bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactivity of sodium arenesulfinates in the substitution reaction to γ‐functionalized allyl bromides
Authors: Khamis Galina , Stoeva Stoyanka , Aleksiev Dimitar 
Published: November 2009

AbstractThe kinetics of nucleophilic bimolecular substitution reactions of γ‐functionalized allyl bromides with non‐substituted and p‐substituted sodium arenesulfinates has been studied. Both the structure of allyl bromides and nucleophilicity of arenesulfinate ions exerted a significant effect on the values of the kinetic parameters such as the second‐order rate constants k, activation energy EA, and changes in the entropy ΔS≠, enthalpy ΔH≠, and free energy ΔG≠ of the formation of the activated complex from reactants. Based on the evaluation of kinetic parameters, the reactants could be arranged, according to their decreasing reactivity in the SN2‐reactions as follows: p‐toluenesulfinate ion > benzenesulfinate ion > p‐chlorobenzenesulfinate ion and 4‐bromo‐2‐butenenitrile > 1,3‐ dibromopropene, respectively. Comparison was also made between the kinetic data obtained and some delocalization reactivity indexes for both the substrates and nucleophiles. The enthalpy–entropy compensation effect was observed for the reactions of sodium arenesulfinates with γ‐functionalized allyl bromides. Copyright © 2009 John Wiley & Sons, Ltd.
Effects of substituents on activation parameters in SN2 reactions at aliphatic carbon in solution
Authors: Vlasov Vladislav M. 
Published: November 2009

AbstractChanges of the activation parameters in aliphatic SN2 reactions with anionic and neutral nucleophiles in various solvents, ΔH≠ and ΔS≠, were correlated with σ constants of the substituents. The resultant δΔH≠ and δΔS≠ reaction constants are linearly related for variations of substituents at the substrate, leaving group and nucleophile. Correlations of δΔH≠ versus δΔS≠ allow the estimation of the contribution of changes of the internal enthalpy, δΔH, to the enthalpy reaction constant, δΔH≠, which gives a single linear dependence on the Hammett ρ reaction constants. The deviations from the dependence of δΔH versus ρ can be interpreted in terms of changes in the transition state structure in SN2 reactions. The results obtained show that the substituent effects on the charge development in the transition state are governed by the magnitude of δΔH. Copyright © 2009 John Wiley & Sons, Ltd.
The production of high polymer to surfactant microlatexes
Authors: Moraes Raul P. , Hutchinson Robin A. , McKenna Timothy F. L. 
Published: November 2009

AbstractStarved‐feed microemulsion polymerization of styrene was investigated. The influence of the type (SDS or Dowfax 2A1) and concentration of anionic surfactant on the final particle size of latex made by the polymerization of microemulsions of styrene was studied. In addition, the influence of 1‐pentanol and acrylic acid as cosurfactants was examined. Latexes with 20% solids content and polymer to surfactant ratio of 22 were produced, with a particle diameter of 42 nm and very low polydispersity indexes. Smaller particles are produced using SDS than Dowfax 2A1 for the same weight fraction of surfactant; however, similar particle sizes were obtained with the same molar concentrations of SDS and Dowfax 2A1. Further shot additions of monomer increased solids level as high as 40% and polymer to surfactant ratios greater than 40, with particles remaining monodisperse with average diameter smaller than 60 nm. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 48–54, 2010
Modifying an amorphous polymer to a fast crystallizing semi‐crystalline material by copolymerization with monodisperse amide segments
Authors: Stephen Ranimol , Gibon Cécile M. , Weber Martin , Gaymans Reinoud J. 
Published: November 2009

AbstractSegmented block copolymers of polysulphone with monodisperse amide segments were synthesized by a melt and a solution polymerization method. Both triblock and multiblock copolymers were prepared. The length of the difunctional polysulphone was varied from 2000 to 20,000 g/mol. The monodisperse amide segment was the tetra‐amide T6T6T based on terephthalic acid (T) and hexamethylene diamine (6) units. The main goal of this work was to study if the high Tg amorphous polysulphone could be modified to a high Tg semi‐crystalline PSU‐T6T6T copolymer. The copolymers were characterized by viscosity measurements, NMR, FTIR, MALDI‐TOF, DSC, and DMA. Depending on the amide concentration in the copolymers the T6T6T melting temperatures ranged between 220 and 270 °C and thus the crystallization window was small 50–100 °C. From the FTIR results, it was revealed that the crystallinity of the T6T6T segments in the copolymer could be very high, up to 92–97%. The T6T6T has crystallized out into nanoribbons with a high aspect ratio. These high Tg semi‐crystalline copolymers had a high dimensional and solvent resistance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 63–73, 2010
Syntheses, properties, and field‐effect transistors of small band gap quinoxaline‐ and thienopyrazine‐vinylene/ethynylene conjugated polymers
Authors: Chueh Chu‐Chen , Lai Mei‐Hsiu , Tsai Jung‐Hsun , Wang Chih‐Feng , Chen Wen‐Chang 
Published: November 2009

