bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chiral discrimination of a helically organized crown ether array parallel to the helix axis of polyisocyanate
Authors: Sakai Ryosuke , Otsuka Issei , Satoh Toshifumi , Kakuchi Ryohei , Kaga Harumi , Kakuchi Toyoji 
Published: November 2005

AbstractThe asymmetric polymerization of 4′‐isocyanatobenzo‐18‐crown‐6 with the lithium amide of (S)‐(2‐methoxymethyl)pyrrolidine successfully proceeded to afford end‐functionalized poly(4′‐isocyanatobenzo‐18‐crown‐6) with (S)‐(2‐methoxymethyl)pyrrolidine (polymer 2). In the circular dichroism (CD) spectrum of 2, a clear positive Cotton effect was observed in the range of 240–350 nm corresponding to the absorption of the polymer backbone, indicating that 2 partially formed a one‐handed helical structure, which was preserved by the chirality of (S)‐(2‐methoxymethyl)pyrrolidine bonding to the terminal end in 2. In the titration experiments for the CD intensity of 2 in the presence of D‐ and L‐Phe·HClO4 (where Phe is phenylalanine), a small but remarkable difference was observed in the amount of the chiral guest needed for saturation of the CD intensity and in the saturated CD intensity, indicating that the extremely stable, one‐handed helical part should exist in the main chain of 2, which was not inverted even when the unfavorable chiral guest for the predominant helical sense, L‐Phe·HClO4, was added. In addition, helical polymer 2 exhibited a chiral discrimination ability toward racemic guests; that is, the guests were extracted from the aqueous phase into the organic phase with enantiomeric excess. The driving force of the chiral discrimination ability of 2 should certainly be attributed to the one‐handed helical structure in 2. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 325–334, 2006
Investigations of the dissociation behavior and interfacial adsorption characteristics of polyelectrolytes from poly(acrylamido‐2‐methyl‐1‐propane sulfonic acid) with an octadecyl side chain
Authors: Chandrasekar K. , Baskar Geetha 
Published: November 2005

AbstractWater‐soluble polymeric amphiphiles derived from acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and octadecyl monomers in which the linker groups vary among acryloyl [octadecyl methacrylate (ODMAc)], maleate [octadecyl maleate ester (ODME)], and maleamic acid [octadecyl maleamic acid (ODMA)] have been synthesized. The dissociation behavior in water from potentiometric titration suggests that these polymers show resistance to neutralization. This might arise from coil structures, which effect the destabilization of sulfonate ions because of a proximity effect. The effect of the COOH group in modifying the dissociation behavior in the copolymers AMPS–ODME and AMPS–ODMA is indicated. The ratio of the intensities of the third vibronic peak (I3) to the first vibronic peak (I1) of the fluoroprobe pyrene in the presence of polymer solutions shows negligible changes as a function of pH, and this suggests the retention of micropolarity. The high I3/I1 value observed in the presence of the ODMAc polymer suggests intermolecular association. The reduction in the reduced viscosity with the concentration of the polymers suggests the polyelectrolyte behavior of all the copolymers. The progressive decrease in the reduced viscosity from 120 to 95 mL/g when the degree of ionization increases from 0.5 to 1 for the ODME polymer suggests changes in the solution structure. AMPS–ODMA and AMPS–ODME polymers exhibit significant adsorption at the interface and exhibit equilibrium surface tensions of 58.8 and 56.3 mN/m, respectively. The lower surface activity and higher reduced viscosity of ODMAc polymer solutions further support the formation of intermolecular associated or network structures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 314–324, 2006
Characterization and corrosion resistance of organically modified silicate/MO2 (M = Zr, Ti, or Ce) hybrid coatings on a 6061‐T6 aluminum alloy
Authors: Wu K. H. , Li M. C. , Chang T. C. , Yang C. C. 
Published: November 2005

AbstractHybrid coatings based on organically modified silicate (Ormosil)/ZrO2 (0–1.0 wt %) and Ormosil/MO2 (M = Ti or Ce) were synthesized through a sol–gel technique. Tetraethylenepentamine, 3‐glycidoxypropyltrimethoxysilane, tetraethoxysilane, and MO2 (M = Zr, Ti, or Ce) metallic particle were used as precursors for the hybrid coatings. These hybrid films were deposited via spin coating onto an aluminum alloy to improve the corrosion protection. The effects induced by the ZrO2 content and the metallic particle type on the chain dynamics, thermal stability, and corrosion performance of the coated samples were investigated. The rotating‐frame spin–lattice relaxation times and scale of the spin–diffusion path length indicated that the configuration of the hybrid films was highly crosslinked and dense and adhered to the aluminum alloy substrates. The thermal stability and the apparent activation energy, evaluated by van Krevelen's method, of the hybrid coatings depended on the ZrO2 content and on the metallic particle type. Potentiodynamic and salt‐spray analysis revealed that the hybrid films provided exceptional barrier and corrosion protection in comparison with untreated aluminum alloy substrates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 335–342, 2006
Syntheses of cyclodextrin–3′‐azido‐3′‐deoxythymidine conjugates and their sulfates with improved anti‐HIV activities
Authors: Chung Ildoo , Lee Chong‐Kyo , Ha Chang‐Sik , Cho Won‐Jei 
Published: November 2005

