bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some characteristics of a new and novel melt preparation method for poly(phenylene sulfide)
Authors: Rule M. , Fagerburg D. R. , Watkins J. J. , Lawrence P. B. , Zimmerman R. L. , Cloyd J. D. 
Published: March 2011

AbstractPreparation of poly(phenylene sulfide) (PPS) by the new and novel melt phase reaction of p‐diiodobenzene and sulfur is reported. This new, unique polymerization process can be carried out either entirely in the melt or by a combination of melt and solid state polymerization. Elemental iodine was the reaction by‐product. This process produced very high melt viscosity PPS with degrees of polymerization of several hundred or more. A more Newtonian viscosity over a range of shear rates indicated more linearity of the PPS chains than commercial materials. IR analysis of meta‐ and ortho‐copolymers showed a very high reaction specificity for ipso substitution. Disulfide linkages present in the polymer appeared to be involved in rapid chain equilibration of melt‐mixed samples but did not appear to adversely affect overall stability of the final polymer. Disulfides also appeared to be a reactive species for chain buildup, and an initial mechanism based on this is proposed. Crystallization rates can be tailored from moderate to very fast. Although only PPS has been addressed in this report, extensions to other poly(arylene sulfide)s are obvious.
Studies of the mechanism of formation of poly(1,4‐phenylene sulfide) from copper(I) 4‐bromobenzenethiolate
Authors: Archer Adrian C. , Lovell Peter A. 
Published: March 2011

AbstractThe mechanism of formation of poly(1,4‐phenylene sulfide) (PPS) by solution polymerisation of copper(I) 4‐bromobenzenethiolate (CBT) at 200 °C in quinoline under nitrogen at atmospheric pressure has been investigated. The polymerisation has been monitored as a function of reaction time by electron spin resonance (ESR) spectroscopy and by evaluating the yield and molar mass of the PPS formed. The ESR spectra provided direct evidence for the operation of a mechanism involving single electron transfer processes. The results are discussed in terms of possible mechanisms for polymerisation of CBT, leading to the conclusion that a SRN1‐type mechanism predominates and that a free‐radical mechanism also may be involved.
Synthesis of soluble poly(arylene ether)s with high glass transition temperatures from hindered biphenols
Authors: Kim Whan Gi , Hay Allan S. 
Published: March 2011

AbstractPoly(ether ketone)s and poly(ether sulfone)s have been synthesized from biphenols which contain four to six substituents (phenyl, methyl, chloro) on the biphenyl moiety. Polymers with glass transition temperatures approaching 300 °C are obtained from the most highly substituted biphenols. The polymers are amorphous and very soluble in solvents such as methylene chloride at room temperature
New synthetic functional polyesters
Authors: Chiellini Emo , Solaro Roberto 
Published: March 2011

AbstractAn overview is reported of the work so far performed by us and co‐workers in the preparation of new functional polyesters designed to the fulfilment of structure‐property relationships in novel mesomorphic polymers and in polyhydroxylated polyesters, potentially appealing for their solubility properties, binding capability and reactivity. Polycondensation procedures have been used as based on: 1) Michael‐type addition of a α,ω‐bis hydrogen‐active component (diamines and dithiols) to a component containing two α,ω‐activated double bonds (bisacrylates); 2) reaction of a selectively protected polyol with a diacid chloride; 3) self‐condensation of a selectively protected (polyhydroxy)acid; 4) addition of an epoxide containing protected hydroxyl group to cyclic anhydrides, including also carbon dioxide.
Mechanistic studies on the reverse phase suspension copolymerization of vinyldimethylazlactone and methylenebisacrylamide
Authors: Rasmussen Jerald K. , Hembre Jim I. , Koski Nancy I. , Milbrath Dean S. , Coleman Patrick L. , Stauffer Darlene M. , Walker Margaret M. , Heilmann Steven M. , Krepski Larry R. , Smith Howell K. , Loer Richard J. , Keuren Steven A. Van. , Calubayan Zonia L. , Conway Wilfriede T. , Johnson Warren J. , Rossiter Richard C. , Swenson Donald A. 
Published: March 2011

