bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of N‐phenylmaleimide on a novel chemically bonded polymerizable photoinitiator comprising the structure of planar N‐phenylmaleimide and benzophenone for photopolymerization
Authors: Wang Hongyu , Wei Jun , Jiang Xuesong , Yin Jie 
Published: November 2006

AbstractA novel chemically bonded polymerizable photoinitiator 4‐[(4‐maleimido)phenoxy]benzophenone (MPBP) comprising the structure of planar N‐phenylmaleimide (NPMI) and benzophenone (BP), compared with the physical mixtures of NPMI/BP or NPMI/4‐hydroxybenzophenone, was investigated to disclose the mutual influence between NPMI and BP. A BP derivative, 4‐phenoxylbenzophenone, was selected as the model compound. Electron spin resonance spectra of such photoredox systems indicated MPBP and BP possess the same initiation mechanism. The large red‐shifted π–π* absorption of MPBP should be because of the phenoxyl group in MPBP but not the maleimide group. The photopolymerization of methyl methacrylate (MMA) and 1,6‐hexanediol diacrylate (HDDA) initiated by those systems, using the unsaturated tertiary amine N,N‐dimethylaminoethyl methacrylate (DMAEMA) as the coinitiator (H donor), was studied through dilatometry and photo‐differential scanning calorimetry. The results showed that MPBP was more efficient for the photopolymerization of MMA and HDDA than its physical mixture counterpart. The high efficiency of MPBP may be mainly because of the interaction between NPMI and BP group but not the phenoxyl group alone. A certain amount of NPMI can accelerate the photopolymerization when added to the formulations, but too much NPMI will eventually decrease the photoefficiency. Copyright © 2006 Society of Chemical Industry
Entirely aqueous synthesis of polyimide–silsesquioxane nanocomposites
Authors: Arkhireeva Anna , Groth Andrew M , Hay John N 
Published: November 2006

AbstractA novel combination of a modified Stöber sol–gel technique to prepare silsesquioxane nanoparticles with an aqueous synthesis of polyimide resin has been used to prepare polyimide–silsesquioxane nanocomposites. The products have been analysed to ascertain the degree and mode of association between the polyimide matrix and silsesquioxane nanoreinforcement. Thermal analysis techniques have been used to quantify the attraction between the resin and four different surface‐functionalised silsesquioxanes. Scanning electron microscopy has been used to assess qualitatively the nature of the interaction between the two components. In general, aminopropyl–functionalised silsesquioxanes have the lowest level of interaction with the polyimides used in this study, while methyl‐ and phenyl‐functionalised nanoparticles bind more strongly with the resin. Silica nanoparticles have a relatively strong association with the polyimide and appear to be largely attached to the surface of the polymer. Copyright © 2006 Society of Chemical Industry
Crystallinity, thermal properties, morphology and conductivity of quaternary plasticized PEO‐based polymer electrolytes
Authors: Wang Yan‐Jie , Pan Yi , Kim Dukjoon 
Published: November 2006

AbstractQuaternary plasticized solid polymer electrolyte (SPE) films composed of poly(ethylene oxide), LiClO4, Li1.3Al0.3Ti1.7(PO4)3, and either ethylene carbonate or propylene carbonate as plasticizer (over a range of 10–40 wt%) were prepared by a solution‐cast technique. X‐ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) indicated that components such as LiClO4 and Li1.3Al0.3Ti1.7(PO4)3 and the plasticizers exerted important effects on the plasticized quaternary SPE systems. XRD analysis revealed the influence from each component on the crystalline phase. DSC results demonstrated the greater flexibility of the polymer chains, which favored ionic conduction. SEM examination revealed the smooth and homogeneous surface morphology of the plasticized polymer electrolyte films. EIS suggested that the temperature dependence of the films' ionic conductivity obeyed the Vogel–Tamman–Fulcher (VTF) relation, and that the segmental movement of the polymer chains was closely related to ionic conduction with increasing temperature. The pre‐exponential factor and pseudo activation energy both increased with increasing plasticizer content and were maximized at 40 wt% plasticizer content. The charge transport in all polymer electrolyte films was predominantly reliant on lithium ions. All transference numbers were less than 0.5. Copyright © 2006 Society of Chemical Industry
Synthesis and characterization of amine‐functionalized amphiphilic block copolymers based on poly(ethylene glycol) and poly(caprolactone)
Authors: KC Remant Bahadur , Bhattarai Shanta Raj , Aryal Santosh , Bhattarai Narayan , Lee Byoung Min , Kim Hak Yong 
Published: November 2006