AbstractNew anti‐HIV agents, cyclodextrin–3′‐azido‐3′‐deoxythymidine (CD–AZT) conjugates, were synthesized and characterized. A succinate diester spacer was used to covalently couple 3′‐azido‐3′‐deoxythymidine (AZT) onto cyclodextrin. In addition, their sulfates were prepared by the reaction of CD–AZT conjugates and a sulfur trioxide/pyridine complex at 80 °C. The degree of AZT substitution of the synthesized conjugates and the sulfur contents of their sulfates were calculated from elemental analysis and ranged from 1.3 to 4.7 and from 8.4 to 12.1, respectively. These resulting sulfated conjugates were expected to have a synergistic effect against HIV because of the two anti‐HIV active agents (sulfate group and AZT) by the inhibition of virus attachment to cells and that of reverse transcriptase. The in vitro antiviral activity of these conjugates was determined and used to evaluate the potential applications in anti‐AIDS drugs. The in vitro anti‐HIV activities indicated that the synthesized conjugates and their sulfates against HIV‐1 and HIV‐2 strains were much better inhibitors than AZT. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 295–303, 2006
Mono‐, bis‐, and trismaleimides having electron‐donating chromophores: Fluorescence, electrochemical properties, polymerization, and cure monitoring
Authors: Zhang Xin , Li Zi‐Chen , Wang Zhe‐Ming , Sun Hao‐Ling , He Zheng , Li Kai‐Bo , Wei Liu‐He , Lin Song , Du Fu‐Sheng , Li Fu‐Mian 
Published: November 2005

AbstractMono‐, bis‐, and trismaleimides (MM‐2, BM‐4, and TM‐6, respectively) bearing electron‐donating chromophores generally displayed strong fluorescence quenching. The quenching mechanism of fluorescence was revealed by electrochemical studies. On the basis of the electrochemical data, an energy level diagram was established for these maleimides. The electron‐donating ability increased in the order of TM‐6 < BM‐4 < MM‐2. The electron‐accepting ability increased in the opposite order, that is, from MM‐2 to BM‐4 to TM‐6. The copolymerization of multimaleimides with diamine could be well monitored by fluorescence spectroscopy. Compared with fluorescence probe techniques, the fluorescence monitoring could directly reflect the consumption of CC bonds. Furthermore, a novel trismaleimide resin was preliminarily studied, in which TM‐6 was a dual‐purpose functional monomer acting not only as a crosslinker but also as an intrinsic fluorophore to monitor its crosslinking or cure process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 304–313, 2006
Preparation, morphology, and thermoresponsive properties of poly(N‐isopropylacrylamide)‐based copolymer microgels
Authors: Lin Chia‐Lung , Chiu Wen‐Yen , Lee Chia‐Fen 
Published: November 2005

AbstractIn this research, thermoresponsive copolymer latex particles with an average diameter of about 200–500 nm were prepared via surfactant‐free emulsion polymerization. The thermoresponsive properties of these particles were designed by the addition of hydrophilic monomers [acrylic acid (AA) and sodium acrylate (SA)] to copolymerize with N‐isopropylacrylamide (NIPAAm). The effects of the comonomers and composition on the synthesis mechanism, kinetics, particle size, morphology, and thermoresponsive properties of the copolymer latex were also studied to determine the relationships between the synthesis conditions, the particle morphology, and the thermoresponsive properties. The results showed that the addition of hydrophilic AA or SA affected the mechanism and kinetics of polymerization. The lower critical solution temperature (LCST) of the latex copolymerized with AA rose to a higher temperature. However, because the strong hydrophilic and ionic properties of SA caused a core–shell structure, where NIPAAm was in the inner core and SA was in the outer shell, the LCST of the latex copolymerized with SA was still the same as that of pure poly(N‐isopropylacrylamide) latex. It was concluded that these submicrometer copolymer latex particles with different thermoresponsive properties could be applied in many fields. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 356–370, 2006
“One‐pot” synthesis of aromatic poly(1,3,4‐oxadiazole)s in novel solvents—ionic liquids
Authors: Lozinskaya Elena I. , Shaplov Alexander S. , Kotseruba Mariya V. , Komarova Lidiya I. , Lyssenko Konstantin A. , Antipin Mikhail Y. , Golovanov Denis G. , Vygodskii Yakov S. 
Published: November 2005

