bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen diffusion in poly(dimethyl siloxane) using fluorescence quenching. I. Measurement technique and analysis
Authors: Cox M. E. , Dunn B.
Published: April 2003

The transport properties of oxygen in poly(dimethyl siloxane) have been measured using the method of quenching of fluorescence. This paper discusses the uniqueness of this method and its use in measuring the diffusion coefficient of oxygen in unfilled PDMS. The results show (1) a large value for the diffusion coefficient of oxygen in pure PDMS at 25°C, D = 3.55 × 10−5 cm2/s, (2) a low value of the acitivation energy, ED = 4.77 kcal/mole, which was not temperature dependent in the ranges evaluated, and (3) a large value of the preexponential term, D0 = 0.115 cm2/s. The diffusion coefficient was found to be independent of both the oxygen concentration and fluorophor concentration in the pressure and temperature ranges used in these experiments. The import of these experiments lies in their application to a unique biomedical oxygen sensor which is fast, sensitive, and does not consume oxygen.
Mechanism of plasma‐initiated polymerization: Concerning the nature of solvent effects on the lifelike polymerization of water‐soluble vinyl monomers
Authors: Kuzuya Masayuki , Kawaguchi Tohru , Yanagihara Yasukichi , Nakai Sachihiko , Okuda Takachiyo
Published: April 2003

To provide a satisfactory basic understanding of the solvent effect of plasma‐initiated polymerization, we have carried out several kinds of polymerizations of various water‐soluble vinyl monomers. It has been shown that aqueous solution of such vinyl monomers underwent the polymerizations induced by methyl isobutyrate (MIB) plasma‐exposed glass surface. The invisible ultrathin polymer film trapping an active radical species deposited on the plasma‐exposed glass surface apparently induced the polymerizations. The efficiency, however, was largely dependent on the solvent used: the solvent can be considered to act as “an initiation‐activator” for the lifelike postpolymerization. The nature of the solvent effect was ascribed to the physicomechanical property such as swelling ability and/or solubility toward the ultrathin film formed on the glass surface. Thus it has been suggested that the choice of good‐balanced combination between the structural feature of the plasma‐induced ultrathin polymer film and the solvent as an initiation‐activator is important to achieve activity of a desired solution polymerization.
Kinetic study of the reaction between hydroxylated polybutadienes and isocyanates. 1. Reaction with tolylene diisocyanate (TDI)
Authors: Coutinho Fernanda M. B. , Rezende Luis C. , Quijada Raul
Published: April 2003

A comparative kinetic study of the reaction of three different hydroxylated liquid polybutadienes (Mn ⋍ 3000) — R ‐ 45M, R‐45HT, and H‐034—and tolylene diisocyanate (TDI), was carried out in toluene solution. An analytical method was used to follow the kinetics of the reactions at four different temperatures. The reactions presented an apparent second‐order rate law. In the second‐order plots, a discontinuity was observed. The R‐45M polybutadiene was about twice more reactive than R‐45HT and H‐034; these latter two polybutadienes presented similar reactivities.
Cerium (IV)‐2‐chloroethanol redox‐pair initiated polymerization of acrylamide in aqueous medium
Authors: Gupta K. C. , Behari K.
Published: April 2003

The kinetics of acrylamide polymerization has been investigated by employing cericammoniumnitrate‐2‐chloroethanol redox pair under nitrogen atmosphere at 30 ± 1°C. The rate of monomer disappearance is directly proportional to the concentration of 2‐chloroethanol (1.0 × 10−2 − 10.0 × 10−2 mol. dm−3) and is inversely proportional to the ceric ion concentration (2.5 × 10−3 − 10.0 × 10−3 mol. dm−3) but shows square dependence to the concentration of monomer (5.0 × 10−2 − 25.0 × 10−2 mol. dm−3). The rate of ceric ion disappearance is directly proportional to the initial concentration of ceric ion and 2‐chloroethanol but independent of acrylamide concentration. The viscometric average molecular weight (Mv) decreases on increasing the concentration of ceric ion and increases on increasing the concentrations of acrylamide and 2‐chloroethanol. A tentative mechanism has been proposed.
Miniemulsion copolymerization of vinyl acetate and butyl acrylate. I. Differences between the miniemulsion copolymerization and the emulsion copolymerization processes
Authors: Delgado Joaquin , El‐Aasser Mohamed S. , Vanderhoff John W.
Published: April 2003

Differences between the emulsion copolymerization and miniemulsion copolymerization processes, in terms of emulsifier adsorption, emulsion stability, polymerization kinetics, copolymer composition and dynamic mechanical properties were studied for the comonomer mixture of 50:50 molar ratio vinyl acetate (VA+)—butyl acrylate (BuA), using sodium hexadecyl sulfate (SHS) as a surfactant and hexadecane (HD) as a co‐surfactant. The use of hexadecane with the appropriate SHS initial concentration led to a higher adsorption of surfactant, smaller droplet size, higher stability of the emulsions, lower polymerization rates, and larger latex particle size. The copolymer composition during the initial 70% conversion was found to be less rich in Vac monomer units for the miniemulsion process. The dynamic mechanical properties of the copolymer films showed less mixing between the BuA‐rich core and the VAc‐rich shell in the miniemulsion latexes compared to the conventional latex films.
Polymérisation radicalaire du pentadiène‐1,3. I. Copolymérisation des cis et trans pentadiènes‐1,3 avec l'acrylonitrile. Détermination des rapports de réactivité
Authors: Petit A. , Neel J.
Published: April 2003

