bluuebunny/crossref_metadata_2025 huggingface dataset:
Photopolymerization of thiol‐ene systems based on oligomeric thiols
Authors: Clark Tolecia , Kwisnek Luke , Hoyle Charles E. , Nazarenko Sergei
Published: November 2008

Thiol oligomers were copolymerized with a triallyl ether by a photoinduced polymerization process. These oligomeric thiol‐ene systems comprise the same components as a photopolymerized thiol‐ene‐acrylate ternary system, yet the photopolymerized networks have much lower glass transition temperatures. An investigation into the effect of oligomeric thiol design on network formation was conducted by analyzing the reaction kinetics and thermal/mechanical properties of the thiol‐ene networks. Real‐time FTIR analysis shows that total conversion is >90% for all thiols investigated. Photo‐DSC analysis shows that the maximum exotherm rate is roughly equivalent for all of the thiols when the equivalent weight of the thiol is taken into account. As would be expected, the glass transition temperature and tensile strength increase with thiol functionality and lower thiol equivalent weight for thiols with functionality from 2 to 4. Films made using the oligomeric thiols have essentially the same glass transition temperatures and tensile modulus values regardless of thiol design. These results distinguish the method for generation of networks consisting of an initial Michael reaction of thiols and acrylates followed by a photoinitiated copolymerization with a multifunctional ene from the traditional photolysis of the corresponding thiol‐ene‐acrylate ternary systems with no Michael reaction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 14–24, 2009
Solid‐supported amphiphilic triblock copolymer membranes grafted from gold surface
Authors: Rakhmatullina Ekaterina , Mantion Alexandre , Bürgi Thomas , Malinova Violeta , Meier Wolfgang
Published: November 2008

Gold‐supported amphiphilic triblock copolymer brushes composed of two hydrophilic poly(2‐hydroxyethyl methacrylate) (PHEMA) blocks and a hydrophobic poly(n‐butyl methacrylate) (PBMA) middle part were synthesized using a surface‐initiated ATRP. Attenuated total reflectance Fourier transform infrared spectroscopy, polarization modulation infrared reflection absorption spectroscopy (PM‐IRRAS), ellipsometry, contact angle measurements, and atomic force microscopy were used for the characterization of PHEMA‐co‐PBMA‐co‐PHEMA brushes. The PM‐IRRAS analysis revealed an increase of the chain tilt toward the gold surface during growth of the individual blocks. We suggest that the orientation of the amphiphilic polymer brushes is influenced by both the chain length and the interchain interactions. Additionally, a detachment of the polymer membranes from the solid support and subsequent gel permeation chromatography analyses allowed us to establish their compositions. We applied block‐selective solvents (water and hexane) as well as a good solvent for the whole polymer chain (ethanol) to study the morphology and solvent responsive behavior of the amphiphilic brushes. The presented results could serve as a good starting point for the fabrication of functional solid‐supported membranes for biosensing applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1–13, 2009
Evaluation of automated synthesis for chain and step‐growth polymerizations: Can robots replace the chemists?
Authors: Rojas Ramiro , Harris Nicole K. , Piotrowska Karolina , Kohn Joachim
Published: November 2008

This article explores current challenges in the use of automated parallel synthesizers in polymeric materials research. Four types of polymerizations were investigated: carbodiimide‐mediated polyesterification, diphenol phosgenation, free radical, and reversible addition‐fragmentation chain‐transfer (RAFT). Synthetic challenges of condensation polymerization, such as liquid and solid dispensing accuracy, dropwise addition, and toxic chemical handling, were successfully met using the automated synthesizer. Both solid and liquid dosing of the diphenol and diacid were successful for polyarylate synthesis. The high precision of liquid dispensing made it possible to achieve stoichiometric balance using reagent stock solutions. For all reactions, molecular weights and their reproducibility were comparable to those obtained with manual synthesis. For RAFT polymerizations, solvent and mol ratio of chain transfer reagent to initiator were successfully optimized on the automated synthesizer and a library of over 60 polymethacrylate copolymer compositions was generated. Considerable savings in time relative to manual methods were achieved when generating polymer libraries (e.g., 4.5× faster for 96 polymethacrylates and 20× faster for 45 for polycarbonates). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 49–58, 2009
Model‐based design and synthesis of gradient MMA/tBMA copolymers by computer‐programmed semibatch atom transfer radical copolymerization
Authors: Zhao Ying , Luo Ying‐Wu , Ye Changhuai , Li Bo‐Geng , Zhu Shiping
Published: November 2008

Methyl methacrylate (MMA)/tert‐butyl methacrylate (tBMA) gradient copolymers having linear and hyperbolic composition profiles were synthesized. These special copolymer products were achieved via a model‐based computer‐controlled semibatch atom transfer radical copolymerization (ATRcoP) process. A simple ATRcoP model was developed based on the terminal model. The equilibrium constants in the ATRP of MMA and tBMA were estimated by the data correlation. The model was verified by batch experiments and was found to give good correlation for the polymerization rate, molecular weight, and copolymer composition data. The model coupled with a reactor model was then applied to the semibatch ATRcoP and was used to calculate comonomer feeding rates for the targeted gradient composition profiles. It was found that the experimental monomer conversion, molecular weight, and cumulative copolymer composition were in good agreement with their targeted theoretical values. The gradient copolymers had low polydispersities close to 1.1. This work demonstrated the feasibility of the model‐based semibatch ATRcoP in fine‐tuning gradient copolymer composition profiles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 69–79, 2009
Linear and comb‐like acrylonitrile/N‐isopropylacrylamide copolymers synthesized by the combination of RAFT polymerization and ATRP
Authors: Wan Ling‐Shu , Lei Hao , Ding Yao , Fu Lei , Li Jing , Xu Zhi‐Kang
Published: November 2008

