bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneous catalysis by polyelectrolyte. I. Polyelectrolyte influence on the solvolysis and deamination
Authors: Nishiyama Yoshihiro , Moroe Ichiro , Kitano Hiromi , Okubo Tsuneo , Ise Norio
Published: April 2003

Heterogeneous or homogeneous polyelectrolyte influences on the solvolyses of t‐butyl chloride and α‐phenethyl chloride were studied. Anionic polymers enhanced the reaction rate by stabilizing the intermediate point dipole (ionic strength effect); cationic polymers with chloride ions as gegenions retarded the reaction by the mass action law (common ion salt effect), thus supporting the theory of Ingold et al. On the other hand, neutral polymer resins retarded the reaction probably because of the binding of the substrate on the resin surface. By the addition of a neutral polymer resin. Amberlite XAD‐4 the net steric course of the solvolysis of α‐phenethyl chloride was slightly changed from inversion to racernization, whereas anionic resins (Amberlite IR‐124) showed no effect. The heterogeneous polymer resin effect on the dearnination of α‐phenethyl amine was also studied. An anionic resin (IR‐124) retarded the reaction slightly and a neutrai resin (XAD‐4) retarded it to a great extent. A cationic resin (Dowex 1 × 8) accelerated the reaction, although slightly. The net steric course of the deamination was changed from inversion to racemization in the order XAD‐4 > Dowex 1 × 8 > IR 124. The heterogeneous polymer effect of the stereochemistry depended mainly on the hydrophobicity: i.e., the ability to bind the substrate on the surface of resin.
Relationships of graft polymerization of vinyl monomers onto cellulose. Reaction kinetics and polymer structure
Authors: Kurliankina V. I. , Molotkov V. A. , Klenin S. I. , Liubina S. Ya.
Published: April 2003

Graft polymerization of acrylamide and sulfuric salt of 2‐methyl‐5 vinylpyridine onto cellulose using CO(III) salts was studied. It was shown that graft polymerisation of water‐soluble polymers can be described by general relationships of radical reaction. The relation between elementary reaction constants of the formation and termination of active centers in cellulose, as well as relation between constants of the propagation, transfer and termination of chains were determined for different cellulose materials and monomers. The translational diffusion, sedimentation, viscosity, and flow birefringence of copolymers have been investigated in different solvents. Experimental data showed that the copolymers obtained are graft copolymers with two to five grafted chains onto macromolecules. The minimum distance between the branch points is 100 ± 20 glucoside units. The peculiarity of these copolymers is relatively low polydispersity. The conformation of macromolecules of such copolymers in solution depends on the compatibility of the copolymer components and the thermodynamic properties of the solvent.
Synthesis and polymerization of γ‐alkoxy‐β‐hydroxypropyl acrylates
Authors: Lu Chengxun , Chen Naichun , Gu Zhong Wei , Feng Xinde
Published: April 2003

Several γ‐alkoxy‐β‐hydroxypropyl acrylates were synthesized and polymerized. Both poly(MHPA) (IVd) and poly(MHPMA) (IVa) hydrogels possess high values of equilibrium water content, about seven and three times, respectively, that of the poly(β‐hydroxyethyl methacrylate) hydrogel. These rather high values are attributed tentatively to the presence of a hydrophilic γ‐methoxy‐β‐hydroxypropyl side group on the acrylic backbone.
Polymerization of oriented monomers. V. Radiation‐induced polymerization of 3n‐dodecyl‐1‐vinylimidazolium iodide in micellar aggregates
Authors: Paleos C. M. , Voliotis S. , Margomenou‐Leonidopoulou G. , Dais Photis
Published: April 2003

In the present study radiation‐induced polymerization of 3n‐dodecyl‐1‐vinylimidazolium iodide (I) in micellar aggregates was investigated. For comparison, the corresponding isotropic polymerization of I was also studied. Micellization was obtained in concentrated aqueous solutions; that is, above the monomer's critical micelle concentration (CMC) polymers obtained by both modes of polymerization were treated similarly and subsequently subjected to physical characterization. The main purpose of this study was to investigate whether the degree of organization of the monomer in micelles would affect polymer properties. Attempts to determine tacticity by 13C‐NMR spectrometry failed because of the particular structure of the polymer. Crystallization of these polymers from ethyl alcohol or acetone was not possible as indicated by x‐ray powder diffraction patterns that were characteristic of amorphous polymers. On the other hand, viscosity data of polymers do not depend on the mode of polymerization. It is therefore concluded that micellar aggregates are not sufficiently organized to affect polymer properties.
Starshaped block copolymers. I. Synthesis of new A(B)2 starshaped block copolymers based on vinyl or diene hydrocarbons (A) and oxirane (B)
Authors: Huynh‐Ba‐Gia  , Jérôme R. , Teyssié Ph.
Published: April 2003

Naphthalene‐terminated polyvinyl aromatics and polyisoprene were obtained successfully. These functional polymers were metalated by potassium in THF at 25°C. The formation of a stable dinegative ion is observed unless the naphthalene is directly attached to the end of the polyvinyl aromatics, in which case a few isoprene units can be advantageously inserted between the naphthalene end group and the polyvinyl aromatics. The polymeric and stable dinegative ion polymerizes oxirane by both anionic sites and forms three‐branched starshaped block copolymers.
Asymmetric porous emulsion film
Authors: Okubo Masayoshi , Takeya Tetsuro , Tsutsumi Yoshitaka , Kadooka Tsuneo , Matsumoto Tsunetaka
Published: April 2003