AbstractThe reverse phase suspension copolymerization of vinyldimethylazlactone (VDM) and methylenebisacrylamide (MBA) has been studied by isolation and analysis of samples over the course of a typical polymerization. Results indicate that MBA is incorporated rapidly to provide a macroporous skeleton. VDM, initially distributed primarily in the organic continuous phase, becomes grafted onto this skeleton at a slower rate upon diffusion into the aqueous disperse phase. The effects of polymerization time and aqueous/organic phase ratio on the development of surface area and porosity, and on protein immobilization have been studied.
Polymerization of exo‐methylene styrenic monomers: Effect of α,α‐cyclization on reactivity and stereoregularity
Authors: Ito Hiroshi , Ueda Mitsuru 
Published: March 2011

Abstractα‐Substituted styrene derivatives are reluctant to undergo radical homopolymerization in general due to steric hindrance. However, α‐acetoxystyrene (ACOST) polymerizes by radical initiation, which is a slow equilibrium process with a ceiling temperature of 47 °C at 1 mol/L of monomer. Cyclic analogs of ACOST such as 4‐methylene‐4H‐1,3‐benzodioxin‐2‐one (MBDOON) and 3‐methylenephthalide (MP) provide a high yield of polymer in a short period of time in solution whereas the radical polymerization of ACOST is slow in bulk. The overall activation energy for radical polymerization of MBDOON with α,α′‐azobis(isobutyronitrile) in N‐methylpyrrolidinone is 75.7 kJ/mol, much smaller than that for ACOST (116 kJ/mol) and even smaller than the value for styrene (100 kJ/mol). The cyclic acetophenone enol ester polymers are heterotactic, which is in contrast with the sydiotactic poly(ACOST). α‐Methyleneindane (MI) undergoes radical homopolymerization in contrast to its acyclic analog, α‐methylstyrene. Anionic and cationic polymerizations of MI are facile. The both radical and anionic poly(MI)s are heterotactic as opposed to syndiotactic poly(α‐methylstyrene). Thus, the steric hindrance in the transition state of propagation is very much reduced by α,α‐cyclization, resulting in increased reactivity and reduced stereoregulation.
The synthesis and reactivity of ω‐(P‐vinylbenzyl ether) macromonomer of poly(2,6‐dimethyl‐1,4‐phenylene ether)
Authors: Percec Virgil , Wang James H. 
Published: March 2011

AbstractThis paper describes the synthesis and reactivity of ω‐(p‐vinylbenzyl ether) macromonomer of poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE‐VBE). The reactivity of PPE‐VBE macromonomer, as determined from the free radical copolymerization of PPE‐VBE with either methyl methacrylate (MMA) or n‐butyl methacrylate (BMA), is influenced by the molecular weight of PPE‐VBE, by the concentration of the macromonomer or total comonomers, and by the nature of the polymerization solvent. The dependence of the reactivity on the molecular weight of the PPE‐VBE macromonomer was interpreted based on the kinetic excluded volume theory and by a micelle formation model. This paper demonstrates that the reactivity of PPE‐VBE macromonomers can be explained by the micelle formation model alone. Thus the influence of both the concentration and the nature of the polymerization solvent on the reactivity was satisfactorily interpreted based on this micelle model. The formation of micelles was caused by the difference between the solubility of the PPE‐VBE macromonomer segment and the homopolymer of MMA or BMA which comprises the propagating chains in the polymerization solvent. The analysis of all the reactivity data of PPE‐VBE macromonomers can now be correlated with respect to the extents of the micelle formation as characterized by the partition coefficient, k. The value of k represents the concentration difference of both the PPE‐VBE macromonomer and its comonomer between the bulk of the free solvent and around the growing chain. The determined reactivity ratio is a product of the real reactivity ratio and the partition coefficient.
Multiple phases of gels and biological implications
Authors: Tanaka Toyoichi , Annaka Masahiko 
Published: March 2011