We describe the synthesis of three novel thermoresponsive copolymers of acrylonitrile (AN) with N‐isopropylacrylamide (NIPAM) by a combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). Linear copolymer polyacrylonitrile (PAN)‐b‐PNIPAM was directly prepared by RAFT polymerization. Comb‐like copolymers were synthesized by ATRP using brominated AN/2‐hydroxyethyl methacrylate copolymers as macroinitiators, which were prepared by RAFT polymerization. FT‐IR, NMR, and GPC were employed to characterize the synthesized copolymers. Results indicate that the polymerization processes can be well controlled and the resultant copolymers have well‐defined structures as well as narrow polydispersity. Then dense films were fabricated from these thermoresponsive copolymers and the surface wettability was evaluated by water contact angle measurements at different temperatures. It is found that the surface wettability is temperature‐dependant and both the transition temperature and decrement of water contact angle are affected by the copolymer shapes as well as the length of PNIPAM blocks. Considering the excellent fiber‐ and membrane‐forming properties of PAN‐based copolymers, the obtained thermoresponsive copolymers are latent materials for functional fibers and membranes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 92–102, 2009
Field‐effect transistors based on PPV derivatives as a semiconducting layer
Authors: Lee Woo‐Hyung , Kong Hoyoul , Oh Se‐Young , Shim Hong‐Ku , Kang In‐Nam
Published: November 2008

A series of modified thiophene groups containing PPV‐based semiconducting materials, poly[(2,5‐bis(octyloxy)‐1,4‐phenylenevinylene)‐alt‐(2,2′bithienylenevinylene)] (PPBT), poly[(2,5‐bis(octyloxy)‐1,4‐phenylenevinylene)‐alt‐(5,5‐thiostilylenevinylene)] (PPTVT), have been synthesized through a Horner coupling reaction. From the FTIR and 1H NMR spectroscopy, the configuration of the vinylene groups in the polymers was all trans (E) geometry. The weight‐average molecular weights (Mw) of PPBT and PPTVT were found to be 11,700 and 11,800, with polydispersity indices of 2.51 and 2.53, respectively. PPBT and PPTVT thin films exhibit UV–visible absorption maxima at 538 and 558 nm, respectively, and the strong absorption shoulder peaks at 578 and 602 nm, respectively. Solution processed field‐effect transistors (FET) fabricated using all the polymers showed p‐type OTFT characteristics. The field‐effect mobility of the PPTVT was obtained up to 2.3 × 10−3 cm2 V−1 s−1, an on/off ratio of 1.0 × 105 with ambient air stability. Studies of the atomic force microscopy (AFM) and X‐ray diffraction (XRD) analysis of the polymer thin films revealed that all the polymers were amorphous structure. The greater planarity and rigidity of PPTVT compared to PPBT results in elongation of conjugation length and better π–π stacking of polymer chains in amorphous region, which leads to improved FET performance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 111–120, 2009
Synthesis of original para‐sulfonic acid aminoethylthioethylbenzenesulfonic by telomerization, and its grafting onto poly(VDF‐co‐HFP) copolymers for proton exchange membrane for fuel cell
Authors: Taguet Aurelie , Ameduri Bruno , Boutevin Bernard
Published: November 2008

The synthesis of a novel aromatic sulfonic acid bearing an amino function H2NC2H4SC2H4C6H4SO3Na (1) from the radical addition of mercaptoethylamine hydrochloride onto styrene sodium sulfonate, and its subsequent grafting onto poly(vinylidene fluoride‐co‐hexafluoropropylene), poly(VDF‐co‐HFP), copolymer are presented. First, the radical telomerization, carried out under radical conditions and in water, led to various products [monoadduct (1), multiadducts, and polymers], the amounts of which depend on the experimental conditions and [mercaptan]0/[monomer]0 initial molar ratio (R0). An R0 ≥ 1 led to the monoadduct (1) only and achieved in ∼85% yield. The zwitterionic isomer was obtained mainly and its chemical modification was possible to get an original aromatic sodium sulfonate containing an amino end group. A kinetic study of the telomerization was presented for R0 < 1. Thermogravimetric analysis of the telomer showed that this compound was stable up to 200 °C. Second, the grafting of (1) onto poly(VDF‐co‐HFP) copolymer was also investigated. Such a grafting proceeded as expected by a classic mechanism of grafting of amines. Molar percentages of grafted telomer were assessed by 1H NMR spectroscopy and by elemental analysis. Ion exchange capacity (IEC) values of the membranes were deduced from the mol % grafted telomer. Scanning electron microscopy pictures showed a good homogeneity in the cross‐section of membranes, and energy dispersive X‐ray evidenced that all SO3Na groups of the grafted amine were changed into SO3H after treatment with concentrated HCl. Method involving an impedance analyzer, working at increasing high frequencies was used to assess the protonic conductivities, σ. These values were lower than that of Nafion117®, but σ increased with the IEC to 0.4 mS/cm at room temperature and 95% relative humidity. Water and methanol uptakes were also assessed, and it was shown that σ increased when water uptakes increased. Membranes started to decompose from 170 °C under air. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 121–136, 2009
Synthesis, characterization, and application of light‐emitting copolyfluorenes slightly doped with distyrylbenzene derivatives
Authors: Liao Chiung‐Feng , Hsieh Bar‐Yuan , Chen Yun
Published: November 2008

