bluuebunny/crossref_metadata_2025_split huggingface dataset:
FEM‐BEM coupling for the exterior Stokes problem with non‐conforming finite elements and an application to small droplet deformation dynamics
Authors: Radcliffe A. J. 
Published: March 2011

AbstractA non‐conforming, discontinuous Galerkin finite element–boundary element coupling procedure is presented for the exterior planar Stokes problem. The novel coupled formulation is developed using that for the conforming case as a guide to the introduction of extra mortar variables used to couple a discontinuous interior finite element solution with a continuous exterior boundary element solution. Convergence results for the new scheme are presented, for a range of different interior penalties, on computational domains discretized with regular structured meshes.To illustrate an application, the excitations required to model two‐phase droplet deformations in an extensional flow, under simple surface tension, with the new scheme are also presented. For a selection of different drop viscocities and exterior flows, with and without a rotational component, the progression to a steady‐state deformation of initially undeformed circular drops is calculated and the results compared with those from both a conforming FEM‐BEM equivalent scheme and from a small perturbation analysis where available. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis of novel pyrazolopyridine and pyridopyrimidine derivatives
Authors: Soliman A. M. 
Published: March 2011

Abstract2‐Amino‐6‐chloropyridine‐3,5‐dicarbonitrile was used as an intermediate for synthesis of new pyrazolopyridine, pyridopyrimidine, benzodiazepine, and benzothiazipine derivatives. J. Heterocyclic Chem., (2011).
Ammonium metavanadate as an efficient catalyst for the synthesis of 2,4,5‐triaryl‐1H‐imidazoles
Authors: Niralwad Kirti S. , Shingate Bapurao B. , Shingare Murlidhar S. 
Published: March 2011

AbstractAmmonium metavanadate (NH4VO3) is an inexpensive, efficient and mild catalyst for the synthesis of 2,4,5‐triaryl‐1H‐imidazole from the one‐pot three‐component condensation of benzil/benzoin, an aldehyde and ammonium acetate in excellent yield. This method has the advantages of good yield, green catalyst, simple procedure, much faster reactions. J. Heterocyclic Chem., (2011).
Ligand Accessibility to Receptor Binding Sites Enhanced by Movable Polyrotaxanes
Authors: Hyun Hoon , Yui Nobuhiko 
Published: March 2011

AbstractFunctionalized polyrotaxanes are utilized to investigate the relation to multivalent interactions between the mannose moiety and Con A immobilized surfaces. According to the results of SPR spectroscopy, the mannose‐conjugated polyrotaxanes show a higher response than any other mannose conjugate on both surfaces of high‐ and low‐density Con A. Moreover, the results of the FRET analysis suggest that the mobility of α‐cyclodextrins in the polyrotaxane more efficiently contributes to their binding interactions in a multivalent manner. This well‐defined polyrotaxane system provides control over ligand density, ligand mobility, and gives an efficient response to the biological interaction receptor, which has not been easy to achieve in covalently bound polymeric systems. magnified image
Blue‐Emitting Polymers Based on 4‐Hydroxythiazoles Incorporated in a Methacrylate Backbone
Authors: Menzel Roberto , Breul Alexander , Pietsch Christian , Schäfer Johann , Friebe Christian , Täuscher Eric , Weiß Dieter , Dietzek Benjamin , Popp Jürgen , Beckert Rainer , Schubert Ulrich S. 
Published: March 2011

AbstractThe synthesis of two new monomers based on 4‐hydroxythiazoles, with a non‐classical chromophore structure similar to the luciferin dye of glowworms, is presented. These dyes are functionalized with methacrylates and copolymerized with methyl methacrylate using a RAFT polymerization process. The obtained polymers reveal PDI values below 1.2 and are characterized by NMR spectroscopy, SEC including a diode‐array detector, UV‐vis and fluorescence spectroscopy. In addition, thin films of the polymers are prepared by spin‐coating and investigated regarding their optical properties. magnified image
Synthesis of Thermo‐Responsive Polymers With Both Tunable UCST and LCST
Authors: Tian Hai‐Ying , Yan Jun‐Jie , Wang Di , Gu Chen , You Ye‐Zi , Chen Xue‐Si 
Published: March 2011

