 × 10^?7 cm²/Vs) < μ_TOL (6.9 × 10^?7 cm²/Vs) < μ_CB (2.3 × 10^?6 cm²/Vs). Observed variations in mobilities were attributed to different morphologies of MDMO PPV chains in thin films cast using the aforesaid solvents. Nature of the interchain interactions and aggregate formation were obtained using photoluminescence (PL), Raman spectroscopy, and AFM studies. Ratio of PL peak intensities of 0–0 and 0–1 transitions, which is a direct measure of interchain interaction, was the highest in CB and lowest in CF. Variation in the relative intensities of out‐of‐plane wagging of vinylene group (～963 cm^?1 mode) in Raman spectra suggested different extent of coiling of polymer chains in these thin films. From these observations, it was elicited that aggregate size and interchain interactions are highest in CB and least in CF. AFM‐based topographic images of thin films further supported these variations in the size of aggregates. Variation in the aggregate sizes and interchain interactions explained the corresponding variation in the mobility. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1431–1439