bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of primary hydroxyl functional poly(propylene oxide) of controlled molecular weight by direct polymerization
Authors: Yoo Y. , McGrath J. E.
Published: March 2011

Utilization of aluminiumporphyrin catalyst/initiator structures was demonstrated to be highly capable of producing controlled molecular weight/narrow molecular weight distributions and in several cases good functionalities. Further extension of our studies to systems wherein benzyl alcohol is first reacted with the aluminiumporphyrin initiator have been conducted. The resulting aluminiumporphyrin benzyl alcohol alkoxide is capable of initiating propylene oxide in a controlled manner. After work‐up, the resulting material can be subjected to hydrogenolysis and this regenerates a very desirable primary hydroxyl group at the initiating site. Moreover, the hydrogenolysis disrupts the aromatic character of the porphyrin species and greatly diminishes any residual color which is usually attributed to the initiator fragments. Difunctional species can be generated by a coupling reaction with terephthaloyl chloride and star‐shaped macromolecules are possible via coupling with bisphenol‐A diglycidyl ether. Synthesis of these materials and characterization is discussed herein. In particular, fluorine‐19 NMR derivatization has been quite effective at distinguishing between the derived primary hydroxyl species and the usual secondary hydroxyl systems.
Development of an advanced process for manufacturing trioxane ethylene oxide copolymer
Authors: Masamoto J. , Iwaisako T. , Yoshida K. , Matsuzaki K. , Kagawa K. , Nagahara H.
Published: March 2011

An advanced process for manufacturing trioxane ethylene oxide copolymer has been developed.

First, a new technology for production of highly concentrated aqueous formaldehyde was developed by oxidizing methylal. Whereas oxidation of methanol yields 1 mol of water per mole of formaldehyde, methylal oxidation produces only 1 mol of water for every 3 mol of formaldehyde.

Thus the output from methylal oxidation is more than 70% formaldehyde, compared with 55% from methanol.

The relatively high formaldehyde concentration enhances formation of trioxane.

Purified trioxane is copolymerized with ethylene oxide in the presence of an end‐capping agent such as methylal producing an end‐capped polymer with high thermal stability.

Two new intermediates in the initiation reaction of the copolymerization, 1,3,5,7‐tetraoxacyclononane (TOCN) and 1,3,5,7,10‐ pentaoxacyclododecane(POCD) were isolated and a new initiation mechanism was proposed.

A commercial plant employing this process with a capacity of 15 000 tons/year is operating well.
Copolymers of trioxane with 2,3‐epoxypropyl acrylate: Thermally stable polyacetal copolymer networks
Authors: Pesce‐Rodriguez R. A. , Yang N. L. , Auerbach A. , Paul J.
Published: March 2011

Cationic copolymerization of trioxane with 2,3‐epoxypropyl acrylate gives thermally stable crosslinked copolymer in high yield. The structure of the crosslinked copolymer has been characterized by solid state 13C NMR spectroscopy. The comonomer acrylate group functions as a crosslinking agent in the polymerization process as well as a bound stabilizer in the resulting network. The crystallinity of the copolymer is unusually low compared to copolymers with comparable incorporation levels of the comonomers. The crosslinked acetal copolymer has the potential for further modification through its pendant acrylate group.
Anionic synthesis and characterization of poly(styrene‐block‐ethylene oxide) polymers with fluorescent probes at the block junctions
Authors: Quirk Roderic P. , Kim Jungahn , Rodrigues Klein , Mattice Wayne L.
Published: March 2011

Fluorescent‐labeling reactions of poly(styryl)lithium were effected with either 2‐(1‐phenylethenyl)naphthalene or 1‐phenyl‐1‐(1‐pyrenyl)ethylene followed by functionalization of the resulting 1‐phenyl‐1‐arylalkyllithium species with ethylene oxide. The resulting polymeric alkoxylithiums were used to initiate the anionic polymerization of ethylene oxide in a mixture of benzene and dimethyl sulfoxide. A series of block copolymers [Mn(PS)=5.1 × 103 g/mol); Mw/Mn=1.02] with 20–40wt% ethylene oxide were characterized by thin‐layer chromatography, size exclusion chromatography, 1H NMR and quantitative UV‐visible spectroscopy. Fluorescence measurements on the block copolymers were carried out in 1,2‐dichloroethane with varying amounts of methanol. No excimer formation was detected for either naphthalene‐ or pyrene‐labeled block copolymers. Energy transfer from the naphthalene‐ to the pyrene‐labeled polymers was observed at about 80 vol.% methanol. These results are discussed in relationship to the interfacial boundary distances in the block copolymer micelles as deduced by application of the “Spectroscopic Ruler”.
Activated monomer polymerization of oxiranes. Micro‐structure of polymers vs. kinetics and thermodynamics of propagation
Authors: Bednarek Melania , Biedron Tadeusz , Kubisa Przemyslaw , Penczek Stanislaw
Published: March 2011