AbstractNew water‐soluble block copolymers of 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO2MA), oligo(ethylene glycol) methacrylate (OEGMA), and N‐(3‐(dimethylamino) propyl) methacrylamide (DMAPMA) (poly(OEGMA‐co‐MEO2MA)‐b‐poly(DMAPMA)) were prepared via sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization. Selective quaternization of poly(DMAPMA) block gives poly(OEGMA‐co‐MEO2MA)‐b‐poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide), such block copolymer exhibits double thermo‐responsive behavior in water, poly(MEO2MA‐co‐OEGMA) block shows a lower critical solution temperature (LCST), and poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide) block shows a upper critical solution temperature (UCST). Both of LCST and UCST can be controlled: LCST could be tuned by the fraction of OEGMA units in poly(OEGMA‐co‐MEO2MA), and UCST was found to be dependent on the degree of quaternization (DQ). magnified image
Fluorescent Core‐Shell Star Polymers Based Bioassays for Ultrasensitive DNA Detection by Surface Plasmon Fluorescence Spectroscopy
Authors: Feng Chuan Liang , Yin Meizhen , Zhang Di , Zhu Shenmin , Caminade Anne Marie , Majoral Jean Pierre , Müllen Klaus 
Published: March 2011

AbstractMultilayers containing a perylene diimide labelled star polymers (FSP) donor adjacent to phosphorus dendrimer layer on a silver substrate were constructed by layer by layer (LBL) approach. Using Surface Plasmon Enhanced Fluorescence Spectroscopy (SPFS) technique, a time‐resolved ultrasensitive and selective detection of DNA targets relying on enhanced optical fields associated with energy transfer (ET) were achieved under the excitation at 543 nm. The detection limit is about 8 orders of magnitude better than the achieved one under the excitation at 632 nm, which is ascribed to no energy transfer from the donor to the acceptor under the excitation at 632 nm, resulting in much weak detection signal in turn. magnified image
Blends of poly(2,6–dimethyl–1,4–phenylene oxide) with styrene copolymers
Authors: Gottschalk Axel , Mühlbach Klaus , Seitz Friedrich , Stadler Reimund , Auschra Clemens 
Published: March 2011

AbstractBinary blends of poly(2,6–dimethyl–1,4–phenylene oxide) (PPE) with various styrene copolymers were investigated. Poly(styrene–co–acrylonitrile) (SAN), poly[styrene–co–(methyl methacrylate)] (SMMA), poly[styrene–co–(acrylic acid)] (SAA) and poly[styrene–co–(maleic anhydride)] (SMA) are only miscible with PPE when the amount of comonomer is rather small. From calculated binary interaction densities it can be concluded that the strong repulsion between PPE and comonomer limits miscibility. In blends of PPE with SAN, as well as with ABS, the inter‐facial tension between the blend components is significantly reduced upon addition of polystyrene–block–poly–(methyl methacrylate) diblock copolymers (PS–b–PMMA) and polystyrene–block–poly (ethylene–co–butylene)–block–poly–(methyl methacrylate) triblock copolymers (PS–b–PEB–b–PMMA). They show a profound influence on morphology, phase adhesion and mechanical blend properties.
Characterization of the segmental mobility of liquid‐crystalline side‐chain polyesters by fourier‐transform infrared spectroscopy
Authors: Kulinna Ch. , Zebger I. , Hvilsted S. , Ramanujam P. S. , Siesler H.W. 
Published: March 2011

AbstractFourier‐Transform infrared (FTIR) polarization spectroscopy has been applied to study segmental orientation of a new class of liquid‐crystalline side‐chain (LCSC) polyesters as a function of laser irradiation. From the experimental results qualitative structural models and quantitative results in terms of an order parameter were derived. Time‐dependent investigations yielded a detailed insight into the orientational response of the mesogens, and temperature‐dependent studies were applied to monitor the erasure of the induced orientation.
Polymer blends: Structure and specific interaction of components ‐ poly(phenylene sulfide) and its oligomers
Authors: Kryszewski Marian 
Published: March 2011

AbstractPoly(phenylene sulfide) (PPS) and its blends with oligomers of PPS have been investigated. It was shown that such a system shows changes in the crystallization behaviour, in the amount of rigid amorphous phase, in the glass transition temperature and in the electrical conductivity (after doping).
Investigations on the structure of regenerated cellulose fibers; Herrn Professor Janeschitz‐Kriegl zum 70. Geburtstag mit den besten Wünschen gewidmet
Authors: Schurz Josef , Lenz Jürgen 
Published: March 2011