AbstractA series of amine‐functionalized block copolymers, poly(caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), were synthesized by ring‐opening bulk polymerization (ROP) of ε‐caprolactone (ε‐CL) initiated through the hydroxyl end of the amino poly(ethylene glycol) (PEG) used as a macroinitiator in the presence of stannous 2‐ethylhexonoate [Sn(Oct)2]. The polymerization and end functionality of the polymer were studied by different physicochemical techniques (1H NMR, Fourier transform infrared and X‐ray photoelectron spectroscopy, gel permeation chromatography and thermogravimetric analysis). Thermal, crystalline and mechanical properties of the polymer were thoroughly analyzed using differential scanning calorimetry, wide‐angle X‐ray diffractometry and tensile testing, respectively. The results showed a linear improvement in crystallinity and mechanical properties of the polymer with the content of PEG. Thus the synthesized functional polymers can be used as excellent biomaterials for the delivery of polyanions, as well as macroinitiators for the synthesis of A–B–C‐type block copolymers. Copyright © 2006 Society of Chemical Industry
Zero‐field splitting parameters of quintet 2,6‐dinitrenopyridines
Authors: Chapyshev Sergei V. , Lahti Paul M. 
Published: November 2006

AbstractThe zero field splitting parameters of two 2,6‐dinitrenopyridines were estimated to be |D/hc| ≅ 0.19–0.20 cm−1 and |E/hc| ≅ 0.064–0.066 cm−1 by lineshape simulation of frozen solution X‐band ESR spectra. This large ratio of |E/D| is consistent with a dominating dipolar interaction between the two nitrene units having a relative interaction vector angle of about 114°–116°. UB3LYP/6‐31G* computations of 2,6‐dinitrenopyridine predict a very similar interaction vector angle. These results are quite different from analogous results observed for meta‐dinitrenobenzenes. The experimental zero‐field splitting (zfs) and computational results indicate that the ESR spectroscopy of 2,6‐dinitrenopyridines are dominated by the one‐center interactions between unpaired electrons on the nitrene units (the triplet mononitrene zfs), and the relative geometry of interaction between the mononitrenes caused by the molecular geometry of the dinitrenopyridine (the interaction vector angle). Copyright © 2006 John Wiley & Sons, Ltd.
Cationic copolymerization of ε‐caprolactone and L,L‐lactide by an activated monomer mechanism
Authors: Baśko Małgorzata , Kubisa Przemysław 
Published: November 2006

AbstractThe cationic homopolymerization and copolymerization of L,L‐lactide and ε‐caprolactone in the presence of alcohol have been studied. The rate of homopolymerization of ε‐caprolactone is slightly higher than that of L,L‐lactide. In the copolymerization, the reverse order of reactivities has been observed, and L,L‐lactide is preferentially incorporated into the copolymer. Both the homopolymerization and copolymerization proceed by an activated monomer mechanism, and the molecular weights and dispersities are controlled {number‐average degree of polymerization = ([M]0 − [M]t)/[I]0, where [M]0 is the initial monomer concentration, [M]t is the monomer concentration at time t, and [I]0 is the initial initiator concentration; weight‐average molecular weight/number‐average molecular weight ∼1.1–1.3}. An analysis of 13C NMR spectra of the copolymers indicates that transesterification is slow in comparison with propagation, and the microstructure of the copolymers is governed by the relative reactivity of the comonomers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7071–7081, 2006
Synthesis and stability study of dental monomers containing methacrylamidoethyl phosphonic acids
Authors: Xu Xiaoming , Wang Rubin , Ling Long , Burgess John O. 
Published: November 2006