AbstractSynthetic polymer gels are known to exist in two phases, swollen and collapsed. Volume transition occurs between the phases either continuously or discontinuously. More than two phases are found in gels consisting of copolymers of randomly distributed positively and negatively charged groups. They are characterized by distinct degrees of swelling; the gel can take one of a set of swelling values, but none of the intermediate values. The number of phases depends on the composition of positively and negatively charged monomers, and decreases from a maximum of seven at a particular composition to one at pure cationic or anionic gel compositions. In these gels, polymer segments interact with each other through attractive or repulsive electrostatic interactions and through hydrogen bonding. The combination of these forces appears to result in multiple phases. The multiple phases seem to have important biological implications. The finding demonstrates that a polymer system can take a stable state other than swollen and collapsed phases, which was known only for proteins. Studying them may lead us to the principle with which linear chains of amino acids form unique and stable structures, a question of protein folding, and how they create marvellous functions such as molecular recognition, catalysis, and motion.
Surface state of polymers investigated by low temperature plasmas
Authors: Yasuda H. 
Published: March 2011

AbstractThe concept of the equilibration of surface states in contact is examined by the measurement of the contact electrification and separation currents, and applied to the investigation of the evolution of the surface state due to a change of contacting medium (from air to water) by following the surface concentration (by ESCA) of labeling atoms (F), which were incorporated by a low temperature plasma (of CF4), as a function of water immersion time and temperature. The kinetic rate constants for such changes of surface configuration follow a typical Arrhenius plot, which shows a conspicuous break at a surface transition temperature Ts. Ts's observed against air coincide with the glass transition temperature Tg's of the corresponding polymers. Ts's observed against water, however, are found to be independent of Tg and consistently near 15 °C, which coincides with the major Drost‐Hansen temperature of vicinal water. The surface state of water is the dominant factor in this case.
Design of soluble conjugates of biodegradable polymeric carriers and adriamycin
Authors: Hoes C. J. T. , Boon P. J. , Kaspersen F. , Bos E. S. , Feijen J. 
Published: March 2011

AbstractTo improve the therapeutic index of the cytostatic drug adriamycin (ADR), conjugates of ADR with poly(α‐L‐glutamic acid) (PGA), poly[N5‐(2‐hydroxyethyl)‐L‐glutamine] (PHEG) and conjugates of polymer‐bound ADR and a human monoclonal antibody directed against colon tumour‐associated antigens (IgM 16.88) have been prepared. Amide‐bound conjugates of PGA and ADR were designed as macromolecular prodrugs for drug release mediated by the tumour cell‐associated enzyme γ‐glutamyl transferase but were inactive in vitro. PGA‐peptide spacer‐ADR conjugates have been designed to effect drug release mediated by lysosomal enzymes after pinocytic entry of the conjugate in tumour cells. These conjugates were only weakly active in vitro against L1210 leukemia and B16 melanoma cells even with a lysosomally cleavable GlyGlyGlyLeu spacer. In contrast, the latter conjugate inhibited the growth of L1210 cells implanted intraperitoneally in mice to a significant extent. Polymeric ADR conjugates were studied with respect to their association behaviour in solution, their interaction with cells and their immunogenicity in mice. The biodistribution of conjugates of IgM 16.88 and PGA or PHEG in mice indicates that both polymers are useful as drug carrier in immunoconjugates. A multistep preparation of ADR bound to a conjugate of PHEG and IgM 16.88 has been developed with the aim of selective drug release in the acidic environment of the tumour. The immunoreactivity of IgM‐PHEG‐ADR with colon tumour antigen was retained to the extent of 70 % relative to IgM. PHEG‐bound ADR shows an effective release of ADR at a pH of 6.0 as shown by incubation in buffer and by inhibition of the growth of HT‐29 colon tumour cells in vitro. The data are consistent with the acid‐labile nature of the drug‐carrier bond.
Use of poly(ortho esters) in the controlled release of therapeutic agents
Authors: Heller J. , Roskos K. V. , Duncan R. 
Published: March 2011

AbstractPoly(ortho esters) have been under development since 1970 and are the first polymer system that has been specifically designed for drug delivery applications. At this time, three distinctly different families of polymers have been described. One family is prepared by a transesterification reaction between diethoxytetrahydrofuran and a diol, another family is prepared by the reaction of polyols with diketene acetals and the third family is prepared by a transesterification reaction between a triol and an alkyl orthoacetate. The use of these polymers in drug delivery applications is illustrated with 5‐fluorouracil devices used in the treatment of human colorectal cancer xenografted in nude mice and with the delayed release of lysozyme, used as a model protein.
Controlled release of macromolecules from electrical and chemical stimuli‐sensitive hydrogels
Authors: Bae You Han , Kwon Ick Chan , Pai Chaul Min , Kim Sung Wan 
Published: March 2011

