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A catalyst comprised of Pd2(dba)3·CHCl3 and an N–Ar axially chiral mimetic-type ligand, (S)-N-[2-(diphenylphosphanyl)naphthalene-1-yl]-2-(piperidinylmethyl)piperidine, provides good enantioselectivities for the asymmetric Kumada–Corriu cross-coupling reaction of 1-phenylethylmagnesium chloride and E-β-bromostyrene derivatives with which it is more difficult to achieve high enantioselectivity. Furthermore, in the case of styrene derivatives bearing both vinyl and aryl bromide groups, the chemoselective asymmetric cross-coupling reaction of the vinyl bromide group is observed. This N–Ar axially chiral mimetic-type ligand allows easy synthesis of a wide variety of analogues, and starting from the initial ligand, the enantioselectivity of coupling products is improved by modifying the structure in the ligand. [Copyright &y& Elsevier]

Abstract: Fungal cells immobilized with ballooned polyacrylonitrile (PAN) microsphere (MS) on an interface between a liquid medium and a hydrophobic organic solvent efficiently catalyze various microbial transformations such as hydrolysis, reduction, hydroxylation, and epoxidation of lipophilic substrates dissolved in the organic phase (liquid–liquid interface bioreactor; L–L IBR). In this study, the electric charge of MS layer in the L–L IBR was modified by mixing 4 kinds of anion-exchange, 2 kinds of cation-exchange or a chelating resin microparticles, and applied to regio- and stereoselective subterminal hydroxylation of n-decane to (−)-4-decanol by Monilliera sp. NAP 00702. In general, the addition of cation-exchange and chelating resin microparticles into a PAN-MS layer led to the strong inhibition of fungal growth and hydroxylation activity. On the other hand, the addition of anion-exchange resin microparticles having moderate total capacity (≤1.00meq/g) significantly increased hyphal growth and hydroxylation activity. Especially, the addition of IRA910CT microparticles (total capacity≥1.00meq/g) into a PAN-MS layer led to 1.6-fold increase of 4-decanol production. Thus, it was concluded that the moderate addition of anion-exchange resin microparticles into an MS layer in the L–L IBR system was effective to enhancement of fungal growth and hydroxylation activity. [Copyright &y& Elsevier]

In a liquid–liquid interface bioreactor, fungal cells locate in a hydrophilic polyacrylonitrile microsphere layer on an aqueous–organic interface. In this article, effects of hydrophobicity of the interface on n-decane hydroxylation activity of Monilliera sp. NAP 00702 was examined. (−)-4-Decanol production was significantly enhanced to 132% by addition of polytetrafluoroethylene. [Copyright &y& Elsevier]

For fabricating semiconductor devices and for microelectromechanical systems, photoresists are important materials supporting photolithography processes. However, photoresists must be removed for subsequent processes. An earlier study demonstrated that adding a small amount of oxygen gas to the atmosphere in which hydrogen radicals are produced increased the decomposition rate of a positive-tone novolac photoresist. For this study, we prepared polymers with different side chain structures based on poly(vinyl phenol) (PVP). We examined the effects of added oxygen and the oxygen-added hydrogen radicals on the decomposition rates of PVP-based polymers. Hydroxyl groups of PVP are partly substituted with tert -butoxycarbonyl groups in order to use for base polymer of KrF photoresist. Results show that oxygen addition can be useful for KrF photoresist removal. • Decomposition of poly(vinyl phenol)-based polymers by H radicals was examined. • Decomposition rate of the polymers increases when a trace of O 2 is added to H 2. • The optimum additive amount of O 2 for the rate enhancement was identified. • The effect of oxygen addition on removal of KrF photoresist was discussed. [ABSTRACT FROM AUTHOR]

Abstract The alternating copolymer of a conjugated diene monomer and oxygen, i.e., polyperoxide, is a main-chain degradable polymer and undergoes radical chain degradation by heating. During the degradation process, oxygen-centered radicals are formed and thus side reactions such as hydrogen abstraction from the polymer by the oxygen-centered radicals and subsequent coupling, which prevent the degradation, sometimes take place. In this study, in order to promote the degradation of polyperoxides only at elevated temperatures while maintaining their stability at ambient temperature, appropriate organic reductants, which do not significantly react with the polyperoxides at 30 °C but react at 100 °C, were explored. N , N -Dimethylaniline, which is a conventional reductant for redox initiation systems, initiated the redox degradation of cyclopentadiene-based polyperoxides even at 30 °C due to the very high nucleophilicity. The introduction of an electron donating group at the para position, i.e., 4-dimethylaminoacetophenone, 4-dimethylaminobenzaldehyde, and 4-dimethylaminobenzonitrile, successfully maintained the stability of the polyperoxide at 30 °C and accelerated the degradation at 100 °C due to the reduced nucleophilicity. Similar results were obtained by using 1-acetyl-2-phenylhydrazine and 1-phenyl-3-pyrazolidone (PhP) as a reductant, and PhP resulted in the most significant acceleration effect at 100 °C. The activation energy for the overall degradation of the polyperoxide in the presence of PhP was much lower than that of the polyperoxide in the absence of a reductant. In the case of sorbic ester-based polyperoxides, their stabilities at 30 °C were not maintained in the presence of the reductants and the stability was improved by increasing the 2,5 structure regarding the diene moiety in the main-chain. Highlights • Accelerated degradation of polyperoxides only at elevated temperatures was achieved by the selection of reductants. • The activation energies for the degradation of the polyperoxides in the presence of the reductants were determined. • Effects of the main chain structures of the polyperoxides containing the reductants on their stability were determined. [ABSTRACT FROM AUTHOR]

