bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric behavior characterization of a fibrous‐ZnO/PVDF nanocomposite
Authors: Dagdeviren Canan , Papila Melih
Published: July 2010

This study is focused on forming a fibrous‐zinc oxide/polyvinylidine fluoride (ZnO/PVDF) nanocomposite and characterizing its dielectric behavior. The nanocomposite is prepared in two steps. First, a network of nanoscale diameter ZnO fibers is produced by sintering electrospun PVA/Zinc Acetate fibers. Second, the ZnO fibrous nonwoven mat is sandwiched between two PVDF thermoplastic polymer films by hot‐press casting. Scanning electron microscope images of the nanocomposite show that hot‐press casting of the fibrous‐ZnO network breaks the network up into short fibers. The in‐plane distribution of the ZnO fillers (i.e., the short fibers) in the PVDF matrix appears to comply with that of the pristine ZnO fibers before hot‐pressing, indicating that the fillers remain well‐dispersed in the polymer matrix. To the authors' knowledge, the work reported herein is the first demonstration of the use of electrospinning to secure the dispersion and distribution of a network of inorganic fillers. Moreover, processing a fibrous‐ZnO/PVDF flexible composite as described in this report would facilitate material handling and enable dielectric property measurement, in contrast to that on a fibrous mat of pure ZnO. Because of the high surface area of the short ZnO fibers and their polycrystalline structure, interfacial polarization is pronounced in the nanocomposite film. The dielectric constant is enhanced significantly‐up to a factor of 10 at low frequencies compared to the dielectric constant of constituent materials (both bulk ZnO and PVDF), and up to a factor of two compared to a bulk‐ZnO/PVDF composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
A pictorial Attitude IAT as a Measure of Implicit Motives
Authors: Slabbinck Hendrik , De Houwer Jan , Van Kenhove Patrick
Published: July 2010

We tested the hypothesis that a pictorial attitude variant of the Implicit Association Test (PA–IAT) is a valid measure of implicit motives. The PA–IAT aims to capture attitudes towards pictures that are related to implicit motives. In the first two studies, we showed that the pictorial attitude Implicit Association Test (IAT) correlated more highly with non–IAT measures of implicit motives than other IAT variants. In the third study, we established the validity of the PA–IAT experimentally and showed that the pictorial attitude IAT correlated with non–declarative behavioural measures only if implicit motives were aroused. Copyright © 2010 John Wiley & Sons, Ltd.
Self–Regulation and Well–Being: The Influence of Identity and Motives
Authors: Hofer Jan , Busch Holger , Kärtner Joscha
Published: July 2010

The relationship between self–regulatory capacities and self–esteem as well as well–being is examined by a mediation model that views self–regulation as promoting the development of identity achievement which, in turn, is expected to be associated with well–being. Among secondary school students (Study 1) identity achievement mediated the association between the self–regulatory capacity of attention control and self–esteem. In Study 2 (university students), the mediational effect of identity achievement was found for the relationship between the self–regulatory capacity of action control and well–being. Explicit motives moderated this association. In sum, a firm identity enhances well–being by lending a sense of continuity to one's life. However, explicit motives have a substitution effect by giving direction to life when lacking firm identity commitments. Copyright © 2010 John Wiley & Sons, Ltd.
Mechanisms of fracture in filled thermosetting resins
Authors: Brown Stephen K.
Published: July 2010

Fracture properties of a wide range of filled unsaturated polyester resin composites have been investigated with respect to filler size, shape, loading and adhesion to the matrix resin. Mechanisms are proposed for the fracture behaviors found, based on geometrical considerations of interacting filler particles and stress concentrations which result from them.
The refraction correction for the Fica 50 type of light scattering photometer
Authors: Suzuki Hidematsu , Muraoka Yoichior , Inagaki Hiroshi
Published: July 2010

The factor for the refraction correction was considered for the Fica 50 type of light scattering photometer, in which the scattered light is twice refracted before reaching the detector. The correction factor was first calculated after Hermans and Levinson, which elucidated that the factor is just the same as for the Brice type of photometer, and a vat liquid has no further effects on the final form of the correction factor. This result was examined and found to be practically applicable to a Fica 50 photometer by measuring the scattering intensities of several liquids and the RAPRA PS2 standard polystyrene in solvents of varying refractive index.
Highly conjugated organic polymers as heterogenous catalysts (II): The interaction of nitrogen monoxide and pyrolysed polyacrylonitrile
Authors: Cooper David R. , Tighe Brian J.
Published: July 2010

The interaction of nitrogen monoxide (nitric oxide, NO) with pyrolysed polyacrylonitrile (PANP) has been examined together with the feasibility of the use of PANP based catalysts for the removal of small quantities of NO from the exhaust systems of internal combustion engines. Kinetic studies indicated that PANP was capable of interacting with and removing NO from an inert carrier gas and that the initial specificity of this interaction was little affected by hydrogen, hydrocarbons, carbon monixide or oxygen, the initial rates of removal being appreciably higher than those obtainable with conventional inorganic catalysts or graphitised carbon. The activation energy and kinetic features of the reaction suggested that the interaction involved the odd electron nature of NO and the free spin generated at the polymer surface. Once adsorbed the nitric oxide decomposes to form dinitrogen oxide (N2O) which is further reduced to nitrogen with concurrent assimilation and rearrangement of oxygen within the polymer structure. As a result the PANP gradually loses its capacity to adsorb and decompose NO. In addition, it appears that the structural features which promote the oxidative instability of PANP also govern its NO removal ability. Consequently, the lifetime and therefore practical utility of these systems is governed by the limits of oxidative stability and catalytic capacity.
The Copolymerisation of Vinyl Chloride with Allyl Chloride
Authors: Lewis John , Okieimen Felix E. , Park Geoffrey S.
Published: July 2010

