Photo-crosslinking of polymeric photobase generator bearing O-acyloxime moieties with low eliminating by-products and high sensitivity

O-Acyloximes are a class of photobase generators (PBGs) that release a primary amine upon irradiation. The generated amine can be used as a crosslinker for polymers bearing epoxy groups, providing a novel photo-induced crosslinking system. However, O-acyloximes also release a ketone by-product that migrates and exudes from the crosslinked polymer. To reduce the migration and elimination of the ketone, 4-vinylacetophenone O-phenylacetyloxime (PaVO) was proposed as a monomeric PBG, and its copolymer with glycidyl methacrylate (PaVO-co-GMA) was compared to poly(glycidyl methacrylate) (PGMA) containing acetophenone O-phenylacetyloxime (PaApO) as a molecular PBG (PaApO/PGMA). Film thickness, infrared (IR), and ultraviolet (UV) spectral changes upon irradiation clarified the vaporization of photoproducts from the PaApO/PGMA films, while such behavior was not observed for the PaVO-co-GMA films. Furthermore, when PaVO-co-GMA was blended with PGMA, less irradiation energy was required for its crosslinking when compared to that of PaApO/PGMA, which contained the same molar ratio of the O-acyloxime unit.     

Orientation of B-C-N hybrid films deposited on Ni (111) and polycrystalline Ti substrates explored by X-ray absorption spectroscopy

Orientation of sp²-bonded boron carbonitride (BCN) hybrid films has been investigated. The films were synthesized on Ni (111) and polycrystalline Ti substrates by radio frequency plasma enhanced chemical vapor deposition using tris-dimethylamino borane as a single-source molecular precursor. The deposition was performed at the radiofrequency power 400-800 W at the working pressure 2.6 Pa. Formation of sp²-BCN hybrids in the samples was confirmed by X-ray diffraction (XRD). In the XRD profile, the peak at 26.3° revealed formation of crystalline phase in the samples in which the lattice planes are separated from each other by around 3.5 Å. The D band at ~ 1350 cm^− 1 and the G band at ~ 1570 cm^− 1 in Raman spectra also suggested presence of graphite-like sp²-B-C-N hybrid bonds. The films were composed of different B-N, B-C, and C-N bonds to form sp²-BCN atomic hybrids confirmed by X-ray photoelectron spectra. Orientation and local structures of the films were studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The dominant presence of π* and σ* resonance peaks of the sp² hybrid orbitals in B K-edge NEXAFS spectra revealed preferred formation of sp²-BCN atomic hybrids around B atoms like-BN₃ configuration in respect to the plane of Ni (111) substrate. Different orientations were suggested on the basis of polarization dependence of B K-edge and N K-edge of the NEXAFS spectra.     

14-3-3beta protein associates with insulin receptor substrate 1 and decreases insulin-stimulated phosphatidylinositol 3'-kinase activity in 3T3L1 adipocytes

The 14-3-3 protein family has been implicated in growth factor signaling. We investigated whether 14-3-3 protein is involved in insulin signaling in 3T3L1 adipocytes. A significant amount of insulin receptor substrate 1 (IRS-1) was immunodetected in the immunoprecipitate with anti-14-3-3beta antibody at the basal condition. 100 nM insulin increased the amount of IRS-1 in the immunoprecipitate 2.5-fold. The effect of insulin was abolished by 100 nM wortmannin. An in vitro binding study revealed that glutathione S-transferase-14-3-3beta fusion protein directly associates with recombinant IRS-1. Pretreatment of recombinant IRS-1 with alkaline phosphatase clearly decreased this association. Because the recombinant IRS-1 was not phosphorylated on its tyrosine residues, the results suggest that serine/threonine phosphorylation of IRS-1 is responsible for the association. When the cells are treated with insulin, phosphatidylinositol 3'-kinase (PI3K) is supposed to complex either 14-3-3beta-IRS-1 or IRS-1. The 14-3-3beta-IRS-1-PI3K and IRS-1-PI3K complexes were separately prepared by a sequential immunoprecipitation, first with anti-14-3-3beta and then with anti-IRS-1 antibodies. The specific activity of the PI3K in the former was approximately half of that in the latter, suggesting that 14-3-3beta protein bound to IRS-1 inhibits insulin-stimulated lipid kinase activity of PI3K in 3T3L1 adipocytes.     

Effects of liquid–liquid phase separation on crystallization of poly(ethylene glycol) in blends with isotactic poly(methyl methacrylate)

To analyze the interplay between crystallization and liquid–liquid phase separation (LLPS), isothermal crystallization behavior of poly(ethylene glycol) (PEG) in blends with isotactic poly(methyl methacrylate) (i-PMMA) was investigated by differential scanning calorimetry (DSC). The blend system had an upper critical solution temperature (UCST) type phase diagram. When the crystallization occurred simultaneously with LLPS, the overall crystallization rate was enhanced at high crystallization temperatures T_c, relatively compared with that of neat PEG. This behavior was interpreted by the combination of the effects of spinodal quench depth ?T_s and usual supercooling degree ?T_c, according to the theory of Mitra and Muthukumar, namely, the crystallization rate is enhanced by the concentration fluctuation-assisted nucleation at high T_c. In the crystallization after LLPS proceeded, on the other hand, the overall crystallization rate was slow and less dependent on the blend composition. In addition, it was revealed by small-angle X-ray scattering measurements that amorphous i-PMMA was excluded from the interlamellar region of PEG crystals in SQ as well as WQ.     