AbstractA review is given on comparative investigations onto the structure of regenerated cellulose fibers of the regular viscose type (modal) and of solvent spun fibers of the lyocell type, namely the NMMO fiber spun from a solution of cellulose in N–methylmorpholine N–oxide and water. It was found that in the lyocell fiber the mechanical properties in the wet state detoriate less. This is explained by an increased length of the crystallites, less clustering of the crystalline regions, and a shorter and better oriented amorphous portion. These structural features could be caused by a different spinning mechanism due to a preordered spinning solution in which the stiff complexed cellulose molecules are oriented lengthwise in the spinning direction. This will greatly facilitate their orientation during fiber formation in the elongtional deformation velocity field of the draw down zone.
Fascinated by a chain molecule review of 35 years' research on cellulose
Authors: Fengel Dietrich 
Published: March 2011

AbstractFor over 35 years the author has been involved in cellulose research and his retirement next year is the reason why he has undertaken to present a review on some aspects of his investigations on the fascinating substance cellulose. One topic of his research activities is electron microscopy. At the very start, at the Institute for Cellulose Chemistry (T.H. Darmstadt), observations were made on bordered pits and structural details on the walls of wood and pulp fibres. He was able to continue his teacher's, Georg Jayme's, traditional basic research on cellulose at the Institute for Wood Research (University of Munich) where “dreams” of the fifties and sixties such as the visualization of individual molecules and the growing of macrocrystals of cellulose could be realized. Here, the electron microscope became a vital instrument for the study of cellulose chemistry.
Spontaneous copolymerizations in the reactions of electron‐rich dienes with electrophilic olefins
Authors: Hall H. K. , Padias Anne Buyle 
Published: March 2011

AbstractThe spontaneous thermal reactions of electron‐rich dienes with electrophilic olefins lead to both [4+2] cycloadducts and copolymers. The mechanism proposed for the initiation of the copolymerization involves the formation of a 2‐hexene‐1,6‐diradical. Structure‐reactivity relationships are discussed.
Polymerization of surface‐active monomers and applications
Authors: Nagai Katsutoshi 
Published: March 2011

AbstractThe results on radical polymerization and copolymerization of alkyl bromide salts of 2‐dimethylaminoethyl methacrylate having a different alkyl chain length in various solvents giving micellar and isotropic solutions are summarized to obtain an insight into micellar polymerization. The monomer micellization of the cationic surface‐active monomers at concentrations far above their critical micelle concentration (cmc) leads to great increases in the rate of polymerization and the molecular weight of the resulting polymers for both aqueous and inverse micellar systems and the tendency toward alternation of the copolymerization for aqueous micellar systems, whereas it has little influence on the tacticity of the resulting polymers. Applications of the polimerization and the copolymerization of the surface‐active monomer to the polymer encapsulation of silica particles are also reported.
Synthesis and structure of polyisopeptides
Authors: Sekiguchi Hikaru , Coutin Bernard , And Soufiane Bechaouch , Gachard Isabelle 
Published: March 2011

AbstractPolyisopeptides are non‐peptidic polymers formed by α,ω‐polycondensation of tri‐ or multi‐functional α‐amino acids. They are expected to possess physical and mechanical properties of synthetic polyamides (or polyesters) and to be biodegradable. In the present paper, the methods of polyisopeptide synthesis are reviewed. Many of them are specific to a given α‐amino acid (and sometimes its derivatives, too). We discuss here about two methods giving satisfactory results. One is the polymerization of L‐aspartic β‐lactam α‐esters, in which the structure of a resulting polymer varies according to the solvent used. A new interpretation on the basis of the nature of catalyst anion species (free ion, ion pair) is presented. The other subject is the active ester polycondensation method applied to the amino‐ and carboxyl‐ protected L‐cystine polyisopeptide and its selective deprotection successively until total deprotection to free amino‐ and free carboxylic groups. The final polymer is the first poly‐L‐cystine ever reported in the literature.
Styrene and methyl methacrylate polymerization using diphenylzinc‐cocatalyst systems. part II.
Authors: Rabagliati Franco M. , Terraza Claudio A. , Ramirez Luis A. , Contreras Jesús M. 
Published: March 2011

AbstractVarious diphenylzinc–additive systems were used to initiate homopolymerization of styrene and of methyl methacrylate. The polymers obtained were characterized by size exclusion chromatography, by 1H– and 13C–NMR and measurements of intrinsic viscosities [η]. These data indicated that polymerization is much influenced by: The nature of the additive employed, the proportion of the additive relative to diphenylzinc and the condition of polymerization.
Synthetic routes to block copolymerization by changing mechanism from cationic polymerization to free radical polymerisation
Authors: Yagoi Yusuf , Hizal Gürkan , Önen Ayşen , Serhatli İErsin 
Published: March 2011