In the Activated Monomer (AM) polymerization of substituted oxiranes (propylene oxide ‐ PO, epichlorohydrin ‐ ECH), the microstructure of the chain is governed exclusively by the kinetics of the propagation step. In the copolymerization of ECH with 5‐membered (tetrahydrofuran ‐ THF) or 6‐membered (1,4‐dioxane ‐ Diox) cyclic ethers, the distribution of comonomer units depends on both kinetic and thermodynamic factor, which allows preparation of oligodiols having regular (i.e. alternating) distribution of comonomer units in the chain.
Ring‐opening polymerization of oxetanes by cationic initiators: Polymerization of 3‐azidomethyl‐ 3 ‐ methyloxetane with bis(chlorodimethylsilyl)benzene/silver hexafluoroantimonate initiating system
Authors: Talukder M. A. H.
Published: March 2011

Quasi‐living cationic polymerization of 3‐azidomethyl‐3‐methyloxetane (AMMO) was achieved with a bis(chlorodimethylsilyl)benzene/silver hexafluoroantimonate (BSB/AgSbF6) initiating system in methylene chloride at −78°C. The average molecular weight (Mn) increased linearly with an increasing monomer/ initiator ([M]/[I]) ratio and a linear Mn vs. [M]/[I] ratio plot passes through the origin. Mn's observed were higher than the calculated value. This indicates the initial loss of initiator or slow initiation during the polymerization of AMMO with BSB/AgSbF6 initiating system, or the combination of both. Theoretically, in a system where the initiation is slower than the propagation, a diblock copolymer will be formed. Similarly, impurities, such as water, will cause chain transfer to the propagating chains during polymerization and form a homopolymer and a diblock copolymer in addition to the desired triblock copolymer. In short, a perfect triblock copolymer will be formed for a difunctional cationic initiator when the system is pure and dry and the initiation of polymerization is faster than the propagation.
Novel synthetic approaches to poly(ε‐caprolactam)‐based materials
Authors: Russo Saverio , Biagini Emilio , Bonta Giorgio
Published: March 2011

Our study has been focused on the fast anionic polymerization of ϵ‐caprolactam (CL) under isothermal conditions, both in bulk and in suspension, in the temperature range between 150 and 200°C.

A careful choice of the reaction parameters (type and concentration of activator, polymerization temperature and rate, cooling rate after polymerization) enabled us to find experimental conditions suitable for minimizing the extent of side reactions and, consequently, the concentration of UV‐absorbing structures incorporated in the poly(ϵ‐caprolactam) (PCL) chain. In terms of structural regularity, the resultant PCL compares favorably to the corresponding polyamide synthesized by the hydrolytic process. Moreover, extension of this approach to the anionic polymerization of CL in suspension allowed us to obtain particulated PCL, characterized by controlled size and surface porosity. Several PCL‐based materials, formed by seeded suspension polymerization, have been obtained. Potentials of this new synthetic approach are outlined.
Model polyisoprenes with associating end‐groups
Authors: Hadjichristidis Nikos
Published: March 2011

A series of narrow distribution ω‐functionalized linear polyisoprenes were prepared by converting the tertiary amine group of polyisoprene ‐ obtained by anionic polymerization of isoprene with 3‐(dimethylamino)propyl lithium ‐ to the highly polar sulfo‐zwitterion group by treatment with cyclopropane sultone. The dilute solution properties of these polymers were mainly examined in cyclohexane and cyclohexane/1‐heptanol mixtures. In cyclohexane the sulfo‐zwitterion polymers were highly aggregated. The degree of association generally decreases with increasing base chain length, due to excluded volume repulsions of the polymeric tails, except at very low molecular weights (2 400–4 800) where the different microstructure of these polymers may play a role. Depending on the molecular weight of the linear precursor, the aggregates may resemble star polymers or may exhibit a more extended core morphology. These findings, regarding the shape of the aggregates, are also supported by melt viscosity mesurements and x‐ray scattering studies.
Synthesis, structure and properties of a helical nylon‐3 derivative
Authors: Muñoz‐Guerra S.
Published: March 2011