The formation mechanism of an “asymmetric” porous structure for the film cast from ethyl acrylate‐methyl methacrylate copolymer emulsion prepared by emulsifire‐free emulsion polymerization was investigated. The formation of this structure was affected by the emulsion stability which was varied by the postaddition of sodium sulfate or sodium dodecyl benzene sulfonate. It is concluded that it is derived from the production of porous skin film at the emulsion‐air interface and the precipitation of flocculated particles at the bottom of emulsion during drying process.
Cyclopentadienylation of PVC: Characterization and thermal and thermooxidative degradation studies
Authors: Iván Béla , Kennedy Joseph P. , Kelen Tibor , Tüdös Ferenc
Published: April 2003

PVC has been cyclopentadienylated by two conventional basic, LiCp and NaCp, and a new acidic, Me2CpAl, cyclopentadienylating agent. PVCs treated with basic cyclopentadienylating agents undergo severe random dehydrochlorination and exhibit a significant decrease in thermal and thermooxidative stability. In contrast, according to ozonization and degradation experiments, Me2CpAl does not cause dehydrochlorination during cyclopentadienylation. The thermal stability of PVC treated with relatively high concentrations of Me2CpAl and Me3Al at 25°C markedly increases due to substitution of labile chlorines in PVC with methyl groups. Initial thermal dehydrochlorination behavior of virgin PVC and samples treated with Me2CpAl at −30°C are similar. In contrast, thermooxidative stability decreases on Me2CpAl treatment at −30°C; this is attributed to ease of oxidation of pendant cyclopentadienyl groups; that is, the formation of peroxy radicals that may initiate dehydrochlorination by attacking unchanged repeat units in PVC. Acceleration of thermal dehydrochlorination disappears and the length of polyene sequences is reduced on Me2CpAl and Me3Al treatment. These observations are attributed to differences in rates of protonation‐deprotonation; that is, rates of reinitation of zipping of treated and untreated PVCs during thermal degration. The effect of traces of aluminum residues on degradation of modified PVCs, however, cannot be neglected.
The influence of steric factors on the mechanism of copolymerization of phenylvinyl alkyl ethers and maleic anhydride
Authors: Fleš D. , Vuković R. , Kurešević V. , Radičevic R.
Published: April 2003

By assuming that the initial rate of copolymerization (Rp) of phenylvinyl alkyl ether (I) and maleic anhydride (MAn) equals the sum of the rate of polymerization of free monomers Rp(f) and CT complex monomers Rp(CT) the reactivity ratios k1c/k12 and k2c/k21 were calculated for copolymerization of I(R = Me, n‐Pr, iso‐Pr, and sec‐Bu) and MAn from the change of copolymerization rate with monomer feed at a constant total monomer concentration. From the equation Rp = Rp(f) + Rp(CT) were calculated Rp(f) and Rp(CT) by applying the generalized model described by Shirota and coworkers and it was found that the participation of CT complex monomers increases with an increase in total monomer concentration in the feed. It was also found that the degree of CT complex monomer participation depends largely on the steric factors. In the copolymerization of I which contains bulky isopropyl or sec‐butyl group even in the dilute solutions, copolymerization proceeds by the addition of CT complex monomers.
Propagation/depropagation equilibrium and structural factors in the radiation degradation of poly(olefin sulfone)s
Authors: Bowmer Trevor N. , O'Donnell James H.
Published: April 2003

The principal volatile products observed after γ irradiation of nine different poly(olefin sulfone)s in the solid state were the two comonomers, i.e., the respective olefin and sulfur dioxide. An exponential increase in yield, G(volatile products), with increasing irradiation temperature, Tirr, was observed for each copolymer through the ceiling temperature, Tc, for the corresponding propagation/depropagation equilibrium. Thus the G value increased by ca. 3 orders of magnitude from Tirr = 0.7 Tc to Tirr = 1.3 Tc for all of the poly(olefin sulfone)s. Depropagation sensitivity was considered to be best measured by G(SO2) since radiation induced, cationic homopolymerization of the product olefin occurred to a variable extent. Five of the poly(olefin sulfone)s had similar rates of depropagation at their respective Tc's but the polysulfones of 1‐hexene, cyclohexene and 2‐butene showed anomalously high depropagation rates. This may be related to greater steric hinderance to segmental chain mobility in the polysulfones of the 1,2 disubstituted olefins. Poly(1‐hexene sulfone) appears to be anomalous, as in other respects.
Copolymerization of studies. Copolymerization of methyl α‐cyanocrotonate with styrene, acrylonitrile, and vinyl acetate
Authors: Raiter Julia , Kohn David H.
Published: April 2003

Copolymers of methyl α‐cyanocrotonate with styrene, acrylonitrile, and vinyl acetate were prepared in bulk by free radical initiation. The copolymerization parameters were determined for each pair by several methods. The basic properties, that is, intrinsic viscosity, solubility, melting range, and glass transition temperature of the obtained copolymers, were determined.
Polymerization of aromatic nuclei. XXV. ESR and chemical studies on the radical cation nature of poly(p‐phenylene)
Authors: Jones Martin B. , Kovacic Peter , Howe Russell F.
Published: April 2003

The radical cation nature of poly(p‐phenylene) (PPP) was examined by electron spin resonance (ESR) and chemical means. ESR studies revealed a radical concentration of 1.0 × 1021 spins/g for the crude polymer. Workup with aqueous acid decreased the value to 1.5 × 1018 spins/g. Reactions of the polymer with certain nucleophiles followed the half‐regeneration mechanism, whereas with others, electron transfer mainly occurred. The origin of halogen in the polymer was found to arise from reaction of the radical cation with the oxidant, and not with halide during workup. Oxidation of PPP with various species increased the concentration of radical cations.
N‐vinyl carbazole copolymers
Authors: Mulvaney J. E. , Gromelski S. , Rupp R.
Published: April 2003

