Photoinduced depolymerization in poly(olefin sulfone) films comprised of volatile monomers doped with a photobase generator

Photoinduced depolymerization of poly(olefin sulfone)s mixed with a photobase generating compound was investigated. Irradiation of 254 nm UV light to films comprising of a mixture of a photobase generating compound and poly(olefin sulfone)s with volatile monomers caused photoinduced depolymerization and the irradiated part of the film vaporized. The effect of the poly(olefin sulfone) structure on the photoinduced depolymerization process was investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Oblique waves lift the flapping flag

The flapping of the flag is a classical model problem for the understanding of fluid-structure interaction: How does the flat state lose stability? Why do the nonlinear effects induce hysteretic behavior? We show in this Letter that, in contrast with the commonly studied model, the full three-dimensional flag with gravity has no stationary state whose stability can be formally studied: The waves are oblique and must immediately be of large amplitude. The remarkable structure of these waves results from the interplay of weight, geometry, and aerodynamic forces. This pattern is a key element in the force balance which allows the flag to hold and fly in the wind: Large amplitude oblique waves are responsible for lift.     

Effect of metalloidal elements on corrosion resistance of amorphous iron-chromium alloys

Corrosion and electrochemical behaviours of amorphous iron-chromium alloys containing different sets of glass-forming metalloidal elements, boron, carbon, silicon and phosphorus, have been investigated. The corrosion resistance in 0.1N H₂SO₄ increases in the order of alloys containing silicon, boron, carbon and phosphorus, and the corrosion resistance in 3% NaCl increases in the order of alloys containing boron, silicon or carbon, and phosphorus. Difference in the corrosion resistance of amorphous alloys containing various metalloids has been interpreted in terms of the difference in the formation rate of the chromium-enriched protective film on the surface of alloys.     

Synthesis of gold nanoparticles modified with ionic liquid based on the imidazolium cation

The synthesis and processing of nanoparticles consisting of metallic nanocrystal cores and organic monolayer shells promise interesting technological applications. Here, we report the synthesis of gold nanoparticles modified with ionic liquids based on the imidazolium cation. Aggregation-induced color changes of the gold nanoparticles in an aqueous solution were used as an optical sensor for anions via anion exchange of ionic liquid moiety. We also demonstrated the phase transfer of the gold nanoparticles from aqueous media to ionic liquid.     

Synthesis and polymerization of phenylacetylene having two carbazole units and properties of the formed polymer

Novel carbazole‐containing acetylene monomer, 1‐(3‐ethynyl‐9‐carbazoyl)?4‐(9‐carbazoyl)benzene 1 was synthesized, polymerized, and copolymerized with phenylacetylene ( PA ) using [(nbd)RhCl]₂‐Et₃N, Rh⁺(nbd)[η⁶‐C₆H₅B^–(C₆H₅)₃], and WCl₆‐Ph₄Sn as catalysts. Polymers with number‐average molecular weights ranging from 7800 to 33,200 were obtained in 60%–quantitative yields. The absorption band edge of poly( 1 ‐co‐ PA ) ( 1 :PA = 8:2) was positioned at a wavelength longer than those of 1 and polyvinylcarbazole. Poly( 1 ‐co‐ PA ) ( 1:PA = 8:2) emitted fluorescence with 60% quantum yield. Poly( 1 ‐co‐ PA ) ( 1:PA = 8:2) worked as a hole transport material of an OLED with tris(8‐hydroxyquinoline)aluminum (Alq3) as an emission material. © 2015 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 2015 , 53, 1245–1251     

Syntheses of biphenyl‐terminated polyhedral oligomeric octasilicate‐core dendrimers and their single‐component optical transparent free‐standing thermoplastic films