A review of the polyamide poly(α‐isobutyl‐L‐aspartate), embracing synthesis, crystal structure and properties, is reported. The interest in this nylon‐3 derivative arises from its ability to adopt conformations similar to the characteristic α‐helix of polypeptides. Two different synthetic approaches, both of them starting from L‐aspartic acid, have been followed for the preparation of this polyamide. Poly‐condensation in solution of α‐isobutyl‐L‐aspartate pentachlorophenyl ester yielded polymers with molecular weights up to near 80 000. About six times higher values were obtained by anionic polymerization of β‐lactam of α‐isobutyl‐L‐aspartate. Highly regular chains were attained in both cases. Two crystalline forms, hexagonal and tetragonal, made of helices with 3.25 and 4 residues per turn, respectively, were characterized by X‐rays and electron microscopy. Transitions between these two forms in the solid state were induced by heating, whereas a helix‐coil conversion promoted by acids was found to take place in solution. Liquid crystal properties have been observed for solutions of this polymer in helicogenic solvents, and films with cholesteric structure were spontaneously generated from them by casting. On the contrary, uniaxially oriented films could be obtained when cast under the effect of an electric field. A shear piezoelectric response of about 12–13 pC/N was measured for these films.
Mechanical aspects of polymer blending
Authors: Kausch H.H.
Published: March 2011

“Improving through mixing” is a fundamental human concept; as applied to polymers, there are thermodynamic, processing related and mechanical obstacles. In this paper some mechanical consequences of structural heterogeneity on a molecular and microscopic level are discussed.

The second aspect to be treated is that of the molecular mechanisms contributing to deformation and fracture, especially void formation, crazing, and shearbanding. To develop these ideas, reference to two systems will be made, a core‐shell particle modified polyamide and an epoxy resin.
Functional polypropylene blend compatibilizers
Authors: Mülhaupt Rolf , Duschek Thomas , Rieger Bernhard
Published: March 2011

Solid phase dispersants, often referred to as blend compatibilizers, are the key components of high‐value‐in‐use polypropylene blends with unusual property combinations. In multiphase polypropylene blends, functional blend compatibilizers enhance the dispersion of incompatible polymeric blend components, in particular of polar polymers, fibers or fillers, and improve the interfacial adhesion between polymer matrix and dispersed phases. Some of the major synthetic routes to functional polypropylene blend compatibilizers are discussed. A novel range of monofunctional polypropylenes containing a variety of functional endgroups, e.g., anhydrides, esters, amines, carboxylic acids, silanes, boranes, alcohols, and thiols, has been derived from mono‐olefin‐terminated polypropylenes. These olefinic polypropylene intermediates have been prepared with soluble metallocene catalysts which give excellent control of polypropylene molecular weight, molecular weight distribution, microstructure, and olefinic endgroups. Thiol‐terminated isotactic polypropylenes have been used as polymeric chain transfer agents in styrene and styrene/acrylonitrile polymerization to form novel polypropylene‐block‐polystyrene and polypropylene‐block‐poly(styrene‐co‐acrylonitrile) block copolymers. In the case of poly(styrene‐co‐acrylonitrile) blends with polypropylene morphological studies demonstrate the efficiency of propylene block copolymer blend compatibilizers.
Stereospecific polymerizations with metallocene catalysts: Products and technological aspects
Authors: Antberg M. , Dolle V. , Haftka S. , Rohrmann J. , Spaleck W. , Winter A. , Zimmermann H.J.
Published: March 2011

Polypropylene homopolymers made by three different stereorigid metallocene catalysts (two isospecific, one syndiospecific) are compared with each other and with commercial samples made by a heterogeneous catalyst. The comparison includes mechanical properties, DSC‐, 13‐C NMR‐ and WAXS‐data. The correlation between microscopic data and macroscopic properties is discussed.

A novel particle‐forming process in propylene bulk polymerization with stereorigid metallocene catalysts is demonstrated and discussed.
Molecular arrangements and conformations of chain molecules near impenetrable surfaces
Authors: Vacatello Michele , Yoon Do Y.
Published: March 2011

The Monte Carlo method has been used to model liquids of chain molecules confined between two impenetrable surfaces (walls). Two kinds of chains have been simulated in two separate calculations: short n‐alkane (n‐tridecane) chains represented at the atomic level in the first case and long polymer chains represented as necklaces of beads in the second case. Molecules located far from the walls are in remarkable agreement with ideal unperturbed chains in both calculations. The shapes and orientations of chain segments located near the walls are substancially different from those in the bulk. Starting from the walls, n‐tridecane exhibit progressively less dense and less ordered segmental layers of ca. 0.4 nm thickness, with most of the units in the first segmental layer belonging to nearly two‐dimensional chains. Long chains with center of mass close to the walls assume open, practically two‐dimensional conformations comprised mainly of surface trains and loops. The interface corresponds then to a region where the conformations of the chains evolve from these nearly two‐dimensional structures near the walls to the unperturbed, three‐dimensional Gaussian conformations in the bulk.
Polymer interfaces and ultrathin films characterized by optical evanescent wave techniques
Authors: Knoll Wolfgang , Hickel Werner , Sawodny Michael , Stumpe Joachim , Schmitt Franz‐Josef , Knobloch Harald
Published: March 2011

