Advanced Materials Research Vols. 11-12

Abstract: Monodispersed poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM/AAc) microgels with acrylic acid (AAc) and N,N’-methylenebisacrylamide (MBAAm) were prepared by surfactant-free emulsion polymerization. It was found for the PNIPAM microgel that bovine serum albumin (BSA) could be loaded and released depending on temperature. The microgel of PNIPAM/AAc showed that the uptake and release of BSA was controlled by both pH and temperature.

Abstract: Inner surface of capillary plates (CP) was coated with TiO2 to fabricate a micro-channel reactor with 6-μm diameter. Titania sol was used to coat the surface of channel wall of CP and then it was calcined at 400°C for 4 h. The photocatalytic micro-channel reactors were evaluated by measuring the decomposition rate of methyleneblue (MB) in aqueous solution circulating at the rate ranging from 1.2 to 5.8 cm3 min-1. The TiO2-coated CP showed a larger efficiency in decomposing MB solution, comparing with the previously reported reactor using porous ceramics. The reaction rate increased with the flow rate, while it decreased at higher flow rates for the previous reactor.

Abstract: We have attempted phase identification of carbon nanosized powders prepared by pulsed wire discharge (PWD) to clarify the cooling process of PWD plasma. To prepare the carbon nanosized powders, carbon fibers were discharged in nitrogen gas at 26 – 101 kPa by PWD. Volume fractions of phases in the carbon nanosized powders were analyzed by thermogravimetric analysis and powder X-ray diffraction. The volume fraction of amorphous carbon, which must be formed by quenching of carbon plasma, was increased with increasing nitrogen gas pressure. This result suggested that the cooling rate of PWD plasma increased with increasing ambient gas pressure.

Abstract: Chromium magnesium oxynitride ((Cr,Mg)(N,O)) thin films have been prepared by pulsed laser deposition (PLD) method with changing the surface area ratio of Mg target (SR) from 0 to 100 %. As a result of the analysis by energy dispersive X-ray spectroscopy (EDX), it was found that magnesium content in the total metallic elements (Cr1-x, Mgx) are controlled by changing SR from 0 to 100 % to be the x ranging from 0 to 1.0. Since the crystal structure of main phase in all thin films was found to be NaCl type, the XRD results showed that the thin films were mainly consisted of (Cr,Mg)(N,O). The hardness of (Cr,Mg)(N,O) thin films were increased almost linearly up to SR = 50 %, above which it decreases rapidly. The maximum Vickers hardness (HV) of 3600 was obtained for the thin film which was prepared by SR = 50 %, and the minimum HV of 1650 was obtained for the thin film which was prepared by SR = 100 %.

Abstract: A pulsed wire discharge (PWD) apparatus for mass production of nanosized powders was developed. The apparatus had a wire feeder, and could prepare 1.5 g of Cu powder in 200 sec. The mean surface diameter of Cu powder was 86 nm. The particle size distribution of the powder prepared by 100 discharges was increased than that by one discharge. In addition, the median diameter of the powder after the 100 discharges was larger than that by one discharge. A part of the nanosized powders in production chamber of the apparatus would be grown by the deposition of plasma or vapor formed by the next discharge.

Abstract: Octaphenylsilsesquioxane (OPS) and Octa(nitrophenyl)silsesquioxane (ONPS) were synthesized by a conventional approach. The structure was characterized by FTIR, GPC, 1H NMR and 29Si NMR. Then ONPS was added into the latex to modify polyacrylic ester (PAE) emulsion. The compatibility, mechanical and thermal properties of modified PAE emulsion were investigated through di.erential scanning calorimetry (DSC), the tensile strength tester and transmission electron microscopy (TEM) micrographs.The studies on TEM and the particle size distribution showed that the Octa(nitrophenyl)silsesquioxane particles homogeneously disperse in the emulsion at a nanometer scale. Differential scanning calorimetry showed that the addition of ONPS increased Tg of PAE emulsion significantly. The tensile strength of films increased with the addition of ONPS, but rupture elongation decreased slightly. The general properties obtained optimum when the content of ONPS was 2∼3%.