The kinetics of copolymerisation of vinyl chloride with allyl chloride in chlorobenzene and in dichloroethane solvent have been studied by a dilatometric method. The compositon of the copolymers was determined by reduction with tributyltin hydride followed by infrared examination. Molecular weights obtained by g.p.c. enable as estimate of the transfer constant for degradative transfer to allyl chloride to be made for both the chlorobenzene and dichloroethane solvent systems. The results show that allyl chloride retards vinyl chloride polymerisation by degradative transfer and that the resulting radicals combine with the growing polymer chains. The dependence of copolymer composition on the composition of the monomer feed reveals that one of the pair of reactivity ratios associated with this reaction in either solvent has a negative value.
Catalyst Systems in Anionic Copolymerisations
Authors: Richards David H.
Published: July 2010

The paper considers three areas of current interest in anionic polymerisation. Firstly, the factors governing the efficiencies of initiation of anionic electron transfer catalysts are discussed, and the differences between the initiation mechanism of this class of catalysts and that of alkali metals are highlighted. Secondly, the problems relating to the synthesis of telechelic polydienes of high 1,4 content by an anionic technique are examined in relation to the contradictory claims of recent authors. Finally an account is given of the present position in developing transformation reactions to prepare novel block copolymers.
X‐Ray Powder Diffraction Studies of Hydrocerussite (Basic Lead Carbonate) as a Stabiliser in Plasticised Polyvinyl Chloride
Authors: Michell E. W. John , Ng Kok Y.
Published: July 2010

Strips from a plasticised PVC blend containing pure hydrocerussite, 2PbCO3.Pb(OH)2, as stabiliser were heated under nitrogen at 180°C for various periods up to the time when hydrogen chloride (HC1) was liberated and could be detected externally by Congo‐red indicator paper. Evolved carbon dioxide (CO2) was measured and crystalline phases in the heated samples were studied by X‐ray powder diffraction (X.R.P.D.).

Qualitative X.R.P.D. showed that the hydrocerussite reacted to form the uncharacterised basic lead chloride X (B.L.C.X.) and normal lead chloride, PbCl2, in sequence. Quantitative X.R.P.D. showed that the hydrocerussite reacted according to first order kinetics, and the rate constant and half‐life were confirmed by data from the CO2 measurements. These results accord with previous studies using the other basic lead carbonate ‘plumbonacrite’, 6PbCO3.3Pb(OH)2.PbO, as stabiliser. However, the rates of stabiliser reaction differed and, surprisingly, efficient stabilisation continued long after the hydrocerussite had all reacted in the present experiments, whereas stabilisation failed soon after the plumbonacrite had all reacted previously.

These findings are interpreted on the basis of a free‐radical exchange and temporary esterification mechanism in which mobile lead salts of organic acids are regenerated as the active stabilising intermediates, and which is believed to retard the PVC thermal decomposition (preventing the formation of HCl). This is called ‘true stabilisation’. The popular idea that basic lead stabilisers merely behave as scavengers for HCl from the hot polymer is rejected because this cannot be reconciled with the fact that stabilisation continued in the absence of hydrocerussite, or with the observed first order kinetics of stabiliser reaction. These studies are briefly related to commercial PVC processing.
Rheololgy of Mesomorphic Solutions of Cellulose
Authors: Navard Patrick , Haudin Jean‐Marc
Published: July 2010

Solutions of cellulose were prepared with liquid crystal phases by mixing cellulose, water and N‐methylmorpholine N‐oxide under appropriate conditions of concentration and temperature. Their rheological behaviour was studied using capillary rheometry. For each solution, flow curves were plotted over a temperature range of 70‐‐120°C, and a shear rate range of 1‐‐500 sec−1.

Considerable agreement was found between the rheological and optical characterisations of the anisotropic‐isotropic transition temperature T*. The variations of the strain rate sensitivity parameter m were studied over a large temperature range and particularly around T*. These results, new for cellulose solutions, provide some valuable information about the rheology of anisotropic polymer fluids.
Aspects of Vinyl Chloride Suspension Polymerisation
Authors: Sanderson Albert K.
Published: July 2010

Some observations on the formation and growth of PVC granules during polymerisation are described, particularly with reference to granule morphology. The physical structure of the final granule is very dependent on polymerisation variables and of these, the influence of reactor agitation, temperature of polymerisation and protective colloid are briefly discussed.
Synthesis of Poly(p‐Benzenesulphonamide). Part III Solution Polymerisation
Authors: Contreras Jordi , Jones J. Idris
Published: July 2010

Poly (p‐benzene sulphonamide) has been prepared from N‐sulphinylaniline‐4‐sulphoch‐loride, aniline‐4‐sulphochloride, and aniline‐4‐sulphochloride hydrochloride by solution polymerisation at low temperatures in the presence of a base. In the case of aniline‐4‐sulphochloride and its hydrochloride, clear evidence has been obtained of the intermediacy of a sulphene species, 4‐imino‐cyclohexadiene sulphene. With the addition of one equivalent of water in the polymerisation of the N‐sulphinyl monomer, aniline‐4‐sulphochloride is first formed and polymerisation ensues through the same sulphene intermediate. Poly(p‐benzene‐N‐methylsulphonamide) similarly results from the solution polymerisation of N‐methylaniline‐4‐sulphochloride hydrochloride. Polymerisation of crystalline aniline‐4‐sulphochloride hydrochloride has also been effected in the solid state in a non solvent.