AbstractThree new dental monomers containing methacrylamidoethyl phosphonic acids were synthesized. The structures of the synthesized monomers were determined with electrospray mass spectrometry (ESMS), Fourier transform infrared, and NMR. The hydrolytic stabilities of the synthesized monomers and a commercial monomer, 2‐methacryloyloxyethyl phosphoric acid (MEP; used as a control), were studied with flow injection (FI)/ESMS, 1H NMR, and 31P NMR analysis of a CD3OD/D2O (4:1 v/v) solution of each monomer before and after storage at 60 °C for 2 months. The 1H NMR and 31P NMR chemical shifts of the monomers 2‐methacrylamidoethylphosphonic acid (I) and N,N′‐[4,4′‐(propane‐2,2‐diyl)‐bis(phenoxy‐2‐hydroxypropyl)]‐bis(2‐methacrylamidoethylphosphonic acid) (II) showed little change after storage at 60 °C for 2 months, but those of MEP changed significantly. FI/ESMS also showed that MEP was nearly completely decomposed, whereas monomers I and II remained largely intact. MEP could react with H2ZrF6 to form ternary zirconium fluoride complexes that were partially soluble in methanol, but all the monomers containing phosphonic acids formed precipitates. This study demonstrates that ESMS is a more sensitive and effective method than NMR for studying the hydrolytic stability or degradation of dental monomers. The new monomers containing methacrylamidoethyl phosphonic acids have higher hydrolytic stability than methacrylate phosphate monomers and may be used in dental bonding agents and other dental materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 99–110, 2007
Thermal and mechanical cracking in bis(triisopropylsilylethnyl) pentacene thin films
Authors: Chen Jihua , Tee Chee Keong , Yang Junyan , Shaw Charles , Shtein Max , Anthony John , Martin David C. 
Published: November 2006

AbstractBis(triisopropylsilylethnyl) pentacene (TIPS pentacene) was synthesized to increase its solubility in common liquid solvents and, at the same time, enhance the π–π stacking between neighboring acenes in the crystallized state in comparison with unmodified pentacene. Hot‐stage microscopy experiments revealed that during heating voids develop along the long axis of the TIPS pentacene films {along the [210] direction/parallel to the (120) planes} and crystals overlap along the short axis {along the [120] direction/parallel to the (210) planes}. From molecular mechanics simulations, the predominant twin boundaries of (120) and commonly observed cracking planes of (120), (120), and (210) had relatively low surface energies in comparison with planes with similar Miller indices. Organic thin‐film transistors with TIPS pentacene as the active layer were fabricated, and the mobility values decreased from 0.4–1.0 cm2/V s before cracking to ∼0.2 cm2/V s after cracking. To maintain the high charge carrier mobility of TIPS pentacene devices, these cracks should be avoided. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3631–3641, 2006
Mixed solvent effect on lithium‐coordination to poly(ethylene oxide)
Authors: Hakem Ilhem F. , Lal Jyotsana , Bockstaller Michael R. 
Published: November 2006

AbstractThis article presents a comparative study of the structure formation of poly (ethylene oxide) PEO/Li complexes in aqueous and acetonitrile solutions using small‐angle neutron scattering (SANS). We demonstrate that in acetonitrile solutions, Li‐cations coordinate to the ether–oxygen of the monomeric unit, and this results in charging and stretching of the polymer chains. This is found to be in contrast to aqueous solutions, where the ions remain free in solution. In particular, we demonstrate that the “binding” and “screening” regimes that were observed in case of PEO/K+ solutions in acetonitrile are also found in the respective PEO/Li+ solutions. The addition of water to solutions in acetonitrile increasingly diminishes the ion‐coordination to the polymer, eventually resulting in neutral polymer chains at water contents above ϕ*water = 30% (w/v). The preferential adsorption of water on PEO in mixtures of acetonitrile and water is evidenced by the pronounced stretching of polymer chains, in particular, at a water content of ϕwater = 25% and 33.33% (w/v) where complete stretching of the chains is observed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3642–3650, 2006
Relationships between unfolded configurations of proteins and dynamics of folding to the native state
Authors: Gursoy Attila , Keskin Ozlem , Turkay Metin , Erman Burak 
Published: November 2006