Copolyfluorenes PFG1∼PFG4 slightly doped with 0.006–0.5 mol % of 2,5‐dihexyloxy‐1,4‐bis(2‐phenyl‐2‐cyanovinyl)benzene (green chromophore) were synthesized by the Suzuki coupling reaction to be evaluated as hosts for white‐light electroluminescent (EL) devices. Their optical, thermal and electrochemical properties were almost identical to those of polyfluorene (PF) due to minimal chromophore content. However, the electroluminescent (EL) spectra of the PFGn were very different from photoluminescence spectra in film state. Relative intensity of green emission (ca. 521 nm) in EL spectra are much stronger than those in PL spectra, which can be attributed to charges trapping in the chromophores due to its narrow band gap (Eg ≈ 2.56 eV). The performance of EL devices [ITO/PEDOT:PSS/polymer/Ca (50 nm)/Al (100 nm)] were improved with an increase in chromophore content. The PFG4 device revealed the best performance (6790 cd/m2, 1.69 cd/A), and the PFG1 and PFG2 devices exhibited comparable intensity in blue and green emissions. Blend EL devices were fabricated by using the PFGn as the hosts and a red iridium complex [Ir(piq)2(acac)] as dopant. By controlling the amount of the iridium complex, the white‐light emitting device was achieved with PFG2, with maximum brightness and CIE coordinate being 4120 cd/m2 and (0.31, 0.28), respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 149–160, 2009
Cinnamate‐functionalized poly(ester‐carbonate): Synthesis and its UV irradiation‐induced photo‐crosslinking
Authors: Hu Xiuli , Chen Xuesi , Cheng Haibo , Jing Xiabin
Published: November 2008

A functionalized cyclic carbonate monomer containing a cinnamate moiety, 5‐methyl‐5‐cinnamoyloxymethyl‐1,3‐dioxan‐2‐one (MC), was prepared for the first time with 1,1,1‐tri(hydroxymethyl) ethane as a starting material. Subsequent polymerization of the new cyclic carbonate and its copolymerization with L‐lactide (LA) were successfully performed with diethyl zinc (ZnEt2) as initiator/catalyst. NMR was used for microstructure identification of the obtained monomer and copolymers. Differential scanning calorimetry (DSC) was used to characterize the functionalized poly(ester‐carbonate). The results indicated that the copolymers displayed a single glass transition temperature (Tg) and the Tg decreased with increasing carbonate content and followed the Fox equation, indicative of a random microstructure of the copolymer. The photo‐crosslinking of the cinnamate‐carrying copolymer was also demonstrated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 161–169, 2009
Syntheses of aliphatic polyesters catalyzed by lanthanide triflates
Authors: Garaleh Mazen , Lahcini Mohammed , Kricheldorf Hans R. , Weidner Steffen M.
Published: November 2008

Polycondensations of 1,6‐hexane diol and sebacic acid were conducted in bulk with addition of a lanthanide triflate as acidic catalyst. With exception of promethium triflate all lanthanide triflates were studied. A particularly low molecular weight was obtained with neodym triflate and the best results with samarium triflate. With Sm(OTf)3 weight average (Mw) values up to 65 kDa (uncorrected SEC data) were achieved after optimization of the reaction conditions. Comparison of these results with those obtained from bismuth, magnesium, and zinc triflates, on the one hand, and comparison with the acidities of all catalysts, on the other, indicates that the esterification mechanism involves complexation of monomer by metal ions. Preparation of multiblock copoly(ether ester)s failed due to insufficient incorporation of poly(tetrahydrofuran) diols. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 170–177, 2009
Multiarm star block copolymers via Diels‐Alder click reaction
Authors: Dag Aydan , Durmaz Hakan , Tunca Umit , Hizal Gurkan
Published: November 2008

Two types of multiarm star block copolymers: (polystyrene)m‐poly(divinylbenzene)‐poly(methyl methacrylate)n, (PS)m‐polyDVB‐(PMMA)n and (polystyrene)m‐poly(divinylbenzene)‐poly(tert‐butyl acrylate)k, (PS)m‐polyDVB‐(PtBA)k were successfully prepared via a combination of cross‐linking and Diels–Alder click reactions based on “arm‐first” methodology. For this purpose, multiarm star polymer with anthracene functionality as reactive periphery groups was prepared by a cross‐linking reaction of divinyl benzene using α‐anthracene end functionalized polystyrene (PS‐Anth) as a macroinitiator. Thus, obtained multiarm star polymer was then reacted with furan protected maleimide‐end functionalized polymers: PMMA‐MI or PtBA‐MI at reflux temperature of toluene for 48 h resulting in the corresponding multiarm star block copolymers via Diels–Alder click reaction. The multiarm star and multiarm star block copolymers were characterized by using 1H NMR, SEC, Viscotek triple detection SEC (TD‐SEC) and UV. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 178–187, 2009
Block copolymer micelles as nanoreactors for single‐site polymerization catalysts
Authors: Bouilhac Cécile , Cloutet Eric , Taton Daniel , Deffieux Alain , Borsali Redouane , Cramail Henri
Published: November 2008