Cis (CP) and trans (TP) isomers of 1,3‐pentadiene (piperylene) were homo and copolymerized with acrylonitrile (A) in bulk and emulsion, at 50°C, using azobisisobutyronitrile and potassium persulfate as free radical initiators. The cis isomer reacts more rapidly than the trans monomer. The copolymer compositions were determined from nitrogen analysis, 100‐MHz 1H‐NMR and 25‐MHz 13C‐NMR spectra. The results thus obtained show that both the bulk and emulsion processes yield copolymers characterized by a very similar composition. Data plotted according to the Kelen‐Tüdös method indicate that the terminal‐unit model is applicable to the piperylene‐acrylonitrile system. Reactivity ratios for bulk copolymerization were as follows: rA = 0.079, rTP = 0.114, and rA = 0.033, rCP = 0.188. These values are very small and hence suggest a strong alternating tendency for acrylonitrile and 1,3‐pentadiene in both comonomer systems. This latter conclusion is corroborated by the comparison of the NMR spectra of the synthesized copolymers with that of a standard alternating sample. The reactivity (Q) and electronegativity (e) of the 1,3‐pentadiene isomers calculated from the reactivity ratios by the Alfrey—Price equations were QTP = 0.56, eTP = −0.97 and QCP = 1.215, eCP = −1.055 for trans and cis dienes, respectively.
Chain scission efficiency and reactive‐ion etch resistance of alternating copolymers of styrene and olefins trisubstituted or tetrasubstituted with electron‐withdrawing groups
Authors: Ito Hiroshi , Hrusa Claudia , Hall H. K. , Padias Anne B.
Published: April 2003

Alternating copolymers of styrene (St) with electron‐deficient olefins trisubstituted or tetrasubstituted with cyano and carboalkoxy groups have been subjected to 60Co γ‐radiolysis together with a series of copolymers of methyl methacrylate (MMA) and St. The chain scission susceptibility Gs—Gx determined by membrane osmometry drastically decreases as St is incorporated in poly(methyl methacrylate) (PMMA). Whereas the alternating St‐MMA copolymer is slightly crosslinked upon irradiation, an alternating copolymer of St with diethyl 2‐cyano‐1,1‐ethylenedicarboxylate maintains a fairly high degradation sensitivity (Gs—Gx = 1.2). The reactive‐ion etch rates were determined for the series of polymers in CF4/O2 (92/8). The etch resistance is significantly increased by introduction of St units in PMMA, and the highly substituted alternating copolymer etches as slowly as the MMA(50)—St(50) copolymers. Thus the alternating copolymer of NCCH=C(CO2Et)2 with St behaves like PMMA when exposed to high‐energy radiation but is comparable to PSt in plasma environments.
Photopolymerization of methyl methacrylate using a combination of rhodamine 6G and benzoyl peroxide as photoinitiator in nonaqueous media
Authors: Ghosh Premamoy , Biswas Samir , Niyogi Utpal
Published: April 2003

Photopolymerization of methyl methacrylate (MMA) in visible light was studied at 40°C using Rhodamine 6G—Benzoyl peroxide combination as photoinitiator. The photopolymerization proceeds by a free radical mechanism and the radical generation process occurs by an initial complexation reaction between the initiator components. Kinetic data indicated a lower‐order dependence of Rp on initiator concentrations (initiator exponent < 0.5). Initiator‐dependent chain termination was significant along with the bimolecular mode of chain termination.
Polydimethylsiloxane–vinyl block polymers. I. The synthesis of polydimethylsiloxane macroinitiators containing thermolyzable bis(silyl pinacolate) groups in their backbones
Authors: Crivello J. V. , Conlon D. A. , Lee J. L.
Published: April 2003

This first paper on the topic of polydimethylsiloxane–vinyl block polymers describes the development of a unique class of vinyl functional silicon containing free–radical initiators which can be used in the synthesis of block polymers. Details of the synthesis and characterization of these initiators are described together with the kinetics of their thermolysis. Specific conditions are described under which these initiators can be condensed with α,ω‐hydrogen functional polydimethylsiloxane oligomers by a platinum‐catalyzed hydrosilylation reaction to yield macroinitiators.
High‐temperature reactions of hydroxyl and carboxyl PET chain end groups in the presence of aromatic phosphite
Authors: Aharoni S. M. , Forbes C. E. , Hammond W. B. , Hindenlang D. M. , Mares F. , O'Brien K. , Sedgwick R. D.
Published: April 2003

When melt‐extruded in the presence of triphenylphosphite (TPP), the molecular weight of polyesters such as poly(ethylene terephthalate) (PET) increases with time. Analysis of the PET chain end groups and model studies of high‐temperature reactions indicate that, most likely, the process leading to chain extension of PET in the presence of TPP takes place in two steps. In the first step, TPP rapidly reacts with the hydroxyl end groups by displacing one phenoxy group from the TPP. In the second step, a slow reaction takes place between the alkyldiphenyl phosphite and carboxylic chain end groups, forming an ester bond between the carboxyl and alkyl groups, and producing diphenylphosphite (DPP) as a reaction by‐product. The DPP tautomerizes to its pentacovalently bonded stabler form of diphenylphosphate, the form in which the DPP was usually detected in our analyses. The ester formation results in the extension of the PET chains. Model studies are presented which support the proposed mechanism.
Inhibition by red phosphorus of unimolecular thermal chain‐scission in poly(methyl methacrylate): Investigation by NMR, FT‐IR and laser desorption/fourier transform mass spectroscopy
Authors: Brown Charles Eric , Wilkie Charles A. , Smukalla Jeffrey , Cody Robert B. , Kinsinger James A.
Published: April 2003

The reaction of red phosphorus with poly(methyl methacrylate) under pyrolysis conditions was investigated with a number of physical techniques. A random methyl methacrylate/cyclic anhydride copolymer is formed from atatic PMMA, whereas a random methyl methacrylate/methacrylic acid copolymer is obtained with isotactic PMMA. The backbones of both these copolymers are more stable toward depolymerization than that of PMMA. The flame‐retardant activity of red phosphorus with PMMA may arise in part from stabilization of the polymer toward depolymerization via modification of the sidechains.
Preparation and structure of polymers from methoxy and hydroxy alkyl phenyl vinyl ketones
Authors: Aglietto Mauro , Cioni Luca , Ruggeri Giacomo , Taburoni Elisa , Tomei Edoardo
Published: April 2003

