bluuebunny/crossref_metadata_2025_split huggingface dataset:
Network formation of a phenyl vinyl ketone copolymer with 4‐vinylbenzil and its photodecrosslinking in films
Authors: Mosnáček Jaroslav , Lukáč Ivan , Chromik Štefan , Kostič Ivan , Hrdlovič Pavol 
Published: December 2003

AbstractThe irradiation (λ > 400 nm) in air of a copolymer of phenyl vinyl ketone with 4‐vinylbenzil (VBZ) containing 1.5 wt % VBZ structural units in film, followed by the thermal decomposition of the resulting pendant benzoyl peroxide groups, leads to crosslinking. The subsequent irradiation of the crosslinked polymer at 366 nm results in the cleavage of the poly(phenyl vinyl ketone) chain between the junction points of the polymer network through a Norrish type II reaction. Therefore, poly(phenyl vinyl ketone‐co‐4‐vinylbenzil) represents a novel type of photoresist based on polymer network decrosslinking. The process involves three steps: photogeneration of peroxide, crosslinking by its thermal decomposition, and subsequent photodecrosslinking of the polymer network. This material provides positive‐tone images after UV exposure (λ > 330 nm) and development in an organic medium such as isopropyl methyl ketone. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 765–771, 2004
Novel reaction between cyclic formal and ethylene oxide
Authors: Yamasaki Naoaki , Masamoto Junzo 
Published: December 2003

AbstractNovel reactions between trioxane and ethylene oxide were discovered, and three novel cyclic formals were isolated and identified. These novel cyclic compounds clarified the initiation mechanism of the copolymerization of trioxane and ethylene oxide. This type of reaction was not limited to the reaction between trioxane and ethylene oxide but was also generalized to the reaction between the cyclic formal and ethylene oxide. Although an NMR method for analyzing the ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide has not yet been established, the three newly found novel cyclic compounds, composed of 1 mol of ethylene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane, were useful for analyzing the ethylene oxide sequences. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different 1H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that had one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the 1H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequences by the 1H NMR method for the copolymer from trioxane and ethylene oxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 520–533, 2004
Studies of the surface layer structure and properties of poly(styrene/α‐t‐butoxy‐ω‐polyglycidol) microspheres by carbon nuclear magnetic resonance, X‐ray photoelectron spectroscopy, and the adsorption of human serum albumin and γ‐globulins
Authors: Basinska Teresa , Slomkowski Stanislaw , Kazmierski Slawomir , Dworak Andrzej , Chehimi Mohamed M. 
Published: December 2003

AbstractThe composition and properties of the surface layers of poly(styrene/α‐t‐butoxy‐ω‐polyglycidol) [poly(styrene/VB‐polyGL)] microspheres synthesized by the radical copolymerization of styrene and α‐t‐butoxy‐ω‐vinylbenzyl‐polyglycidol (VB‐polyGL) macromonomers [number‐average molecular weight (Mn) = 950 or 2700] were investigated with X‐ray photoelectron spectroscopy, 13C NMR, and the adsorption of human serum albumin and γ‐globulins. The number‐average diameter of the synthesized microspheres was 220 nm. Their surface layers were rich in polyglycidol, with polyglycidol‐to‐polystyrene unit ratios of 0.443 (VB‐polyGL with Mn = 950) and 0.427 (VB‐polyGL with Mn = 2700). In suspensions of poly(styrene/VB‐polyGL) particles in D2O, the polymer chains in the polyglycidol‐rich surface layers were highly mobile, allowing the registration of polyglycidol 13C NMR spectra with standard procedures for polymer solutions. In these spectra, the signals of the relatively immobile polystyrene segments were absent. The spin–lattice relaxation times (T1) measured for polyglycidol in the microsphere surface layers and for VB‐polyGL macromonomers in solution were very close, indicating similar degrees of motion in bound (in particle surface layers) and free (in solution) polyglycidol macromolecules. Studies of protein adsorption revealed that hydrophilic polyglycidol layers were protein‐repellent. It was found that longer polyglycidol chains in particle surface layers were more mobile (higher T1 values) and provided better protection against protein adsorption. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 615–623, 2004
Life—a complex polymer system
Authors: Schurz Josef 
Published: December 2003

AbstractAfter a discussion of the different levels of macromolecules, the phenomenon of life is regarded as a complex polymer system. The thermodynamic basis of general system theory is explained as well as the character of system laws. The important notion of emergent system properties is stressed, and life is explained as a system property of a sufficiently complex system. The general applicability of the systemic approach is pointed out, and some examples are provided. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 471–478, 2004
Preparation of polyethylene block copolymers by a combination of postmetallocene catalysis of ethylene polymerization and atom transfer radical polymerization
Authors: Inoue Yoshihisa , Matyjaszewski Krzysztof 
Published: December 2003