AbstractThe new convenient method for the synthesis of high molecular weight aromatic poly(1,3,4‐oxadiazole)s (PODs) has been proposed. These polymers were prepared by “one‐pot” procedure from dicarboxylic acid and hydrazine's salt (sulfate, phosphate) or dicarboxylic acid dihydrazides. The mixture of ionic liquid and triphenyl phosphite was used both as a solvent and condensing agent. The polycyclization occurred at a sufficiently low temperature of 210 °C for 2–5 h and resulted in obtaining film‐forming PODs having inherent viscosities up to 0.9 dL/g and good thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 380–394, 2006
Nitroxide‐mediated radical polymerization of 2‐(dimethylamino)ethyl acrylate and its sequential block copolymerization with styrene and N‐butyl acrylate
Authors: Bian Kejian , Cunningham Michael F. 
Published: November 2005

AbstractNitroxide‐mediated radical polymerization (NMRP) of 2‐(dimethylamino)ethyl acrylate (DMAEA) was carried out at 100–120 °C, initiated by MONAMS, an alkoxyamine based on N‐tert‐butyl‐N‐(1‐diethyl phosphono‐2,2‐dimethylpropyl)nitroxide, SG1. Controlled polymerization can be achieved by the addition of free SG1 (the initial molar ratio of SG1 to MONAMS ranged from 0.06 to 0.12), giving a linear first‐order kinetic plot up to 55–70% conversion depending on the reaction conditions. The molecular weights show a near linear increase with conversion; however, they deviate to some extent with theoretical values. SG1‐mediated polymerization of DMAEA at 112 °C is also controlled in organic solvents (N,N‐dimethylformide, anisole, xylene). Polymerization rate increases with increasing solvent polarity. Chain transfer to polymer produces ∼1 mol % branches in bulk and 1.2–1.9 mol % in organic solvents, typical of those for acrylates. From poly(styrene) (pS) and poly(n‐butyl acrylate) (pBA) macroinitiators, amphiphilic di‐ and triblock copolymers p(S‐b‐DMAEA), p(DMAEA‐b‐S‐b‐DMAEA), p(BA‐b‐DMAEA), and p(DMAEA‐b‐BA‐b‐DMAEA) were synthesized via NMRP at 110 °C. Polymers were characterized by GPC, NMR, surface tension measurements, and DSC. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 414–426, 2006
Isoconversional method to explore the cure reaction mechanisms and curing kinetics of DGEBA/EMI‐2,4/nano‐SiC system
Authors: Zhou Tianle , Gu Mingyuan , Jin Yanping , Wang Junxiang 
Published: November 2005

AbstractThe curing kinetics of the diglycidyl ether of bisphenol‐A (DGEBA)/2‐ethyl‐4‐methylimidazole (EMI‐2,4)/nano‐sized carborundum (nano‐SiC) system was studied by means of nonisothermal differential scanning calorimetry (DSC). An isoconversional method of kinetic analysis yields a dependence of the effective activation energy E on the extent of conversion that decreases initially, and then increases as the cure reaction proceeds. The variations of E were used to study the cure reaction mechanisms, and the Shrinking Core Model was used to study the resin–particle reaction. The results show that the presence of nano‐SiC particles prevents the occurrence of vitrification, as well as inhibits the cure reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 371–379, 2006
Synthesis and characterization of saccharide‐based latex particles
Authors: Imaz Ainara , Ayerbe Mirari , Ramos Jose , Forcada Jacqueline 
Published: November 2005