The preparation of 2‐methoxy‐5‐t‐butylphenyl vinyl ketone (MeOBVK), 2‐hydroxy‐5‐t‐butylphenyl vinyl ketone (HOBVK), and 2‐methoxy‐5‐isooctylphenyl vinyl ketone (MeOOVK) is reported. These compounds can be considered as precursors of polymerizable derivatives of polyoxyethylated alkylphenols—a very important class of nonionic surface active compounds. The homopolymerization and copolymerization of MeOBVK, HOBVK, and MeOOVK with butylacrylate (BA), (–) menthylacrylate [(–)MtA], styrene (STY), and vinylacetate (VA) by free radical initiators, both in solution and emulsion, have been investigated. Copolymer formation has been demonstrated by fractionation and by the presence of induced optical activity in the electronic transitions of the achiral MeOBVK and HOBVK units in copolymers with the optically active comonomer (—)MtA. MeOBVK, HOBVK and MeOOVK give substantially random copolymers with STY, BA, or VA under all conditions investigated, and always show larger reactivity; thus, depending on feed composition, sequences of the vinyl ketone units can be expected in the macromolecules.
Poly(vinyl ether)s and poly(propenyl ether)s containing mesogenic groups: A new class of side‐chain liquid‐crystalline polymers
Authors: Rodriguez‐Parada Jose M. , Percec Virgil
Published: April 2003

A new series of thermotropic liquid‐crystalline polymers, poly(vinyl ether)s and poly(propenyl ether)s, containing the mesogen 4‐methoxy‐4′‐hydroxybiphenyl in the side chain and different spacers between the mesogens and the backbone were synthesized and characterized by DSC and optical microscopy. Their mesomorphic behavior was compared to that of the corresponding polymethacrylates. In general the poly(propenyl ether)s showed lower transition temperatures and larger thermal stability ranges of their mesophases than the respective polymethacrylates, reflecting the effect of substituting the rigid ester bond connecting the spacer to the backbone in polymethacrylates by a more flexible ether bond. Also, poly(propenyl ether)s showed more ordered mesophases than the polymethacrylates, suggesting that a better decoupling of the mesogen and polymer backbone is obtained through the ether linkage.
Radical copolymerization of acrylic monomers. VIII. Copolymerization of methyl methacrylate with methyl α‐p‐chlorobenzylacrylate and methyl methacrylate with methyl α‐p‐methoxybenzylacrylate
Authors: Madruga E. L. , Roman J. San , Lavia M. A.
Published: April 2003

Free‐radical copolymerization of methyl methacrylate with methyl α‐p‐chlorobenzylacrylate and methyl methacrylate with methyl α‐p‐methoxybenzylacrylate have been studied in benzene solution at 40°C. Although a simple copolymerization model fits the composition data, the kinetic behavior of both copolymerization systems are analyzed from simple and reversible copolymerization models, taking into account the relatively low ceiling temperature of both methyl α‐(p‐substituted benzyl)acrylates and considering that the overall rate of copolymerization drastically decreases with the increase of the corresponding methyl α‐(p‐substituted benzyl)acrylate molar fraction in the feed.
Some aspects of the bimetallic μ‐oxo‐alkoxides for polymerizing epoxides to polyether elastomers
Authors: Vandenberg E. J.
Published: April 2003

The bimetallic catalysts of Osgan and Teyssie, (RO)2Al‐O‐Zn‐O‐Al(OR)2, are effective, unusual catalysts for polymerizing epoxides. The polymer obtained from propylene oxide when R = n‐Bu is preponderantly isotactic and highly crystalline and thus, largely head‐to‐tail. Crystallizable, sulfur vulcanizable propylene oxide rubber was made by copolymerizing propylene oxide (PO) with allyl glycidyl ether (AGE) with this catalyst. This product after S vulcanization exhibited gum tensile and other properties which were superior to the commercially available, amorphous PO–AGE copolymer of similar composition. However, the Osgan–Teyssie catalyst is very sensitive to reactive, polar impurities. Hindered alkyl aluminums and especially alkoxides such as Et2AlOtert–Bu can be added to help alleviate this problem. The reported favorable (but slow) copolymerization of epichlorohydrin with propylene oxide in nonpolar media with the Osgan–Teyssie catalyst has been confirmed and an alternate explanation for this unusual result suggested.
Charge mosaic membranes: Microdomain fixing of (polystyrene–poly‐4‐vinylpyridine) sequential copolymers prepared by macromonomer methods
Authors: Ishizu Koji , Murakami Atsushi , Fukutomi Takashi
Published: April 2003

Polystyrene (PST) macromonomers having several allyl groups at the ends were synthesized by the mechanical scission reaction of the main chain in the presence of diallylmalonic acid diethyl ester (DAME). Photosensitive benzophenone groups were introduced on a PST macromonomer molecule by the reaction of these PST macromonomers with benzoyl chloride. The palm‐treelike (PST–poly‐4‐vinylpyridine (P4VP)) sequential copolymers with different compositions were prepared by the radical copolymerization of PST macromonomer with 4VP. The morphological observation of these sequential copolymers was carried out by the transmission electron microscopy. The PST block microdomains were fixed by photocrosslinks (UV irradiation) in the presence of mono‐ and bifunctional unsaturated compounds in the state of mesomorphic structures. The microdomain fixing of P4VP blocks was carried out by using the vapor of 1, 4‐dibromobutane (DBB). After subsequent chemical modifications (quaternization of residual P4VP blocks and sulfonation of PST blocks), the effect of microdomain fixings was elucidated from the moisture content of positive and negative regions. These results are discussed in some detail.
An unusual reaction polymerization in nitric acid medium
Authors: Bugni Ednéia A. , Lachtermacher Marly G. , Monteiro Elisabeth E. C. , Mano Eloisa B. , Overberger C. G.
Published: April 2003