The synthesis of N‐vinyl carbazole (VCbz) copolymers, some of which contain electron‐accepting groups, is described. The new copolymers are: copoly[N‐vinyl carbazole‐di(2‐N‐carbazylethyl)‐fumarate](II); copoly(N‐vinyl carbazole‐vinyl‐2,4‐dinitrobenzene‐sulfonate)(IV); copoly(N‐vinyl carbazole‐vinyl‐2,4‐dinitrobenzene‐sulfenate)(V); copoly(n‐butyl acrylate‐t‐butyl peracrylate)(VII); copoly(n‐butyl acrylate‐t‐butyl acrylate‐graft‐N‐vinyl carbazole)(VIII).
Synthesis of asymmetric cyclopropyl acids and amines
Authors: Overberger C. G. , Nishiyama T.
Published: April 2003

(+) (S)‐ and (−) (R)‐trans‐1,2‐cyclopropanedicarboxylic acids (C3A), (+) (S)‐ and (−) (R)‐trans‐1,2‐diaminocyclopropanes (C3B), (+) (S)‐ and (−) (R)‐trans‐2‐phenylcyclopropylamines (øC3B), (+) (S)‐ and (−) (R)‐trans‐1,2‐bis(methylamino)‐cyclopropanes (C3MB), and (+) (S)‐ and (−) (R)‐trans‐(2‐phenylcyclopropyl)‐methylamines (øC3MB) were prepared.
Copolymerization parameters of methyl methacrylate and acrylic acid
Authors: Stahl G. Allan
Published: April 2003

The relative reactivity of acrylic acid is known to be influenced by the polymerization medium. Nonetheless, the more commonly used reactivity ratios do not show this dependence because they were calculated from low‐conversion polymerizations. We have studied the copolymerization of acrylic acid and methyl methacrylate in a number of non‐hydrogen‐bonding and hydrogen‐bonding solvents. We found that the acrylic acid fraction in the copolymer was larger when copolymerized in a non‐hydrogen‐bonding medium and that the methyl methacrylate fraction was larger when copolymerized in a hydrogen‐bonding medium. The precise reactivity ratios were reported when toluene, benzene, isopentyl, acetate, ethyl acetate, methyl formate, and tert‐butyl alcohol were used as the polymerization medium. The values were obtained by chromatographic analysis of residual monomer, followed by computation based on the nonlinear, least‐squares technique of Tidwell and Mortimer.
Kinetics and mechanism of urethane formation catalyzed by organotin compounds. I. The reaction of phenyl isocyanate with methanol in dibutyl ether under the action of dibutyltin diacetate
Authors: Van Der Weij F. W.
Published: April 2003

The kinetics of the dibutyltin diacetate (DBTDA) catalyzed reaction of phenyl isocyanate with methanol in dibutyl ether at 25°C were studied by monitoring the rate of change in the absorbance of the reaction mixture at 281.6 nm. The rate equation was

The value of k was calculated at 0.96 liter/(mole sec). In addition, it was ascertained that protons behave like extremely strong inhibitors for the catalyzed reaction. On the basis of these data a mechanism for urethane formation is proposed. The subsequent reaction steps are (1) complexation of methanol to DBTDA, (2) dissociation of the complex into a proton and an anion of composition {(n‐C4H9)2Sn(OCOCH3)2(OCH3)}‐, (3) insertion of the isocyanate into the tin‐alkoxy bond (the rate‐determining step), and (4) methanolysis of the urethane precursor formed with simultaneous regeneration of the anion. With this mechanism it is possible to explain the observed kinetics as well as the deviations that occur in the rate expression if strong acids are added to the reaction mixture. The latter effect is caused by a shift in the equilibrium that describes the dissociation of the complex into ions. The retardation of the reaction by weak acids like acetic acid is caused by complexation of DBTDA by the acid.
The synthesis of biscitraconimides and polybiscitraconimides
Authors: Galanti Anthony V. , Scola Daniel A.
Published: April 2003

A series of N‐alkylene biscitraconimides was synthesized from the corresponding N‐alkylene‐biscitraconamic acids or directly from itaconic anhydride and a homologous series of aliphatic diamines, H2N(CH2)nNH2, where n = 2 through 12. The biscitraconamic acids were synthesized from the α,ω‐diamino‐alkanes and itaconic anhydride. Isomerization of itaconic anhydride to citraconic anhydride occurs in the presence of the diamines to yield biscitraconamic acids instead of bisitaconamic acids expected and observed in similar studies. The intermediate biscitraconamic acids or the biscitraconimides were polymerized thermally between 175 and 225°C to tough ambered‐colored films of polybiscitraconimides that exhibit good thermal stability.
Redox cationic polymerization: The diaryliodonium salt/ascorbate redox couple
Authors: Crivello J. V. , Lam J. H. W.
Published: April 2003

Strong Brønsted acids are produced on reduction of diaryliodonium salts containing anions of the type BF4−, AsF6−, PF6−, SbF6− by ascorbic acid and its derivatives in the presence of catalytic amounts of copper salts. The cationic polymerizations of cyclohexene oxide, tetrahydrofuran, and s‐trioxane were studied using the diaryliodonium salt/ascorbate redox couple.
Stepwise thermal degradation of a polybenzimidazole foam
Authors: Chatfield Dale A. , Einhorn Irving N.
Published: April 2003