AbstractPolymers containing thermolabile groups were synthesized by various cationic polymerization initiation mechanisms, namely; oxo–carbenium, promoted cationic and activated monomer polymerization. These polymers used in a subsequent blocking step in which azo groups were decomposed and converted into initiating centres from which blocks were grown by means of free radical polymerization. This procedure was applied to specific systems in which cationic polymerizable monomers are tetrahydrofuran (THF), cyclohexene oxide (CHO) and epichlorohydrin (ECH), respectively, and the free radical polymerizable monomer is styrene (St).
New polymers for biomedical applications: Synthesis and characterization of acrylic systems with pharmacological activity
Authors: Román Julio San , Gallardo Alberto , Levenfeld Belén 
Published: March 2011

AbstractThe synthesis and characterization of new biocompatible “Polymeric Drugs” on the basis of poly (methacrylic esters) and poly (methacrylamides) with side substituents of pharmacological interest, with analgesic, antiinflammatory, antipyretic and antiaggregating activities, is reported. The preparation of these systems was carried out following the universal model suggested by Ringsdorf, and the polymers prepared by the free radical polymerization of the corresponding acrylic monomers were characterized by 1H‐ and 13C‐NMR spectroscopies. Biocompatible hydrogels were prepared by free radical copolymerization of these monomers with HEMA. The characteristic copolymerization parameters and the microstructural distribution of comonomeric sequences were determined by NMR spectroscopy. The swelling behaviour of copolymer films was followed gravimetrically. Applications of polymer and copolymer systems are being tested in the fields of pharmacology and vascular surgery.
Microporous polymeric materials by microemulsion terpolymerization
Authors: Gan L. M. , Chew C. H. , Chieng T. H. 
Published: March 2011

AbstractTransparent microstructural solid polymers have been prepared by polymerization of methyl methacrylate, 2‐hydroxyethyl methacrylate and reactive sodium 11‐(N‐ethylacrylamido) undecanoate in microemulsions. The transparent polymeric solids could be formed from fluid microemulsions within 10 minutes by photoinitiated polymerization. SEM micrographs of the polymerized samples reveal the existence of microporous structures. The results seem to indicate that the open‐cell porous structures of transparent polymers could be obtained from those precursor microemulsions with water content higher than 20% or the closed‐cell structures from those with less than 20%.
Δχ effects on the miscibility of polymer blends
Authors: Ha Chang Sik , Ki Lee Won , Cho Won Jei 
Published: March 2011

AbstractThe Δχ effect on the miscibility of polymer blends prepared by solution‐casting has been investigated using the mixture of poly(methyl methacrylate)(PMMA) with poly(vinyl acetate) (PVAc). The PMMA/PVAc blends have been prepared by casting from eleven different solutions. The Δχ effect of the solution–cast PMMA/PVAc blends was discussed in terms of Hansen's specified solubility parameters. It was found that the miscibility of the blends could be defined mainly by the solubility parameter contributed by the hydrogen–bonding of a solvent.
Porous structure formation and swelling properties of styrene–divinylbenzene copolymers – effect of diluent nature
Authors: Rabelo D. , Coutinho F. M. B. 
Published: March 2011

AbstractThe effect of the diluent solvating power on the porosity and swelling properties of styrene–divinylbenzene copolymers was investigated. A mechanism for the swelling of macroporous copolymers in good and poor solvent was proposed. The porous structures were classified according to kinetic data of a poor solvent sorption. When the diluent–copolymer affinity was reduced, the fixed pore volume increased, but the nuclei swelling and the elasticity of internuclear chains diminished.
Determination of structure and concentration of growing species in ionic polymerizations: The 31P NMR method
Authors: Penczek Stanislaw , Brzezinska Krystyna 
Published: March 2011