New micelle‐like organic supports for single site catalysts based on the self‐assembly of polystyrene‐b‐poly(4‐vinylbenzoic acid) block copolymers have been designed. These block copolymers were synthesized by sequential atom transfer radical polymerization (ATRP) of styrene and methyl 4‐vinylbenzoate, followed by hydrolysis. As evidenced by dynamic light scattering, self‐assembly in toluene that is a selective solvent of polystyrene, induced the formation of micelle‐like nanoparticles composed of a poly(4‐vinylbenzoic acid) core and a polystyrene corona. Further addition of trimethylaluminium (TMA) afforded in situ MAO‐like species by diffusion of TMA into the core of the micelles and its subsequent reaction with the benzoic acid groups. Such reactive micelles then served as nanoreactors, MAO‐like species being efficient activators of 2,6‐bis[1‐{(2,6‐diisopropylphenyl)imino}ethyl]pyridinyl iron toward ethylene polymerization. These new micelle‐like organic supports enabled the production of polyethylene beads with a spherical morphology and a high bulk density through homogeneous‐like catalysis. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 197–209, 2009
Nearly monochromatic red electroluminescence from a nonconjugated polymer containing carbazole segments and phenanthroline [Eu(β‐diketonate)3] moieties
Authors: Zhang Zhi‐guo , Yuan Ji‐bing , Tang Huai‐jun , Tang Hao , Wang Li‐na , Zhang Ke‐Li
Published: November 2008

A novel nonconjugated copolymer (PVKEu) with carbazole segments and phenanthroline [Eu(β‐diketonate)3] moieties was synthesized via free radical copolymerization, and characterized by FTIR, 1H NMR spectroscopy, GPC, ICP, and elemental analysis. The copolymer exhibited good solubility, as well as good thermal stability and high glass transition temperature. The photoluminescence (PL) of this polymer in solution and in solid film has been studied. A multi‐layer device with the configuration of ITO/PEDOT: PSS (40 nm)/PVKEu (70 nm)/BCP (15 nm)/AlQ3 (30 nm)/LiF/Al exhibited nearly monochromatic red emission at 615 nm and voltage‐independent spectral stability. Our results suggest that enhancing the ligand‐mediated energy transfer between the matrix polymer and europium complex is a potential method to improve the electroluminescence performance of the Eu‐chelated polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 210–221, 2009
Hyperbranched copolymer containing triphenylamine and divinyl bipyridyl units for fluorescent chemosensors
Authors: Feng Jichang , Li Yang , Yang Mujie
Published: November 2008

A fluorescent hyperbranched copolymer (HTP) and a linear copolymer (PTP) as a reference sample to HTP both containing triphenylamine and divinyl bipyridyl units were synthesized via Heck coupling reaction from 5,5′‐Divinyl‐2,2′‐bipyridyl with tris(4‐bromophenyl)amine and with 4,4′‐dibromotriphenylamie, respectively. The chemical structure of HTP was confirmed by FTIR, 1H NMR, and 13C NMR. The polymer HTP had a number‐average molecular weight of 1895 and a weight‐average molecular weight of 2315, and good solubility in conventional organic solvents, such as THF, DMF, and chloroform, and exhibited good thermal stability. The UV–vis absorption and photoluminescence (PL) spectra exhibited absorption maximum at 428 nm and emissive maximum at 531 nm for the HTP solution. The spectroscopic results of HTP and PTP indicated that hyperbranched conjugated structure increases the effective conjugation length, as compared with corresponding linear conjugated structure. The fluorescence of the polymer in solution can be quenched by various transition metal ions. The effect of backbone structure of the conjugated polymer‐based chemosensors on the sensitivity and selectivity in metal ions sensing have been investigated, and the quenching effect of HTP is more sensitive toward transition metal than linear copolymer PTP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 222–230, 2009
A novel hydroxy functionalized polyester obtained by ring opening copolymerization of L‐lactide with a pyrolysis product of cellulose
Authors: Dobrzynski Piotr , Fabbri Daniele , Torri Cristian , Kasperczyk Janusz , Kaczmarczyk Bozena , Pastusiak Malgorzata
Published: November 2008

