bluuebunny/crossref_metadata_2025 huggingface dataset:
Radical addition to 2‐isopropenyl‐5‐butoxyoxazole
Authors: Drapier J. , Parla D. , Moniotte Ph. , Warin R. , Hubert A. J. , Teyssie Ph.
Published: April 2003

The preparation and the spectroscopic analysis of a dimeric adduct (V) obtained from 2‐isopropenyl‐5‐butoxyoxazole (III) and α,α‐azobis‐isobutyronitrile (AIBN) (IV) are reported. It is noteworthy that (III) inhibits completely the homopolymerization of styrene. This is in strong opposition to the facile homopolymerization and copolymerization of 2‐isopropenyl‐4,5‐dimethyloxazole with styrene. The smooth formation of (V) is also in sharp contrast to the lack of reactivity of (III) towards cationic initiators.
Monomer chain transfer in the copolymerization of styrene and butyl acrylate
Authors: Devon Michael J. , Rudin Alfred
Published: April 2003

Free radical chain transfer constants have been measured by copolymerizing styrene and butyl acrylate in emulsion at 60°C. Some improvements to this experimental technique are reported and estimates are given of the sensitivity of the calculated values to experimental uncertainties. Monomer chain transfer constants were found to be 1.2 × 10−4 (styrene) and 2.5 × 10−4 (butyl acrylate). The sum of the cross‐transfer constants is 2.7 × 10−4. The activation energy for chain transfer to styrene monomer is found to be 24 Kcal/mol in the 44°–60°C range.
A model study for coatings containing hexamethoxymethylmelamine
Authors: Meijer E. W.
Published: April 2003

Using a model reaction we have studied the crosslinking chemistry of hydroxy‐functional polymers and hexamethoxymethylmelamine. The transetherification of optically active monofunctional alcohols and hexamethoxymethylmelamine was monitored with polarimetry and 1H‐NMR. The reaction rate constants for both the forward (k1) and the backward (k−1) reaction of the sulphonic‐acid‐catalyzed alcoholysis were determined. Primary and secondary alcohols showed the same reaction rate and activation energy (Ea = 96 kJ/mol) for the forward reaction. However, the backward reaction in the equilibrium is considerably slower for primary alcohols than for secondary alcohols, with activation energies of Ea = 96 and 79 kJ/mol, respectively. When amine salts of sulphonic acids are used as catalysts, the Ea is increased from 97 to 116 kJ/mol in the case of primary alcohols. In concentrated aprotic solutions the reaction order in acid is 2.5. The same order in acid is found for the alcoholysis of acetaldehyde diethyl acetal. All the results strongly support the statement that the crosslinking reaction proceeds by an Sn‐1 mechanism. The results of this model study are compared with results obtained in network‐forming reactions. The important role of the evaporation of the condensation product methanol is discussed.
Thermotropic copolyesters containing the 1,4‐cyclohexylenedimethylene spacer
Authors: Onwumere Fidelis C. , Polk Malcolm B.
Published: April 2003

Poly[oxy(2‐methyl‐1,4‐phenylene)oxyterephthaloyl‐co‐oxy(2‐methyl‐1,4‐phenylene)oxy‐1,4‐cyclohexanediacetoyl] (I), poly[oxy(2‐chloro‐1,4‐phenylene)oxyterephthaloyl‐co‐oxymethylene‐1,4‐cyclohexylenemethyleneoxyterephthaloyl] (II), and poly[oxy(2‐methyl‐1,4‐phenylene)oxyterephthaloyl‐co‐oxymethylene‐1,4‐cyclohexylenemethyleneoxyterephthaloyl] (III) were synthesized and shown to form birefringent fluid states in the melt.
Living polymerization of isobutyl vinyl ether by HI/I2 initiator in polar solvents
Authors: Enoki Takashi , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