The stepwise thermal degradation of a polybenzimidazole (PBI) foam, prepared from 3,3′‐diaminobenzidine and isophthaldiamide, has been studied under conditions of pyrolysis and nonflaming oxidative degradation in a thermal analyzer using gas and liquid chromatographic separation and mass spectrometric and infrared detection techniques. The recoveries of sample weight, as degradation products, were quantitative over the entire temperature ranges studied (100–300, 300–570, 570–700, and 700–1000°C for pyrolysis; and 100–570 and 570–900°C for nonflaming oxidation). In pyrolysis, 17 volatile compounds were identified with NH3 and CH4 accounting for 94 and 57 mole % of the total mass loss between 300–570 and 570–700°C, respectively. Above 700°C, HCN and H2 were formed from degradation of arylnitrile‐containing oligomers. The thermal and oxidative degradation of three substituted benzimidazole monomers was also studied, and the relative ratios of N2, NH3, and HCN that were produced from each, when compared with PBI, support a mechanism for degradation that favors cleavages that least alter the conjugation of the polymer backbone. In the presence of air, PBI formed stable oxygen‐containing residues that decomposed at high temperatures to N2, CO2, and H2O almost exclusively. Large quantities of H2 and N2 from model compounds support results from PBI that suggest that degradation begins with total erosion of the imide ring at 570°C and the formation of more condensed heterocyclic species. These quantitative techniques are generally applicable to the study of all polymeric materials.
Chemistry of dicumyl peroxide‐induced crosslinking of linear polyethylene
Authors: Hulse George E. , Kersting R. James , Warfel David R.
Published: April 2003

The course of intermolecular reactions induced by peroxide decomposition in linear polyethylene has been determined and compared with similar reaction systems in which the substrate is a lowmolecular‐weight alkane. Efficiency of intermolecular coupling is 40% for an alkane and 25–30% for the polymer system. Competing reactions, which reduce coupling efficiency, are mainly disproportionation of the initially formed radicals and to a minor extent further reactions involving the products from the peroxide decomposition. The low efficiencies found are similar to those well studied when initial radicals are produced by radiolysis in polymer and alkane systems.
Controlled introduction of allylic chlorines into poly(vinyl chloride)
Authors: Iván Béla , Kennedy Joseph P. , Kelen Tibor , Tüdos Ferenc
Published: April 2003

Colorless poly(vinyl chloride)s (PVC) containing up to 1.6 allylic chlorines per molecule have been prepared by controlled random dehydrochlorination with a strong base. The effect of temperature in the −50 to +24°C range on the number of allylic chlorines and color of PVC has been investigated by ozonization experiments and UV–visible spectroscopy. A two‐parameter kinetic model has been developed which quantitatively accounts for the observations and points the way for further research.
Synthesis and properties of novel poly(N‐oxyimide)s
Authors: Ibrahim A. Mahammad , Mahadevan V. , Srinivasan M.
Published: April 2003

Novel poly(N‐oxyimide)s (PNOI) were synthesized by the room temperature polycondensation of N,N′‐dihydroxypyromellitimide (I) with dichloro compounds in N,N‐dimethylformamide (DMF) in the presence of triethylamine both as base as well as catalyst. The dichloro compounds used were 1,4‐bis(chloromethyl)‐2,5‐dimethylbenzene (II), 1,5‐bis(chloromethyl)‐2,4‐dimethylbenzene (III), 1,4‐bis(chloromethyl)‐2,5‐dimethoxybenzene (IV) and 1,4‐dichlorobut‐2‐yne (V). Polymer synthesis, characterization, and properties such as density, viscosity, solubility, crystallinity, and thermal stability were described. Two model compounds, viz. (i) MNOI‐1 from N‐hydroxyphthalimide and a dichloro compound (III), (ii) MNOI‐2 from I and benzyl chloride were also synthesized to confirm the formation of polymers. The polymers thus obtained had high intrinsic viscosities in the range 1.09–1.18 dl/g. The thermal decomposition of the polymers started around 260°C with 20–25% decomposition and about 50% weight loss was observed at 400°C.
Synthesis and characterization of polyesters derived from polychlorinated aromatic diacids
Authors: D´iaz Fernando R. , Larraín Rafael R. , Fresno Andrés , Ramirez René S.
Published: April 2003

New, thermally stable polyesters with varying chlorine content were prepared by solution and interfacial polycondensation between chlorinated aromatic dichlorides (perchloroterephthaloyl dichloride, 2,5‐dichloroterephthaloyl dichloride, and perchloro‐4,4′‐dichloroformyl biphenyl with different aliphatic and aromatic diols). The polymers were characterized by infrared spectroscopy, elemental analysis, differential scanning calorimetry, and thermogravimetric analysis. Their solubilities and molecular weights were also determined. The influence of chlorine content on the thermal properties of the polymers is discussed.
Silylation of water glass. II. Synthesis and copolymerization of carbon‐functional silylated silicic acid
Authors: Inoue Hiroshi , Kohama Shigemi
Published: April 2003

Carbon‐functional silylates were prepared by reacting trialkoxysilanes and trimethylchlorosilane with silicic acid which had been derived from aqueous sodium silicate solution. The trialkoxysilanes used here were polymerizable silanes, i.e., vinyltriethoxysilane, (γ‐methacryloyloxypropyl)trimethoxysilane, and (p‐vinylphenyl)triethoxysilane. Molecular weights of these silylates containing more than one mole of the functional group ranged from 4000 to 9000. These silylates were found to serve as effective crosslinking agents for vinyl polymerization. However, soluble copolymers could be obtained under appropriate conditions, such as high dilution and low conversion in copolymerization. Glass transition temperatures (Tg) of the soluble copolymers were measured by differential scanning calorimetry to determine the effect of the silylates on the thermal properties of the copolymers. A slight variation of the Tg of these copolymers was observed when small amounts of the silylates were incorporated. It was also noticed that the water repellency of these copolymers was influenced by their composition.
Kinetics of the reaction of poly(α‐methylstyryl sodium, potassium, and cesium) with t‐butyl chloride in tetrahydrofuran
Authors: East G. C. , Ellis H. A.
Published: April 2003