A hydroxylactone ((1R,5S)‐1‐hydroxy‐3,6‐dioxabicyclo [3.2.1] octan‐2‐one, abbreviated as LAC) obtained from catalytic pyrolysis of cellulose was investigated as a monomer in the synthesis of polyesters by ring‐opening polymerization (ROP) with L‐lactide. Although stannous octoate resulted inactive, ROP initiated by zirconium (IV) acetylacetonate afforded novel copolyesters from LAC and lactide mixtures in the bulk at 110 °C. Copolymers were obtained with different LAC content (from 19 to 45%) with a random microstructure as established by detailed NMR analysis. FTIR spectrometry confirmed the presence in the polymer chain of the OH groups originally present in LAC, which do not react during polymerization due to steric hindrance and inter/intramolecular hydrogen bonding. Reaction with trichloroacetylisocyanide proved that OH groups of the polyesters can be readily derivatized. The application of LAC as a comonomer enables the insertion of the alcohol functionality in polylactide avoiding protection/deprotection steps and potentially expanding the realm of biomaterials affordable from carbohydrate feedstock. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 247–257, 2009
Microdomain morphology of lamella‐forming diblock copolymer confined in a thin film
Authors: He Linli , Zhang Linxi , Liang Haojun
Published: November 2008

We report the self‐consistent field theory (SCFT) of the morphology of lamella‐forming diblock copolymer thin films confined in two horizontal symmetrical/asymmetrical surfaces. The morphological dependences of thin films on the polymer‐surface interactions and confinement, such as film thickness and confinement spatial structure, have been systematically investigated. Mechanisms of the morphological transitions can be understood mainly through the polymer‐surface interactions and confinement entropy, in which the plat confinement surface provides a surface‐induced effect. The confinement is expressed in the form of the ratioD/L0, hereDis film thickness, andL0is the period of bulk lamellar‐structure. Much richer morphologies and multiple surface‐induced morphological transitions for the lamella‐forming diblock copolymer thin films are observed, which have not been reported before. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1–10, 2009
Viscoelastic properties of Nafion at elevated temperature and humidity
Authors: Satterfield M. Barclay , Benziger Jay B.
Published: November 2008

Tensile stress–strain and stress relaxation properties of 1100 equivalent weight Nafion have been measured from 23 to 120 °C at 0–100% relative humidity. At room temperature, the elastic modulus of Nafion decreases with water activity. At 90 °C, the elastic modulus goes through a maximum at a water activity of ∼ 0.3. At temperatures ≥90 °C, hydrated membranes are stiffer than dry membranes. Stress‐relaxation was found to have two very different rates depending on strain, temperature, and water content. At high temperature, low water activity, and small strain, the stress relaxation displays a maximum relaxation time with stress approaching zero after 103–104s. Water absorption slows down stress‐relaxation rates. At high water activity, the maximum stress relaxation time was >105s at all temperatures. No maximum relaxation time was seen atT≤ 50 °C. Increasing the applied strain also resulted in no observed upper limit to the stress relaxation time. The results suggest that temperature, absorbed water, and imposed strain alter the microstructure of Nafion inducing ordering transitions; ordered microstructure increases the elastic modulus and results in a stress relaxation time of >105s. Loss of microphase order reduces the elastic modulus and results in a maximum stress relaxation time of 103–104s. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 11–24, 2009.
Suppressed coalescence of dispersed viscous poly(methyl methacrylate) phase in polystyrene matrix by glass beads
Authors: Chen Peng , Chen Jun , He Jiasong
Published: November 2008

The effect of glass beads (GB) on morphology of polystyrene (PS)/poly(methyl methacrylate) (PMMA) blends has been studied by scanning electron microscopy (SEM) at different shear rates and during quiescent annealing. For the viscosity ratio of PMMA to PS greater than unity, the dispersed viscous PMMA phase in the blend coalesced during the shear flow or quiescent annealing. However, the domain size of the PMMA phase decreased significantly under shear even though a small amount of GB was added. The PMMA domain size further decreased and the size distribution became narrower with increasing GB content. According to SEM images, the quiescent coalescence of the PMMA phase was effectively inhibited by adding large amounts of GB, and the breakup of PMMA domains in shear flow was greatly favored by the high local shear prevailed between GB. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 25–35, 2009
Effects of nucleating agents on microstructure and fracture toughness of poly(propylene)/ethylene‐propylene‐diene terpolymer blends
Authors: Bai Hongwei , Wang Yong , Song Bo , Huang Ting , Han Liang
Published: November 2008

The effects of nucleating agents (NAs) on fracture toughness of injection‐molded isotactic poly(propylene)/ethylene‐propylene‐diene terpolymer (PP/EPDM) were studied in this work. Compared with PP/EPDM blends without any NA, PP/EPDM/NA blends show very small and homogeneous PP spherulites. As we expected, PP/EPDM blends nucleated with β‐phase NA aryl amides compound (TMB‐5) present not only a significant enhancement in toughness but also a promotion of brittle‐ductile transition. However, the addition of α‐phase NA 1,3:2,4‐bis(3,4‐dimethylbenzylidene) sorbitol (DMDBS) has no apparent effect on the toughness of the blends. The impact‐fractured surface morphologies of such samples were analyzed via scanning electronic microscope (SEM). More detail work about the toughening mechanisms of elastomer and NA based on elastomer particles size and matrix crystal structures were carried out. Our results suggest that, besides the crystal structures of matrix, the elastomer particles size and size distribution plays an important role in controlling the toughening effect of nucleated PP/elastomer blends. The smaller the elastomer particles size and lower the polydispersity, the more apparent the synergistic toughening effect of NA and elastomer is. This investigation provides a fresh insight into the understanding of toughening mechanism of elastomers in PP blends and facilitates to the design of super toughened PP materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 46–59, 2009
Novel poly(N‐isopropylacrylamide)/clay/poly(acrylamide) IPN hydrogels with the response rate and drug release controlled by clay content
Authors: Li Biao , Jiang Yongmei , Liu Yang , Wu Yongtao , Yu Hao , Zhu Meifang
Published: November 2008