AbstractThe controlled release of drugs from hydrogels has progressed from systems that merely swell in water, to novel hydrogels with specific chemical properties which respond to various stimuli to facilitate drug release.Specifically, electro‐erodible hydrogels are synthesized by polymer chain complexation and precipitation through hydrogen or ionic bonds. The surface of the solid polymer device is eroded or dissolved in response to an applied electric current. When a constant electric current is applied, zero‐order release of entrapped drug is achieved. However, if a step‐function current is applied, the drug can be released in an on‐off pattern.Concanavalin A microspheres, a protein gel, has been synthesized to release insulin in response to glucose concentrations. This microsphere gel has specific binding affinity for glucose and mannose. A synthesized glycosylated insulin was loaded on the microspheres and then released in response to glucose concentrations via a competitive binding exchange mechanism.
Polymer blends and alloys
Authors: Barlow J. W. 
Published: March 2011

AbstractThe state of thermodynamic miscibility of a polymer blend and its resulting phase behavior and mechanical properties is largely determined by the balance between enthalpic and entropic contributions to the free energy of mixing. Recent applications of this thermodynamic consideration are reviewed for a variety of binary and ternary blends of homopolymers and copolymers. Recent advances in predicting polymer blend miscibility and Lower Critical Solution Temperature behavior from liquid heats of mixing data, through use of a modified Guggenheim quasichemical model combined with the Sanchez lattice fluid model are discussed. Qualitative application of partial miscibility ideas to interfacial adhesion in multiphase polymer blends is also presented.
Processing‐property relationships for pet sheet composites
Authors: Bigg D. M. 
Published: March 2011

AbstractGlass mat thermoplastics were produced with PET by both melt impregnation and slurry deposition. While both processes resulted in strong, impact resistant composites, the melt impregnated composites, which had longer fibers and higher fiber concentrations than the slurry formed composites, had the greater properties. An in‐mold coating based on reversible crosslinked isocyanate copolymers produced a durable Class “A” finish in laboratory experiments.
Design and preparation of novel particulate and continuous polymeric macroporous media for the separation of biological and synthetic molecules
Authors: Fréchet Jean M. J. 
Published: March 2011

AbstractNovel approaches to macroporous polymeric separation media with enhanced pore size distributions, controlled surface chemistries, and excellent separation properties have been explored. In the first of these approaches, size‐monodisperse spherical polymeric particles containing both large and small pores are prepared with the use of a variety of polymeric porogens. The choice of polymeric porogen as well as its concentration greatly affects the pore size and pore size distribution of the final beads. The polymer beads obtained by this technique have been tested in size exclusion chromatography and in the separation of proteins in reversed‐phase mode. Techniques that allow the specific functionalization of pores according to their sizes have been developed. Thus, the surfaces of the large pores of the monodisperse particles can be made hydrophilic or chiral while the smaller pores remain hydrophobic or achiral. Similarly, a novel polymeric separation medium based on a continuous polymer rod incorporating macropores has been prepared by an in situ polymerization within the confines of the tube of a chromatographic column. For example, non‐particulate continuous polymer rods with flow‐through pores as well as separation pores have been prepared from styrene and divinylbenzene and used in the very fast (30 s) separation of proteins by reversed‐phase chromatography. Alternatively, continuous rods prepared from glycidyl methacrylate and ethylene dimethacrylate can be transformed into materials that are suitable for ion exchange or other chromatographic modes. A characteristic of the continuous polymeric rod media is their permeability which allows the mobile phase to flow through the medium without causing a high back‐pressure. The continuous rod‐shaped media can also be modified in pore size‐selective fashion to introduce different chemistries in the large and the small pores. These new media are advantageous as they are extremely easy to prepare, durable, require no packing, and can be used for a variety of separations.
Pervaporation: Fundamentals and practice
Authors: Néel J. 
Published: March 2011