This study has shown a nearly perfect living polymerization of isobutyl vinyl ether (IBVE) to proceed not only in nonpolar media (e.g., n‐hexane) but in relatively polar CH2Cl2 solvent, provided that the HI concentration is sufficiently high. The produced polymers had a nearly monodisperse molecular weight distribution (Mw/Mn ≤ 1.1); the number‐average molecular weight (Mn) increased in direct proportion to IBVE conversion and its increase continued on the addition of a fresh feed of the monomer at the end of the polymerization. The use of a more polar medium (PhNO2/CH2Cl2) or a lower HI concentration leads to chain transfer reactions, by promoting the ionic dissociation of the “nondissociated” living propagating species. The successful living polymerization by HI/I2 in CH2Cl2 indicates a very strong interaction between the iodide anion and the growing end.
Poly(enamine‐ketones) from aromatic diacetylenic diketones and aromatic diamines
Authors: Sinsky M. S. , Bass R. G. , Connell J. W. , Hergenrother P. M.
Published: April 2003

Novel poly(enamine‐ketones) were prepared with inherent viscosities as high as 1.99 dL/g using the Michael‐type addition of various diamines to 1,1′‐(1,3 or 1,4‐phenylene)bis(3‐phenyl‐2‐propyn‐1‐one) in m‐cresol at 60–130°C. Tough, clear, amber films with tensile strengths of 12, 400 psi and tensile moduli of 397, 000 psi were cast from solutions of the polymers in chloroform. The polymers exhibited Tgs as high as 235°C and weight losses of 14% after aging at 232°C in circulating air for 60 h. The synthesis and characterization of several poly(enamine‐ketones) are discussed.
Crosslinked polydiacetylene and its two‐ and three‐component interpenetrating polymer networks (IPNs)
Authors: Ika Prasad V. S. , Frisch Harry L. , Walters Gary R. , Painter Paul C. , Frisch Kurt C.
Published: April 2003

The synthesis of crosslinked polydiacetylene [poly4ECMU (a polydiacetylene with ethoxy carbonyl methylene urethane substitution): where R = (CH2)4OCONHCH2COOCH2CH3] was carried out utilizing its polar and flexible substituent groups. Polydiacetylene was crosslinked by the formation of allophanate linkages utilizing urethane groups in the substituent groups of the polydiacetylene. Two‐component IPNs of polydiacetylene [poly4BCMU (a polydiacetylene with butoxy carbonyl methylene urethane substitution): where R = (CH2)4OCONHCH2COO(CH2)3CH3] and an epoxy resin (diglycidyl ether of Bisphenol A) were synthesized. Two‐component IPNs of poly4ECMU with the above epoxy resin were also synthesized. For the first time, two‐component stiff‐backbone IPNs of two different kinds of polydiacetylene (poly4BCMU and polyECMU) and a three‐component IPN of poly4BCMU, poly4ECMU, and the epoxy resin were synthesized. IPNs with fewer allophanate linkages were also made in order to examine morphological differences between them. The glass transition behavior of these networks was studied using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) by means of a Rheovibron.
Polymerization using palladium (II) salts: Homopolymers and copolymers from phenylethynyl compounds and aromatic bromides
Authors: Trumbo D. L. , Marvel C. S.
Published: April 2003

Low‐molecular‐weight homopolymers of m‐bromophenylacetylene, as well as copolymers and networks of select di‐ and triethynyl benzenes with di‐ and tribromobenzenes, have been synthesized via a coupling reaction utilizing a palladium (II) salt, triphenylphosphine, cuprous iodide catalyst system.
Products characterization of tung oil–phenol reactions based on analysis of a model reaction
Authors: Yoshimura Yukio , Nomoto Masahiro
Published: April 2003

A method of determining the molecular species composition distributions of products obtained by reaction of tung oil with various phenols in the presence of acid catalyst has been studied. Methyl α‐eleostearate was used as a model substance in place of tung oil. The product composition analysis of methyl α‐eleostearate reactions with phenols was done by HLC. From these results, the molecular weight distributions and molecular species composition distributions of the reaction products were calculated according to a statistical procedure. Good agreement was found between the calculated and experimental molecular weight distribution, which enabled prediction of the molecular species composition distribution.
Studies on some radical transfer reactions by entrapping the radicals as polymer end groups. I. Reaction of hydroxyl radicals with amines
Authors: Pramanick Dinabandhu , Bhattacharyya Ramanath
Published: April 2003