Novel interpenetrating network (IPN) hydrogels (PNIPAAm/clay/PAAm hydrogels) based on poly(N‐isopropylacrylamide) (PNIPAAm) crosslinked by inorganic clay and poly(acrylamide) (PAAm) crosslinked by organic crosslinker were prepared in situ by ultraviolet (UV) irradiation polymerization. The effects of clay content on temperature dependence of equilibrium swelling ratio, deswelling behavior, thermal behavior, and the interior morphology of resultant IPN hydrogels were investigated with the help of Fourier transform infrared spectroscopy, differential scanning calorimeter (DSC), scanning electron microscope (SEM). Study on temperature dependence of equilibrium swelling ratio showed that all IPN hydrogels exhibited temperature‐sensitivity. DSC further revealed that the temperature‐sensitivity was weakened with increasing amount of clay. Study on deswelling behavior revealed that IPN hydrogels had much faster response rate when comparing with PNIPAAm/clay hydrogels, and the response rate of IPN hydrogels could be controlled by clay content. SEM revealed that there existed difference in the interior morphology of IPN hydrogels between 20 [below lower critical solution temperature (LCST)] and 50 °C (above LCST), and this difference would become obvious with a decrease in clay content. For the standpoint of applications, oscillating swelling/deswelling behavior was investigated to determine whether properties of IPN hydrogels would be stable for potential applications. Bovine serum albumin (BSA) was used as model drug for in vitro experiment, the release data suggested that the controlled drug release could be achieved by modulating clay content. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 96–106, 2009
Caregiving Consequences Inventory: a measure for evaluating caregiving consequences from the bereaved family member's perspective
Authors: Sanjo Makiko , Morita Tatsuya , Miyashita Mitsunori , Shiozaki Mariko , Sato Kazuki , Hirai Kei , Shima Yasuo , Uchitomi Yosuke
Published: November 2008

Objective: The aims of this study were to validate an instrument for measuring bereaved family members' perceptions of caregiving consequences and to examine the association between caregiving consequences and psychological distress.

Methods: Cross‐sectional questionnaires were administered to family members of patients who had died in regional cancer centers. We measured the Caregiving Consequences Inventory (CCI), respondent's optimism, overall reward scale, and psychological distress and collected background data. A retest was conducted.

Results: Bereaved families from two regional cancer centers were surveyed (N=189 and 109; effective response rate, 57 and 80%). By exploratory and confirmatory factor analyses, we identified four perceived reward domains: ‘mastery’, ‘appreciation for others’, ‘meaning in life’, and ‘reprioritization’, and one perceived burden domain. Although the four reward domains were highly correlated with each other (0.47<r<0.69), the 4‐domain model was superior. The respondents with less education, strong faith, and less optimism reported fewer perceived rewards, thus demonstrating known group validity. In addition, perceived reward had little or no correlation with psychological distress. The psychometric properties of this scale were good (α=0.78–0.93, ICC=0.60–0.73) and construct validity was supported (GFI=0.929; AGFI=0.819; CFI=0.749; RMSEA=0.097).

Conclusions: The CCI is valid for measuring caregiving consequences from the bereaved family member's perspective in Japan. Furthermore, it is important to use perceived rewards and burdens as a measure of caregiving consequences for improving the quality of the caregiving and bereavement experience. Copyright © 2008 John Wiley & Sons, Ltd.
Perceived risk for gastric cancer among the general Korean population: a population‐based survey
Authors: Kwak Min‐Son , Choi Kui Son , Park Sohee , Park Eun‐Cheol
Published: November 2008

Objective: We measured the perceived risk for developing gastric cancer and investigated how a range of socio‐demographic, lifestyle, health, and psychological factors were associated with risk perception in a population‐based sample in Korea.

Methods: This study was based on the 2006 Korean National Cancer Screening Survey conducted by the National Cancer Center, in which trained interviewers met face‐to‐face with participants selected by a nationally representative random sampling. The participants included 1673 adults, aged 40 years or older, who had not previously been diagnosed with cancer. Simple and multiple ordinal regression were used to determine the associations between perceived risk and socio‐demographic, lifestyle, health, and psychological factors.

Results: Almost half of the subjects (48.3%) thought their chance of developing gastric cancer was lower than that of other men or women of the same age. A higher level of worry concerning gastric cancer was strongly associated with a higher perceived risk for gastric cancer development. Those who drink alcohol two or more days per week, and who are unmarried all perceived their risk as being higher. However, those without a previous gastric cancer screening, a personal history of gastric disease, or a good overall health status had a lower perceived risk for gastric cancer development.