2‐Biphenylethyl and 2‐biphenylhexyl‐terminated polyhedral oligomeric octasilicate (OS)‐core polyester‐typed dendrimers, denoted as OS‐C2‐BP and OS‐C6‐BP, respectively, were prepared by ring‐opening reaction and subsequent condensation of octakis(propenyl succinicanhydrido)polyhedral octasilicate (OS‐SA) with 2‐(4‐phenylphenoxy)ethanol (BP‐C2‐OH) and 6‐(4‐phenylphenoxy)hexanol (BP‐C6‐OH), respectively. OS‐C2‐BP formed a transparent film, whereas OS‐C6‐BP formed an opaque whitish waxy film. The coating film of OS‐C2‐BP was easily peeled off from a substrate and formed a free‐standing film. The results of X‐ray diffraction and differential scanning calorimeter suggest that the film of OS‐C2‐BP was amorphous, whereas OS‐C6‐BP contained crystalline domains. Thermogravimetric analysis of OS‐C2‐BP and OS‐C6‐BP showed 5 wt % weight losses at 362 °C and 283 °C, respectively. OS‐C2‐BP offered higher thermal resistance than OS‐C6‐BP. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1437–1443     

Preparation of microspheres by radiation-induced polymerization. II. Mechanism of microsphere growth

The effects of the monomer concentration were investigated on the preparation of diethylene glycol dimethacrylate (2G) microspheres by radiation-induced polymerization. The monomer concentration strongly affected the conversion and the shape of the microspheres. The particles were obtained in the range from 2 to 24 vol % of 2G monomer. The effective concentration for the preparation of monodisperse microspheres is around 10 vol %. Higher monomer concentrations up to 24 vol % gave rough surface particles. Considering the effects on the number of microspheres in the solution, the authors introduced the inhibiting region, where one microsphere disturbs the existence of another microsphere, and tried to explain the mechanism of the microsphere growth. The competition between the propagation and the crosslinking reactions is balanced to give the microspheres.     

Bioaccumulation of arsenic and its fate in a freshwater food chain

Accumulation, biomethylation and excretion of arsenic by an autotrophic freshwater alga, and the transport and transformation of the arsenic in the freshwater food chain [alga (autotroph)-moina (planktonic grazer) or shrimp (herbivore)-guppy (carnivore)] were investigated. These experimental results lead to the conclusion that total arsenic concentrations in organisms after accumulation from foods decreased one order of magnitude per elevation of the trophic level and biomethylation of the arsenic increased successively with an elevation in the trophic level. Predominant methylated arsenic species in moina and guppy were dimethyl- and trimethyl-arsenic compounds, respectively. Shrimp accumulated dimethyl- and trimethyl-arsenic compounds in nearly equivalent quantities. No or little monomethylarsenic compound was detected either in herbivores or carnivores.     

Oxidation polymerization of a charge‐transfer complex of 2,6‐bis(2‐thienyl)‐1,4‐dithiafulvene with 7,7,8,8‐tetracyanoquinodimethane

A π‐conjugated poly(α‐dithienylen‐dithiafulvene) ( 2 ) was obtained by the oxidation polymerization of 2,6‐bis(2‐thienyl)‐1,4‐dithiafulvene ( 1 ) as a dithiafulvene monomer derived from 4‐(2‐thienyl)‐1,2,3‐thiadiazole. When a solution of 1 in CHCl₃ was added to a stirred solution of FeCl₃ in CHCl₃, only the low‐molecular‐weight product 2 was obtained. The mixture was stirred for 15 h with an N₂ flow. The polymerization at higher temperatures resulted in polymers with large insoluble fractions. A higher molecular weight polymer was obtained by the oxidation polymerization of a charge‐transfer complex of 1 with 7,7,8,8‐tetracyanoquinodimethane (compound 3 ). In contrast to 2 , polymer 4 was readily soluble in dimethyl sulfoxide, dimethylformamide, and acetone and partially soluble in tetrahydrofuran and methanol and had a larger molecular weight (peak top molecular weight = 37,000). The conductivity of polymer 4 was 3 orders of magnitude larger than that of polymer 2 . © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6592–6598, 2005