The reaction of OH radicals with a number of amines has been studied by entrapping the resultant radicals as polymer end groups which have been detected and estimated by the sensitive dye partition technique. Expressions have been developed relating the average amounts of end groups per polymer molecule to the rate constant of the radical transfer reaction, the rate constants determined for reaction with n‐butyl, n‐hexyl, and n‐octyl amine being 1.00 × 1010, 1.31 × 1010, and 1.46 × 1010 mol−1 L s−1, respectively, at 25°C. The order of reactivity for amines of different classes has been found to be as primary < secondary > tertiary, the rate constants for reaction with n‐butyl, dibutyl, and tributyl amine being 1.00 × 1010, 1.81 × 1010, and 1.67 × 1010 mol−1 L s−1, respectively, at 25°C. The change in the reactivity of the amine with chain length and amine class has been explained by activation and deactivation of the CH2 group from which H abstraction by OH radicals occurs, respectively, by the alkyl group and by the protonated amino nitrogen under the acidic condition of the medium. Between pH 1.00 and 2.17, the rate of the reaction with n‐butyl amine remains practically unchanged, but from pH 2.20 to 2.72 the rate constant increases with increasing pH, indicating that deprotonation of the positively charged nitrogen starts at about pH 2.20. The method is simple and accurate and can be applied to detect and estimate very reactive radicals.
The curing of epoxy resins with aminophenoxycyclotriphosphazenes
Authors: Kumar Devendra , Fohlen George M. , Parker John A.
Published: April 2003

Aminophenoxycyclotriphosphazenes have been used as curing agents for epoxy resins. The thermal curing was performed in stages at 120–125 and 175–180°C followed by postcuring at 225°C to give tough brown polymers. The thermal curing reaction was monitored using FTIR and differential scanning calorimetry. Thermogravimetric analysis of the cured resins has shown thermal stability up to 350–340°C. The char yield obtained in nitrogen at 800°C was about 55–42% and in air at 700°C was about 40–32%. Graphite cloth laminates were prepared. The mechanical properties evaluated were found superior to those of commonly used epoxy resin systems. These resins are useful for making fire‐ and heat‐resistant composites, laminates, molded parts, and adhesives.
Recovery of thick shear bands in atactic polystyrene
Authors: Kung Teh‐Ming , Li J. C. M.
Published: April 2003

The DSC thermograms of the shear band material cut out by a diamond saw to include some undeformed material revealed two Tg's clearly separated by about 10°C. The first Tg was at the same temperature as the Tg of the undeformed material. The second Tg, which was at a higher temperature than the first Tg, appeared shortly after the shear strain recovery during the heating of the shear band material in the DSC. When the shear strain in the shear band was partially reversed by mechanical means before taking the DSC thermogram, the ΔT between the two Tg's decreased and when the shear strain was mechanically reversed to almost zero, the second Tg disappeared. The stored energy of shear band material was found to be similar to that of the bulk compressed material for large strains. Dimensional recovery during heating of specimens with thick and fine bands was similar, both taking place above Tg.
Displacement polymerization. III. Synthesis and characterization of polyazoxyarylethers
Authors: Mandal Braja K. , Maiti Sukumar
Published: April 2003

A new class of polyazoxyarylethers was prepared by nucleophilic displacement polymerization using an activated dichlorocompound and a bisphenol dianion in anhydrous aprotic solvent. Model reactions were studied with 3,3′‐ and 4,4′‐dichloroazoxybenzene and various phenol and thiophenol salts to find out the reaction conditions for polycondensation. IR, 1H NMR, and elemental analyses were used to establish the structure of the model compounds and the polymers. Thermal analysis indicated that the oxy derivative is less prone to thermo‐oxidative degradation than the corresponding thio derivative of polyazoxyarylether. The polymers are crystalline and soluble in halogenated hydrocarbons and polar solvents.
Radiation‐induced graft copolymerization of N‐vinyl carbazole and methyl methacrylate onto cellulose acetate film
Authors: Bhattacharyya S. N. , Maldas D. , Pandey V. K.
Published: April 2003