Certain amide solvents, which have proved to be very effective in the polymerisation of 4‐aminobenzoyl chloride hydrochloride to give poly(p‐benzamide), do not appear to be suitable for the polymerisation of aniline‐4‐sulphochloride hydrochloride. With dimethyl formamide and N‐methyl pyrrolidone, aniline‐4‐sulphochloride hydrochloride undergoes a condensation reaction. With tetramethyl urea, some polymerisation occurs but the yield and molecular weight of the polymer are low. A copoly (amide‐sulphonamide) has been prepared by polymerising molar equivalents of 4‐aminobenzoyl hydrochloride and aniline 4‐sulphochloride hydrochloride in pyridine.
Incorporation of a conjugated side‐chain in regioregular polythiophenes: Chiroptical properties and selective oxidation
Authors: Peeters Helmuth , Verbiest Thierry , Koeckelberghs Guy
Published: July 2010

The synthesis, aggregation, and optical properties of a chiral, regioregular polythiophene, substituted with a conjugated substituent, are described. The polymer was prepared using a Stille coupling reaction. The fact that the side‐chain contributes to the absorption (UV‐vis), emission (fluorescence), and redox behavior (cyclic voltammetry) of the material demonstrates that the substituent contributes to the electronic properties. It was shown that the conjugated side‐chain chirally stacks in conditions in which the polymer backbone aggregates, which demonstrates the ability of conjugated polymers to induce a (chiral) lamellar organization of conjugated moieties, present in their side‐chain. The aggregation of both the side‐chain and the backbone was monitored using UV‐vis and CD spectroscopy. Finally, it is shown that the conjugated side‐chain can selectively be oxidized, without oxidizing the polythiophene backbone. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1891–1900, 2009
Block copolymers of poly(ethylene oxide) and poly(vinyl alcohol) synthesized by the RAFT methodology
Authors: Tong Yin‐Yin , Dong Yong‐Quan , Du Fu‐Sheng , Li Zi‐Chen
Published: July 2010

A methodology for the synthesis of well‐defined poly(ethylene oxide)‐block‐poly(vinyl alcohol) (PEO‐b‐PVA) and PVA‐b‐PEO‐b‐PVA polymers was reported. Novel xanthate end‐functionalized PEOs were synthesized by a series of end‐group transformations. They were then used to mediate the reversible addition–fragmentation chain transfer polymerization of vinyl acetate to obtain well‐defined poly(ethylene oxide)‐b‐poly(vinyl acetate) (PEO‐b‐PVAc) and PVAc‐b‐PEO‐b‐PVAc. When these block copolymers were directly hydrolyzed in methanol solution of sodium hydroxide, polymers with brown color were obtained, which was due to the formation of conjugated unsaturated aldehyde structures. To circumvent these side reactions, the xanthate groups were removed by adding a primary amine before hydrolysis and the products thus obtained were white powders. The polymers were characterized by gel permeation chromatography, 1H NMR spectroscopy and FT‐IR. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1901–1910, 2009
Synthesis and evaluation of new dental monomers with both phosphonic and carboxylic acid functional groups
Authors: Sahin Gorkem , Albayrak Aylin Ziylan , Bilgici Zeynep SaraylI , Avci Duygu
Published: July 2010

Novel dental monomers containing both phosphonic and carboxylic acid functional groups were prepared. The monomers were based on t‐butyl α‐bromomethacrylate (t‐BuBMA) and synthesized in three steps: The reaction of o‐hydroxyaryl phosphonates [diethyl (2‐hydroxyphenyl) phosphonate, tetraethyl (2,5‐dihydroxy‐1,4‐phenylene) diphosphonate and tetraethyl 5,5′‐(propane‐2,2‐diyl)bis(2‐hydroxy‐5,1‐ phenylene) diphosphonate] with t‐BuBMA, the hydrolysis of phosphonate groups to phosphonic acid using trimethyl silylbromide, and the hydrolysis of the t‐butyl groups to carboxylic acid with trifluoroacetic acid. The monomers were solids and soluble in water and ethanol. The structures of the monomers were determined by Fourier transform infrared (FTIR), 1H, 13C, and 31P nuclear magnetic resonance (NMR) spectroscopy. The copolymerization behaviors of the synthesized monomers with glycerol dimethacrylate were first investigated in bulk using photodifferential scanning calorimetry at 40 °C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as photoinitiator. Then, the solution copolymerization of the monomers with acrylamide in ethanol and water was studied, indicating that the synthesized monomers are incorporated into the copolymers. The acidic nature of the aqueous solutions of these monomers (pH values 1.72–1.87) is expected to give them etching properties important for dental applications. The interaction of the monomers with hydroxyapatite was investigated using 13C NMR and FTIR techniques. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1953–1965, 2009
Preparation of comb‐like copolymers with amphiphilic poly(ethylene oxide)‐b‐polystyrene graft chains by combination of “graft from” and “graft onto” strategies
Authors: Sun Ruiming , Wang Guowei , Liu Chao , Huang Junlian
Published: July 2010