Polymer surfaces and ultrathin films are characterized by novel optical techniques based on evanescent waves. We first describe photo‐ablation studies with polysilane films investigated by surface plasmon microscopy, a technique which is particularly well‐suited for ultrathin samples. Thicker films that are homogeneous enough to carry optical waveguide modes can be characterized with high lateral resolution by the recently developed waveguide microscopy. The next example concerns the application of surface plasmon microscopes to the investigation of a biopolymer adsorption from an aqueous phase to a functionalized membrane interface: We present a quantitative kinetic analysis of the specific recognition reaction between streptavidin and biotin. Finally, we report on surface plasmon field‐enhanced Raman‐spectroscopic and imaging investigations of ultrathin Langmuir‐Blodgett‐Kuhn‐layers of cadmium arachidate.
Cationic polymerization of alkenes and heterocyclics. More similarities than differences
Authors: Matyjaszewski Krzysztof
Published: March 2011

The cationic polymerization of alkenes and heterocyclics is compared in a critical way. After a brief introduction to the polymerizability of various monomers and efficiency of initiators, various active sites involved in propagation are discussed. They include covalent species, onium ions and carbenium ions of different degrees of association. Proportions and reactivities of these active sites are discussed for different monomers. Structure‐reactivity correlations for both systems are described. The construction of a general unifying theory of cationic polymerization is attempted, with peculiarities typical for each system pointed out.
Synthesis and polymerization of imines and azadienes: New polymerizable monomers
Authors: Hall H. K.
Published: March 2011

We have begun an exploratory program on the synthesis of imines and azadienes (α, β‐unsaturated imines) to find the best structures for monomers which will form high polymers. Imines display a very wide range of stability from existing only in the gas phase or at liquid nitrogen temperatures to complete stability depending on the substituents on the nitrogen and carbon. Among the simple imines, benzylidene cyanamide gave oligomers of DP‐8 with either free radical or anionic initiators. Tricyanomethanimine, C4N4, could only be obtained in solution and spontaneously homopolymerized and copolymerized with paramethoxystyrene. Among the l‐azabutadienes, 1‐phenyl‐l‐aza‐1,3‐butadiene polymerized to reasonably high molecular weight polymers using anionic initiators. Cationic initiation was less successful and free radical initiators gave no polymers. Similarly, N‐carboethoxy‐3‐methyl‐l‐aza‐l,3‐butadiene gave moderate yields of polymers with modest molecular weights. Our conclusions at this stage of our investigations are that simple imines are a quite restricted class of monomers. On the other hand, owing to ease of synthesis and ability to polymerize the l‐azadienes represent a new class of reactive monomers.
Palladium catalyzed routes to polyimides
Authors: Perry Robert J. , Turner S. Richard
Published: March 2011

Several polyimides were prepared by the palladium catalyzed carbonylation and condensation of tetraiodoaromatic compounds and diamines. This new reaction for preparing polyimides was found in model compound work to be an efficient, high yield route to cyclic imides. Since fully imidized groups are formed during the polymerization, it was necessary to limit the diamines to those that would impart solubility to the polymer. In contrast to the model compound work, the polymerization reaction yielded an appreciable concentration of amide functional groups due to incomplete cyclization and/or branching reactions. Mixed haloaromatic compounds were also examined as monomers in this reaction. Model reactions between o‐bromoiodobenzene and aniline indicated that amide formation through the iodide was preferred and that imide formation through the bromide occurred later. Extension of this chemistry to dibromodiiodobenzene and diaminophenylindane DPI, gave low molecular weight oligomers at low phosphine levels and branched material at higher levels.
Aromatic biphenylene polymers: Synthesis via nickel coupling of aryl dichlorides
Authors: Kwiatkowski G. T. , Colon I. , El‐Hibri M. J. , Matzner M.
Published: March 2011