N‐Vinyl carbazole methyl methacrylate, and the binary mixtures of these monomers were grafted onto cellulose acetate films by taking recourse to Co‐60 simultaneous irradiation grafting technique. The effect of various parameters (e.g., solvents, radiation dose, compositions of the monomers, and concentration of the monomers) on the extent of grafting in unitary and binary systems were studied. The optimum conditions for grafting were evaluated. The sensitizing effect of one monomer in the presence of other in the binary system was identified. The relative molecular reactivity and reactivity ratios were computed and these were used in explaining sensitization and the effect of monomer compositions on the extent of grafting in the binary system.
Novel polybenzoxazinones with tricyclic fused‐rings
Authors: Subramaniam Prema , Srinivasan Mahalingam
Published: April 2003

A series of polybenzoxazinones containing phenoxathiin and phenoxaphosphine units were prepared from tricyclic diacid chlorides and 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid and 4,4′‐diamino‐3,3′‐diphenylmethane dicarboxylic acid. The low temperature solution polymerization technique afforded polyamic acid which subsequently underwent cyclization along the polymer chain in a solvent mixture of refluxing N,N′‐dimethylacetamide, acetic anhydride, and pyridine to give polybenzoxazinones in moderate yields. The polymers thus obtained had inherent viscosities in the range of 0.15–0.23 dL/g, were sparingly soluble in N‐methyl‐2‐pyrrolidone, and were found to be thermally more stable than the corresponding open‐chain polymer with diphenylether linkage.
Free‐radical polymerization of methyl methacrylate and p‐fluorostyrene in the presence of the Mn(acac)3–AlEt3 catalyst system
Authors: Kothandaraman H. , Palanivelu K.
Published: April 2003

Methyl methacrylate and p‐fluorostyrene were polymerized with manganese (III) acetylacetonate–aluminum triethyl catalyst at 60°C in a benzene medium. Maximum activity was found at Al/Mn ratio of 4. Maximum percent conversion of polymer was obtained when the aging time of the catalyst was 10 min. The rate of polymerization was first order with respect to monomer. The rate of polymerization with respect to catalyst and cocatalyst were found to be 0.5 and 1.5, respectively. The overall energy of activation for the polymerization of methyl methacrylate and p‐fluorostyrene were found to be 52.6 and 57.0 kJ/mole, respectively. A free‐radical mechanism is postulated.
Investigation of polymer miscibility by spectroscopic methods V. Effect of molecular weight and block copolymerization of syndiotactic poly(methyl methacrylate) on its miscibility with poly(vinyl chloride)
Authors: Albert B. , Jerome R. , Teyssie Ph. , Baeyens‐Volant D.
Published: April 2003

Investigated by nonradiative energy transfer (NRET), the state of mixing of PVC and s.PMMA which is on the dimensional scale of a few nanometers is significantly affected by the chain length. When PVC is blended with s.PMMA of increasing molecular weight (MW), the longest chains of s.PMMA are likely to segregate from a homogeneous blend formed by PVC and low‐MW s.PMMA. The phase separation should therefore be of purely entropic origin and strongly dependent on both the relative percentage and the chain length of each component. These results are in qualitative agreement with conclusions previously drawn from DSC and transmission electron microscopy. NRET is a more powerful tool in probing heterogeneities compared to DSC and the thermally stimulated depolarization current method; it provides evidence against the previously suggested model of a 1:1 PVC/s.PMMA aggregate.
Influence of preferential solvation on the interpolymer complex formation between methacrylic acid–methacrylamide copolymer and poly(vinyl pyrrolidone)
Authors: Chatterjee S. K. , Malhotra A. , Yadav D.
Published: April 2003