AbstractThe synthesis of new polymer colloids based on renewable resources, such as sugar‐derived monomers, is nowadays a matter of interest. These new polymeric particles should be useful in biomedical applications, such as drug delivery, because of their assumed biodegradability. In this work, two new families of polymer latex particles, based on a sugar‐derived monomer, 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (3‐MDG), were produced and characterized. The syntheses of poly(3‐MDG) crosslinked particles and those obtained by copolymerization with methacrylic acid (MAA), poly(3‐MDG‐co‐MAA) crosslinked particles, were prepared by surfactant‐free emulsion polymerization in a batch reactor. The average particle diameter evolutions, the effect of pH of the dispersion medium on the final average diameters, together with the microscopic and morphological analysis of the particle's surface and inner dominium, were analyzed. Poly(3‐MDG‐co‐EGDMA) stable particles were obtained by adding low amounts of initiator. The surface‐charge density of these particles corresponded to the sulfate groups coming from the initiator. In the second family of latices, poly(3‐MDG‐co‐MAA‐co‐EGDMA) particles, DCP measurements and SEM and TEM observations showed that the sizes and surface characteristics depended on the amounts of MAA and crosslinker used in the reaction mixture. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 443–457, 2006
Synthesis and polymerization reactions of cyclic imino ethers. I. Ring‐opening homopolyaddition of AB‐type hydroxyphenyl‐substituted 2‐oxazolines
Authors: Lustoň Jozef , Kronek Juraj , Böhme Frank 
Published: November 2005

AbstractHomopolyaddition reactions of AB‐type monomers containing a 2‐oxazoline and a phenol group in different positions of the phenyl ring, namely, 2‐(4‐hydroxyphenyl)‐2‐oxazoline, 2‐(3‐hydroxyphenyl)‐2‐oxazoline, 2‐(2‐hydroxyphenyl)‐2‐oxazoline, and 2‐(4‐hydroxyphenyl)‐4,4‐dimethyl‐2‐oxazoline, were studied. Except for 2‐(4‐hydroxyphenyl)‐4,4‐dimethyl‐2‐oxazoline, the reaction carried out in bulk or a solution of highly boiling solvents resulted in the formation of poly(ether amide)s with molecular weights in the range of 103to 104as measured by vapor pressure osmometry and gel permeation chromatography. A mechanism of the growth reaction, including a nucleophilic attack of a phenol group to a 2‐oxazoline ring in the 5‐position, was suggested. The polymerization was accompanied by a side reaction of the amido groups formed by the primary reaction of the 2‐oxazoline ring. This led to branching of the main chain. The thermal properties of the prepared polymers were evaluated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 343–355, 2006
Homo‐ and copolymerization of methyl methacrylate with ethylene by novel Ziegler‐Natta‐Type nickel catalysts based on N,O‐nitro‐substituted chelate ligands
Authors: Carlini Carlo , De Luise Valentina , Martinelli Marco , Galletti Anna Maria Raspolli , Sbrana Glauco 
Published: November 2005

AbstractNew Nickel (II) catalytic systems based on N,O chelate ligands, activated by methylaluminoxane, have been checked in the homopolymerization of methyl methacrylate (MMA) and its copolymerization with ethylene. In particular, the bis(8‐hydroxy‐5‐nitro‐quinolate)nickel(II)/methylaluminoxane system as well as the catalysts obtained by oxidative addition of either 8‐hydroxy‐5‐nitro‐quinoline or 8‐hydroxy‐5,7‐dinitro‐quinoline or 4‐nitro‐2‐(p‐nitrobenzylideneamino)‐phenol to Ni(cod)2, subsequently activated by methylaluminoxane, have been employed. The influence of the reaction parameters on the catalytic activity and the characteristics of the resulting polymers has been investigated. All the obtained poly(methyl methacrylate) samples display a largely prevailing syndiotacticity degree, high molecular weights and a rather large polydispersity. The catalytic systems obtained through the oxidative procedure are able also to give copolymers of MMA with ethylene producing highly linear polyethylenes containing a low amount (1.5–2 mol %) of MMA counits, thus affording materials with improved surface properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 620–633, 2006
Iron‐mediated atom transfer radical polymerization of styrene with tris(3,6‐dioxaheptyl) amine as a ligand
Authors: Wang Gang , Zhu Xinlin , Zhu Jian , Cheng Zhenping 
Published: November 2005

AbstractThe atom transfer radical bulk polymerization of styrene with FeX2 (X = Br or Cl)/tris(3,6‐dioxaheptyl) amine as the catalyst system was successfully implemented at 110 °C. The number‐average molecular weight of the polymers with a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight = 1.2–1.5) increased linearly with the monomer conversion and matched the predicted molecular weight. The polymerization rate, initiation efficiency, and molecular weight distribution were influenced by the selection of the initiator and iron halide. The high functionality of the halide end group in the obtained polymers was confirmed by both 1H NMR and a chain‐extension reaction. Because of its water solubility, the iron complexes could be removed easily from the reaction mixture through the washing of the polymerization mixture with water. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 483–489, 2006
Versatile and controlled synthesis of resorbable star‐shaped polymers using a spirocyclic tin initiator—Reaction optimization and kinetics
Authors: Odelius Karin , Finne Anna , Albertsson Ann‐Christine 
Published: November 2005