A new method for the formation of high molecular weight aromatic biphenylene polymers via the nickel coupling of aromatic dichlorides is described. Aromatic biphenylene polymers display a number of highly attractive features which are discussed. The novel reaction is performed in a dry aprotic solvent (e.g., in DMAC) using catalytic amounts of zero‐valent nickel, triphenylphosphine ligand and excess zinc metal. The reactions must be performed under an inert atmosphere and in the absence of water. In order to obtain high polymer, one must use low amounts of nickel, high triphenylphosphine/nickel ratios, excess zinc metal, and moderate temperatures (70 °C). Variables such as the choice of ligand or co‐ligand, salt addition, ligand and zinc concentration, etc … allow for optimization of the reaction efficiency. The method is general and allows for the preparation of an almost infinite variety of polymers. Polymerizations and copolymerizations involving aryl dichlorides possessing dissimilar chloro‐moieties are particularly intriguing since a number of sequence distributions are possible. The two prerequisites for a successful preparation of high molecular weight product are solubility of the monomer, and more particularly of the obtained polymer, in the reaction medium; and the necessity that any functional groups present in the monomer(s) (and in the resulting polymer) be inert toward the zinc/nickel system.

Critical features of the polymerization mechanism are also reviewed.
A germylene and stannylene as polymerization comonomer and initiator
Authors: Kobayashi Shiro , Iwata Satoru , Abe Mitsunori , Yajima Kazuo , Kim Hyun Joon , Shoda Shin‐ichiro
Published: March 2011

Novel polymerization reactions utilizing a divalent germanium or tin species, germylene or stannylene, have been developed. Copolymers having a germanium(IV) or tin(IV) unit in the main chain have been prepared by the reaction of oxidant monomers (Mox) and reductant monomers (Mred, germylene or stannylene). Oxidant monomers employed are p‐benzoquinones, N‐phenyl‐p‐quinoneimines, cyclic α, β‐ unsaturated ketones, and cyclic sulfides. A new aspect of these divalent chemical species as an initiator for vinyl monomers has also been investigated.
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

Preparation 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

The 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

Poly(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

An 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

The 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

α‐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

This 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

Synthetic 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

The 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

To 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

Poly(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

The 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

The 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

Glass 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

Novel 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

Membranes 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

This 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

Multiphase 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

Proper 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.
Coordination of fingertip forces during precision grip in premanifest Huntington's disease
Authors: Rao Ashwini K. , Gordon Andrew M. , Marder Karen S.
Published: March 2011

Precision grip control is important for accurate object manipulation and requires coordination between horizontal (grip) and vertical (load) fingertip forces. Manifest Huntington's disease (HD) subjects demonstrate excessive and highly variable grip force and delayed coordination between grip and load forces. Because the onset of these impairments is unknown, we examined precision grip control in premanifest HD (pre‐HD) subjects. Fifteen pre‐HD and 15 age‐ and sex‐matched controls performed the precision grip task in a seated position. Subjects grasped and lifted an object instrumented with a force transducer that measured horizontal grip and vertical load forces. Outcomes were preload time, loading time, maximum grip force, mean static grip force, and variability for all measures. We compared outcomes across groups and correlated grip measures with the Unified Huntington's Disease Rating Scale and predicted age of onset. Variability of maximum grip force (P < .0001) and variability of static grip force (P < .00001) were higher for pre‐HD subjects. Preload time (P < .007) and variability of preload time (P < .006) were higher in pre‐HD subjects. No differences were seen in loading time across groups. Variability of static grip force (r2 = 0.23) and variability of preload time (r2 = 0.59) increased with predicted onset and were correlated with tests of cognitive function. Our results indicate that pre‐HD patients have poor regulation of the transition between reach and grasp and higher variability in force application and temporal coordination during the precision grip task. Force and temporal variability may be good markers of disease severity because they were correlated with predicted onset of disease. © 2011 Movement Disorder Society
Single scan PC‐MRI by alternating the velocity encoding gradient polarity between phase encoding steps
Authors: Jonathan Bremer , Liu Qingwei , Steele Brooke , Lucas Carol , Dennis Robert , Lin Weili
Published: March 2011

The purpose of this study was to develop a faster approach to phase contrast magnetic resonance imaging. This article proposes a phase contrast imaging scheme called single scan phase contrast in which the polarity of the velocity‐encoding gradient is alternated between phase encoding steps. In single scan phase contrast, ghost images due to moving spins form. The signal intensity of the ghost images is modulated by the sine of the motion‐induce phase shift. Prior to image acquisition, the region of interest containing moving spins is identified, and the field of view is configured so to avoid overlap between the object in the image and the ghost image(s) due to motion in the region of interest. The image values of the region of interest and the ghost image are used to quantify velocity. At best, single scan phase contrast reduces the total acquisition time by a factor of two when compared to phase contrast. In this study, single scan phase contrast is validated against phase contrast in phantom and in vivo. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.