AbstractThe synthesis of block copolymers consisting of a polyethylene segment and either a poly(meth)acrylate or polystyrene segment was accomplished through the combination of postmetallocene‐mediated ethylene polymerization and subsequent atom transfer radical polymerization. A vinyl‐terminated polyethylene (number‐average molecular weight = 1800, weight‐average molecular weight/number‐average molecular weight =1.70) was synthesized by the polymerization of ethylene with a phenoxyimine zirconium complex as a catalyst activated with methylalumoxane (MAO). This polyethylene was efficiently converted into an atom transfer radical polymerization macroinitiator by the addition of α‐bromoisobutyric acid to the vinyl chain end, and the polyethylene macroinitiator was used for the atom transfer radical polymerization of n‐butyl acrylate, methyl methacrylate, or styrene; this resulted in defined polyethylene‐b‐poly(n‐butyl acrylate), polyethylene‐b‐poly(methyl methacrylate), and polyethylene‐b‐polystyrene block copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 496–504, 2004
Cellulose structure and biosynthesis: What is in store for the 21st century?
Authors: Brown R. Malcolm 
Published: December 2003

AbstractThis article briefly summarizes historical developments in fundamental research related to the structure and biosynthesis of cellulose. Major advances concerning the structure of cellulose include the discovery of a new suballomorph of cellulose I, the lattice imaging of glucan chains showing no fringe micelle structure, parallel chain orientation in cellulose I, and the discovery of nematic ordered cellulose. Major advances in biosynthesis include the discovery of the terminal synthesizing complex, the isolation and purification of cellulose synthase, the in vitro synthesis of cellulose I, and synthetic cellulose assembly. This article focuses on recent advances in molecular biology with cellulose, including the cloning and sequencing of cellulose synthase genes from bacteria, cyanobacteria, and vascular plants; proof of the terminal synthesizing complex as the site of the catalytic subunit of cellulose synthase; cellulose and callose synthase expression during growth and development; and phylogenetic aspects of cellulose synthase evolution. This article concludes with thoughts about future uses for the accumulating genetic information on cellulose biosynthesis for textiles and forest products and discusses possibilities of new global resources for cellulose production. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 487–495, 2004
Synthesis and characterization of stereoregular poly(methyl methacrylate)–silica hybrid utilizing stereocomplex formation
Authors: Ashok Kumar Achimuthu , Adachi Kaoru , Chujo Yoshiki 
Published: December 2003

AbstractStereoregular poly(methyl methacrylate) (PMMA)–silica nanocomposites were prepared using stereocomplex formation between i‐PMMA and s‐PMMA by an in situ method. The methodology adopted here is the simultaneous formation of organic gel and inorganic gel, the so‐called interpenetrating polymer network (IPN) formation. The gelation of i‐ and s‐PMMA were performed by stereocomplex formation with the associated segments forming the crosslinking points in the presence of tetramethoxysilane (TMOS). The effects of the i/s‐ratio, PMMA concentration, molecular weight, and solvent nature on the hybrid materials formation were addressed. The presence of the stereocomplex in the silica matrix was confirmed by DSC and solvent extraction methods. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 785–794, 2004
Phototriggered atmospheric degradation of poly[methyl(phenyl)silanediyl] in the presence of ultraviolet absorbers
Authors: Meszároš O. , Schmidt P. , Pospíšil J. , Nešpůrek S. 
Published: December 2003

AbstractOxidative changes in poly[methyl(phenyl)silanediyl] (PMPSi) films exposed in a Weather‐O‐Meter ATLAS Ci 3000+ were monitored by Fourier transform infrared spectroscopy. Increases in absorption in the siloxane, carbonyl, and hydroxyl regions, decreases in absorption in the SiSi region, and changes in the aromatic CH bond region were monitored. Experiments in argon and air indicated the key role of oxygen in the process. The photooxidation of PMPSi was retarded by triazine‐ and oxalanilide‐based ultraviolet absorbers [2‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)‐5‐(hexyloxy)phenol and N‐(4‐tert‐butyl‐2‐ethoxyphenyl)‐N′‐(2‐ethylphenyl)oxalanilide] protecting the polymer by the excited‐state intramolecular proton‐transfer mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 714–721, 2004
Poly(vinyl chloride) on the way from the 19th century to the 21st century
Authors: Braun D. 
Published: December 2003

