Conversion of poly(ethylene‐alt‐tetrafluoroethylene) copolymers into polytetrafluoroethylene by direct fluorination: A convenient approach to access new properties at the ETFE surface

Direct fluorination of poly(ethylene‐alt‐tetrafluoroethylene) copolymer (ETFE) was carried out on commercially available ETFE films with pure fluorine gas at ambient atmosphere. Reaction temperature was either 95 °C or 150 °C and exposure time was 20 hours. Analysis of the fluorinated samples was performed by attenuated total reflection Fourier transform Infrared, confocal micro‐Raman and ¹H and ¹⁹F magic angle spinning nuclear magnetic resonance spectroscopies, scanning electron microscopy, electron diffraction and X‐Ray photoelectron spectroscopies, contact angle determination, atomic force microscopy and nanoindentation measurements, and compared to those of the virgin ETFE copolymer. Integrity of the bulk materials was verified by investigating the thermal behavior of the polymers by thermogravimetric analysis and differential scanning calorimetry. Evidence for the formation of a homogeneous layer of polytetrafluoroethylene with a thickness of several microns at the surface of the copolymers with no degradation of the materials was observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Biomimetic dopamine derivative for selective polymer modification of halloysite nanotube lumen

We demonstrate the use of a catecholic anchor (Dopa) for selective modification of the inner surface of an halloysite clay nanotube. Aqueous Dopa binds to alumina at the tube lumen and does not bind the silica surface under the same conditions. Selectivity of surface modification was evidenced using X-ray photoelectron spectroscopy (XPS) and (13)C solid state NMR spectroscopy. Surface-initiated atom transfer radical polymerization (SI-ATRP) was performed through selectively adsorbed Dopa to graft a layer of polymer brush into the nanotube lumen.     

Hydrogen production by conversion of methane over nickel-supported USY-type zeolite catalysts

Hydrogen production by conversion of methane over Ni-supported zeolite catalysts was investigated, and Ni-supported USY-type zeolite (Si/Al₂ = 14.0, 360) was found to have longer catalytic lifetime than Ni-supported silica (Cab-O-Sil) catalyst, which had been reported to have the longest catalytic lifetime for this reaction.     

Vis‐sensitive photopolymer containing vinyl ether compound and pyrromethene dye

A visible light(vis)‐sensitive photoresist based on the concept of chemical amplification was developed utilizing poly(p‐hydroxystyrene) (PHS), 2,2‐bis[4‐(2‐(vinyloxy)‐ethoxy)phenyl]propane (BPA‐DEVE) as a crosslinking agent, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIT) as a photoacid generator (PAG) and pyrromethene dyes such as 1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRH) and 2,8‐diethyl‐1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRE) and 3,3′‐carbonylbis(7,7′‐diethylaminocoumarin) (KCD). On irradiation with an argon ion laser, the photopolymer comprising PRH and PRE exhibited a high sensitivity of 65 and 46 mJ cm^?2, respectively. It is suggested that the sensitization mechanism of the pyrromethene dye/PAG system involves singlet electron transfer. The sensitivity of the photoresist increased with the decreasing molecular weight of PHS because of the high dissolution rate. Copyright © 2002 John Wiley & Sons, Ltd.     

Pyrromethene dye sensitized photopolymer—photochemical behavior in polymer matrix and application to photoresist for printed circuit board

The photochemical behavior of the visible light initiating system that consists of a sensitizing dye, 2,6‐diethyl‐8‐phenyl‐1,3,5,7‐tetramethylpyrromethene BF₂ complex (EPP), and a photoacid generator, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIOTf), was studied mainly by means of absorption and fluorescence spectrometry not in solution but in a polymer matrix which is a closer medium to the one currently employed in the field of photoresists. Excited singlet electron transfer from EPP to NIOTf was considered as the main reaction pathway in this system. The EPP/NIOTf system was applied to a photoresist for printed circuit board with an appropriate binder polymer which contains an acetal protection group. A pattern profile of the photoresist was exceedingly affected by the amount of photogenerated acids, their diffusion, and amine in the atmosphere. Finally, by controlling exposure energy and the post‐exposure bake (PEB) process, a photoresist with a high resolution (8 µm line and space) was obtained under argon ion laser irradiation. Copyright © 2006 John Wiley & Sons, Ltd.     