Interpolymer complex formation has been studied between methacrylic acid–methacrylamide copolymer and poly(vinyl pyrrolidone) in acetone–water mixtures of different compositions. At a specific composition of the solvent (e.g., 70% water + 30% acetone by volume), the intrinsic viscosity of the copolymer and the reduced viscosity of 1:1 interpolymer complex had minimum values. Preferential solvation coefficients (λ/C) have been calculated for the various compositions of the solvent mixtures. An excellent coincidence could be obtained between the maximum (λ/C) and the minimum in the viscosity of the polymer solutions. Interpretations have been sought in terms of conformational change of the copolymer at the specific composition of the solvent mixture.
Water‐soluble copolymers. XIII. Copolymers of acrylamide with sodium‐3‐acrylamido‐3‐methylbutanoate: Solution properties
Authors: McCormick C. L. , Blackmon K. P. , Elliott D. L.
Published: April 2003

Dilute solution properties of copolymers of acrylamide (AM) with sodium‐3‐acrylamido‐3‐methylbutanoate (NaAMB) of known molecular weight have been studied as a function of composition, temperature, time, pH, and added electrolytes. Phase separation and potentiometric studies have also been performed. The AM–NaAMB copolymers exhibit high solution viscosities, good salt tolerance, and moderate viscosity‐temperature coefficients. In addition, these copolymers exhibit no phase separation in the presence of divalent cations as is common with many such carboxylated polyelectrolytes. These properties are due to favorable conformations in solution resulting from microstructure and hydrogen bonding effects.
Nucleic acid base grafted polyethylenimine. Cytosyl pendant groups synthesis and characterization
Authors: Chu V. P. , Overberger C. G.
Published: April 2003

Poly(N‐acyl ethylenimine) of various molecular weights was synthesized by the cationic ring‐opening polymerization of 2‐H‐2‐oxazoline and 2‐methyl‐2‐oxazoline. Acid hydrolysis afforded the linear poly(ethylenimine) which was used in the following grafting reactions. Vapor pressure osmometry, gel permeation chromatography and viscosity measurements were used to characterize the polymers synthesized.

Potassium 2‐(cytos‐1‐yl)propanoate and potassium 3‐(cytos‐1‐yl)butanoate were synthesized in good yield from the nucleic acid base. These cytosyl pendant groups were grafted onto the poly(ethylenimine) using 4‐chloro‐1‐(4‐chlorobenzenesulfonyl)benzotriazole, 93% graft, and norborn‐5‐ene‐2,3‐carboximido diphenyl phosphate, 70% graft. Grafting of the t‐butoxycarbonyl and n‐butoxycarbonyl protected cytosyl pendant groups resulted in a 47% and 40% graft, respectively.
Quenching of photo‐excited state of copolymer pendant Ru(bpy) complexes with methylviologen
Authors: Hou Xiao‐Huai , Kaneko Masao , Yamada Akira
Published: April 2003

Copolymer pendant tris(2,2′‐bipyridine)ruthenium(II) complexes were prepared from the copolymers of 4‐methyl‐4′‐vinyl‐2,2′‐bipyridine with styrene, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate, acrylonitrile, N‐vinylpyrrolidone, 4‐vinylpyridine, and quaternized 4‐vinylpyridine. The quenching of the photo‐excited state of the polymer complexes by methylviologen was studied. Pendant anionic groups such as acrylate enhanced remarkably the quenching of the cationic sensitizer by the cationic substrate, however, pendant cationic groups such as quaternized pyridine did not affect the reaction. The polymer chain showed generally retarding effect on the quenching reaction.
Gold(III) fluorosulfate as an initiator of the polymerization
Authors: Nevius M. , Dreyfuss P.
Published: April 2003

Gold(III) fluorosulfate was shown to have potential for initiating the polymerization and graft copolymerization of tetrahydrofuran (THF) and similar monomers at room temperature. Addition to THF of either gold(III) fluorosulfate or of gold(III) fluorosulfate and acetyl chloride (a model for a reactive polymer backbone) led to high yields (60–70%) of polytetrahydrofuran. IR, NMR, HPLC, and other studies were used to determine the mechanism of initiation in each case. They showed that in the absence of halide, the gold salt led to hydrogen abstraction from THF and formation of protonic acid, which then initiated polymerization. In the presence of halide, concurrent initiation due to the formation of tertiary oxonium ion by acetylation occurred. Gold(III) chloride precipitated simultaneously.
Synthesis and polymerization of racemic and optically active β‐substituted β‐propiolactones. III. β‐monosubstituted monomers and polymers
Authors: Voyer Richard , Prud'Homme Robert E.
Published: April 2003