AbstractDespite all the technical and economic problems and the public discussions on the environmental dangers and hazards of chlorine chemistry, poly(vinyl chloride) (PVC) is the second most produced plastic (with a worldwide capacity of about 31 million tons), placing after polyolefins and before styrene polymers. Presently, PVC production worldwide is growing at a rate of more than 4% per year. The application of PVC was first described in a patent in 1913, but only after 1930 did a sustained interest in PVC arise in several industrial laboratories. The most remarkable milestones in PVC history and their importance to the development of macromolecular chemistry are briefly described, and some present PVC research and industrial applications, with respect to polymerization, stabilization, bulk property modification, and chemical and material recycling of PVC waste, are discussed. Some actual selected topics include the emulsion polymerization of vinyl chloride with polymeric surfactants and controlled free‐radical polymerization with nitroxyls, whereas ionic and metal organic initiators have not found any technical applications. Chemical reactions offer many possibilities for the modification of PVC, but they have been not used on a technical scale yet. Much work has been done on stabilization with nontoxic or metal‐free systems. The bulk properties of PVC can be influenced by impact modification through the addition of graft copolymers or by blending with other polymers. Also presented are some problems and recent developments in PVC recycling. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 578–586, 2004
Simultaneous introduction of phosphonic and carboxylic acid functions to hydroxylated macromolecules
Authors: Penczek Stanislaw , Pretula Julia , Kaluzynski Krzysztof 
Published: December 2003

AbstractNovel diblock and dihydrophilic ionic–nonionic copolymers, having phosphonic and carboxylic functions at the same carbon atom in the repeating units of the ionic block, were prepared. The addition of 2‐diethylphosphono‐ethyl acrylate (PC) to hydroxyl groups of the polyglycidol block of the poly(ethylene glycol)‐b‐polyglycidol block copolymer was followed by the dealkylation of phosphonic acid esters and the hydrolysis of carboxylic acid esters. The polymer was characterized by 1H, 13C, and 31P NMR. The kinetics of the PC addition and the hydrolysis of the ethyl carboxylate function were also studied, and a simple bimolecular second‐order reaction was established. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 432–443, 2004
Competition between the formation of excimers and excitons during the photoluminescence of light‐emitting polymer blends
Authors: Lee J. S. , Kim C. H. , Yu J.‐W. , Kim J. K. , Kim D. Y. , Song N. W. , Kim C. Y. 
Published: December 2003

AbstractDivinylenediethylhexyloxyphenyl and either triphenyltriazine (PTPV) or diphenoxyphenyltriazine (POTPV) were alternately connected to inhibit the dimer emission of the divinylenediethylhexyloxyphenyl unit and to enhance the electron mobility of light‐emitting polymers. A photoluminescence (PL) spectrum of a PTPV film showed characteristics of excimer emissions, whereas POTPV generated a singlet exciton PL emission. A blend of POTPV with poly(vinyl carbazole) (PVK) enhanced the PL intensity of POTPV upon the photoexcitation of PVK, and this indicated efficient energy transfer between the two polymers. Contrary to expectations based on the good overlap of spectra for the PL emission of the donor and the light absorption of the acceptor, the energy transfer from PVK to PTPV was incomplete upon the photoexcitation of the blend at the ultraviolet–visible absorption maximum of PVK. However, the excimer PL emission of PTPV was completely suppressed. The lifetime ratio of the excitations of the donor and the acceptor was proven to be one of the critical factors in the energy transfer, in addition to the Förster energy‐transfer principle. The excimer emission was suppressed by the photoexcitation of the chromophores below a certain critical energy level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 557–565, 2004
Polycationic salts. VI. Synthesis and in vitro studies of 2‐ionene oligomer derivatives of styrene as bile acid sequestering agents
Authors: Zarras Peter 
Published: December 2003

AbstractSeveral vinylbenzyltri‐n‐alkylammonium salts were prepared via the Menshutkin reaction in high yields by the reaction of vinyl benzyl chloride (VBC) and tertiary amines. Additional salts based on 2‐ionene oligomers were synthesized via a sequential Menshutkin reaction. The 2‐ionene oligomers were further reacted with VBC to afford the vinyl benzyl chloride‐2‐ionene halide monomers in nearly quantitative yield. The monomers were polymerized in either aqueous or organic solvents with azo initiators in high yield with correspondingly high inherent viscosities. The polymers were measured spectrophotometrically for their bile acid sequestering activity with an in vitro enzymatic reaction. Several of the measured polymers exhibited 15–28% greater activity relative to cholestyramine. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 701–713, 2004
Synthesis, structural analysis, and self‐assembly of phenylene ethynylene oligomers and their F, CF3, and CH3 substituted derivatives
Authors: Percec Simona , Getty Ross , Marshall Will , Skidd Gabriel , French Roger 
Published: December 2003