AbstractNew conjugated copolymers of quinoxaline (AQ) and thienopyrazine (ATP) with vinylene (V) or ethynylene (E), poly[2,3‐bis(4‐(2‐ethylhexyloxy)phenyl)‐quinoxaline vinylene] (PAQV), poly[2,3‐bis(4‐(2‐ethylhexyloxy)phenyl)‐quinoxaline ethynylene)] (PAQE), poly[2,3‐bis(4‐(2‐ethylhexyloxy)phenyl)‐thieno[3,4‐b]pyrazine vinylene] (PATPV), and poly[2,3‐bis(4‐(2‐ethylhexyloxy)phenyl)‐thieno[3,4‐b]pyrazine ethynylene] (PATPE), were successfully synthesized by Stille coupling reaction. The optical band gaps of the PAQV, PAQE, PATPV, and PATPE were 1.86, 2.00, 0.88, and 0.90 eV, respectively, whereas the electrochemical band gaps were 1.99, 2.06, 1.00, and 1.06 eV, respectively. The reduced steric hindrance by the incorporation of the V or E linkage or the intramolecular charge transfer between the acceptor and the V or E linkage led to the small band gap. The AQ/ATP‐vinylene copolymers exhibited much higher vis/near infrared absorption intensity than the AQ/ATP‐ethynylene suggested the stronger π–π* transition intensity in the former and led to better charge‐transporting characteristics. The saturation field‐effect hole mobilities of the PATPV were 2.1 × 10−3, 1.7 × 10−2, and 1.1 × 10−2 cm2 V−1 s−1 on bare, octyltrichlorosilane (OTS)‐treated, and octadecyltrichlorosilane(ODTS)‐treated SiO2, respectively, with on‐off current ratios of 35, 6.02 × 102, and 7.56 × 102. On the other hand, the estimated field‐effect transistor hole mobility of the PATPE was in the range of 1.7 × 10−6–8.1 × 10−4 cm2 V−1 s−1, which was significantly smaller than those of the PATPV. The small band gaps and high charge carrier mobility of the prepared copolymers suggested their potential applications for near‐infrared electronic and optoelectronic devices. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 74–81, 2010
Synthesis, characterization, and electroluminescence of polyfluorene copolymers containing T‐shaped isophorone derivatives
Authors: Park Moo‐Jin , Lee Jonghee , Jung In Hwan , Park Jong‐Hwa , Kong Hoyoul , Oh Ji‐Young , Hwang Do‐Hoon , Shim Hong‐Ku 
Published: November 2009

AbstractWe have successfully synthesized a series of new fluorene‐based copolymers, poly[(9,9‐bis(4‐octyloxy‐phenyl)fluorene‐2,7‐diyl)‐co‐[2(3{2[4(2{4[bis(bromophenyl‐4yl) amino]phenyl}vinyl)‐2,5‐bisoctyloxyphenyl]vinyl}‐5,5‐dimethyl‐cyclohex‐2‐enylidene)malononitrile] (PFTBMs), with varying molar ratios of the low‐energy band gap comonomer, 2(3{2[4(2{4[bis(4‐bromophenyl)amino]phenyl}vinyl)‐2,5‐bisoctyloxyphenyl]vinyl}‐5,5‐dimethyl‐cyclohex‐2‐enylidene)malononitrile (BTBM). To prepare BTBM (which has a T‐shaped structure) from triphenylamine, dialkoxy phenyl, and isophorone, we introduced three individual segments of an isophorone derivative containing two cyanide groups at the carbonyl position, a dialkoxy phenyl group for increased solubility, and a triphenyl amine for effective charge transfer. Furthermore, we introduced vinyl linkages between each segment to increase the length of π‐conjugation. The synthesized polyfluorene copolymers with the BTBM, PFTBMs, were synthesized via palladium‐catalyzed Suzuki coupling reactions. The photoluminescence emission spectra of the synthesized polymers in solution did not show significant energy transfer from PBOPF segments to the BTBM units. Light‐emitting devices based on these polymers were fabricated with an indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/polymers/Balq/LiF/Al configuration. Examination of the electroluminescence emission of the synthesized polymers showed that the maximum wavelength shifted continuously toward long wavelengths with as the number of BTBM units in the polymer main chain was increased. In particular, a device using PFTBM 05 exhibited a maximum brightness of 510 cd/m2 and a maximum current efficiency of 0.57 cd/A. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 82–90, 2010
Synthesis and properties of new fluorinated polymers bearing pendant imidazole groups for fuel cell membranes operating over a broad relative humidity range
Authors: Frutsaert Guillaume , Delon Louis , David Ghislain , Améduri Bruno , Jones Deborah J. , Glipa Xavier , Rozière Jacques 
Published: November 2009