AbstractA spirocyclic tin initiator was synthesized from pentaerythritol ethoxylate and dibutyltin oxide and used to polymerize L‐lactide with dichloromethane, chloroform, toluene, and chlorobenzene as solvents. The reactions were performed at different temperatures and it is concluded that neither the temperature nor the solvent affects the molecular weight or the molecular weight distribution of the star‐shaped polymers. The reaction rate was significantly increased by raising the reaction temperature or choosing a solvent with a low dielectric constant. All polymers showed a molecular‐weight distribution below 1.19 and a molecular‐weight determined by the initial monomer to initiator concentration ([M]0/[I]). No induction period was seen for the polymerizations. They were all first order in initiator and the degree of aggregation in toluene at 110 °C was found to be 4/5. The glass transition temperature and the melting temperature of the star‐shaped polymers increase with increasing arm length. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 596–605, 2006
Double hydrophilic block copolymers of sodium(2‐sulfamate‐3‐carboxylate)isoprene and ethylene oxide
Authors: Pispas Stergios 
Published: November 2005

AbstractPoly(sodium(2‐sulfamate‐3‐carboxylate)isoprene)‐b‐poly(ethylene oxide) and poly(ethylene oxide)‐b‐poly(sodium(2‐sulfamate‐1‐carboxylate)isoprene)‐b‐poly(ethylene oxide) double hydrophilic block copolymers were prepared by selective post polymerization reaction of the polyisoprene block, of poly(isoprene‐b‐ethylene oxide) diblocks or poly(ethylene oxide‐b‐isoprene‐b‐ethylene oxide) triblock precursors, with N‐chlorosulfonyl isocyanate. The precursors were synthesized by anionic polymerization high vacuum techniques and had narrow molecular weight distributions and predictable molecular weights and compositions. The resulting double hydrophilic block copolymers were characterized by FTIR and potentiometric titrations in terms of the incorporated functional groups. Their properties in aqueous solutions were studied by viscometry and dynamic light scattering. The latter techniques revealed a complex dilute solution behavior of the novel block copolymers, resulting from the polyelectrolyte character of the functionalized PI block and showing a dependence on solution ionic strength and pH. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 606–613, 2006
Sizing effects on main relaxation process of cyanate ester glass fiber composites using dynamic mechanical and microthermal analyses
Authors: Mallarino S. , Chailan J. F. , Vernet J. L. 
Published: November 2005

AbstractThe influence of sizing/polymer interaction or interphase on dynamic mechanical relaxation properties of cyanate ester composites was investigated by means of dynamic mechanical analysis. The dynamic mechanical behavior of different samples (three types of composites with different sizing and neat resin) was analyzed by using two phenomenological models (TFV and WLF). Related coefficients such as C1, C2, and T∞ (Vogel temperature) were evaluated. Results have shown that these parameters were strongly dependent on sizing state, therefore, on interphase. In addition, the frequency dependence of the molecular relaxation process was well described by the Cole‐Cole plot. These results were confirmed by the sizing extract/resin blend study. Microthermal analysis has shown that partial miscibility existed between resin and sizing extract. Local thermal analyses were carried out by positioning the probe over selected regions: bulk resin and sizing/resin blend. A decrease in resin glass‐transition temperature was observed in the sizing resin blend. The different results have shown that a local plasticization of resin by sizing occurred with crosslink density modification. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 205–214, 2006
Development and initial validation of a family appraisal of caregiving questionnaire for palliative care
Authors: Cooper Brian , Kinsella Glynda J. , Picton Cliff 
Published: November 2005

AbstractThis article describes the derivation and initial psychometric validation of a multi‐dimensional Family Appraisal of Caregiving Questionnaire for Palliative Care (FACQ‐PC). The 25‐item measure consists of four theoretically derived subscales: (i) caregiver strain, (ii) positive caregiving appraisals, (iii) caregiver distress, and (iv) family well‐being. Based on a sample of 160 family caregivers of a relative with cancer receiving palliative care, reliability analyses demonstrated the subscale scores to be internally consistent and factor analysis revealed evidence of factorial validity. Correlations of the four subscales with measures of family functioning, positive and negative affect, and subjective burden provided evidence of convergent and discriminant validity. The FACQ‐PC provides a measure of the family's appraisal of caregiving that can be used in clinical assessment, and has potential utility for evaluating the effectiveness of palliative care interventions. Copyright © 2005 John Wiley & Sons, Ltd.