We are investigating an unusual reaction that occurs when methyl methacrylate (MMA) is kept in contact with concentrated nitric acid1(65% HNO3, sp. gr. 1.41). Polymer of high molecular weight is formed, showing about one unit of methacrylic acid (MAA) per unit of MMA, when equilibrium is reached. The reaction depends on the temperature, the molar ratio MMA:HNO3, and the reaction time. Although we also found polymer at temperatures in the range 50–70°C,2in this paper we only report the results when the temperature was kept between 25 and 40°C. Methacrylic acid (MAA) was found to homopolymerize under those mild conditions; its behavior was investigated. Although we also observed that polymer is formed with sulfuric acid (96%) and that acrylic acid polymerizes with both nitric and sulfuric acid at 20–30°C, we are limiting this article to the observed polymerizing action of nitric acid on methyl methacrylate and on methacrylic acid. Work proceeds on this matter in this laboratory.
Amino acid end‐group in commercial heparin. II. Reaction kinetics of the amino end groups with 2,4,6‐trinitrobenzenesulfonic acid
Authors: Arai Kozo , Nakamura Yoshio , Edwards H. E. , Phillips G. O.
Published: April 2003

Three different commercial heparins were trinitophenylated with 2,4,6‐trinitrobenzenesulfonic acid (TNBS) under aqueous conditions. The reaction kinetics of amino groups in heparin with TNBS showed that the reactivities of amino groups were significantly different for free amino groups on heparin, compared to reactivities in peptides and amino acid residues attached to heparin molecules. With TNBS, unreactive amino groups were always present during the reaction.
Monomer‐isomerization polymerization. XXI.. Monomer‐isomerization copolymerization of 3‐methyl‐1‐butene and 2‐pentene with ziegler–natta catalyst
Authors: Endo Kiyoshi , Otsu Takayuki
Published: April 2003

3‐Methyl‐1‐butene (3M1B) was found to undergo monomer‐isomerization copolymerization with 2‐pentene (2P) in the presence of Ziegler–Natta catalyst to give a copolymer exclusively consisting of 3M1B and 1‐pentene (1P) units, the same as that obtained from copolymerization of 3M1B and 1P. The apparent copolymerization parameters were determined. The amount of 3M1B unit incorporated in the copolymers was found to increase in the copolymerization system of 3M1B‐2P more than in that of 3M1B‐1P. The polymers consisting of nearly complete 3M1B units were produced at a rapid rate through monomer‐isomerization copolymerization of 3M1B with 2P in the presence of TiCl3 − (C2H5)3Al catalyst.
Preparation of conducting copolymers by oxidative electropolymerization of 2,2′‐bithiophene with pyrrole
Authors: Funt B. Lionel , Peters Eric M. , Van Dyke John D.
Published: April 2003

Various feed ratios of 2,2′‐bithiophene (BT) and pyrrole (PY) were electropolymerized to low conversion and the polymers analyzed for their mer ratios. The polymeric product was rich in polypyrrole (PPY), but the composition could be varied by control of the electrode potential. The increase in BT content is not linear with composition, and the physical evidence indicates oxidative copolymerization and not the formation of the two homopolymers. The data can be interpreted on a copolymerization equation despite the absence of steady state conditions. Sets of reactivity ratios were determined for the polymers formed at two potentials. The electrical efficiencies for polymer formation approach stoichiometric values for oxidative polymerization.
Thermal properties of nylons containing carbonyl groups
Authors: Do C. H. , Pearce E. M. , Bulkin B. J. , Reimschuessel H. K.
Published: April 2003

Nylons containing carbonyl groups in backbone chains were prepared and their response to heat was studied. The carbonyl groups were introduced using either HOOC(CH2)4CO(CH2)4COOH or H2N(CH2)5CO(CH2)5NH2 in the initial monomer compositions. In addition to pyrolysis of these polyamides, the progress of chemical and physical changes as a function of temperature was continuously monitored and analyzed by FT–IR spectroscopy on cast films placed in an environmental chamber. Introduction of the carbonyl groups into the polymer backbone resulted in a significant reduction of the thermal stability of the corresponding polyamide. Possible mechanisms for the thermal degradation entailing these carbonyl groups and N‐acylamide compounds are discussed.
Semiconducting polymers via the high temperature free radical polymerization of multinitriles
Authors: Padias Anne Buyle , Hall H. K.
Published: April 2003

The polymerizability of a variety of mono‐ and multi‐ nitriles in the presence of free radical initiators at high temperature is determined by the concentration of available cyano‐groups. Mononitriles do not polymerize, but multinitriles do so readily. If alkyl substituents are introduced in a molecule that easily polymerizes, this concentration and the ability to polymerize are lowered; if several or bulky substituents are introduced, the polymerization is completely prevented. Multinitriles containing ester groups undergo decarbomethoxylation in these polymerizations. The polymers are black and highly insoluble. From the few reactions that were attempted on these polymers, we can conclude that the structure is probably not the simple conjugated imine structure proposed by earlier investigators, but more experiments are needed to prove this point. The black polymers had conductivities less than 10−9 Ω−1 but, after heating at 700°C, conductivities in the range from 10−3 to 10−6 Ω−1 are observed.
Synthesis and properties of semiconducting aromatic polyquinonediimines
Authors: Everaerts A. , Roberts Sue , Hall H. K.
Published: April 2003