Optically active β‐(1,1‐dichloroethyl)‐β‐propiolactone (CH3CCl2‐PL), β‐(1,1‐dichloropropyl)‐β‐propiolactone (C2H5CCl2‐PL), and β‐(1,1‐dichlorobutyl)‐β‐propiolactone (C3H7CCl2‐PL) were synthesized with enantiomeric excesses of 100, 100, and 84%, respectively. Polymerization was conducted in bulk and toluene solution, under vacuum, using mainly ZnEt2/H2O as initiator. Osmometry analyses indicate molecular weights in the range 10,000–25,000. The polymers thus prepared are semi‐crystalline and show large optical rotation values.13 C‐NMR was used to show that they have a high degree of isotacticity, indicating that little or no racemization occurs in the course of polymerization. Glass transition, melting and decomposition temperatures are given as a function of the size of the substituent, and their variations are discussed.
Preparation and properties of polyazo Schiff‐bases
Authors: Gopal Jayalakshmi , Srinivasan M.
Published: April 2003

Five colored polymeric Schiff‐bases were synthesized from 4,4′diaminoazo benzene and different dialdehydes and diketones. All the polymers were characterized by UV, IR, and NMR spectroscopy. Their physical properties and thermal characteristics are discussed.
Synthesis of poly(ethylene glycol methyl ether)‐b‐poly(ethylenimine) and its derivatives containing thymine and amino acids as pendants
Authors: Overberger C. G. , Peng L.
Published: April 2003

Poly(ethylene glycol methyl ether)tosylate was prepared and used to initiate the polymerization of 2‐methyl‐2‐oxazoline. The resulting poly(ethylene glycol methyl ether)‐b‐poly(N‐acetyl ethylenimine) was hydrolyzed and neutralized to give poly(ethylene glycol methyl ether)‐b‐poly(ethyl‐enimine) (PEO–PEI). 2‐(thymin‐1‐yl)propionic acid, N‐Cbz‐alanine, N‐Cbz‐proline, N‐Cbz‐O‐t‐Bu‐serine. and N‐FMOC‐proline were grafted onto the PEO–PEI copolymer; attempts were then made to remove the Cbz and FMOC protecting groups.
Preparation and characterization of polysuccinimides
Authors: Woo Edmund P.
Published: April 2003

A series of polysuccinimides has been prepared from 1,4‐bis(tetrahydrofuran‐2,5‐dion‐3‐yl)benzene and characterized by various thermal and mechanical methods. This new class of polyimides showed excellent solvent and heat resistance, balanced mechanical property profile, and toughness.
Poly(methyl methacrylate‐g‐urethane). II. Thermal and mechanical behavior
Authors: Akcelrud L. , Gomes A. S.
Published: April 2003

The thermal and mechanical behavior of poly(methyl methacrylate‐g‐urethane) has been investigated. Thermal analysis indicated compatibility between the two polymeric segments up to 15% polyurethane content. Tensile tests revealed progressive change in mechanical properties with composition, and the materials varied from glassy to leathery to rubberlike. Thermal and mechanical results suggested a morphological model where a glassy matrix of poly(methyl methacrylate) mixed with polyurethane is the continuous phase up to 25% polyurethane content, when a phase inversion occurs.
Poly(ethylene‐co‐propylene)‐g‐polystyrene through macromer polymerization: Preparation, morphology, and structure–properties relationships
Authors: Ma Jingjing , Pang Deren , Huang Baotong
Published: April 2003