AbstractWe compare folding trajectories of chymotrypsin inhibitor (CI2) using a dynamic Monte Carlo scheme with Go‐type potentials. The model considers the four backbone atoms of each residue and a sphere centered around Cβ the diameter of which is chosen according to the type of the side group. Bond lengths and bond angles are kept fixed. Folding trajectories are obtained by giving random increments to the φ and ψ torsion angles with some bias toward the native state. Excluded volume effects are considered. Two sets of 20 trajectories are obtained, with different initial configurations. The first set is generated from random initial configurations. The initial configurations of the second set are generated according to knowledge‐based neighbor dependent torsion probabilities derived from triplets in the Protein Data Bank. Compared to chains with randomly generated initial configurations, those generated with neighbor‐dependent probabilities (i) fold faster, (ii) have better defined secondary structure elements, and (iii) have less number of non‐native contacts during folding. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3667–3678, 2006
Monte Carlo study of the coil‐to‐globule transition of a model polymeric system
Authors: Rissanou Anastassia N. , Anastasiadis Spiros H. , Bitsanis Ioannis A. 
Published: November 2006

AbstractMonte Carlo computer simulations of single, flexible, self‐avoiding chains on a cubic lattice have been performed upon conditions of increasing segment–segment cohesive energy (deteriorating solvent quality). The simulations spanned a wide range of chain lengths (20–10,000, i.e., up to molecular weights of a few millions) and cohesive energies (0.0–0.45kBT, i.e., from athermal to very poor solvents). The chain length dependence of the chain size in poor solvents was characterized by a wide plateau of almost null growth for intermediate chain lengths. This plateau was linked to the development of the incipient constant density core, while genuine power law dependence (1/3) was not reached even for the longest chains and poorest solvents simulated here. The mere appearance of a core required substantial chain lengths (higher than 1000; molecular weights of a few hundred thousands), while short chains underwent a gradual densification devoid of any qualitative changes in the density distribution. Sufficiently long chains became more but not quite spherical and underwent a reasonably sharp second order phase transition. The findings were generally in agreement with predictions of mean‐field theory and with the use of the standard scaling variables, despite slight inconsistencies. Nevertheless, the results stress the fact that short chains never form a constant density core and that core‐dominance on the globule's properties (“volume approximation”) is only valid for extraordinarily long chains [molecular weight of O(109)], an effect linked to the relatively diffuse nature of the surface layer and originating from chain connectivity in conjunction with spherical geometry. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3651–3666, 2006
The Effects of Reaction Conditions on Liquid‐Phase Hydroxyl Radical Production in Gas‐Liquid Pulsed‐Electrical‐Discharge Reactors
Authors: Sahni Mayank , Locke Bruce R. 
Published: November 2006

AbstractSummary: High‐voltage gas‐, liquid‐ and gas‐liquid‐phase pulsed electrical discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH•, H• and H2O2. This paper focuses on quantification of hydroxyl radicals using chemical probes (DMSO and NaTA) in three different reactor configurations: reference (purely liquid‐phase discharge), hybrid‐series (combined gas‐liquid discharge), and hybrid‐parallel (combined gas‐liquid discharge) for a wide range of operating conditions. The operating conditions that are evaluated are: input power, initial conductivity of solution, temperature of solution, presence of radical scavengers and additives in solution.Schematic view of the different hybrid reactor configurations (series and parallel) used in this study.imageSchematic view of the different hybrid reactor configurations (series and parallel) used in this study.
Wear Resistance of Low‐Temperature Plasma‐Polymerized Organosilica Deposited on Poly(ethylene terephthalate): The Effect of O2 Addition
Authors: Lin Yung‐Sen , Chen Ching‐Lun 
Published: November 2006