A novel method for preparation the comb‐like copolymers with amphihilic poly(ethylene oxide)‐block‐poly(styrene) (PEO‐b‐PS) graft chains by “graft from” and “graft onto” strategies were reported. The ring‐opening copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out first using α‐methoxyl‐ω‐hydroxyl‐poly(ethylene oxide) (mPEO) and diphenylmethyl potassium (DPMK) as coinitiation system, then the EEGE units on resulting linear copolymer mPEO‐b‐Poly(EO‐co‐EEGE) were hydrolyzed and the recovered hydroxyl groups were reacted with 2‐bromoisobutyryl bromide. The obtained macroinitiator mPEO‐b‐Poly(EO‐co‐BiBGE) can initiate the polymerization of styrene by ATRP via the “Graft from” strategy, and the comb‐like copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] were obtained. Afterwards, the TEMPO‐PEO was prepared by ring‐opening polymerization (ROP) of EO initiated by 4‐hydroxyl‐2,2,6,6‐tetramethyl piperdinyl‐oxy (HTEMPO) and DPMK, and then coupled with mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] by atom transfer nitroxide radical coupling reaction in the presence of cuprous bromide (CuBr)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) via “Graft onto” method. The comb‐like block copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐(PS‐b‐PEO)] were obtained with high efficiency (≥90%). The final product and intermediates were characterized in detail. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1930–1938, 2009
Precision synthesis and characterization of thymine‐functionalized polyisobutylene
Authors: Sen Mustafa Y. , Puskas Judit E. , Dabney David E. , Wesdemiotis Chrys , Absalon Christelle
Published: July 2010

A new two‐step synthesis of polyisobutylene (PIB) with precisely one thymine functionality per chain (PIB‐T) is reported. The primary hydroxyl‐functionalized PIB (PIB‐OH) precursor was prepared by direct functionalization via living carbocationic polymerization of isobutylene initiated by the α‐methylstyrene epoxide/TiCl4 system. Matrix assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS) of a low molecular weight PIB‐OH precursor demonstrated the effectiveness of direct functionalization by this method. A PIB‐acrylate precursor (PIB‐Ac) was obtained from such a PIB‐OH, and the PIB‐T was subsequently prepared by Michael addition of thymine across the acrylate double bond. MALDI‐ToF MS of the products verified that all polymer chains carried precisely one thymine group. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3501–3506, 2010
Synthesis of polyethylene and polypropylene containing fluorene units in the side chain
Authors: Naga Naofumi , Sakai Hiroki , Usui Chiharu , Tomoda Haruhiko
Published: July 2010

Copolymerizations of ethylene or propylene and allyl monomers containing 9‐fluorenyl group, diallyl‐di‐9‐fluorenylsilane (DAFS), 9,9‐diallylfluorene (DAF), and 9‐allylfluorene (AF), were investigated with various zirconocene catalysts using methylaluminoxane as a cocatalyst. The bridged zirconocene catalysts, especially a syndioselective catalyst, showed a higher reactivity for all the comonomers than the nonbridged catalysts. DAFS was mainly incorporated into the polymer chain via cyclization insertion, whereas DAF was copolymerized via both 1,2‐ and cyclization insertions. Cyclization selectivity, ratio of cyclized insertion unit, of DAF in the copolymerization with propylene was higher than that in the copolymerization with ethylene. Copolymerization with AF yielded low‐molecular weight copolymer because of frequent chain transfer reaction. Optical properties of the propylene based‐copolymers were investigated by UV‐vis and photoluminescence spectroscopy, and absorption‐ and emission‐derived from fluorenyl groups were detected in the copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3542–3552, 2010
Synthesis and characterization of epoxy functionalized cooligomers based on chlorotrifluoroethylene and allyl glycidyl ether
Authors: Santhosh Kumar K. S. , Ameduri Bruno
Published: July 2010

The synthesis of functionalized fluorocooligomers based on chlorotrifluoroethylene (CTFE) and allyl glycidyl ether (AGE) under radical copolymerization is presented. The compositions of comonomers in the cooligomers were determined by three different analyses viz: from 1H and 19F NMR spectroscopy by using 1,3‐bis(trifluoromethyl) benzene as the external standard, epoxy equivalent weight value, and elemental analyses. The compositions determined by three methods were matching reasonably well and showed that the resulting poly(CTFE‐co‐AGE) cooligomers exhibit a tendency for alternation. The distribution of the monomers in the cooligomers was proposed based on the assessment of the reactivity ratios, ri, of both comonomers. These values were determined from the kinetics of radical copolymerization of CTFE with AGE from Fineman‐Ross, Kelen‐Tudos, and extended Kelen‐Tudos methods which led to the assessment of the average reactivity ratios as: rCTFE = 0.20 ± 0.03 and rAGE = 0.15 ± 0.08 at 74 °C. The lower Mn values substantiated the formation of cooligomers rather than copolymers. The formation of cooligomers was attributed to the chain transfer to AGE (by hydrogen abstraction from AGE) from the allylic transfer. The poly(CTFE‐co‐AGE) cooligomers were soluble in most of the common organic polar solvents. An optimization of cooligomer yields was investigated by using ethyl vinyl ether as a third comonomer and from different initiators. The thermal stabilities of the cooligomers, obtained by thermal gravimetric analysis, showed a 5% weight loss at temperatures over 225 °C under air. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3587–3595, 2010
Facile synthesis of polyaniline hemispheres in diethyl ether/ice mixture solvent and growth mechanism study
Authors: Ma Hui‐yan , Li Yun‐wu , Cao Fei , Gao Yu , Gong Jian , Deng Yu‐lin
Published: July 2010

