Surface and interfacial segregation in blends of polystyrene with functional end groups and deuterated polystyrene

The effect of chain-end chemistry on surface and interfacial segregation in symmetric blends of polystyrene (hPS)/deuterated polystyrene (dPS) has been investigated by X-ray photoelectron and secondary ion mass spectroscopy in conjunction with neutron reflectivity measurements. Alpha,omega-fluoroalkyl- and alpha,omega-carboxy-terminated polystyrenes (alpha,omega-hPS(Rf)2 and alpha,omega-hPS(COOH)2) were used as end-functionalized polymers; the former possesses chain ends with lower surface energies, and the latter possesses higher surface energies compared with that of the main chain. In the case of an alpha,omega-hPS(Rf)2/dPS blend film, alpha,omega-hPS(Rf)2 was enriched at the surface owing to the surface localization of the Rf groups, although the surface energy of the hPS segments was slightly higher than that of the dPS ones. On the contrary, in the case of an alpha,omega-hPS(COOH)2/dPS blend film, dPS was preferentially segregated at the surface. This may be due to a surface depletion of COOH ends and an apparent molecular weight increase of alpha,omega-hPS(COOH)2 produced by a hydrogen-bonded intermolecular association of COOH ends in addition to the surface energy difference between hPS and dPS segments. Interestingly, both Rf and COOH chain ends were partitioned to the substrate interface for the alpha,omega-hPS(Rf)2/dPS and alpha,omega-hPS(COOH)2/dPS blend films, resulting in the segregation of the hPS component at the substrate interface for both blends. The results presented imply that surface and interfacial segregation in polymer blends could be regulated by incorporating functional groups into the end portions of one component.     

Wettability and antifouling behavior on the surfaces of superhydrophilic polymer brushes

The surface wettabilities of polymer brushes with hydrophobic and hydrophilic functional groups were discussed on the basis of conventional static and dynamic contact angle measurements of water and hexadecane in air and captive bubble measurements in water. Various types of high-density polymer brushes with nonionic and ionic functional groups were prepared on a silicon wafer by surface-initiated atom-transfer radical polymerization. The surface free energies of the brushes were estimated by Owens-Wendt equation using the contact angles of various probe liquids with different polarities. The decrease in the water contact angle corresponded to the polarity of fluoroalkyl, hydroxy, ethylene oxide, amino, carboxylic acid, ammonium salt, sulfonate, carboxybetaine, sulfobetaine, and phosphobetaine functional groups. The poly(2-perfluorooctylethyl acrylate) brush had a low surface free energy of approximately 8.7 mN/m, but the polyelectrolyte brushes revealed much higher surface free energies of 70-74 mN/m, close to the value for water. Polyelectrolyte brushes repelled both air bubbles and hexadecane in water. Even when the silicone oil was spread on the polyelectrolyte brush surfaces in air, once they were immersed in water, the oil quickly rolled up and detached from the brush surface. The oil detachment behavior observed on the superhydrophilic polyelectrolyte brush in water was explained by the low adhesion force between the brush and the oil, which could contribute to its excellent antifouling and self-cleaning properties.     

Formation and dichroism of poly(vinyl alcohol)–iodine complex in photocurable film

The formation of polyiodine complexes was investigated in a photocurable poly(vinyl alcohol) modified N‐methyl‐4(4′‐formylstyryl)pyridinium methosulfate acetal (PVA‐SbQ), which is a photofunctional group that causes photodimerization. PVA‐SbQ films with polyiodine complexes were prepared to be photocured, iodinated and soaked in a boric acid solution. The formation of PVA–polyiodine complexes was studied during iodinating and while in the boric acid treatment through UV–vis absorption spectrometry, resonance Raman spectrometry and IR absorption spectrometry. As a result, polyiodines were formed in the photocurable PVA‐SbQ films, and the formation of PVA–polyiodine complexes was enhanced by boric acid treatment. It was found that the SbQ‐ratio of PVA‐SbQ affects the formation of PVA–polyiodine complexes. The photocrosslinking by the dimerization of SbQ groups helps to form the PVA–I₅⁻ complex during the boric acid treatment. Based on this effect, we demonstrated a unique recording method by the PVA–polyiodine complex formation. The PVA‐SbQ film cured by the irradiation of the liner polarized light showed that dichroism of the PVA–polyiodine complexes formed after iodination. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of Zr-containing FSM-16 as an effective support for Co catalyst in the Fischer-Tropsch synthesis

Zr⁴⁺ ions have been introduced into the framework of FSM-16 using a sol-gel method at Si/Zr ≥ 200 (molar ratio). Co/Zr-FSM-16 showed high CO conversion and a high selectivity for C₅₊ hydrocarbons in the Fischer-Tropsch synthesis due to the high surface area of FSM-16 and the isomorphously substituted Zr⁴⁺ as a co-catalyst.     

Phase transition of alkylsilane monolayers studied by temperature-dependent grazing incidence X-ray diffraction

The phase transition of organosilane monolayers on Si-wafer substrate surfaces prepared from octadecyltrichlorosilane (OTS) or docosyltrichlorosilane (DOTS) was investigated on the basis of grazing incidence X-ray diffraction (GIXD) at various temperatures. The OTS monolayer was prepared by a chemisorption method. The DOTS monolayer was prepared by a water-cast method (DOTS). The GIXD measurement clarified that the OTS monolayer also changed from hexagonal phase to amorphous state above a melting point of otadecyl groups. The GIXD measurements also clarified that the molecular aggregation state of the DOTS monolayer changes from an anisotropic phase to an isotropic phase with an increase in temperature. An estimated linear thermal expansion coefficient of the lattice lengths of a and b of the DOTS monolayer in the rectangular crystalline state assigned a similar value to those of bulk polyethylene with an orthorhombic crystalline lattice. The setting angle of the ab plane of the rectangular DOTS monolayer also showed similar behavior to that of the ab plane of bulk polyethylene.     

Supramolecular network polymers formed from polyamidine and carboxy‐terminated telechelic poly(n‐butyl acrylate) via amidinium‐carboxylate salt bridges

We have prepared the amidinium‐carboxylate salt bridge‐based supramolecular network polymers from a carboxy‐terminated telechelic poly(n‐butyl acrylate) and a linear polyamidine having N,N′‐di‐substituted acetamidine group in the main chain. FTIR measurements indicated that the salt bridge was attributed to the three‐dimensional network formation. Virtually, no fluidity was observed for the blend containing equimolar amounts of the carboxyl group and the amidine group, which showed a high G′ value of about 1 MPa at ?5 °C. For comparison, the supramolecular network polymers crosslinked by ammonium‐carboxylate salt were prepared using a linear polyethyleneimine instead of the polyamidine. The blend with equimolar amounts of the carboxyl group and the secondary amino group showed liquid‐like fluidity with a G′ value of about 0.01 MPa at ?5 °C, which was attributed to the fact that a certain amount of the carboxyl group remained as its free form, as evidenced by FTIR analysis. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2148–2155     

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.     

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.