Graft copolymers with ethylene‐propylene (EPR) backbone and polystyrene (PS) grafts, EPR‐g‐PS, were prepared by terpolymerization of a PS macromer with ethylene and propylene using a vanadium catalyst, with graft efficiency of up to 80% and PS content in the copolymer 5–45%. Such polymerization parameters as molecular weight and dosage of the macromer, catalyst concentration, and reaction temperature which affect the mobility and hence polymerizability of the macromer may have a marked influence on the polymerization and the structure of the products. The molecular architecture of the copolymers was characterized by osmometry, UV, NMR, and GPC methods. TEM and torsional pendulum studies revealed that EPR‐g‐PS possessed a phase separation morphology with PS domains evenly dispersed in the EPR matrix. The PS content and average number of grafts strongly influence the tensile properties of the copolymers. EPR‐g‐PS graft copolymers prepared by macromer copolymerization exhibit the mechanical properties of a typical thermoplastic elastomer having two or more branches of a certain length.
Catalysis in competing isocyanate reactions. II. Competing phenyl isocyanate reactions catalyzed with N,N′,N″‐pentamethyldipropylenetriamine
Authors: Wong Shaio‐Wen , Frisch Kurt C.
Published: April 2003

The kinetics of the N,N′,N″‐pentamethyl dipropylene triamine (PMPT)‐catalyzed reaction of phenyl isocyanate with n‐butanol was studied in acetonitrile between 26.5 and 50°C by measuring the NCO disappearance as well as the formation of the various reaction products by means of the standard dibutylamine back‐titration method and the high‐performance liquid chromatography (HPLC) method. The resulting products from the phenyl isocyanate and n‐butanol reaction were found to be N‐butyl phenylcarbamate, N‐butyl‐α,γ‐diphenylallophanate, and triphenylisocyanurate. Trimer formed at the expense of carbamate formation even at a high OH/NCO ratio. Allophanate appeared to be an intermediate in the formation of trimer. PMPT was found to be a urethane and trimerization catalyst for the model reaction of phenyl isocyanate with n‐butanol in acetonitrile. The PMPT‐catalyzed reaction of phenyl isocyanate with n‐butanol in the presence of water in acetonitrile at 50°C was also investigated. The resulting reaction products consisted of n‐butyl phenylcarbamate, n‐butyl‐β,γ‐diphenylallophanate, triphenylisocyanurate, sym‐triphenylbiuret, and N,N′‐diphenylurea. The presence of water retarded the disappearance of NCO groups as well as the trimer formation. Aniline (the product of phenyl isocyanate and water) was detected in the reaction of equivalent amounts of phenyl isocyanate and water in acetonitrile.
Synthesis of block cotelomers involving a perfluorinated chain and a hydrophilic chain. II. Use of fluorinated telogens with iodine or thiol end groups
Authors: Boutevin Bernard , Mouanda Justin , Pietrasanta Yves , Taha Mohamed
Published: April 2003

Radical acrylamide telomerization was carried out with three fluorinated telogens, C6F13C2H4I, C6F13I, and C6F13‐C2H4SH with AIBN as initiator. Transfer constants were determined to be 40 × 10−4, 550 × 10−4, and 6500 × 10−4, respectively. Reactions were carried out in butyronitrile, a solvent which also transfers to the growing chain. In the telomerization, the intervention of the solvent, whose transfer constant was also determined, is evaluated quantitatively. Thus the formation of side products, which may reach proportions on the order of 50% compared with the telomer expected, can be explained.
Living cationic polymerization of cis‐ and trans‐ethyl propenyl ethers and synthesis of block copolymers with isobutyl vinyl ether
Authors: Sawamoto Mitsuo , Ebara Kenji , Tanizaki Akio , Higashimura Toshinobu
Published: April 2003

The cationic polymerization of cis‐ and trans‐ethyl propenyl ethers (EPE, CH3CHCHOC2H5), initiated by a mixture of hydrogen iodide and iodine (HI/I2 initiator) at −40°C in nonpolar media (toluene and n‐hexane), led to living polymers of controlled molecular weights and a narrow molecular weight distribution (MWD) (M̄w/M̄n = 1.2–1.3). The geometrical isomerism of the monomer did not affect the living character of the polymerization. 13C NMR stereochemical analysis of the polymers showed that the living propagating end is sterically less crowded than nonliving counterparts generated by conventional Lewis acids (e.g., BF3OEt2). New block copolymers between EPE (cis or trans) and isobutyl vinyl ether were also prepared by sequential living polymerization of the two monomers.
Photocrosslinking of polymers bearing epoxy or epithio groups by quinones in the solid state
Authors: Cha Younsik , Kawasaki Motohiro , Tsunooka Masahiro , Tanaka Makoto
Published: April 2003