AbstractThe quantitative transformation of the ionic growing species (∼ ∼ ∼*) into the P atom containing end‐groups (∼ ∼ ∼P) allows to determine by 31P NMR their structures and concentrations, down to 10−4 mol‐L−1, or even lower with a further progress of the NMR equipment:magnified imageThe P atoms are exclusively located at the chain ends, the known excess of the reagent “P” being used as an internal standard. The chemical shifts of thus prepared chain ends, when compared with models, give information on the chemical structure of the parent active species. This paper reviews the earlier work on ionic ring‐opening polymerization and more recent work, concerning cationic and anionic vinyl polymerization, particularly polymerization of vinyl ethers, styrene, methacrylates and some diene monomers. In the polymerization of vinyl ethers the stereochemistry of the chain ends was studied; it has also been shown, that chemical shift changes with the polymerization degree; thus the first addition products could separately be observed.
Some new developments in vinyl ether polymerization
Authors: Goethals Eric J. , Haucourt Nancy , Peng Li‐Bing 
Published: March 2011

AbstractDifferent combinations of acetals with trimethylsilyl iodide have been explored as new initiating systems for the vinyl ether polymerization. The resulting polymers are characterized by controlled molecular weights and narrow molecular weight distributions, confirming the living polymerization mechanism.Acetals can also be used as transfer agents in the polymerization of vinyl ethers. When using 1,1‐diethoxyethane (DEE) as transfer agent and isobutyl vinyl ether (IBVE) as monomer, a transfer constant of 0.2 was obtained (at −40°C in toluene). This method, transposed to functional acetals, provides a new way to prepare polyvinyl ethers with one or two functional end groups.The cationic polymerization of isobutyl vinyl ether initiated with the combination triflic acid/thietane, where thietane acts as electron donating moderator, leads to star‐shaped polyvinylether‐polythietane block‐copolymers (at −40°C in dichloromethane). The block‐copolymer structure is obtained because the vinyl ether polymerization is stopped when the α‐alkoxy thietanium ion (active species) is attacked by a thietane molecule, which is at the same time an initiation reaction for the thietane polymerization. The star‐shaped structure of the block‐polymer is the result of the intermolecular termination in the cationic polymerization of thietane. When using a bifunctional initiator system, a polymer network is obtained consisting of linear polyIBVE‐segments interconnected by branched polythietane segments. These findings support the sulfonium ion structure of the active species in the cationic polymerization of vinyl ethers initiated by the acid‐sulfide system.
Tailor‐made polymers and copolymers from aziridines and 1,3‐oxacyclanes
Authors: Velichkova Rumiana , Christova Darina , Gancheva Valeria 
Published: March 2011

AbstractTelechelic poly(tert‐butylaziridine)s (polyTBA) and poly(1,3,6‐trioxocane)s (polyTOC) and macromonomers were synthesized mainly by living cationic polymerization. Both, molecular weight and end‐functionality distributions of polyTOC oligomers and polymers were studied using a combination of HPLC under “critical conditions”, gradient HPLC and SEC with double detection following a preparative HPLC fractionation.Monofunctional and bifunctional polyTBA with various end‐groups were synthesized by the end‐capping method. Several modification reactions were examined for terminal transformation of polyTBA and polyTOC hydroxy‐telechelics into mono‐ and bifunctional vinyl ether macromonomers. Various tailor‐made polymers based on uniform size telechelics and macromonomers were prepared using: 1. polymer‐polymer coupling to produce block copolymers; 2. polyaddition of amino‐functionalized telechelics to bisacrylamides; 3. addition of amino‐polyTBA to polydienes; 4. synthesis of graft copolymers with well‐defined graft component and networks.
Functionalization of poly(1,3‐dioxolane)
Authors: Franta E. , Lutz P. , Reibel L. , Sahli N. , Kada S. Ould. , Belbachir M. 
Published: March 2011

Abstract1,3‐Dioxolane was polymerized in the presence of ethylene glycol in order to prepare α,ω‐dihydroxylated polymers which, upon reaction with pluriisocyanates yielded networks swellable in water. The crosslinks were made of urethane groups, which are bulky and hydrophobic. In order to expand the scope of the networks that can be envisioned, we have studied the replacement of the two end‐standing hydroxylic groups by unsaturated polymerizable groups. Several methods are presented which allow successfully the quantitative endowment of the polymer endings with methacryloyl‐ or styryl‐ or vinylether‐type groups.α,ω‐dihydroxylated poly(1,3‐dioxolane) was also metallated and used as a macroinitiator for the polymerization of ethylene oxide: the α,ω‐dihydroxylated triblock copolymer obtained is made of a central poly(1,3‐dioxolane) block flanked by two poly(ethylene oxide) ones.Several methods are also shown to be efficient in the characterization of the hydroxylic end‐standing functions of the polymer.