Negative‐working photoresist of methacrylate polymers based on the transesterification of the 2‐hydroxyethyl group in the presence of an acid

This article reports a novel crosslinking functionality of the 2‐hydroxyethyl methacrylate unit (HEMA) in the presence of an acid. The polymeric compositions, consisting of a polymer containing the HEMA unit and a photoacid generator, were insolubilized in an aqueous base developer on exposure to UV light and a successive baking process to provide a negative‐working photoresist. A series of poly(benzyl methacrylate‐co‐methacrylic acid‐co‐2‐hydroxyethyl methacrylate) terpolymers with various contents of HEMA were prepared to elucidate the photopolymeric characteristics. The polymer behavior in films was examined by a comparison of the photosensitivity and IR spectroscopic method. Experiments with a model compound were also carried out. On the basis of the results, we found that the resist was insolubilized by crosslinking through the transesterification of HEMA segments due to acid generated from the photoacid generator and subsequent heating. The advantage of using the 2‐hydroxyethyl group is that in the terpolymer, the HEMA unit is transparent at a short‐wavelength region and is a promising crosslinking unit for ArF lithographic photoresists. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1858–1867, 2002     

Super-liquid-repellent surfaces prepared by colloidal silica nanoparticles covered with fluoroalkyl groups

A simple and easy method to prepare super-liquid-repellent surfaces is proposed. Sol-gel films were prepared by hydrolysis and condensation of alkoxysilane compounds. Both surface energy and roughness were controlled using colloidal silica particles and fluoroalkylsilane. When the fractional amounts of both colloidal silica and fluoroalkylsilane were optimized in the films, the film surface exhibited repellency to both water and oil. Finally, it was shown that the method proposed here would be applied to a simple one-pot coating for a uniform large area, and be useful for practical use.     

Extended Hartree-Fock (EHF) theory of chemical reactions

The triplet-instability analysis of the closed-shell RHF solutions has been carried out in relation to the orbital and spin correlation effects for various transition structures (TS) and reaction intermediates. It is found that the RHF solutions even for cyclic transition states of the Woodward-Hoffmann symmetry-allowed reactions often involve the triplet instability, indicating the crucial role of correlation corrections. The di- and tetra-radical characters for the transition structures are calculated by the projected UHF (PUHF) solutions resulting from the instability. The spin projection is also crucial for the UHF Møller-Plesset (UMP) correlated wavefunctions obtained for the transition structures of 1,3-dipolar, Diels-Alder, ene and related reactions. The relative stability between cyclic and acyclic TS for these reactions is examined at the approximately projected UHF MP2 (APU MP2) level. The former is found to be more favorable than the latter if the correlation correction is taken into account for TS in a well-balanced manner.Dedicated to Professor J. Koutecký on the occassion of his 65th birthday     

Fischer-Tropsch synthesis over Ru/Al2O3 catalysts

Fischer-Tropsch syntheses (FTS) were carried out in a slurry phase over Ru/Al₂O₃ catalysts using hexadecane as a solvent. The outcome of the FTS was dependent on the oxide support, calcination temperature, synthesis gas composition and sulfur content. The addition of Mn/Na to Ru/Al₂O₃ was effective in raising the initial activity and C5+ selectivity, but after 20 hours, the performance of the modified catalyst was similar to that of the unmodified catalyst. An additional investigation involving the use of fresh vs used catalysts demonstrated that an agglomeration of the metallic Ru, at least in part, does occur during the reaction.