The kinetics of the reaction of “living” poly(α‐methylstyrl sodium, potassium, and cesium) with t‐butyl chloride have been studied spectrophotometrically in tetrahydrofuran (THF) in the temperature range 283–303 K. The reactions, when the free ions present in solution are suppressed by tetraphenylboron salt, are first order with respect to both living ends and halide concentrations. Additions of tetraphenylboron salts produce a slight retardation effect on the rate of reaction in the case of sodium, indicating only a small contribution of free ions to the overall rate; in the case of potassium, there is no apparent effect. Analysis of the data indicates that the free ion is approximately 30 times more reactive than the sodium ion pair. The Arrhenius plots for contact ion‐pair termination are linear and the activation energies and preexponential factors determined are E = 38.6 kJ mole−1, log A = 4.44 liter mole−1 sec−1 and E = 46.0 kJ mole−1, log A = 5.10 liter mole−1 sec−1. The reaction mechanism is interpreted in terms of elimination plus some side reaction to produce two unexpected reaction products—isobutane and a 315–320‐nm absorbing grouping in the polymer.
Thermal degradation of vinyl alcohol/vinyl acetate copolymers. III. Study of the reaction products
Authors: Vasile Cornelia , Cas̨caval C. N. , Barbu P.
Published: April 2003

The thermal decomposition of vinyl alcohol/vinyl acetate copolymers have been studied at p = 10−2–10−4 Torr and T = 0–600°C. The decomposition products (solids, liquids, and gases) have been characterized by infrared (IR) and ultraviolet (UV) spectroscopy, gas chromatography, vapor pressure osmometry, and elemental analysis. It has been ascertained on the basis of the obtained data that the decomposition mechanism of the vinyl alcohol/vinyl acetate copolymers depends on the chemical composition and sequence distribution of comonomers.
Synthesis and thermal properties of crosslinkable phosphazene copolymers
Authors: Zeldin Martel , Jo Won Ho , Pearce Elim M.
Published: April 2003

Polyphosphazenes of formula [NP(OC6H4CN)x(OCH2CF3)2−x] (x = 0.04–2) were prepared. The copolymers were crosslinked via cyclotrimerization of the nitrilic function, using acid catalysts (chlorosulfonic acid, aluminum chloride) at elevated temperatures. The thermal properties of the crosslinked cyclomatrix polymer were compared to the linear polymer by thermogravimetric analysis and differential scanning calorimetry. When the 4‐cyanophenoxy‐2,2,2‐trifluoroethoxy ratios were less than 0.2, the crosslinked polymers were soluble in polar organic solvents.
Etude structurale du polypentadiene‐1,3 par spectrometrie de RMN du 13C
Authors: Aubert Patrick , Sledz Joseph , Schué F. , Brevard Christian
Published: April 2003

The structure of stereoregular polymers of 1,3‐pentadiene was determined by 13C‐NMR spectroscopy at 22.6 MHz. Not only was it possible to distinguish between cis‐1,4 and trans‐1,4 but also between isotactic and syndiotactic cis‐1,4 structures. Triad effects were detected in the trans‐1,2 syndiotactic polypentadiene; 1,4–1,2 as well as 1,4–4,1 linkages were observed.
Determination of reactivity ratios for the copolymerization of styrene and styrene–acrylonitrile with polybutadienes
Authors: Hayes Robert A.
Published: April 2003

The copolymerization of styrene and styrene–acrylonitrile with polybutadienes of various microstructures was studied and the reactivity ratios determined. It was shown that for the styrene/acrylonitrile/polybutadiene systems the 1,2 structure is twice as reactive as the trans and four times as reactive as the cis. Studies in the temperature range of 50–80°C reveal that the reactivity of the polybutadiene increases as the temperature rises. When styrene is the monomer the reactivity of polybutadiene and the temperature effect is less intense than when styrene–acrylonitrile is used.
Heats of reaction of two common cellulose solvents with various model compounds
Authors: Dale Bruce E. , Tsao George T.
Published: April 2003

Heats of reaction of two common cellulose solvents, cadoxen and ferric sodium tartrate (FeTNa), with a variety of cellulose‐related compounds were obtained with a sensitive adiabatic microcalorimeter. Both solvents require adjacent hydroxyl groups in the equatorial positions of ring systems for maximum reactivity (or maximum exothermic heat of reaction). The cellulose solvent cuprammonium has a significantly different pattern of reactivity toward a number of sugars compared with the patterns observed for cadoxen and FeTNa. These differences are explained in terms of the Jahn‐Teller effect and the preferred sites of reaction and oxidation in ring systems. Calorimetric evidence indicates that complexes containing methoxy groups may be formed by both cadoxen and FeTNa.
Oligomeric bishydroxybutyl terephthalates from terephthalic acid
Authors: Padias A. Buyle , Hall H. K.
Published: April 2003

A process that uses terephthalic acid and excess 1,4‐butanediol for the production of polybutylene terephthalate was investigated and the reaction conditions were maximized for fast reaction and minimal loss of butanediol by dehydration to tetrahydrofuran. For best results a mixed catalyst was selected: butylstannoic acid and titanium tetrabutoxide (0.05 and 0.025 mole %, respectively, versus terephthalic acid) with a starting material ratio of butanediol: terephthalic acid of 1.7 at 210°C. The mixture cleared at 2.5 hr with a loss of 6% of butanediol. HPLC analysis showed that the clearing point corresponds to the disappearance of terephthalic acid and monohydroxybutyl terephthalate from the reaction mixture. Thus the polycondensation conditions can be applied before the clearing point with the result that the reaction is faster and tetrahydrofuran formation is minimized. Tetrahydrofuran is formed from butanediol in the reaction mixture by acid catalysis. Excess butanediol results in the formation of larger amounts. End group cyclization of terephthalate esters accounts for the slow tetrahydrofuran formation in the absence of excess butanediol.
Preparation of phosphorus‐containing polymers. XXV. Polyamide‐imides that contain phenoxaphosphine rings
Authors: Sato Moriyuki , Tada Yuji , Yokoyama Masaaki
Published: April 2003