AbstractNew alternating copolymers comprising a chlorotrifluorinated backbone and imidazole‐terminated pendant ethylene oxide groups have been prepared with a view to their use as a component of proton‐conducting membranes in polymer electrolyte fuel cells. A vinyl ether containing an imidazole (Imi) function protected by a benzyl group (BVI) was first synthesized in a three‐step reaction. It was then copolymerized in solution with chlorotrifluoroethylene (CTFE) by conventional radical copolymerization leading to alternating poly(BVI‐alt‐CTFE) copolymers in good yields. Deprotection of the benzyl group under hydrogen produced a chlorotrifluorinated poly(Imi‐alt‐CTFE) copolymer. The polymer was subsequently used to form blend membranes with sulfonated poly(ether ether ketone) (sPEEK). The conductivity of blend membranes of poly (Imi‐alt‐CTFE) with sPEEK lies in the range of 4–10 mS cm−1 at 40–70 °C and, for blend membranes rich in poly(Imi‐alt‐CTFE), is little dependent on relative humidity between 30 and 100%. It is surmised that the polymer and membrane composition favor microstructural phase separation into chlorotrifluorinated polymer backbone domains and regions in which imidazole groups are clustered. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 223–231, 2010
Multiarm star block and multiarm star mixed‐block copolymers via azide‐alkyne click reaction
Authors: Durmaz Hakan , Dag Aydan , Erdogan Elif , Demirel A. Levent , Hizal Gurkan , Tunca Umit 
Published: November 2009

AbstractThe synthesis of multiarm star block (and mixed‐block) copolymers are efficiently prepared by using Cu(I) catalyzed azide‐alkyne click reaction and the arm‐first approach. α‐Silyl protected alkyne polystyrene (α‐silyl‐alkyne‐PS) was prepared by ATRP of styrene (St) and used as macroinitiator in a crosslinking reaction with divinyl benzene to successfully give multiarm star homopolymer with alkyne periphery. Linear azide end‐functionalized poly(ethylene glycol) (PEG‐N3) and poly (tert‐butyl acrylate) (PtBA‐N3) were simply clicked with the multiarm star polymer described earlier to form star block or mixed‐block copolymers in N,N‐dimethyl formamide at room temperature for 24 h. Obtained multiarm star block and mixed‐block copolymers were identified by using 1H NMR, GPC, triple detection‐GPC, atomic force microscopy, and dynamic light scattering measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 99–108, 2010
AGET ATRP of acrylonitrile using 1,1,4,7,10,10‐hexamethyltriethylenetetramine as both ligand and reducing agent
Authors: Chen Hou , Wang Chunhua , Liu Delong , Song Yuting , Qu Rongjun , Sun Changmei , Ji Chunnuan 
Published: November 2009

AbstractAtom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) of acrylonitrile (AN) initiated by ethyl 2‐bromoisobutyrate was approached for the first time using 1,1,4,7,10,10‐hexamethyltriethylenetetramine (HMTETA) and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) as both ligand and reducing agent. AGET ATRP of AN with HMTETA as both ligand and reducing agent was better controlled than with PMDETA as both ligand and reducing agent under the same experimental conditions. With an increase content of HMTETA, the polymerization provided an accelerated reaction rate and a broader polymer molecular weight distribution. The rate of polymerization with DMF as solvent was faster than with acetonitrile, cyclohexanone, toluene, and xylene as solvents. The polymerization apparent activation energy was calculated to be 45.7 kJ mol−1. The end functionality of polyacrylonitrile (PAN) was confirmed by 1H NMR spectroscopy. The living feature of PAN was verified by chain extensions of PAN with methyl methacrylate and AN. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 128–133, 2010
Synthesis and nonlinear optical properties of side chain liquid crystalline polymers containing azobenzene push–pull chromophores
Authors: Alicante Raquel , Cases Rafael , Forcén Patricia , Oriol Luis , Villacampa Belén 
Published: November 2009