Mass spectrometry was used to identify the decomposition products of two typical photoresist polymers, Novolak and polymethylmethacrylate, by H atoms produced on hot wire surfaces. The production of CH 4 and CO was confirmed for both polymers. Other possible products are C 3 H 8 , C 4 H 10 or C 4 H 8 , and some esters such as CH 3 COOC 2 H 5 . The production of CO 2 , C 2 H 4 , C 2 H 6 , alcohols, and aromatics are minor. The possible decomposition mechanisms are discussed on the basis of density functional calculations of the energetics. [ABSTRACT FROM AUTHOR]

Thermoresponsive properties of poly(7-methacryloyloxycoumarin) ( P1a ) and its derivatives as homopolymers containing a photoreactive coumarin unit were systematically investigated. P1a showed a lower critical solution temperature (LCST)-type phase separation in dichloromethane, chloroform, and 1,1,2-trichloroethane. The temperature producing a 50% transmittance ( T c ) of 0.1 wt% P1a in distilled chloroform was 26 °C, while the T c value decreased to 21 °C in deuterated chloroform i.e., the deuterium isotope effect. The T c values in chloroform were adjustable from 28 to 57 °C by the introduction of the ethyleneoxy spacer and the substitution of α-methyl group by hydrogen. While the polymers containing 4-substituted coumarins were soluble in chloroform and dichloromethane from 0 °C to their boiling points. In the distilled chloroform solution, the coumarin units in P1a underwent a [2 + 2] cycloaddition and the transmittance at 500 nm decreased from 98% to 29% at 25 °C by a 180-s photoirradiation (326 mJ/cm 2 , emission band at 365 nm). [ABSTRACT FROM AUTHOR]

Acetal-protected acrylic copolymers consisting of 1-isobutoxyethyl acrylate (iBEA), 2-ethylhexyl acrylate (2EHA), and 2-hydroxyethyl acrylate (HEA) repeating units were applied to the pressure-sensitive adhesive (PSA) types of dismantlable adhesives. The random and block copolymers with a relatively high HEA content showed good PSA properties before dismantling treatment. The deprotection of the acetal-protected group of the iBEA unit took place in response to individual external stimuli, soaking in boiling water and UV irradiation in the presence of a photoacid generator. The random copolymers containing an HEA unit of more than 10 mol% and an iBEA unit of more than 70 mol% achieved spontaneous debonding with interfacial failures at both the stainless steel and polyethylene terephthalate support film sides by soaking in boiling water within 10 min, whereas the corresponding block copolymer did not achieve interfacial failure even after a 20-min soaking. Photoirradiation of the random copolymers containing N -hydroxynaphthalimide triflate as a photoacid generator resulted in interfacial failures at both sides with a sufficiently reduced peel strength, where cross-linking arose due to the transacetalization and transesterification of a hydroxy group in the HEA unit along with deprotection. [ABSTRACT FROM AUTHOR]

The effect of the high order structure of an isotactic polypropylene (PP) composite on the resistivity of composites containing magnetically aligned Ni particles was studied. Only a small amount of particles needed to be added for the composite material to become conducting after heating while in a magnetic field. The Ni columns formed on applying the field were distorted by the formation of large PP spherulites. Changes to the crystallization process due to the addition of a nucleating agent gave rise to changes in the columnar structure, resulting in large changes in the resistivity of the composite material. Controlling the high order structure of the polymer matrix including its morphology is very important in order to be able to control the magnetically aligned Ni structure. [ABSTRACT FROM AUTHOR]

Abstract: Composites containing carbon nano tube (CNT) or carbon black (CB) conductive particle filler have the special characteristics of positive-temperature-coefficient (PTC) effects of resistivity. We quantitatively studied the relationship between poly(vinylidene fluoride) (PVDF) polymer''s thermal volume expansion and the PTC effects of PVDF/CNT and PVDF/CB. The equation to revise filler content at each temperature due to the considerable thermal volume expansion rate of PVDF polymer indicates that filler content decreased with rising temperature. The graphs of filler content at room temperature plotted against apparent filler content with PTC effect were linear and their slopes were constant. From these graphs, we can determine the filler content necessary to occurring PTC effects. For example, the CNT content was 89% at room temperature, and the CB content was 93%. To our knowledge, this study is the first to report such phenomena. [Copyright &y& Elsevier]

The addition of anion-exchange resin microparticles into a polyacrylonitrile (PAN) ballooned microsphere layer drastically enhanced the fermentative activity of Trichoderma atroviride AG2755-5NM398 in an extractive liquid-surface immobilization (Ext-LSI) system. The production of 6-pentyl-α-pyrone (6PP), a fungicidal secondary metabolite, was 1.92-fold higher than the control (PAN alone). [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses the positive-temperature-coefficient effects of resistivity in Ni particle-dispersed poly(vinylidene fluoride) (PVDF) composites based on experiment results from SEM, DSC, and pressure-volume-temperature (PVT) measurements. The melting points of composites with Ni content of 20, 30, 40, and 50vol.% were equal to that of pure PVDF. The PTC effects in composites with Ni content of 40 and 50vol.% occurred at temperatures near the melting point of the PVDF matrix, whereas those in composites with Ni content of 20 and 30vol.% occurred at temperatures below the melting point of the PVDF matrix. We found that the PTC effect occurs even without melting of the matrix polymer. Moreover, we determined that a slight increase in specific volume at temperatures below the melting point of the matrix polymer acts fully as a driving force for forming a gap between fillers. This suggestion was backed up by theoretical analyses using percolation theory and a thermal-fluctuation-induced tunneling model. [Copyright &y& Elsevier]