A new class of poly‐conjugated polymers has been obtained by condensation of anthraquinones with aromatic diamines in polyphosphoric acid. The polymers are black, intractable powders. Toward obtaining tractable materials, the effect of monomer structure on polymer tractability has been studied. Copolymerizations were also carried out to “soften” these materials. Electrical conductivities in the semiconducting range, 10−4‐ 10−8 (ohm cm)−1 were observed. Doping with iodine showed small increases.
Kinetics of crosslinking reactions. 1. Reaction rate of intramolecular crosslinkings by using a soluble microgel
Authors: Ishizu Koji , Kuwabara Shojiro , Chen Hui , Mizuno Hirohide , Fukutomi Takashi
Published: April 2003

Soluble microgels with several pendant vinyl groups were synthesized by radical copolymerization of methyl methacrylate (MMA) with p‐divinyl benzene (p‐DVB). The polymerization conditions used for intramolecular crosslinking of microgels were chosen from gel permeation chromatograph (GPC) measurements of the reaction products. The rate constant of intramolecular crosslinking (kpi) was estimated from the changes in the concentration of pendant vinyl groups of microgel by using photometrical measurements at 30°C assuming a unimolecular termination mechanism of polymer radicals. As a result, kpi showed larger values than kp of styrene and depended strongly on the internal structure of the microgels.
Configurational stereoselectivity in the nucleophilic substitution of poly(vinyl chloride) with sodium thiophenate: NMR study and Monte‐Carlo simulation of the reaction
Authors: Spitz Roger , Llauro‐Darricades Marie‐France , Michel Alain , Guyot Alain , Mijangos Carmen , Martinez Gerardo , Millan Jose Luis
Published: April 2003

The nucleophilic substitution of the chlorine atoms of poly(vinyl chloride) with sodium thiophenate is assumed to obey an SN2 mechanism with inversion of configuration and a steric control according to which reactivities R of the triads follow the order Rmm > Rmr ≫ Rrr. Such a reaction cannot be described by simple differential equations, but a Monte Carlo simulation, first generating a random Bernouillian chain and then simulating random attack of the chain by the reactant according to the triad reactivities, allows a good agreement with the experimental results of both the kinetics of a reaction carried out in cyclohexanone solution at 40°C and the evolution of the 13C and 1H NMR spectra of the tertiary carbon atoms, assuming the following parameters: Bernouillian probability for a meso placement in the initial chain: 0.431; relative reactivities of the mm, mr and rm, rr triads: 1, 0.5, and 0., respectively. The agreement is excellent until the reaction is about three‐quarters complete; this shows a limiting level of about 60% substitution. Better agreement can be obtained up to the limit, if a secondary process of steric control by the substituant in a partially substituted mr triad is assumed. Other possibilities for that secondary process are discussed.
Synthesis and characterization of fluorescently labelled poly(vinyl acetate) particles
Authors: Egan Luke S. , Wimmik Mitchell A. , Croucher Melvin D.
Published: April 2003

Nonaqueous dispersions of poly(vinyl acetate) particles stabilized with poly(2‐ethylhexyl methacrylate) and labelled with fluorescent dyes in the core and stabilizer polymer phases were prepared. The materials were characterized using a broad range of techniques (NMR, UV, and fluorescence spectroscopy. GPC, particle sizing, and DSC). The data show that dispersion polymerization of vinyl acetate in the presence of stabilizers containing certain fluorescent dye derivatives, instead of unlabelled stabilizer, results in changes in the mean particle size, size distribution, composition, and molecular weights of the colloidal polymer particles. It was found that increasing the amounts of fluorescent groups in the stabilizer resulted in smaller mean particle sizes and larger amounts of irreversibly attached stabilizer. When the average number of labels in stabilizer exceeded one per chain, a new ultra‐high molecular weight polymer fraction appeared. The fluorescence spectra for several of these materials are reported. We describe how fluorescence decay curves can be used to assess block formation and local phase separation in particles labelled with phenanthrene groups. These materials are intended to be used for more detailed studies by fluorescence spectroscopy. Those results will be published in due course.
Thermotropic copolyesters. II. Synthesis and characterization of liquid‐crystal copolyesters containing the bicyclo[2.2.2]octane ring system
Authors: Polk Malcolm B. , Nandu Mahendra , Phingbodhipakkiya Metha
Published: April 2003

The syntheses and characterizations of poly(oxy‐trans‐1,4‐cyclohexyleneoxycarbonyl‐1,4‐bicyclo[2.2.2]octylenecarbonyl) (I) and poly(oxy‐trans‐1,4‐cyclohexyleneoxycarbonyl‐1,4‐bicyclo[2.2.2]octylenecarbonyl‐co‐oxy‐trans‐1,4‐cyclohexyleneoxysebacoyl) (II) are described. The polymer systems were characterized by infrared spectroscopy, proton magnetic resonance spectroscopy, solution viscosity, and differential scanning calorimetry. The random copolyester prepared from 1:0.65:0.35 mol of trans‐1,4‐cyclohexanediol, bicyclo[2.2.2]octane‐1,4‐dicarbonyl chloride, and sebacoyl chloride, respectively, formed a birefringent fluid state in the melt.
Synthesis of dihydroxamic acid chelating polymers and the adsorptive property for uranium in sea water
Authors: Hirotsu Takahiro , Katoh Shunsaku , Sugasaka Kazuhiko , Sakuragi Masako , Ichimura Kunihiro , Suda Yoshio , Fujishima Mitsugi , Abe Yoshimoto , Misonoo Takahisa
Published: April 2003