AbstractAzobenzene monomeric precursors bearing piperazine as donor moiety with different withdrawing groups and derived side chain polymethacrylates have been prepared and characterized. Monomers having terminal cyano or nitro groups, and the corresponding polymers, exhibited smectic A phases. Linear and nonlinear optical properties of every monomer and thin films of the cyano polymer (pol‐PZ‐CN) have been also studied. UV‐vis spectroscopy revealed out‐of‐plane orientation in the as prepared films, as confirmed by waveguide refractive index measurements. Moreover, absorption spectra indicated the presence of azo aggregates in these films. The initial molecular arrangement has been modified by applying thermal annealing within the mesophase range and UV‐blue irradiation. Although thermal annealing resulted in a significant amplification of the out‐of‐plane optical anisotropy due to thermotropic self‐organization of side chain azo moieties, irradiation with 440 nm light induced some disruption of aggregates. The nonlinear optical response of Corona poled films has been studied by second harmonic generation measurements, and the influence of the molecular arrangement on the nonlinear dij coefficients has been analyzed. The more efficient poling corresponded to preirradiated films. In any case, a noticeable degree of polar order (70% of the initial d33 value) remained for several months after the poling in films kept at RT. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 232–242, 2010
Morphology and physical properties of a novel Ramie‐PU blended nonwoven by electrospinning: The effect of cosolvent ratio
Authors: Peng Zhiqin , Yoshida Yoichiro , Sukigara Sachiko 
Published: November 2009

AbstractA novel macro/nano blended nonwoven with excellent physical properties was prepared by electrospinning polyurethane (PU) nanofibers onto the surface of ramie webs under different weight ratios of N,N‐dimethylacetamide (DMAc)/acetone cosolvents. The ratio of cosolvents has a significant influence on the morphology, tensile properties, resilience, and thermal properties of the resultant samples. Bead‐free and fine interconnected nanofibers were obtained with an increase of acetone content up to 60 wt%. The total physical properties of the blended nonwovens were optimal for a DMAc/acetone ratio of 40/60, in which the tensile load at break, extension at break and Young's modulus were 441, 54, and 256% higher than that of pure ramie web, respectively. The resilience of the blended nonwovens was ∼20% higher than that of nonblended ramie web. The significant improvement of physical properties may be due to the good connection between PU nanofiber membranes and ramie webs and the molecular chain structure differences, interconnected structural differences, and high extensibility of PU nanofibers, according to the results of crystallization by differential scanning calorimetry (DSC) and morphological observation by scanning electronic microscopy (SEM). © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1–14, 2010
Crystallization behavior of isotactic propylene‐1‐hexene random copolymer revealed by time‐resolved SAXS/WAXD techniques
Authors: Mao Yimin , Zuo Feng , Keum Jong Kahk , Hsiao Benjamin S. , Thurman Derek W. , Tsou Andy H. 
Published: November 2009

AbstractThe crystallization behavior of isotactic propylene‐1‐hexene (PH) random copolymer having 5.7% mole fraction of hexene content was investigated using simultaneous time‐resolved small‐angle X‐ray scattering (SAXS) and wide‐angle X‐ray diffraction (WAXD) techniques. For this copolymer, the hexene component cannot be incorporated into the unit cell structure of isotactic polypropylene (iPP). Only α‐phase crystal form of iPP was observed when samples were melt crystallized at temperatures of 40 °C, 60 °C, 80 °C, and 100 °C. Comprehensive analysis of SAXS and WAXD profiles indicated that the crystalline morphology is correlated with crystallization temperature. At high temperatures (e.g., 100 °C) the dominant morphology is the lamellar structure; while at low temperatures (e.g., 40 °C) only highly disordered small crystal blocks can be formed. These morphologies are kinetically controlled. Under a small degree of supercooling (the corresponding iPP crystallization rate is slow), a segmental segregation between iPP and hexene components probably takes place, leading to the formation of iPP lamellar crystals with a higher degree of order. In contrast, under a large degree of supercooling (the corresponding iPP crystallization rate is fast), defective small crystal blocks are favored due to the large thermodynamic driving force and low chain mobility. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 26–32, 2010
Fluorescence spectroscopy and thermal relaxation processes of anthracenyl‐labeled polysiloxanes
Authors: Domingues Raquel Aparecida , Yoshida Inez Valéria Pagotto , Atvars Teresa Dib Zambon 
Published: November 2009