By using the new methodology of synthesis of container structure, we demonstrate the ability to control an improved ice‐templating method to synthesis of polyaniline (PANI) in the form of hemisphere. The influence of the synthetic parameters, such as the concentration of doping‐acid, oxidant, and aniline on the morphologies of PANI structures, has been investigated. It is determined that the doping acid and the second solvent added (such as diethyl ether absolute) have great positive influence on the formation of product's micro‐morphology. The structure and morphology of PANI hemispheres are characterized by Fourier transform infrared (FT‐IR) spectra, X‐ray diffraction (XRD) patterns, energy‐dispersive X‐ray analysis (EDX), optical microscope images, and scanning electron microscope images (SEM). The formation mechanism of hemispheres in this article is well suggested. PANI hemispheres have super performance in sensitivity, time response to NH3 compared with traditional polymerization at room temperature. This work extends the field of functional materials with complex container structure and offers a new green route to synthesis of hemispherical container structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3596–3603, 2010
Reducibly degradable hydrogels of PNIPAM and PDMAEMA: Synthesis, stimulus‐response and drug release
Authors: Zhang Bo‐yu , He Wei‐Dong , Li Li‐ying , Sun Xiao‐li , Li Wen‐tao , Zhang Ke‐ren
Published: July 2010

Reducibly degradable hydrogels of poly(N‐isopropylacrylamide) (PNIPAM) and poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by the combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and click chemistry. The alkyne‐pending copolymer of PNIPAM or PDMAEMA was obtained through RAFT copolymerization of propargyl acrylate with NIPAM or DMAEMA. Bis‐2‐azidyl‐isobutyrylamide of cystamine (AIBCy) was used as the crosslinking reagent to prepare reducibly degradable hydrogels by click chemistry. The hydrogels exhibited temperature or pH stimulus‐responsive behavior in water, with rapid response, high swelling ratio, and reproducible swelling/shrinkage cycles. The loading and release of ceftriaxone sodium proved the feasibility of the hydrogels as the stimulus‐responsive drug delivery system. Furthermore, the presence of disulfide linkage in AIBCy favored the degradation of hydrogels in the reductive environment. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3604–3612, 2010
Ring opening polymerization of lactide promoted by alcoholyzed heteroscorpionate aluminum complexes
Authors: Silvestri Antonella , Grisi Fabia , Milione Stefano
Published: July 2010

The alcoholysis of the heteroscorpionate methyl aluminum complex (bpzmp)AlMe2 (1) (bpzmp = 2,4‐di‐tert‐butyl‐6‐(bis‐(3,5‐dimethylpyrazol‐1‐yl)methyl)phenoxo), promoted both by phenol and isopropanol, has been investigated. The reaction of 1 with phenol afforded the dimeric mono(phenoxo) derivative 2, whereas the alcoholysis of 1 with the less acidic isopropanol involved the coordinated heteroscorpionate ligand and led to the tetrahedral complex 3 in which the aluminum atom is surrounded by one κ2‐N,O− coordinated bpzmp ligand and one η1‐O− coordinated ppzmp ligand (ppzmp = 2,4‐di‐tert‐butyl‐6‐(i‐propoxy‐(3,5‐dimethylpyrazol‐1‐yl)methyl)phenoxo). Complexes 1–3 have been tested in the ring opening polymerization (ROP) of L‐lactide. The dimeric mono(phenoxo) derivative 2 was inactive in the ROP of L‐lactide. Quite surprisingly, complex 3 was found to be active in ROP of L‐ and rac‐lactide, showing a good molar‐mass control. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3632–3639, 2010
Specific recognition of syndiotactic poly(methacrylic acid) in porous isotactic poly(methyl methacrylate) thin films based on the effects of stereoregularity, temperature, and solvent
Authors: Kamei Daisuke , Ajiro Hiroharu , Akashi Mitsuru
Published: July 2010

The effects of stereoregularity, temperature, and solvent on the specific recognition of syndiotactic (st)‐poly(methacrylic acid) (PMAA) in macromolecularly porous isotactic (it)‐poly(methyl methacrylate) films were investigated to give important insights into the regularity and stability of nanospaces in the it‐PMMA films as well as template polymerization. The porous it‐PMMA films were fabricated on quartz crystal microbalance (QCM) substrates via the layer‐by‐layer (LbL) assembly of it‐PMMA/st‐PMAA, plus the st‐PMAA extraction from the assembly. QCM analysis and infrared spectroscopy revealed the first case of stereocomplex formation using st‐PMAA with lower stereoregularity (rr = 73%) in the LbL films, while st‐PMAA obtained with conventional free radical polymerization (rr = 62%) was barely incorporated into the porous it‐PMMA films. The maximum st‐PMAA incorporation increased from 25 to 40 °C, but there were almost no difference between 40 and 55 °C, indicating that the it‐PMMA crystallization would also be accelerated with increasing temperature. The studies on st‐PMAA incorporation with various complexing solvents revealed that the host it‐PMMA in the porous films could only form the original stereocomplex with 2/1 unit‐molar stoichiometry (st‐PMAA/it‐PMMA) in acetonitrile/water or ethanol/water. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3651–3657, 2010
Synthesis, characterization, electrochromic properties, and electrochromic device application of a novel star polymer consisting of thiophene end‐capped poly(ε‐caprolactone) arms emanating from a hexafunctional cyclotriphosphazene core
Authors: Gorur Mesut , Yilmaz Faruk , Kilic Adem , Demirci Ali , Ozdemir Yusuf , Kosemen Arif , Eren San Sait
Published: July 2010