Conductive fibers based on poly(ethylene terephthalate)–polyaniline composites manufactured by electrochemical polymerization

A novel method of manufacturing composite conductive fibers was developed through electrochemical polymerization with an apparatus consisting of insulating fibers, cotton fabrics as electrolytic solution holders, an electrolytic solution, and planer electrodes. By this method, poly(ethylene terephthalate) (PET) fibers coated with polyaniline (PAN) were prepared readily and yielded PET–PAN composite conductive fibers (PPCFs). The content of PAN in PPCFs increased with an increase in both the aniline concentration in the electrolytic solution and the polymerization voltage, although it did not depend on the load applied to the electrodes. Observations of the PPCF surface by scanning electron microscopy confirmed that the formation processes of PPCFs could be divided into three steps: (1) fine (nanometer‐size) granular PAN was generated from the anode and adsorbed onto the PET fiber surface, (2) the size of the granular PAN increased up to about 90 nm in a short time, and (3) the granular PAN was linked together to form networks. The conductivity of PPCFs increased with an increasing content of PAN networks. The surface resistance of the PPCF fabric was about 3 × 10⁵ Ω/□ at a PAN content of approximately 2 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1073–1078, 2003     

Decomposition characteristics of softwood lignophenol under hydrothermal conditions

Lignophenol is a novel lignin-based functional polymer. Hydrothermal decomposition of ligno-p-cresol derived from softwood (Douglas fir) was studied from 300 to 400 °C as a candidate technology for modification of the molecular structure and the recovery of monophenols. Ligno-p-cresol was promptly depolymerized probably by hydrolysis of aryl ether linkages and the half was converted to ether-soluble compounds at 300 °C for 10 min. With increasing temperature and reaction time, the yields of char and gas were increased, indicating the acceleration of carbonization and decomposition of monophenols. The monophenols obtained were mainly p-cresol and guaiacol. Their yields only exceed 10% at 365 °C and 60 min probably due to the inefficient pyrolysis of 1,1-bis aryl structures.     

Quasi-Drugs Developed in Japan for the Prevention or Treatment of Hyperpigmentary Disorders

Excess production of melanin or its abnormal distribution, or both, can cause irregular hyperpigmentation of the skin, leading to melasma and age spots. To date, various quasi-drugs that prevent or improve hyperpigmentary disorders have been developed and officially approved by the Ministry of Health, Labor and Welfare of Japan. Many of these inhibit the activity of tyrosinase, an enzyme required for melanin synthesis, for example, by competitive or non-competitive inhibition of its catalytic activity, by inhibiting its maturation, or by accelerating its degradation. In this review, we categorize the quasi-drugs developed in Japan to prevent or treat hyperpigmentary disorders, or both, and discuss perspectives for future development.     

UV‐curable positive photoresists for screen printing plate

One of the most interesting application areas of screen printing is the production of microelectronic devices. Although negative photoresists are commonly used for the screen printing plate, their resolution limit is about 30 µm. A higher resolution of resist patterns on the screen plate is essential for microelectronic device applications. This paper describes the novel design of a UV‐curable positive photoresist and its application to the screen printing plate. Positive patterns on the screen plate were obtained by conventional photolithography using a photomask and 365 nm light and the patterns were exposed to 254 nm light to enhance the mechanical strength of the resist patterns. It was essential to use photoacid generators sensitive to 365 nm and photoradical generators sensitive to 254 nm. A screen printing plate, which enabled the formation of 6 µm wide conductive lines, was developed. © 2016 Society of Chemical Industry     

Corrosion behavior of carbon steel coated with a zinc-rich paint containing metallic compounds under wet and dry cyclic conditions

The corrosion behavior of carbon steel coated with a zinc-rich paint containing two metallic compounds, Al₂(SO₄)₃ and CaO, as anticorrosive additives was examined under wet and dry cyclic corrosion test conditions. The zinc-rich paint coating without the two metallic compounds formed a white corrosion product and red iron rust on the surface after the corrosion test, whereas the coating with the metallic compounds showed reduced surface corrosion products. The corrosion current density of the painted steel substrate decreased drastically due to the incorporation of metallic compounds in the paint. The zinc-rich paint coating modified with the metallic compounds contained dispersed simonkolleite (Zn₅(OH)₈Cl₂·H₂O) phase and possibly very fine CaSO₄ particles, which remarkably improved the protectiveness of the zinc-rich paint coating.