New phenoxaphosphine‐containing polyamide‐imides were prepared by cyclodehydration of the polyamide‐amic acids obtained from 8‐chloroformyl‐10‐phenylphenoxaphosphine‐2,3‐dicarboxylic anhydride 10‐oxide and diamines by a low‐temperature solution polycondensation. Polymers with reduced viscosities of 0.10–0.59 dl/g in DMA or concentrated H2SO4 at 30°C were obtained in 64–97% yields. All the polyamide‐imides were soluble in m‐cresol, concentrated H2SO4, and dichloroacetic acid and some of them were soluble in DMF, DMA, and DMSO; the polyamide‐imides had better solubility in organic solvents than phenoxaphosphine‐containing polyimides. The phenoxaphosphine‐containing polyamide‐imides derived from aromatic diamines exhibited excellent thermal properties and little degradation below about 400°C, whereas the polymers from aliphatic diamines began to lose weight at about 250°C. They appeared to have thermal stability between phenoxaphosphine‐containing polyimides and polyamides. These polyamide‐imides exhibited self‐extinguishing behavior.
Syntheses and reduction of polymers with alloxan structures
Authors: Endo Takeshi , Fujiwara Eishuke , Okawara Makoto
Published: April 2003

The polymer(Poly A) which contains alloxan moiety was prepared by the oxidation of the copolymer of allyl barbituric acid and vinyl acetate with chromium trioxide. The photoreduction of Poly A by ultraviolet (UV) irradiation was used to isolate the polymer(Poly A·) in which the alloxan radical was present. The properties of this polymer(Poly A·) thus obtained were investigated. Poly A was also reduced by chemical agents to obtain the polymer(Poly D) which had a dialuric acid structure.
Radical copolymerization of proto‐hemin dimethyl ester
Authors: Nishide Hiroyuki , Shinohara Kenichi , Tsuchida Eishun
Published: April 2003

Iron(III) proto‐porphyrin IX dimethyl ester (HDME) can copolymerize with π‐conjugated monomers binding at one end of the polymer chain. Apparent Q, e values of HDME were Q = 70 and e = −0.17. The copolymerization of HDME with π‐unconjugated monomer was feasible by using π‐conjugated monomer as a third component. When unconjugated vinylimidazoles were used as monomers, the obtained ternary copolymers of HDME formed intramacromolecular complexes of iron(II) porphyrin with vinylimidazole residues, which gave stable carbon monoxide adducts.
Analysis of the linear methods for determining copolymerization reactivity ratios. VI. A comprehensive critical reexamination of oxonium ion copolymerizations
Authors: Tüdos F. , Kelen T. , Turcsányi B. , Kennedy Joseph P.
Published: April 2003

The reactivity ratios of 180 published oxonium copolymerization systems have been reviewed in terms of the extended Kelen–Tüdos method. Only 32 (17.8%) systems were described in sufficient detail for reevaluation and classification. r Values, together with their 95% confidence limits have been calculated. A quantity δ□, suitable for classification of the systems, has been introduced. Of the 32 reevaluated systems, five were found to belong to class I and 14 to class I(!), i.e., 19 systems for which the conventional copolymerization equation was found to be adequate. Class II systems were not found. Finally, 13 systems were judged to belong in class III, i.e., systems for which the experimental data are inconsistent and the published r values meaningless.
ESR of free radical reactions in gamma‐irradiated ethylene–propylene‐based terpolymers. II
Authors: Faucitano A. , Buttafava A. , Cesca S.
Published: April 2003

The gamma irradiation at liquid nitrogen temperature of dicyclopentadiene, 2‐methylennorbornene, and cyclopentadienyl‐5‐endo‐norbor‐2‐enyl‐methane‐based ethylene–propylene terpolymers leads to the formation of macroradicals of the alkyl type by loss of hydrogen atoms from the ethylene–propylene chains. When warmed almost to glass transition temperature these primary alkyl species decay and generate new radicals by the double‐bond addition and/or H abstraction from the unsaturations. The nature of the radical products was determined by ESR and MO methods.
Preparation and properties of aromatic polypyrazoles from branched bis‐β‐diketones and aromatic dihydrazines
Authors: Imai Yoshio , Nakajima Toshio , Ueda Mitsuru
Published: April 2003

Aromatic polypyrazoles were prepared by the cyclopolycondensation of branched bis‐β‐diketones with aromatic dihydrazines. The polymerizations were carried out at 100–150°C in m‐cresol or a polar aprotic solvent like dimethyl sulfoxide to produce polymers with inherent viscosities up to 0.98 dl/g. These polypyrazoles were readily soluble in a wide range of solvents that included chloroform and exhibited 10% weight losses between 380 and 425°C in air and 370 and 500°C in nitrogen.
Radiation‐induced polymerization at high dose rate. V. Butadiene in bulk
Authors: Hayashi Kanae , Tanaka Yoshinori , Okamura Seizo
Published: April 2003

Bulk butadiene was polymerized by a cationic mechanism in a wide dose rate range. The M̄n of the product was about 2300, independent of dose rate. The polymer had 83% residual unsaturation and the remaining double bond was 77% trans and 23% vinyl and had no cis unit. When the polymer yield exceeded 10% gel was formed, but the value of the residual unsaturation in the polymer remained unchanged. This indicated a mechanism that correlated propagation, cyclization, and crosslinking reactions with a cationic intermediate.
Compatibility studies of styrene and hydroxyl containing styrene copolymers with poly(ethylene oxide)
Authors: Ting S. P. , Bulkin B. J. , Pearce E. M. , Kwei T. K.
Published: April 2003