Preparation of new chelating polymers bearing dihydroxamic acid groups and the adsorptive ability for uranium in sea water are described. Chloromethylated polystyrene crosslinked with divinylbenzene was treated with diethyl malonate in N, N‐dimethylformamide to give the polymer having diethyl malonate groups. This polymer was then treated with hydroxylamine in methanol to afford the dihydroxamic acid polymer. The presence of hydroxamic acid groups was confirmed by the appearance of IR absorption band at 1680 cm−1. The dihydroxamic acid polymer contained carboxylic acid groups as well as hydroxamic acid ones, and the contents of carboxylic acid and hydroxamic acid groups were estimated from elemental analysis to be 2–3 and 2–4 mmol/g, respectively. The polymer showed the adsorptive ability of 40 μg‐U/g in 8 days for uranium in sea water. In addition, the polymer showed the selective adsorptivity for iron, nickel, copper, and zinc as well as uranium. The macroreticular‐type polymer showed much higher adsorption rate for uranium in sea water than the gel‐type ones did, suggesting that the rate depends on the diffusion of the uranium in the polymer support.
Magnesium chloride supported high mileage catalysts for olefin polymerization. XIII. Effect of external Lewis base on ethylene polymerization
Authors: Chien James C. W. , Bres Phillipe
Published: April 2003

The effect of external Lewis base (Be) on the polymerization of ethylene by the MgCl2/ethyl benzoate/p‐cresol/AlEt3/TiCl4 catalyst was studied by activation with AlEt3 alone without the use of methyl‐p‐toluate. The initially formed active site concentration, [Ti], is about doubled in the absence of Be; at 50°C about 93% of the total titanium became catalytic. The same increment of [Ti] was observed without Be. The rate constants of propagation are not appreciably affected by Be; the values are the same at 50° with and without Be. At other temperatures the kp values are somewhat smaller without Be. One major effect was the very large k values for chain transfer with aluminum alkyls in the absence of Be as compared to those with Be. This can be attributed to the greater monomeric AlEt3 concentration in the former, but in much smaller amounts in the presence of Be due to complexation. The rate constants of chain transfer with hydrogen are not much affected by Be. However, the termination rate constants are generally much smaller when Lewis base is not present.
Preparation and thermal properties of polyquinazolone containing 4‐substituted phenyl groups on the quinazolone ring
Authors: Kubota Shigeru , Moriwaki Toshimoto , Ando Torahiko , Etoh Shohei , Fukami Akira
Published: April 2003

Polyquinazolones containing 4‐substituted phenyl groups (H, Cl, CH3, CH3O, NO2) on the quinazolone ring were synthesized in m‐cresol and their thermal properties were studied by using dynamic thermogravimetry and isothermal weight loss in nitrogen and air. Polyquinazolones were synthesized with intrinsic viscosities in the range of 0.2–0.7 dL/g when phosphorus pentoxide was used as a catalyst. In TGA studies, there was a difference in the initial decomposition temperature of polyquinazolones with varying substituted groups. The introduction of substituted groups reduced oxidative thermal stability of the polymers. Furthermore, the thermal degradation mechanism was investigated by infrared spectrophotometry.
Radiation‐induced copolymerization of hydrophilic monomers with vinyl acetate: Synthesis and thermal properties
Authors: Ramakrishna M. S. , Dhal P. K. , Deshpande D. D. , Babu G. N.
Published: April 2003

Radiation‐induced copolymerization of hydrophili+ monomers, viz., 2‐hydroxyethyl methacrylate (HEMA), 2‐hydroxypropyl methacrylate (HPMA), and N‐vinyl‐2‐pyrrolidone (NVP) with vinyl acetate (VAc) was carried out in bulk at 25°C. The copolymer composition was determined from the acetoxy content. The copolymerization parameters were determined by a graphical method and compared with those determined by the Yezrielev, Brokhina, and Roskin (YBR) method. Thermal properties of copolymers were studied by GC‐MS. Probable mechanisms were suggested from the products obtained.
Polymerization of methyl methacrylate with ceric ion‐methanol redox system
Authors: Coutinho Fernanda M. B. , Guimarães Maria José O. C. , Gomes Ailton S.
Published: April 2003

The polymerization of methyl methacrylate initiated by Ce4+ methanol redox system was studied in aqueous solution of nitric acid at 15°C. The polymerization was initiated by primary radicals formed from Ce4+/alcohol complex. Poly(methyl methacrylate) chains containing the alcohol residue were obtained. Variations in the temperatuare and concentration of the components of the redox system allowed the control of the rate of polymerization and molecular weight of the polymer. The concentration of the hydroxyl end groups in the poly(methyl methacrylate) of low molecular weight was determined by titration and by spectrometric method.
Polymerization of lignin model compounds with formaldehyde in acidic aqueous medium
Authors: Van Der Klashorst G. H. , Strauss H. F.
Published: April 2003

The reaction of formaldehyde with lignin model compounds in acidic medium was shown to give fast crosslinking of alkyl‐substituted phenolic and etherified phenolic lignin model compounds at positions meta to the aromatic hydroxy groups. This reaction differs from the reaction of formaldehyde with phenolic lignin model compounds in alkaline conditions, where the reaction with formaldehyde always occurs at positions ortho/para to the aromatic hydroxy group., The reaction of formaldehyde with lignin in acidic medium have considerable potential for the crosslinking of lignin, particularly heavily condensed alkali lignin, for use in polymeric products.
Gamma radiation induced graft copolymerization of vinyl monomers onto poly(vinyl alcohol)
Authors: Misra B. N. , Kishore J. , Kanthwal M. , Mehta I. K.
Published: April 2003

In an attempt to modify water‐soluble synthetic polymers, graft Copolymerization of methylmethacrylate (MMA) and ethyl acrylate (EA) onto poly(vinyl alcohol), PVA, has been studied by using gamma irradiation from a Co60 source as initiator. The graft copolymerization was carried out in an aqueous medium by the mutual method in air. The effect of total dose and concentration of vinyl monomers on percentage of grafting has been determined. Water plays a significant role in the enhancement of graft copolymerization and the optimum amount of water to afford maximum grafting has been evaluated. The effect of CH3OH on aqueous grafting of MMA and EA by radiation method has been studied. The graft copolymer has been characterized by IR spectroscopic and thermogravimetric methods.
Magnesium chloride‐supported high‐mileage catalysts for olefin polymerization XI. Determinations of poly(decene‐1) molecular weight chain dimension and thermal transitions
Authors: Chien James C. W. , Ang Tsunle
Published: April 2003