Hexa‐armed and thiophene (Thi) end‐capped poly(ε‐caprolactone) star polymer (N3P3‐(PCL‐Thi)6), containing cyclotriphosphazene core, was prepared in a four‐step reaction sequence. Ring‐opening polymerization (ROP) and “click chemistry” techniques were employed in the first and final steps, respectively. Hexa‐armed PCL star polymer (N3P3‐(PCL‐OH)6) was successfully synthesized via ROP of ε‐caprolactone (ε‐CL) by using hekzakis(p‐(hydroxymethyl)phenoxy) cyclotriphosphazene as the multisite initiator and tin(II) 2‐ethylhexanoate (Sn(Oct2)) as the catalyst in bulk at 115 °C. Further modifications of the N3P3‐(PCL‐OH)6 were accomplished by derivatization of the hydroxyl‐functional chain ends. The obtained N3P3‐(PCL‐OH)6 was then reacted with 2‐bromo‐2‐methylpropanoyl bromide, and this led to a star polymer with bromide end groups, N3P3‐(PCL‐Br)6. In the third step, N3P3‐(PCL‐Br)6 was azidified with sodium azide (NaN3) in DMF affording N3P3‐(PCL‐N3)6. Conversion of the azide chain end groups into Thi was quantitatively accomplished via the “click reaction” between N3P3‐(PCL‐N3)6 and prop‐2‐yn‐1‐yl 3‐thienyl acetate in the final step. Subsequently, the star polymer with six Thi chain ends (N3P3‐(PCL‐Thi)6) was employed in electrochemical copolymerization with both pyrrole and Thi. Electrochromic properties and electrochromic device application of N3P3‐(PCL‐Thi)6/PThi were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3668–3682, 2010
Real‐time SAXS and WAXS study of the multiple melting behavior of poly(ε‐caprolactone)
Authors: Yang I‐Kuan , Liu Chia Yun
Published: July 2010

The multiple melting behavior of poly(ε‐caprolactone) (PCL) was investigated by real‐time small angle X‐ray scattering (SAXS) and wide angle X‐ray scattering (WAXS) measurements coupling with differential scanning calorimetry (DSC). Semicrystalline specimens prepared by a continuous cooling process showed lengthening of the Bragg period during the progress of double melting. A model of variable thickness of lamella was proposed to fit to the SAXS patterns and revealed that both the crystalline lamella and the amorphous layer contributed to the increase in Bragg period while the later dominated the contribution. The model of variable thickness although satisfied the SAXS data was unable to compromise the data from other probing tools. A modification of the model proposed that each lamella piling up to construct the stacks in the crystallites was itself nonuniform in thickness. The modification with the parallel occurrence of the mechanism of surface melting and crystallization successfully compromised the observations from SAXS, DSC, and optical microscopy and provided a new perspective for the explanation to lengthening of the Bragg period related to multiple melting behavior. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1777–1785, 2010
Study of layered silicate clays as synergistic nucleating agent for polypropylene
Authors: Preschilla Nisha , Rasheed A. S. Abdul , Sahadevan Swayajith , Biswas Amit , Bellare Jayesh R. , Shyamroy Subarna
Published: July 2010

Effect of very small quantities of organically modified layered silicate clay on the nucleation of polypropylene (PP), as an additive at ppm levels dosage was investigated, in combination with two of the most commercially exploited organic nucleating agents, one of which is a cyclic aromatic phosphinate salt and the other is bis(3,4‐dimethylbenzylidene) sorbitol, each representing a separate class of nucleating molecules by itself. Substitution of a considerable fraction of either of these organic nucleating agents with organically modified inorganic nanoclay was seen to result in a unique synergy between the two in nucleating PP. Polarized light microscopy studies of these synergistic formulations with organoclay to nucleating agent ratios of 1:1 and 1:3 totaling 0.2 weight percent in PP showed significant reduction in spherulite size from that of non‐nucleated PP, and compared with the samples containing exclusive organic nucleating agent at similar loading. Differential scanning calorimetric studies provided evidence and insight into such synergistic behavior. Crystallization and supercooling temperatures for the synergistic formulations were comparable for those formulations containing only organic nucleating agents, indicating comparable nucleation efficiency, whereas organoclay alone, although showing some extent of nucleation, was clearly poorer in efficiency. Wide and small angle X‐ray scattering studies further explained these observations. An increase in the gamma polytype fraction was seen in samples that contained both organoclay and nucleating agent, pointing to the role of organoclay as a gamma nucleator. Organoclay was found to be completely exfoliated in these synergistic formulations and was seen as well‐dispersed, single platelets in the PP matrix. A hybrid network consisting of exfoliated organoclay platelets and organic nucleating agent molecules was proposed, which is more stable and stiffer than the network formed by nucleating agent alone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1786–1794, 2010
Strength of polymer phase boundaries with large interfacial width: Effects of interfacial profile and phase separation morphology
Authors: Chang Chun‐Jie , Lee Yi‐Huan , Chiang Chi‐Ju , Lee Yu‐Ping , Chien Hao‐Ching , Shih Wen‐Pin , Cheng Yao‐Yi , Dai Chi‐An , Chang Chia‐Hwa
Published: July 2010