Copolymers of styrene with vinylphenyl trifluoromethyl carbinol, p‐vinylphenyl trifluoromethyl carbinol, vinylphenyl hexafluorodimethyl carbinol, and p‐vinylphenol are conditionally compatible with poly(ethylene oxide), depending on their composition and blending ratios, whereas copolymers of styrene and vinylphenyl methyl carbinol are much less compatible with poly(ethylene oxide), as determined by Tg criteria and differential scanning calorimetry. The crystallinity of poly(ethylene oxide) is changed in the copolymer/poly(ethylene oxide) blends, as indicated by depressions of the poly(ethylene oxide) melting point. Hydrogen‐bond formation has been studied in two selected blends by infrared (IR) spectroscopy. Hydrogen bonding dissociation and reassociation as a function of temperature are reported. The conformation changes of poly(ethylene oxide) in the blends, the interaction between copolymer and poly(ethylene oxide) as well as in the reference blend, polystyrene/poly(ethylene oxide), are also investigated.
Radical processes in polymer burning and its retardation. I. ESR methods for studying the thermal decomposition of polymers in the preflame and flame zones
Authors: Tkáč A.
Published: April 2003

The determination of the free radical distribution in the preflame and flame zones of a burning polymer (polypropylene) by ESR leads to the conclusion that in all phases of the burning polymer an exothermic reaction zone encloses an oxygen‐free pyrolytic zone. Whereas in the molten preflame zone (250–350°C) the polymer decomposes to oligomers, dimers, monomers, and the relevant free radicals or biradicals, in the gaseous flame zone the heat transport from the hot outer surface into the surrounding pyrolytic zone leads (with an increasing temperature gradient) to a progressive formation of thermodynamically more stable decomposition products. The CH. radicals generated at 400–800°C, after rapid cooling, yield polyaromaties with delocalized free electrons and the atomized carbon and its dimers at 800–1200°C, after cooling, yield graphite sheets with localized free electrons in its defects. Free radicals and paramagnetic species are trapped (a) in the gaseous pyrolytic products of heated polymers on the surface of a rotating cryostat, (b) in burning polymer drops by quenching in liquid nitrogen, and (c) in different zones of a burning diffuse flame. The superimposed ESR signals of the paramagnetic products are then qualitatively and quantitatively analyzed.
Grafting of monodisperse low‐molecular‐weight polystyrene onto cellulose acetate
Authors: Månsson Per , Westfelt Lars
Published: April 2003

Well‐defined low‐molecular‐weight polystyrene was grafted onto cellulose acetate in a homogeneous solution. The grafting was performed by esterifying the free hydroxyls in the cellulose acetate (acetyl DS 2.5) with anionically prepared polystyrene having a carboxylic acid group at one end of the chain. The carboxylic acid end group of the polystyrene was activated by either conversion to the corresponding acid chloride, or by reaction with trifluoroacetic anhydride. Pyridine and the more active 4‐dimethylaminopyridine were used as catalysts in the esterifications. The polystyrene contents of the copolymers varied between 10 and 80% and the molecular weights of the polystyrene grafts were 2500, 12,100 and 17,100 (M̄w/M̄n = 1.1).
Radiation‐induced copolymerizations of perfluorovinyl acetic acid and its methyl ester with α‐olefin
Authors: Kawaguchi Mitsuo , Watanabe Terutaka , Matsuda Osamu , Tabata Yoneho , Machi Sueo
Published: April 2003

Homopolymerizations and copolymerizations of perfluorovinyl acetic acid (FVA) and its methyl ester (MFVA) were carried out by γ radiation at a temperature of 25°C, a dose rate of 1 × 106 rad/hr, and FVA/α‐olefin and MFVA/α‐olefin ratios of 10/90‐90/10 in the monomer mixture. FVA and MFVA gave small quantities of brown and greasy low‐molecular‐weight homopolymers. The polymerization rates of both FVA and MFVA were extremely small, as shown by the maximum G value of monomer consumption of 12. FVA and MFVA reacted with α‐olefin to form waxlike copolymers. The copolymerization rates of both FVA and MFVA with α‐olefin were remarkably larger than those of the homopolymerizations, particularly with ethylene. The polymer compositions of FVA/ethylene or MFVA/ethylene was nearly 1/2 over a wide range of the monomer compositions. The Mayo–Lewis method gave negative r1 (FVA) and r1 (MFVA). The polymer composition curves could be well interpreted by introducing the penultimate model.
Fundamental considerations on the mechanism of copolymerization of trioxane and ethylene oxide initiated with boron trifluoride dibutyl etherate
Authors: Collins G. L. , Greene R. K. , Berardinelli F. M. , Ray W. H.
Published: April 2003

A comprehensive mechanistic scheme that accounts for the unique experimental features of the copolymerization of bulk trioxane (TOX) with 2% (wt/wt) ethylene oxide (EO) was developed. The formation of the primary initiating species is shown as the diffusion‐limited reaction of trace water with boron triflouride dibutyletherate [BF3O(Bu)2] to form a Bronsted acid. This acid complexes principally with the more basic EO and partly with the less basic TOX. The acid‐complexed TOX depolymerizes to formaldehyde which can react with acid‐complexed EO in an insertion reaction to form an acid‐complexed dioxolane. Further insertion of formaldehyde yields an acid‐complexed trioxepane. This sequence is generalized into a propagation scheme that involves propagation by expansion and ring opening. Displacement of complexed dioxolane and trioxepane can occur in the event that the more basic EO attacks the oxonium‐active site at the reactive position outside the oxonium ring. These displacement reactions account for the observation of formation of dioxolane and trioxepane. The polymerization of formaldehyde is not considered significant until all EO has been consumed. During the latter stages of polymerization, cyclic oxonium‐active sites are transformed into oxocarbenium sites that are stabilized by complexation with the polymer chain. This complexation is the origin of the phenomena of transacetalization and hydride transfer.
Studies of the formation of thermosetting resins. XII. Computer simulation of the reactions of phenols with formaldehyde
Authors: Ishida Shin‐Ichiro , Tsutsumi Yoshitomo , Kaneko Katsumasa
Published: April 2003