Decene‐1 was polymerized with the CW catalyst and fractionated by precipitation technique. Light‐scattering and viscometric measurements on these fractions established the relationship [η] = 5.19 × 10−3 M. The unperturbed mean square end‐to‐end distance is (〈R〉/M)1/2 = (6.17 ± 0.34) × 10−9. Light‐scattering data is consistent with a relatively stiff molecule with length of L = 1.75 × 10−5 cm for poly(decene‐1) with MW = 397,000. Its mean square radius of gyration 〈R〉 is 2.79 × 10−11 cm.2 The ratio of L2/〈R〉 = 11 is close to the theoretical ratio of 12 for this kind of macromolecule.
Polymerization using palladium (II) salts II: Polymerization of 2‐ethynyl‐5‐bromothiophene
Authors: Trumbo D. L. , Marvel C. S.
Published: April 2003

The title monomer was polymerized using a bis(triphenyl phosphine) palladium (II) chloride, cuprous iodide, triphenyl phosphine catalyst system. The products are low‐molecular‐weight materials with thermal stabilities somewhat inferior to corresponding phenylacetylene‐based polymers.
Ion equilibria in THF solutions of models of “living” methacrylonitrile oligomers with Li+ counterion
Authors: Tsvetanov CH. B. , Dotcheva D. T.
Published: April 2003

The electro‐chemical characteristics of isobutyronitrile lithium (P1Li) and 2‐lithio‐4‐cyano‐2,4‐dimethylpentanenitrile (P2Li) are studied. The dissociation constants K of P1Li and P2Li are of the order of 10−11M and show that in THF mainly contact ion pairs exist. The lower value of K for P2Li is an indication for intramolecular complexation between the counterion and the cyano group, next to the active center. Both compounds tend to form ion triples. The results obtained show that in THF the nitrile group of the second monomer unit participates both in intra‐ and intermolecular interactions with the counterion.
Kinetic studies on the radical polymerization of acrylamide initiated by Mn3+–ethoxyacetic acid redox system
Authors: Balakrishnan T. , Subbu S.
Published: April 2003

The kinetics of polymerization of acrylamide (AM) initiated by manganese(III) acetate–ethoxyacetic acid (EAA) redox system in aqueous sulphuric acid was investigated in the temperature range 35–45°C. The effects of variations in [monomer], [Mn3+], [EAA], [H+], and ionic strength on the rates of monomer disappearance (Rp) and Mn3+ disappearance (−Rm) were studied. The polymerization process is initiated by the free radical arising from the oxidation of ethoxyacetic acid by Mn3+ and terminated by the mutual combination of growing polymer radicals. Based on the kinetic results, a suitable reaction scheme is proposed and the rate expressions are derived. The study on degree of polymerization supports the proposed scheme for polymerization. The various rate and thermodynamic parameters are evaluated.
Poly(alkylene oxide) ionomers IX. Polymerization of methyl ω‐epoxyalkanoates and characterization of the polymers
Authors: Muggee John , Vogl Otto
Published: April 2003

Polymerization of linear methyl ω‐epoxyalkanoates of C‐3 to C‐10 carboxylic acids (0 to 7 methylene groups between oxirane ring and carbomethoxy group) was accomplished with a triethylaluminum/water/acetylacetone (1.0/0.5/1.0) initiator system to yield polymers of high molecular weight, apparently via a coordinative anionic mechanism. The rate of polymerization increased as the number of methylene groups between the oxirane ring and the carbomethoxy group increased, up to three methylene groups. When more than three methylene groups separate the polymerizable oxirane group and the carbomethoxy group, the rate of polymerization becomes essentially constant. The polymers were characterized by their infrared and13C‐NMR spectra, DSC, GPC, and inherent viscosity. The lower members of the series (ω‐epoxyalkanoates ofn< 3) gave polymers of lower molecular weight and wider‐molecular‐weight distribution (Mw/Mn> 2), while the higher members had molecular weight distributions between 1.5 and 2. The glass transition temperatures of the polymers also decreased from −26°C forn= 1 to around −50 to −55°C forn≥ 3.
Oxygen diffusion in poly(dimethyl siloxane) using fluorescence quenching. II. Filled samples
Authors: Cox M. E. , Dunn B.
Published: April 2003

The method of fluorescence quenching has been used to measure the transport properties of oxygen in poly(dimethyl siloxane) (PDMS) filled with small weight fractions of fumed silica. The experimental results show that the diffusion coefficient of oxygen and the pre‐exponential term in the Arrhenius relationship are reduced, but the activation energy is not affected. In the pressure and temperature ranges used in these experiments, the diffusion coefficient was found to be independent of both the oxygen and fluorophor concentrations. A discussion concerning the effect of fillers on the pre‐exponential term is presented.
Block copolymers of isotactic polypropylene and 1,4‐polybutadiene
Authors: Drzewinski M. A. , Cohen R. E.
Published: April 2003

Two block copolymers of isotactic polypropylene and 1,4 polybutadiene were synthesized using techniques involving a transformation from anionic to Ziegler–Natta polymerization mechanisms. The yield of block copolymer was about fifteen percent (weight basis) in both polymerizations, the remainder being unreacted polybutadiene from the first block synthesis. Molecular characterization experiments and model reactions were consistent with a block‐like structure for the copolymers; definitive evidence for the proposed molecular structure was obtained through transmission electron microscopy which clearly revealed microphase‐separated morphologies characteristic of block copolymers.
Vinyl polymerization. 432. Initiation mechanism of uncatalyzed polymerization in the presence of copper(II) ion
Authors: Ouchi Tatsuro , Sakamoto Hiroshi , Hosaka Yoshifumi , Imoto Minoru , Konoka Ryusei
Published: April 2003