Conclusion: This study found comparative optimism about the risk for developing gastric cancer in a Korean population. It is necessary to increase people's ability to accurately perceive their risk for cancer. Copyright © 2008 John Wiley & Sons, Ltd.
Increases in core body temperature precede hot flashes in a prostate cancer patient
Authors: Hanisch Laura J. , Mao Jun J. , Gehrman Philip R. , Vaughn David J. , Coyne James C.
Published: November 2008

Objective: An effective and safe alternative treatment to hormone replacement therapy for hot flashes is needed for cancer patients. Interventions targeting the triggering mechanisms of hot flashes hold promise. Increases in core body temperature are a precursor of most hot flashes in women, and similar findings in prostate cancer patients undergoing androgen deprivation therapy would support further research in this area. We present preliminary findings of physiological changes in a prostate cancer patient with frequent hot flashes.

Methods: Physiological changes in sternal skin conductance, heart rate, and core body temperature were continuously measured during two 3.5 h laboratory sessions. Perceived characteristics of hot flashes were recorded in a diary.

Results: Five hot flashes were reported during laboratory sessions. Severity and bother ratings were low. All hot flashes were accompanied by large increases in sternal skin conductance and moderate increases in heart rate. Core body temperature increased 0.11–0.32°C prior to and fell 0.23–0.44°C following the peak increase in skin conductance.

Conclusions: This case study suggests that hot flashes in men may be preceded by increases in core body temperature. Identification of behavioral factors that raise core body temperature may lead to specific treatment strategies to reduce the frequency of hot flashes. Copyright © 2008 John Wiley & Sons, Ltd.
A qualitative proteome investigation of the sediment portion of human urine: Implications in the biomarker discovery process
Authors: Mataija‐Botelho Diane , Murphy Patrick , Pinto Devanand M. , MacLellan Dawn L. , Langlois Chantale , Doucette Alan A.
Published: November 2008

Inherent to the biomarker discovery process is a comparative analysis of physiological states. It is therefore critical that the proteome detection protocol does not bias the analysis. With urine, the sediment portion, obtained upon thawing frozen urine, is routinely discarded prior to proteome analysis. However, our results demonstrate that such a practice inadvertently induces bias, having significant implications in the biomarker discovery process. We present the first proteome investigation of human urinary sediments, identifying 60 proteins in this phase by MS. Many sediment proteins were also detected in the urinary supernatant, indicating that several proteins partition between the two phases. This partitioning is dependant on the pH of the sample, as well as the degree of sample agitation. As a consequence of discarding the sediment portion of urine, the concentration of potential candidate biomarkers in the supernatant phase will be altered or, in other instances, may be completely removed from the sample. To minimize this, the pH of all samples should first be normalized, and the samples vigorously vortexed prior to discarding the sediments. For more comprehensive biomarker investigations, we suggest that urinary sediments be analyzed along with the supernatant proteins.
Proteomic expression analysis and comparison of protein and mRNA expression profiles in human malignant gliomas
Authors: Persson Oscar , Brynnel Ulrika , Levander Fredrik , Widegren Bengt , Salford Leif G. , Krogh Morten
Published: November 2008

Gliomas are highly heterogeneous and therapy resistant tumors with a poor prognosis. Novel experimental therapeutic approaches have shown some promising results, but often target specific molecular mechanisms or antigens, and careful characterization of the molecular subgroup of the tumors will therefore likely be important. Thorough investigations of gene and protein alterations are also important to better understand the tumorigenic mechanisms. We have undertaken a proteomic approach, using 2‐D DIGE and LC‐MS/MS protein identification, to investigate 38 human gliomas and normal brains. We show that the proteome profile can discriminate between normal brain and tumors, and between tumors of varying grade by a supervised classifier. Furthermore, an analysis of the identified proteins shows an enrichment of proteins associated to pathways known to be central in gliomas, such as MEK/Erk signaling and actin cytoskeleton. It also shows a shift between different glial fibrillary acidic protein (GFAP) representatives in different grades. In a previous study the gene expression profile was characterized in an almost identical set of tumors, which enabled a paired analysis of the gene and protein expression profiles. We show that there is often a weak correlation between the mRNA and protein level. This, together with the ability of proteomics to identify PTMs, emphasizes the benefit of characterization on a protein level.
Dissection of the critical binding determinants of cellular retinoic acid binding protein II by mutagenesis and fluorescence binding assay
Authors: Vasileiou Chrysoula , Lee Kin Sing Stephen , Crist Rachael M. , Vaezeslami Soheila , Goins Sarah M. , Geiger James H. , Borhan Babak
Published: November 2008

The binding of retinoic acid to mutants of Cellular Retinoic Acid Binding Protein II (CRABPII) was evaluated to better understand the importance of the direct protein/ligand interactions. The important role of Arg111 for the correct structure and function of the protein was verified and other residues that directly affect retinoic acid binding have been identified. Furthermore, retinoic acid binding to CRABPII mutants that lack all previously identified interacting amino acids was rescued by providing a carboxylic acid dimer partner in the form of a Glu residue. Proteins 2009. © 2008 Wiley‐Liss, Inc.
A novel solid phase approach to Aia‐containing peptides
Authors: Feytens Debby , De Vlaeminck Magali , Tourwé Dirk
Published: November 2008