In this study, we investigate the effect of random copolymer additives on the interfacial profile, the lateral phase separation morphology, and the interfacial fracture toughness (Gc) between two immiscible polymers. The interface between polystyrene (PS)/poly(methyl methacrylate) (PMMA) was reinforced with a random copolymer mixture when two or more PSf ‐r‐PMMA1‐f random copolymers with different volume fraction, f, were blended. For short annealing time (<3 h), the random copolymer mixture exhibits a disordered and large domain structure (>1 lm) from which crazes can be extensively initiated and developed, leading to a large interfacial fracture energy. With increasing annealing time, the random copolymer mixture self‐organizes as multiple layers, with the composition that changes gradually from PS‐rich layers to PMMA‐rich layers across the interface, leading to a large interfacial width. However, within each layer, the random copolymer mixture microphase separates laterally into smaller domains (<200 nm). We found that the microphase‐separated domains with nanometer‐sized structure significantly affect the stability of craze fibrils that can be initiated and widened at the interface, leading to a decrease in the fracture energy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1834–1846, 2010
Characterization of PBT/POSS nanocomposites prepared by in situ polymerization of cyclic poly(butylene terephthalate) initiated by functionalized POSS
Authors: Wu Fumei , Xie Tingxiu , Yang Guisheng
Published: July 2010

Novel poly(butylene terephthalate) (PBT)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were synthesized by ring‐opening polymerization of cyclic poly(butylene terephthalate) initiated by functionalized POSS with various feed ratios. The impact of POSS incorporation on melting and crystallization behaviors of PBT/POSS nanocomposites was investigated by means of X‐ray diffraction and differential scanning calorimetry. It was found that the novel organic–inorganic association result in the significant alterations in the melting and crystallization behavior of PBT. Thermal studies confirmed that the incorporation of POSS can enhance the thermal stability of the polymers, and the copolymer glass transition temperature increased with the increasing of POSS macromonomer content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1853–1859, 2010
Comparison of patient and family assessments of quality of life of terminally ill cancer patients in Japan
Authors: Hisamura Kazuho , Matsushima Eisuke , Nagai Hideaki , Mikami Akihiko
Published: July 2010

Objective: This study examined the extent and the nature of agreement on health‐related quality of life (QOL) assessments between terminally ill cancer patients and their primary family caregivers in Japan, using a multidimensional QOL instrument including psychosocial and spiritual domains.

Methods: The Functional Assessment of Chronic Illness Therapy‐Spiritual well‐being questionnaire was used to assess patients' QOL. Study subjects were inpatients of a palliative care unit (PCU), outpatients who applied for admission to the PCU, and their primary family caregivers.

Results: QOL ratings were obtained from 102 of 197 eligible patient–caregiver dyads. A moderate level of patient–family concordance on patients' overall QOL as well as families' underestimation of patients' QOL were observed. Families reported on observable domains of patients' QOL more reliably and assessed subjective aspects, such as psychospiritual concerns less accurately. Families tended to underrate the patients' social aspect of QOL, whereas most patients gave the highest rating on support from their families. The spiritual domain, particularly regarding faith, showed the least agreement. The size of the systematic bias between patient and family assessments on the patients' QOL was moderate (>0.50).

Conclusions: Families' limited ability to assess psychosocial and spiritual aspects of patients' QOL may suggest the need for better approaches or measures to assess these aspects of a patient's life. The systematic bias was larger than in earlier studies. Further investigation is needed to identify factors affecting patient–family discord on QOL assessments to guide effective interventions to enhance patient–caregiver agreement. Copyright © 2010 John Wiley & Sons, Ltd.
Familial neuroendocrine cell hyperplasia of infancy
Authors: Popler J. , Gower W.A. , Mogayzel P.J. , Nogee L.M. , Langston C. , Wilson A.C. , Hay T.C. , Deterding R.R.
Published: July 2010

Background

Neuroendocrine cell hyperplasia of infancy (NEHI) is a recently described children's interstitial lung disease (chILD) disorder of unknown etiology. It manifests clinically with tachypnea, retractions, hypoxemia, and crackles. The characteristic radiographic appearance consists of pulmonary hyperexpansion and ground‐glass densities on high‐resolution computed tomography (HRCT). Lung histology shows hyperplasia of bombesin‐immunopositive neuroendocrine cells within distal bronchioles and alveolar ducts without other identifiable lung pathology or developmental anomaly.

Methods

We describe four families with multiple siblings diagnosed with NEHI. Cases were identified at three pediatric centers. Inclusion criteria included clinical findings consistent with NEHI, lung biopsy confirmation in the index case, and a diagnostic HRCT or biopsy in other siblings.

Results

Each family had a proband diagnosed with NEHI based upon pathologic review, and at least one additional sibling diagnosed either by pathologic review or HRCT. All patients presented between 2 and 15 months of age. Both male and female children were affected. The majority of the patients underwent both HRCT and lung biopsy. There were no deaths among affected children. No environmental exposures or other potential etiologies were identified as a cause of presenting symptoms.

Conclusions

The familial occurrence of NEHI suggests the possibility of a genetic etiology for this disorder and highlights the importance of taking a complete family medical history for infants presenting with a suggestive clinical picture. Identification of familial NEHI patients allows for the opportunity to further our understanding of this disorder, its natural history, the phenotypic spectrum, and potential genetic causes. Pediatr. Pulmonol. 2010; 45:749–755. © 2010 Wiley‐Liss, Inc.
Reduction of thioredoxin significantly decreases its partial specific volume and adiabatic compressibility
Authors: Kaminsky S.M. , Richards F.M.
Published: July 2010