The initiation mechanisms of the uncatalyzed polymerization of methyl acrylate and methyl methacrylate by the system of starch, α‐amylase or water‐soluble nylon 3/copper(II) ion/H2O were investigated by spin trapping techniques. Using 2,4‐dimethyl‐3‐nitrosobenzene sulfonate d8 and 5,5‐dimethyl‐1‐pyrroline‐N‐oxide as the water‐soluble spin trapping agents, the simultaneous generation of both monomer and hydroxyl radicals has been observed, and the propriety of the initiation mechanism proposed previously was confirmed. Thus, the initiation of polymerization in the presence of copper(II) ion was concluded to take place through a hydrogen atom transfer from the complexed water to the β‐carbon of the complexed monomer.
Factors affecting H2O absorption of the epoxy tetraglycidyl‐4,4′‐diaminodiphenyl methane cured with diaminodiphenyl sulfone
Authors: Yang F. , Gilbert R. D. , Fornes R. E. , Memory J. D.
Published: April 2003

It was found that the amount of water absorbed at room temperature in cured tetraglycidyl‐4,4′‐diaminodiphenyl methane/diaminodiphenyl sulfone epoxy resins increases as the curing time or temperature increases while the amount of tetrahydrofuran‐soluble extractables and the room temperature density decreases. These data suggest that the free volume increases with the extent of cure and the resins become more accessible to water. While the driving force for water absorption is the electrostatic attraction between water and the functional groups in the epoxy, the results suggest that equilibrium H2O absorption is determined primarily by unoccupied volume of the epoxy resin.
Water‐soluble copolymers. XII. Copolymers of acrylamide with sodium‐3‐acrylamido‐3‐methylbutanoate: Synthesis and characterization
Authors: McCormick C. L. , Blackmon K. P.
Published: April 2003

The copolymerization of acrylamide (AM) with sodium‐3‐acrylamido‐3‐methylbutanoate (NaAMB) has been studied. The value of r1r2 has been determined to be 0.56 for the AM–NaAMB pair. The molecular weights of the copolymers were relatively unaffected by monomer feed ratios. The copolymer microstructures, including run numbers and sequence distributions, were calculated from the reactivity ratios. The solution properties of the AM–NaAMB copolymers, as well as the NaAMB homopolymer, will be reported in a subsequent paper.
Poly(2‐imidazolin‐5‐ones)—A new class of heterocyclic polymers
Authors: Rasmussen Jerald K. , Heilmann Steven M. , Krepski Larry R. , Smith Howell K. , Katritzky Alan R. , Sakizadeh Kumars
Published: April 2003

The reaction of bisazlactones (2‐oxazolin‐5‐ones) with primary diamines containing additional secondary or tertiary amine functionality (e.g., diethylenetriamine, triethylenetetramine, or N‐methyliminobispropylamine) readily produces polyamides which serve as precursors to a new class of heterocyclic polymers. Thermal cyclodehydration takes place under relatively mild conditions (180–200°C) to produce water‐soluble polymers containing the 2‐imidazolin‐5‐one heterocycle. Model reactions have been studied to verify this mode of cyclization and confirm the proposed polymer structure.
Catalysis in competing isocyanate reactions. I. Effect of organotin–tertiary amine catalysts on phenyl isocyanate and N‐butanol reaction
Authors: Wong Shaio‐Wen , Frisch Kurt C.
Published: April 2003

An analytical method based on high performance liquid chromatography (HPLC) has been developed to investigate the competing isocyanate reactions under the influence of various catalysts. The kinetics of the model reaction between phenyl isocyanate and n‐butanol was studied in acetonitrile at 50°C. Effects of various catalysts such as an organotin compound, dibutyltin dilaurate, and tertiary amines, 1,4‐diazabicyclo‐(2,2,2)octane,N,N′,N″‐pentamethyldiprophylene triamine,N,N′N″‐tris(3‐dimethyl‐aminopropyl)‐3‐hexahydrotriazine, and N,N,N′‐trimethylaminoethyl‐ethanolamine on the reaction rate and the formation of reaction products were investigated. The reactions were followed by determining the NCO disappearance using the standard di‐n‐butylamine back‐titration method as well as measuring the formation of various reaction products using the HPLC method. The relative specificity of a catalyst in isocyanate reactions can thus be determined from the profile of the model reaction which depends upon the structure of the catalyst employed.
Acid‐catalyzed degradation of poly(2‐butyl‐1, 3, 6‐trioxocane)
Authors: Chien James C. W. , Lillya C. Peter , Xu Bao‐Bei
Published: April 2003

Acid‐catalyzed degradation of poly(2‐butyl‐1,3,6‐trioxocane) (1) has been studied. With ethyl tosylate as the catalyst, the cyclic monomer 2 was the major product. The minor products are cis and trans isomers of C3H7CHCHOCH2CH2OCH2CH2OH, and three stereoisomers of C3H7CHCHOCH2CH2OCH2CH2OCHCHC3H7 elucidated by 1H and 13C NMR, IR, electron impact and chemical ionization MS, and in the case of 2 also by comparison with an authentic sample. With 98% H2SO4 as the catalyst 2 is only a minor product. The major products are diethylene glycol, valeraldehyde, and 1,4‐dioxane with some 2‐butyl‐1,3‐dioxolane. Capillary GC/mass spectrometry led to identification of the following less abundant products: tri‐n‐propylbenzene, α,β‐unsaturated aldehydes, and cyclic dimer. The products of H2SO4‐catalyzed decomposition of polymer were also obtained by heating monomer 2 with H2SO4. A detailed mechanism for the formation of the eight‐member ring 2 in the decomposition is proposed which involves unzipping proceeds via open carbocation intermediates. According to the principle of microscopic reversibility, the same open carbocation is the propagating species in the polymerization of 2 under similar conditions.