AbstractOligomers consisting of aromatic building blocks separated by alkynyl units were synthesized by Sonogashira cross‐coupling of aryl halides with terminal acetylenes. Strong electron acceptors such as F and CF3 and weak electron donors like CH3 were placed as substituents on one of the benzene rings. Acetyl‐protected sulfhydryl groups were attached to one end of these molecules to promote their self‐organization on gold surfaces. The electron‐transport properties of such self‐assembled monolayers (SAMs) are highly sensitive to the local order of the molecules in the solid state. Single crystals were analyzed by X‐ray diffraction experiments that revealed structural details that could lead to a better understanding of the electron‐transport properties. The unsymmetrical substitution of the aromatic rings by electron‐active groups in the ortho‐, meta‐, or para positions resulted in changes of such molecular parameters as bonding and torsion angles and planarity. These parameters, in turn, can affect the angle of the molecular attachment to a gold substrate and the density of the resulting SAMs. Patterned SAMs of some of these molecules and comparison alkane thiols were obtained on gold by microcontact printing or flooding. The SAM thickness was determined by spectroscopic ellipsometry. Surface potential differences between adjacent SAMs or between SAMs and the gold substrate were measured by scanning surface potential microscopy under ambient conditions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 541–550, 2004
Parallel programming library for molecular dynamics simulations
Authors: Trobec R. , Šterk M. , Praprotnik M. , Janežič D. 
Published: December 2003

AbstractA parallel programming library for molecular dynamics (MD) simulations is described and applied to the recently proposed split integration symplectic method (SISM) for MD simulation. The results show that for a system of 1024 linear chain molecules with an integration step of 4.5 fs parallel execution of SISM with the particle–particle interactions (PPIs) library on 32 computers gives efficiency of 95.6%. The results also show the parallel simulation of n particles is scalable with the number of processors p and the time requirement is proportional to n2/p for n/p large enough, which guarantees optimal speed‐up. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Generalization of the Kohn–Sham equations with constrained electron density formalism and its time‐dependent response theory formulation
Authors: Casida Mark E. , Wesołowski Tomasz A. 
Published: December 2003

AbstractThe Kohn–Sham equations with constrained electron density (KSCED) embedding formalism of Wesołowski and coworkers was originally developed and is good for the case of two weakly interacting molecular regions with weakly overlapping densities, such as might be expected in describing solvation. A generalization is given here for the case of three molecular regions with strongly overlapping densities with the idea that this generalized theory can offer a better description of embedding in the context of situations that might be encountered in, for example, chemisorption on surfaces or active sites in enzymes. This three‐partition generalization includes the original two‐partition formalism as a special case. Time‐dependent response theory equations are then developed for the two‐ and three‐partition theories for application to the problem of the calculation of polarizabilities and other response properties, including excitation spectra, of embedded molecules or molecular structures. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical study of the structures and stabilities of AlCn, AlC, and AlC (n = 1–7) monocyclic clusters
Authors: Redondo Pilar , Barrientos Carmen , Largo Antonio 
Published: December 2003

AbstractA theoretical study of the AlCn, AlC and AlC (n = 1–7) monocyclic clusters has been carried out. Predictions for their electronic structures, dipole moments and vibrational frequencies have been made at the B3LYP/6‐311G(d) and B3LYP/6‐311+G(d) levels. For the AlCn monocyclic clusters the ground state is found to be a doublet in all cases, whereas all corresponding cations have singlet ground states. In the case of the anionic clusters, singlet states are favored up to n = 5, whereas triplet ground states are found for clusters with more carbon atoms. An even–odd parity effect, with n‐even clusters being more stable than n‐odd ones, is found for both the neutral and anionic species, whereas in the case of the cations there is no clear alternation in stability. It is in general observed that n‐even clusters have higher electron affinities and ionization potentials than n‐odd species. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Wave packet calculations for the Cl + H2 reaction
Authors: Skouteris Dimitris , Laganà Antonio , Capecchi Gabriella , Werner Hans‐Joachim 
Published: December 2003

AbstractTime‐dependent quantum mechanical calculations have been carried out to estimate the convergence with the total angular momentum quantum number J of the reactive cross‐sections for the reaction Cl + H2 using product Jacobi coordinates. The potential energy surface used for the calculations is that of Capecchi and Werner (to be published) developed recently. The theoretical predictions are compared with results of previous theoretical studies. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Reactivity and aromaticity of polyaromatics in radical cyclization reactions
Authors: Van Speybroeck V. , Hemelsoet K. , Waroquier M. , Marin G. B. 
Published: December 2003

AbstractTheoretical ab initio calculations are presented on cyclization reactions of polyaromatics that occur by a radical mechanism. Such processes are one of the elementary steps for polyaromatic hydrocarbon formation in thermal cracking units and during soot formation. Ring closure can take place at various sites of the polyaromatic surface. It is the aim of this study to obtain insight into the influence of the local structure on the reactivity of the polyaromatics. Aromaticity is a determining factor for the reactivity and can be probed by various magnetic properties such as the diamagnetic susceptibilities, proton chemical shifts, and nucear‐independent chemical shifts. A correlation is established between the magnetic properties and activation energy of the studied reactions. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004