The mechanism of the reaction of phenols with formaldehyde was studied by computer simulation. At first starting molecules were stored in a computer and the hypothetical reaction yielded conditions like the reactivity ratio of hydroxymethyl group to formaldehyde and that of orthohydrogen to parahydrogen. The molecular weight distribution of the hypothetical product in the computer was compared with that of the prepared resin determined from GPC measurement. Reaction mechanisms were discussed. We also confirmed, by computer simulation, that the rate of methylenation is larger than that of hydroxymethylation in an acid‐catalyzed system and that the reactivity ratio of hydroxymethyl group to formaldehyde is 5–12 for the reaction of phenols such as o‐cresol, p‐cresol, and phenol with formaldehyde. The opposite results were obtained in a base‐catalyzed system. It also became apparent that information regarding molecular structures, such as the number of branches, the number of phenolic nuclei in the longest chain, and the number of o,o′‐,o,p′‐ and p,p′‐methylene linkages, can be obtained by computer simulation. The most probable values of these factors for 10 mer of a phenol–formaldehyde condensation molecule are 2, 7, 2, 5, and 2.
Polyethylenimine catalysts containing an isolated apolar binding site: Solovolysis of p‐nitrophenyl esters
Authors: Pavlisko J. A. , Overberger C. G.
Published: April 2003

The preparation dodecane‐block‐poly[ethylenimine‐graft‐4(5)‐methylimidazole] copolymers and related model compounds has been described and such polymers have been described and such polymers have been demonstrated to be efficient catalysts for the hydrolysis of activated phenyl esters in aqueous solutions. Polymeric catalysts that contain isolated apolar blocks exhibited enhanced catalytic activity for the hydrolysis of the p‐nitrophenyl esters of acetate and butyrate compared with polymer model compounds. This rate enhancement was atributed to the apolar binding of substrate within the apolar polymer regime. Twenty‐to 100‐fold increases in the second‐order rate constants were observed for the hydrolysis of the longer‐chain p‐nitrophenyl esters. This is indicative of a significant hydrophobic interaction. The contribution of the apolar block to the hydrophobic interaction was masked in the hydrolysis of the p‐nitrophenyl caproate and p‐nitrophenyl laurate substrates. In both instances the dominant contribution to the hydrophobic interactions was ascribed to a substrate‐imidazole intermediate rather than the apolar block of the catalyst. The pH‐rate profiles for the hydrolysis of p‐nitrophenyl esters by the various catalysts indicated an absence of any cooperative interactions between imidazole residues or amine groups.
Cationic metal nitrosyl complexes. IV. Polymerization of olefins with dinitrosyl iron complexes
Authors: Ballivet‐Tkatchenko D. , Billard C. , Revillon A.
Published: April 2003

The polymerization of styrene was performed with new cationic iron complexes, (Fe(N‐O)2Sn)+PF6−(BF4−, CIO4−), where Sn represents solvent molecules such as CH2Cl2, THF, and MeCN. Kinetic experiments showed a first‐order dependence of (Rp)0 on the monomer and iron complex concentrations. The molecular weight determinations suggested that the termination process is fast and occurs by chain transfer to monomer. An extension of this polymerization to α‐methylstyrene, isobutene, tetrahydrofuran, and styrene‐methylmethacrylmate system emphasized the cationic nature of the reaction.
Functional monomers and polymers. XCIII. Photochemical reactions on the acrylic and methacrylic copolymers containing thymine bases
Authors: Kita Yasuo , Uno Taizo , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

Photodimerization of Polyacrylic and polymethacrylic derivatives with different pendant thymine unit content was studied in dimethylformamide solution. The quantum efficiency of thymine base for the photodimerization increased with increasing thymine content in the copolymers. The quenching study, which used isoprene as the quencher, revealed that the photodimerization resulted from excited singlet state increases with increasing thymine content. The photochemical results were discussed in terms of self‐association of thymine bases in the polymer chain.
Complexation of metal ion with poly(1‐vinylimidazole) resin prepared by radiation‐induced polymerization with template metal ion
Authors: Kato Masayuki , Nishide Hiroyuki , Tsuchida Eishun , Sasaki Takashi
Published: April 2003

Poly(1‐vinylimidazole) (PVI) resin was prepared with Ni2+, Co2+, or Zn2+ as a template to study the adsorption of metal ions. The metal‐1‐vinylimidazole complex was copolymerized and crosslinked with 1‐vinyl‐2‐pyrrolidone by γ‐ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These PVI resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites (As) and the stability constant (K) of Ni2+ complex were larger for the PVI resin prepared with the Ni ion template, caused by the smaller dissociation rate constant of Ni ion from the resin. The composition of the Ni2+ complex in the resin remained constant. This suggests that the complexation proceeded via a one‐step mechanism.
Encapsulation of pesticides in a starch‐calcium adduct
Authors: Shasha B. S. , Trimnell D. , Otey F. H.
Published: April 2003

A simple method of encapsulating water‐insoluble pesticides in a starch matrix is described. The method consists of mixing the pesticide with alkali starch followed by precipitation with a calcium chloride solution. A starch–calcium adduct that entraps the pesticide in small cells within granular particles is formed. Liquid and solid pesticides were successfully encapsulated by the new method. By use of the herbicide trifluralin [2,6‐dinitro‐N,N‐dipropyl‐4‐(trifluoromethyl) benzenamine] as core material more than 90% recovery and encapsulation was achieved. Use of acid‐modified starches and flours resulted in a lower percentage of encapsulation. Effective encapsulation was also achieved by replacing calcium chloride with strontium chloride or barium chloride.