Abstract: Epoxy-cyanate (EP-CE) ester composites containing the inorganic-organic hybrid polyhedral oligomeric silsesquioxane (POSS) octaisobutyl(T8)-POSS (oib-POSS) were prepared. These EP-CE/POSS composites were characterized by gelation characteristics, transmission election microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal gravimetric analyses (TGA) and dynamic mechanical analysis (DMTA). The glass transition temperature (Tg) and thermal decomposition temperature (Tdec) of composites increased compared with the neat epoxy-cyanate ester with the increment of POSS content. Additionally, all the EP-CE/POSS composites exhibited higher storage modulus (E’) values (temperature>Tg) than the pure resins. The loss factor peak intensities decreased as the weight percentage of POSS increases. TEM and XRD showed that phase-separated aggregates of POSS were found in matrix, because POSS did not react with the resin.

Abstract: In this paper, diphenyl-silsesquioxane was synthesized and characterized. Firstly, octa-isobutyl silsesquioxane endo-disilanol (OIBS-EDN) containing two Si-OH functions was formed by base-catalyzed cleavage of octa-isobutyl silsesquioxane (OIBS). Then, oligomeric silsesquioxane containing two phenyl functions (DPS) was prepared by adding diphenyldichlorosilane to the solution of OIBS-EDN in right proportion with the presence of trithylamine in THF. The products were characterized by FTIR, 1HNMR, 13CNMR, 29SiNMR, X-ray diffraction, EA, DSC and GPC respectively. The results show that difunctional POSS with clear structure and high yield can be prepared by this process. And a new simple and feasible approach to design and synthesize difunctional POSS was put forward.

Abstract: Mononuclear FeII complex [FeII(ppba)]2+ (ppba = (6-pivalamido-2-pyridylmethyl) (2-pyridylmethyl)tert-butylamine) (1) has been synthesized and structurally characterized. The addition of H2O2 (10eq) to an acetone solution of 1 at -78°C generated FeIIIPPBA-OOH species, accompanied by a color change from pale yellow to reddish purple, which showed an intense absorption band corresponding to LMCT band (HOO- to Fe) at 528 nm (ε = 1120 M-1cm-1). The ESR spectrum for FeIIIPPBA-OOH species (g// = 4.22, g⊥ = 7.70 in acetone at 77 K) was typical of a high-spin FeIII species, suggesting that the FeIIIPPBA-OOH species is maintained as a mononuclear complex in the solution state. The resonance Raman spectra, when H2 16O2 and H2 18O2 were used, exhibited intense bands characteristic to the O-O stretching vibrations at 880 cm-1 ν(16O-16O) and 824 cm-1 ν(18O-18O), respectively. These findings suggest that FeIIIPPBA-OOH species is [FeIII(ppba)(OOH)]2+ (2). In order to understand the catalytic reactivity of complex 2, oxidative reactions for some organic substrates by complex 2 were carried out in the presence of H2O2; thioanisole was oxidized to the corresponding sulfoxide and sulfone, respectively, and furthermore, cyclohexene was converted to cyclohexene oxide, cyclohexenol and cyclohexenone.

Abstract: A square planar iron complex with H2babp was synthesized and its coordination behaviors with monodentate axial ligands were studied. Cl– or imidazole ligand coordinated at the axial positions of the complex, but pyridine could not be introduced. The heterocyclic nitrogen donors, such as pyridine and imidazole, abstracted the amide protons of the ligand H2babp [1]. The oxidation reactivity was controlled by the presence or absence of amide protons of planar ligand H2babp rather than the axial ligands. The oxidation of cyclohexene by their complexes in the presence of PhIO proceeded catalytically when the iron complexes with protonated H2babp was used, while only a slight amount of oxidation products were obtained when the complexes with deprotonated babp2– were used.