A strategy was developed to directly assemble 4‐amino‐1,2,4,5‐tetrahydro‐indolo[2,3‐c]‐azepin‐3‐ones on solid‐phase‐supported peptide sequences. Fmoc‐ and Boc‐based strategies were investigated. The Fmoc‐strategy approach strongly depends on the peptide sequence being synthesized while the Boc‐based synthesis leads to excellent results for all the selected peptide analogs. The method was applied to prepare Aia‐analogs of several bioactive peptides containing one or more Trp‐residues which were shown to be important for biological recognition. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Washout and delayed start designs for identifying disease modifying effects in slowly progressive diseases using disease progression analysis
Authors: Ploeger Berend Arnold , Holford Nicholas H. G.
Published: November 2008

Treatment of a slowly progressive disease, such as Parkinson's and Alzheimer's disease should slow down or even reverse progression of the disease. For estimating the actual treatment effect a clinical trial should allow the time course of treatment effects to be distinguished from those due to natural disease progression. A symptomatic treatment effect has a rapid onset, which will disappear after treatment cessation, whereas disease modifying effects are slow and persistent. Our objective was to compare the power of washout and delayed start designs for distinguishing symptomatic and disease modifying effects using disease progression modelling. The effect of dropout due to worsening disease status on the power was also considered.

The change in the Unified Parkinson's Disease Rating Scale score over time was simulated, assuming that a treatment has a combined symptomatic and disease modifying effect. The simulated data were then fitted with the combined effect model and also with alternative models with either symptomatic or disease modifying effects alone. The power was derived from the number of times that the true model was correctly distinguished from the alternative models.

Including a washout period in which the subjects are followed up after cessation of treatment substantially increases the power to distinguish different treatment effect types (washout>80%; delayed start<60%). Dropout of 40%–50% during the trial has a small effect on power (7% decrease). Under the assumptions of the simulation we found a clear advantage from using the washout design compared with a delayed start design. Copyright © 2008 John Wiley & Sons, Ltd.
Stakeholders, reciprocity, and firm performance
Authors: Bosse Douglas A. , Phillips Robert A. , Harrison Jeffrey S.
Published: November 2008

The assumption that economic actors behave in a boundedly self‐interested manner promises fruitful new insights for strategic management. A growing literature spanning multiple disciplines indicates most actors' selfish utility maximizing behaviors are bounded by norms of fairness. Rather than being purely self‐interested, people behave reciprocally by rewarding others whose actions they deem fair and willingly incurring costs to punish those they deem unfair. Economists show that employers who are perceived as distributionally fair by their employees generate comparatively more value due to the positively reciprocal behavior of those employees. The organizational justice literature distinguishes two additional types of fairness assessed by employees. Drawing from both these bodies of work, we employ stakeholder theory to propose how perceptions of fairness result in reciprocity (1) extending to all stakeholders of the firm and (2) affecting firm performance. Copyright © 2008 John Wiley & Sons, Ltd.
Metacognitive engagement during field‐trip experiences: A case study of students in an amusement park physics program
Authors: Nielsen Wendy S. , Nashon Samson , Anderson David
Published: November 2008

This article reports on a study that investigated students' metacognitive engagement in both out‐of‐school and classroom settings, as they participated in an amusement park physics program. Students from two schools that participated in the program worked in groups to collectively solve novel physics problems that engaged their individual metacognition. Their conversations and behavioral dispositions during problem‐solving were digitally audio‐recorded on devices that they wore or placed on the tables where groups worked on the assigned physics problems. The students also maintained reflection journals on the strategies they employed to manage their own understanding as well as learning processes. Prior to the amusement park physics discourse, the students completed a specially developed questionnaire instrument. This provided signposts of the students' metacognitive engagement during group problem‐solving at the park and subsequent related physics learning tasks back in the classroom. This data, added to field notes arising from observations, and formal and informal interviews during post‐visit learning activities provided the data corpus on the students' metacognitive engagement. Analysis of this data revealed three types of metacognitive engagement during group learning tasks: collaborative and consensus‐seeking, highly argumentative, and eclectic, resulting from high levels of dissonance. In both cases, evidence of individual students' deeper understandings, which manifested through students' cognitive and social behaviors, demonstrated the invocation of metacognition to varying degrees. The novel physics problems tackled by the students created situations where discrepancies between their prior knowledge and the direct experiences enabled them to explicate their thinking through dispositions of behavior. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 46: 265–288, 2009
Science Motivation Questionnaire: Construct validation with nonscience majors
Authors: Glynn Shawn M. , Taasoobshirazi Gita , Brickman Peggy
Published: November 2008

This study examined how 770 nonscience majors, enrolled in a core‐curriculum science course, conceptualized their motivation to learn science. The students responded to the Science Motivation Questionnaire, a 30‐item Likert‐type instrument designed to provide science education researchers and science instructors with information about students' motivation to learn science. The students' scores on the Science Motivation Questionnaire were reliable and related to students' high school preparation in science, GPA in college science courses, and belief in the relevance of science to their careers. An exploratory factor analysis provided evidence of construct validity, revealing that the students conceptualized their motivation to learn science in terms of five dimensions:intrinsic motivation and personal relevance,self‐efficacy and assessment anxiety,self‐determination,career motivation, andgrade motivation. Women and men had different profiles on these dimensions, but equivalent overall motivation to learn science. Essays by all of the students explaining their motivation to learn science and interviews with a sample of the students were used to interpret Science Motivation Questionnaire scores. The findings were viewed in terms of a social‐cognitive theory of learning, and directions for future research were discussed. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 46: 127–146, 2009