Synthesis and gas permeability of membranes of Poly(vinyl ether)s bearing oxyethylene segments

Cationic copolymerizations of vinyl ether monomers [2-methoxyethyl vinyl ether: MOVE, 2-(2-methoxyethoxy)ethyl vinyl ether: MEEVE, 2-adamantyl vinyl ether: AdVE, 2-(2-vinyloxyethoxy)ethyl methacrylate: VEEM] were performed to obtain three types of vinyl ether copolymers [poly(MOVE-AdVE)s, poly(MEEVE-AdVE)s, and poly(MEEVE-VEEM)s] with different composition rates. Poly(MOVE-AdVE) and poly(MEEVE-AdVE) obtained at monomer feed ratio of 1:1 exhibited the glass transition temperatures (T_g) of 55 and 28 °C, respectively, but the T_g's of copolymers were near or lower than room temperature when the feed ratio of AdVE decreased. Poly(MOVE-AdVE)s and poly(MEEVE-AdVE) with T_g's above room temperature afforded free-standing membranes by casting them from toluene solutions. They exhibited relatively high CO₂ permeability and high CO₂/N₂ separation factors (P(CO₂) = 22–36 barrers, P(CO₂)/P(N₂) = 19–40). The T_g's of poly(MEEVE-VEEM)s were very low and around ?70 °C irrespective of the difference of monomer feed ratio. Methacrylate groups in poly(MEEVE-VEEM)s partially reacted under heating to give crosslinked polymer membranes. The crosslinked membranes showed high CO₂/N₂ selectivity, especially the poly(MEEVE-VEEM) membrane possessing the highest ratio of MEEVE exhibited high CO₂ permeability and high selectivity (P(CO₂) = 120 barrers, P(CO₂)/P(N₂) = 55).     

Chiral specificity in responses by the bark beetleDendroctonus valens to host kairomones

The attraction of the red turpentine beetle,Dendroctonus valens, to the resin volatiles of its host,Pinus ponderosa, is elicited by three chiral monoterpenes. In field assays response was greatest to (S)-(–)--pinene; 92% (S)-(–)--pinene found inP ponderosa resin was not attractive. However, 75% (R)-(+)--pinene, which occurs inPinus lambertiana, a sympatric host ofD. valens, was attractive. (S)-(–)--Pinene interrupted response to (R)-(+)--pinene. (S)-(+)-3-Carene from both hosts was attractive at the (R)-(+)--pinene level. Three sympatric coniferous nonhosts each have the same attractive monoterpenes but produce less resin. These studies demonstrate the importance of chirality of host compounds in the host finding behavior of this bark beetle.     

Functional group selective polymerization of (4-maleimidophenyl)oxirane as a new type of bifunctional monomer

A novel bifunctional monomer, (4-maleimidophenyl)oxirane (MAPO), with very reactive maleimido and epoxy groups, was prepared through the selective oxidation of the two carbon–carbon double bonds of N-(4-vinylphenyl)maleimide. Either of the two different polymerizable groups (vinylene of the maleimide moiety and the mono-substituted epoxide) of MAPO was able to be selectively polymerized by choosing the polymerization method. For radical polymerization, MAPO gave poly{p-[1,2-(epoxyethyl)phenyl]maleimide} (PEPM) with dense pendent epoxy groups in 76% yield without cross-linking. MAPO also gave poly(maleimidostyrene oxide) (PMSO) with dense pendent maleimido groups through cationic polymerization in 60% yield. On the other hand, anionic polymerization with an of MAPO produced only insoluble gel-like materials due to unselective polymerization of the two polymerizable groups (Scheme 1). The vinylene group of the maleimide moiety in PMSO easily reacted with the mercapto group, and the ring-opening reaction of the epoxy groups in PEPM with amino groups took place.     

Surface plasmon resonance immunosensor using Au nanoparticle for detection of TNT

In order to develop the fully integrated portable surface plasmon resonance (SPR) system for detection of explosives, the amplification strategy of SPR signal was investigated. Indirect competitive inhibition method allowed the middle-sized SPR sensor to detect trinitrotoluene (TNT) at ppt level. However, this enhanced SPR signal was not high enough to detect TNT at ppt level by a miniaturized SPR sensor. Therefore, localized surface plasmon resonance (LSPR) effect using Au nanoparticle as further signal amplification approach was used. The amplification method of indirect competitive inhibition and LSPR were combined together for fabrication of the immunosurface using Au nanoparticle. TNT detectable range of this immunosurface was from 10 ppt (10 pg/ml) to 100 ppb (100 ng/ml), which was almost comparable to that without Au nanoparticle. The observed resonance angle change due to binding monoclonal TNT antibody (M-TNT Ab) with the immunosurface modified with Au nanoparticle was amplified to four times higher than that in absence of Au nanoparticle.     

Crack formation,exfoliation, and ridge formation in 500 °C annealed sol–gel silica coatings on stainless steel SUS304: Part I. Microscopic observations and elemental analyses

Uniformly compact silica coatings of thicknesses >400 nm on Cr- and Ni-containing steels are practically desirable but difficult to obtain. A non-aqueous sol–gel silica coating on SUS304 was studied. After the coated substrates were treated at 500 °C in air, coatings with thicknesses of ～350 to ～1000 nm were obtained that were largely uniform, non-porous, adherent, and with minimal residual organic content, although some cracks and exfoliated sites existed. TEM/EDX analysis indicated that three interlayers were observed between silica and SUS. The innermost one was ～5 nm thick, Cr-rich, highly O-deficient, and formed a tenacious bond between SUS304 and silica; the two others were rather diffuse. The web-like development of ridges resulting from the oxidation of metallic elements (mostly Fe) diffused into the silica through nanoscale defects within the innermost interlayer was also observed. Many of the nanoscale defects seem to be related to SUS grain boundaries. Ni was almost absent in silica coating except in the innermost interlayer and ridges. The mechanisms responsible for these observed properties and phenomena are discussed.     

High efficiency ester condensation using hydrophobic zeolite membranes

We successfully developed zeolite membranes with hydrophilic character, by choosing appropriate zeolites in terms of hydrophilicity and high acid tolerance. We evaluated thus developed membranes by their pervaporation (PV) performance, dehydration from acidic organic solvent. The zeolite membranes we developed, based on merlinoite (MER), chabazite (CHA) or phillipsite (PHI), are shown to exhibit stable dehydration performance, respectively. We successfully applied the membranes to the selective removal of water in an ester condensation reaction starting from a stoichiometric mixture of a carboxylic acid and an alcohol. The availability of pervaporation-assisted ester condensation reaction was validated by various kinds of combinations of carboxylic acid and alcohols, which implies the general availability of pervaporation-assisted process intensification by zeolite membranes. This paper was presented at the 11th Korea-Japan Symposium on Catatysis held at Seoul, Korea, May 21–24, 2007.     

Experimental evaluation of a spherical aberration-corrected TEM and STEM

We have successfully developed a spherical aberration (Cs)-corrected electron microscope for probe- and image-forming systems using hexapole correctors. The performance of the microscope has been evaluated experimentally. The point resolution attained using the image-forming Cs-corrector is better than 0.12 nm. For scanning transmission electron microscopy, the Ronchigram flat area was >40 mrad in half-angle using the probe-forming Cs-corrector.