AbstractSummary: The wear resistance of PET substrates can be enhanced by low‐temperature plasma‐polymerization of organosilica (SiOxCy); the effect of varying oxygen flow rates is investigated in this paper. It was found that the low‐temperature plasma‐polymerization of SiOxCy with tetramethylsilane (TMS) and oxygen (O2) at room temperature (23 °C) can be used for improving the wear resistance of PET substrates, as demonstrated by scratch tests. The wear resistance of PET substrates was greatly enhanced from the completely scratched of the untreated PET substrates to no scratched of TMS/O2 plasma‐polymerized PET substrates, which were obtained at high oxygen flow rates with a steel wool for 300 cycles at 300 g loading. The results of this study indicate that the wear resistance of the treated PET substrates was highly dependent on the surface characteristics of bare PET substrates. The hardness of PET substrates was determined by the pencil test, while the surface morphology was monitored by AFM. The atomic compositions and chemical bonding of the TMS/O2 plasma‐polymerized organosilicas were analyzed by XPS.The wear loss ΔT(%) for the TMS/O2 plasma‐polymerized PET substrates for various oxygen flow rates.imageThe wear loss ΔT(%) for the TMS/O2 plasma‐polymerized PET substrates for various oxygen flow rates.
Fine‐Particle Collection Using an Electrostatic Precipitator Equipped With an Electrostatic Flocking Filter as the Collecting Electrode
Authors: Sung Bong‐Jo , Aly Ahmed , Lee Sung‐Hwa , Takashima Kazunori , Kastura Shinji , Mizuno Akira 
Published: November 2006

AbstractSummary: In recent years, special environmental concern is directed towards controlling the emission of fine particles (from 0.1 to 1.0 µm). These fine particles possibly cause serious health hazards because of heavy metals and toxic compounds adsorbed on the particles. To improve the collection efficiency of fine particles, the electrostatic flocking technique has been employed in this study. This technique is based on increasing the surface area of the collecting electrode and on producing a gradient force at the tip of fibers to suppress the re‐entrainment. In this article, an experimental study was performed to evaluate the effect of fine fibers on the collection efficiency of fine particles using the ESP with electrostatic flocking electrodes as collecting plates. The ESP achieved a collection efficiency of about 95% at a d.c. voltage of 9 kV, which was higher than that of flat‐plate electrode for fine particles (0.3–0.5 µmin diameter) with a short residence time (0.06 s). We confirmed that the fine particles agglomerated at the tip of the flocking fibers. These results indicate that the new type of ESP examined in this study is effective to improve the removal performance of fine particles.Model of the precipitation and the re‐entrainment suppression in an ESP equipped with an EF electrode.imageModel of the precipitation and the re‐entrainment suppression in an ESP equipped with an EF electrode.
Kinetic Modeling of the NF3 Decomposition via Dielectric Barrier Discharges in N2/NF3 Mixtures
Authors: Chen Hsin Liang , Lee How Ming , Chang Moo Been 
Published: November 2006

AbstractSummary: Emission of PFCs (perfluorocompound) has attracted much attention in recent years due to its relatively high contribution to the global warming. Non‐thermal plasma is one of the most promising technologies to effectively control the PFC emissions. In this study, a cylindrical DBD (dielectric barrier discharge) reactor is adopted for the treatment of NF3‐containing streams. Besides the experimental work, a numerical model is also developed for better understanding of the reaction mechanism of NF3 abatement in N2/NF3 mixtures. Good agreement is observed between the experimental data and the simulation results. Simulation results indicate that the electrons and the N atoms are the major active species responsible for the NF3 decomposition. In addition, N2(A3Σ) metastables plays a significant role in the NF3 abatement. A simplified mechanism for the NF3 decomposition in the N2 – NF3 plasmas is proposed as well.Reaction mechanisms for the decomposition of NF3 in a N2 – NF3 plasma.imageReaction mechanisms for the decomposition of NF3 in a N2 – NF3 plasma.
Control of DC Corona Discharge Modes by a Switching Operation
Authors: Kanazawa Seiji , Ikeda Takafumi , Mitsugi Fumiaki , Ohkubo Toshikazu , Nomoto Yukiharu 
Published: November 2006

AbstractSummary: Glow and streamer discharges are well known as the typical modes for positive DC corona discharges. In this study, a new method for the control of the corona discharges modes is proposed. The grounded electrode is divided and a switch is attached to one of the electrodes. The results showed that corona discharge mode could be controlled by this switching operation. As the applied positive voltage is increased, corona glow is mostly generated in air at atmospheric pressure, but this mode is changed to streamer mode by switching‐off the operation. Moreover, glow and streamer corona discharges from one stressed wire electrode can be generated simultaneously by modifying the design of the divided plane electrodes and by the switching operation. A mechanism of the controlled streamer discharge by the switching operation is discussed.Simultaneous generation of glow and streamer corona discharges from one stressed wire electrode.imageSimultaneous generation of glow and streamer corona discharges from one stressed wire electrode.