The partial specific volume and adiabatic compressibility were determined at several temperatures for oxidized and reduced Escherichia coli thioredoxin. Oxidized thioredoxin had a partial specific volume of 0.785–0.809 mL/g at the observed upper limit for all proteins whereas the partial specific volume of reduced thioredoxin was 0.745–0.755 mL/g, a value in the range found for a majority of proteins. The adiabatic compressibility of oxidized thioredoxin was also much larger (9.8–18 × 10−12 cm2 dyne−1) than that of the reduced protein (3.8–7.3 × 10−12). Apart from the region immediately around the small disulfide loop, the structures of the oxidized (X‐ray, crystal) and reduced protein (nuclear magnetic resonance, solution) are reported to be very similar. It would appear that alterations in the solvent layer in contact with the protein surface must play a major role in producing these large changes in the apparent specific volumes and compressibilities in this system. Some activities of thioredoxin require the reduced structure but are not electron transfer reactions. The large changes in physical parameters reported here suggest the possibility of a reversible metabolic control function for the SS bond.
Comparison of solution structures of mutant bovine pancreatic trypsin inhibitor proteins using two‐dimensional nuclear magnetic resonance
Authors: Hurle Mark R. , Eads Charles D. , Pearlman David A. , Seibel George L. , Thomason John , Kosen Phyllis Anne , Kollman Peter , Kuntz Irwin D. , Anderson Stephen
Published: July 2010

Structural perturbations due to a series of mutations at the 30–51 disulfide bond of bovine pancreatic trypsin inhibitor have been explored using NMR. The mutants replaced cysteines at positions 30 and 51 by alanine at position 51 and alanine, threonine, or valine at position 30. Chemical shift changes occur in residues proximate to the site of mutation. NOE assignments were made using an automated procedure, NASIGN, which used information from the wild‐type crystal structure. Intensity information was utilized by a distance geometry algorithm, VEMBED, to generate a series of structures for each protein. Statistical analyses of these structures indicated larger averaged structural perturbations than would be expected from crystallographic and other information. Constrained molecular dynamics refinement using AMBER at 900 K was useful in eliminating structural movements that were not a necessary consequence of the NMR data. In most cases, statistically significant movements are shown to be those greater than approximately 1 Å. Such movements do not appear to occur between wild type and A30A51, a result confirmed by crystallography (Eigenbrot, C., Randal, M., & Kossiakoff, A.A., 1990, Protein Eng. 3, 591–598). Structural alterations in the T30A51 or V30A51 mutant proteins near the limits of detection occur in the β‐loop (residues 25–28) or C‐terminal α‐helix, respectively.
Broønsted analysis of aspartate aminotransferase via exogenous catalysis of reactions of an inactive mutant
Authors: Toney Michael D. , Kirsch Jack F.
Published: July 2010

Primary amines functionally replace lysine 258 by catalyzing both the 1,3‐prototropic shift and external aldimine hydrolysis reactions with the inactive aspartate aminotransferase mutant K258A. This finding allows classical Brønsted analyses of proton transfer reactions to be applied to enzyme‐catalyzed reactions. An earlier study of the reaction of K258A with cysteine sulfinate (Toney, M.D. & Kirsch, J.F., 1989, Science 243, 1485) provided a β value of 0.4 for the 1,3‐prototropic shift. The β value reported here for the transamination of oxalacetate to aspartate is 0.6. The catalytic efficacy of primary amines is largely determined by basicity and molecular volume. The dependence of the rate constants for the reactions of K258A and K258M on amine molecular volume is nearly identical. This observation argues that the alkyl groups of the added amines do not occupy the position of the lysine 258 side chain in the wild type enzyme. Large primary Cα and insignificant solvent deuterium kinetic isotope effects with amino acid substrates demonstrate that the amine nitrogen of the exogenous catalysts directly abstracts the labile proton in the rate‐determining step.
Stability, quaternary structure, and folding of internal, external, and core‐glycosylated invertase from yeast
Authors: Kern Gunther , Schülke Norbert , Jaenicke Rainer , Schmid Franz X.
Published: July 2010

The role of carbohydrate chains for the structure, function, stability, and folding of glycoproteins has been investigated using invertase as a model. The protein is encoded by several different genes, and its carbohydrate moiety is heterogeneous. Both properties complicate physicochemical comparisons. Here we used the temperature‐sensitive sec18 secretion mutant of yeast with a single invertase gene (SUC2). This mutant produces the carbohydrate‐free internal invertase, the core‐glycosylated form, and, at the permissive temperature, the fully glycosylated external enzyme, all with identical protein moieties. The core‐glycosylated enzyme resembles the nascent glycoprotein chain that folds in the endoplasmic reticulum. Therefore, it may be considered a model for the in vivo folding of glycoproteins. In addition, because of its uniform glycosylation, it can be used to investigate the state of association of native invertase.

Glycosylation is found to stabilize the protein with respect to thermal denaturation and chaotropic solvent components; the stabilizing effect does not differ for the external and the core‐glycosylated forms. Unlike the internal enzyme, the glycosylated forms are protected from aggregation.

Native internal invertase is a dimer (115 kDa) whereas the core‐glycosylated enzyme is a mixture of dimers, tetramers, and octamers. This implies that core‐glycosylation is necessary for oligomerization to tetramers and octamers. Dimerization is required and sufficient to generate enzymatic activity; further association does not alter the specific activity of core‐glycosylated invertase, suggesting that the active sites of invertase are not affected by the association of the dimeric units.

Reconstitution of the glycosylated and nonglycosylated forms of the enzyme after preceding guanidine denaturation depends on protein concentration. The maximum yield (=80%) is obtained at pH 6–8 and protein concentrations ≤4 μg/mL for the nonglycosylated and ≤40 μg/mL for the glycosylated forms of the enzyme. The lower stability of the internal enzyme is reflected by a narrower pH range of reactivation and enhanced aggregation. As indicated by the sigmoidal reactivation kinetics at low protein concentration both folding and association are rate‐determining.