AbstractMembranes made of various hydrophilic polymers can be efficiently used to dehydrate organic solvents by pervaporation. In that process, mass transport across the membrane involves three successive steps: I. Upstream partitioning of the feed components between the circulating liquid charge and the swollen upstream layer of the membrane; II. Diffusion of the penetrants through the polymer barrier within which swelling decreases from the upstream to the downstream side; III. Desorption taking place at the downstream surface of the permselective film.The selectivity of the most effective barriers results from the cumulative contributions provided by upstream partitioning (preferential solvation of the polymeric material) and by diffusion through the unswollen downstream layer of the membrane working under low downstream pressure. The origin of the latter contribution will be comparatively discussed in the case of ion exchange and non‐ionogenic hydrophilic film‐forming polymers (poly(vinyl alcohol), for instance) which are now used to manufacture the industrial pervaporation membranes designed for dehydration of organic solvents.On the other hand, it cannot be denied that symmetrical efforts aiming at developing efficient organophilic membranes suitable for extracting volatile organics contained in aqueous charges have been only partly successful.
Composite membranes for water purification by low pressure reverse osmosis and for dehydration of aqueous ethanol by pervaporation
Authors: Ohya Haruhiko , Choi Ho Sang , Hino Takeshi , Hara Tatsuya , Ohsawa Futoshi , Shibata Masayuki , Negishi Yoichi 
Published: March 2011

AbstractThis work was carried out to find a possibility of removing organic precursors responsible for the formation of volatile halogenated hydrocarbons (VHH) from drinking water by low‐pressure reverseosmosis composite membranes and to find another possibility of removing VHH by reverse osmosis. Retention potential for trihalomethane precursors in water from lake Izu falls in the range of 87 to 97%. As for the self‐made NS‐300 and 301 membranes, flux stays almost constant until the ratio of isophthaloyl chloride (IPC) to trimesoyl chloride (TMC) exceeds 50%, and then decreases and the retention takes a maximum value at 50% of the ratio. Using FT‐30 membrane, reverse osmosis retention of chloroform decreased from 80% at the feed concentration of 250ppm to 40% at 25ppm. Two types of composite membranes made of a thin poly(vinyl alcohol) (PVA) on poly(acrylonitrile) (PAN) support and a thin poly(acrylic acid) (PAA) on polysulfone (PSf) were fabricated to find out the effect of molecular weight cut‐off of the support on the characteristics of separation of water and ethanol by pervaporation. It was found that there is optimum molecular weight cut‐off of the support regarding the separation.
Effects of the multiphase nature in ABS and related systems on thermal oxidative degradation and stabilization
Authors: Kulich Donald M. , Wolkowicz Michael D. , Wozny John C. 
Published: March 2011

AbstractMultiphase polymer blends contain compositionally distinct polymeric domains which can differ significantly in oxidative stability. Because the solubility parameters of the polymeric components will also differ, stabilizer concentrations in each phase may not be equal. This morphological aspect to the oxidation process was investigated by examining the oxidative behavior of the phase components in ABS. It is shown that the effects of rubber phase level on the oxidation process can be interpreted in terms of stabilizer partitioning. Data utilizing microscopy techniques to assess stabilizer concentrations in the rubber and thermoplastic phases in ABS and related model rubber modified systems are presented. Partitioning behavior is shown to depend on both additive and polymer composition and correlate to calculated solubility parameters.
Comonotonic proper scoring rules to measure ambiguity and subjective beliefs
Authors: Kothiyal Amit , Spinu Vitalie , Wakker Peter P. 
Published: March 2011

AbstractProper scoring rules serve to measure subjective degrees of belief. Traditional proper scoring rules are based on the assumption of expected value maximization. There are, however, many deviations from expected value, primarily due to risk aversion. Correcting techniques have been proposed in the literature for deviations due to nonlinear utility. These techniques still assumed expected utility maximization. More recently, corrections for deviations from expected utility have been proposed. The latter concerned, however, only the quadratic scoring rule, and could handle only half of the domain of subjective beliefs. Further, beliefs close to 0.5 could not be discriminated. This paper generalizes the correcting techniques to all bounded binary proper scoring rules, covers the whole domain of beliefs and, in particular, can discriminate between all degrees of belief. Thus, we fully extend the properness requirement (in the sense of identifying all degrees of subjective beliefs) to virtually all models that deviate from expected value. Copyright © 2011 John Wiley & Sons, Ltd.