AbstractA fluorescent silicone network was prepared by a hydrosilylation reaction using poly(dimethylsiloxane‐co‐methylhydrogensiloxane) terminated by dimethylhydrogensilyloxy groups, poly(dimethylsiloxane‐co‐methylvinylsiloxane) terminated by dimethylvinylsilyloxy groups and 9‐vinylanthracene, as the fluorescent group. These silicone‐based materials were strongly fluorescent. Steady state emission was a convenient technique to prove that reaction occurred, based on the blue‐shift of the emission from anthracenyl moieties compared with the 9‐vinylanthracene. Thermal transitions were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and by fluorescence spectroscopy, indicating that networks with and without lumophores had similar thermal properties. Networks with and without lumophores had the same swelling capability in toluene. Fluorescence spectroscopy was a more sensitive technique to the onset of the glass transition temperature (T = 145 K) than DSC or DMA. Nevertheless, the crystallization temperature at 192 K was determined more precisely by DSC, and the melting point at 237 K was indentified more clearly by both DSC and DMA. These three techniques provided complementary information about transitions in silicone networks. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 74–81, 2010
The effects of rigid polystyrene particles on the glass transition characteristics and mechanical wave attenuation of styrene‐butadiene rubber: Particle size and acoustic mismatch
Authors: Faghihi Farhad , Mohammadi Naser , Haghgoo Majid 
Published: November 2009

AbstractGlass transition characteristics and mechanical wave attenuation of the neat and filled styrene‐butadiene rubber (SBR) containing 10 wt % of rigid monosize polystyrene particles of various diameters from several hundred microns down to several tens of nanometers were investigated by dynamic mechanical thermal analysis, impedance tube, and ultrasonic spectroscopy. The results showed the matrix damping capacity and the breadth of glass transition increase by reducing the size of rigid particles due to the matrix‐particles interfacial area increase as the major governing parameter. Matrix glass transition broadening toward higher temperatures was attributed to the increased dynamic heterogeneity induced by fillers, whereas the damping capacity increase was assigned to contribution of interfacial friction loss mechanism. The proposed postulation was confirmed based on the calculated temperature distribution of the relaxing matrix volume fraction. Sound wave attenuation by the matrix and PS particles filled systems led to a broad absorption peak for the former and appearance of a secondary absorption peak at lower frequencies for the latter. Intensity of this secondary peak was highest for the system containing PS nanoparticles. Finally, ultrasonic attenuation enhanced by the PS particle size to wavelength ratio increase according to αsca ∼ (d/λ)0.38 scaling law and declined by replacing the dense particles with larger hollow PS particles. Comparison of the normalized attenuation of the PS particle filled SBR in various mechanical wave attenuation regimes implied low sensitivity to particle size in vibration, mild differentiation in the sound, and finally severe differentiation in the ultrasound regimes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 82–88, 2010
Plasma‐Mediated Modification of Austenitic Stainless Steel: Application to the Prevention of Yeast Adhesion
Authors: Saulou Claire , Despax Bernard , Raynaud Patrice , Zanna Sandrine , Marcus Philippe , Mercier‐Bonin Muriel 
Published: November 2009

AbstractThe work is focused on defining a stainless steel surface treatment to prevent microbial adhesion. The yeast Saccharomyces cerevisiae was selected as the model for eukaryotic cells. Different surface cleaning procedures, including chemical and plasma‐mediated treatments, were studied. Detachment experiments displayed no modification in yeast adhesion, despite significant variations in the physico‐chemical properties of the solid surface. Plasma‐mediated thin coatings (≈375 nm) were then deposited on stainless steel applying hexamethyldisiloxane/oxygen plasma. FT‐IR study revealed a dense SiOSi network, while XPS analysis detected no more iron or chromium at the extreme surface. Detachment experiments demonstrated that these films were successful in preventing cell adhesion, due to a barrier effect.magnified image