Photocrosslinking of poly(glycidyl methacrylate) (PGMA) and a copolymer of 2,3‐epithiopropyl methacrylate and methyl methacrylate [P(ETMA‐co‐MMA)] was studied in the solid state in the presence of various quinones. The efficiency of photocrosslinking was strongly dependent upon the structures of quinones and the kinds of polymers. For example, the alkyl‐substituted quinones such as 2‐ethyl‐p‐benzoquinone (EQ), 2‐tert‐butyl‐p‐benzoquinone (tBQ) and 2,5‐di‐tert‐butyl‐p‐benzoquinone (2,5‐dtBQ) did not induce photocrosslinking of poly(methyl methacrylate) (PMMA), whereas they acted as efficient photocrosslinking agents in PGMA and P(ETMA‐co‐MMA). The formation of charge transfer complexes did not play a principal role in this effective photocrosslinking, because the order of the photocrosslinking efficiency [EQ > tBQ > 2,5‐dtBQ > p‐benzoquinone (Q)] was not in agreement with that of the magnitude of the electron affinities of quinones, i.e., Q > EQ > tBQ > 2,5‐dtBQ. Photopolymerization of propylene sulfide (PS) in the presence of tBQ or Q was also investigated. The presence of tBQ induced polymerization of PS upon UV irradiation. From these results, it was deduced that the photocrosslinking of P(ETMA‐co‐MMA) film containing tBQ proceeds via a cationic polymerization of epithio groups. A similar mechanism should be applicable to the photocrosslinking of PGMA film containing tBQ.
Equilibrated radical polymerization of acrylic propionic anhydride as a mono‐ene counterpart of acrylic anhydride
Authors: Matsumoto Akira , Funamoto Hisashi , Oiwa Masayoshi , Butler George B.
Published: April 2003

Radical polymerization of acrylic propionic anhydride (APA) as a mono‐ene counterpart of acrylic anhydride (AA) was investigated in order to obtain supporting evidence for a previously proposed mechanism based on polymerization equilibrium for the cyclopolymerization of AA. The deviation from first‐order dependence of the rate of polymerization Rp on monomer concentration was enhanced by a decrease in monomer concentration. The Arrhenius plot of lnRp vs. 1/T was clearly curved in a highly dilute system. These results suggest increased significance of the depropagation reaction equilibrated with propagation under polymerization conditions favorable to five‐membered ring formation in cyclopolymerization of AA. Under these conditions, the disproportionation reaction of APA became important and the liberated AA was incorporated into the polymer chain through copolymerization with APA, resulting in poly(APA‐co‐AA) having five‐membered anhydride units.
SN‐conducting polymers with heterocyclic spacer groups
Authors: Chien James C. W. , Zhou Mei‐Ying
Published: April 2003

Polymer‐containing alternating sulfur nitrogen moieties separated by heterocyclic groups have been synthesized and characterized. The polymers have undoped conductivities of 10−6 to 10−9 (Ω cm)−1; the intrinsic carriers are negatively charged as shown by thermopower coefficient of −1.4 × 103 to −1.9 × 103 μV K−1. The polymers are degraded by AsF5 and cannot be doped by iodine. Exposure to bromine resulted in reversible p‐doping of the SN polymers to the thermopower values of +400 to +820 μV K−1 and conductivities of 0.01 to 0.002 (Ω cm)−1. Removal of dopant by evacuation returns most of the properties of the polymers to the undoped states. Magnetic properties of the materials have been studied.
Gamma‐ray polymerization of phospholipids having diene or triene groups as liposomes
Authors: Ohno Hiroyuki , Ogata Yoshitaka , Tsuchida Eishun
Published: April 2003

Small unilamellar liposomes were prepared in an aqueous medium by the sonication of phospholipids containing diene or triene groups in their hydrocarbon acyl chains. These liposomes were polymerized by gamma‐ray irradiation. Conversion of polymerization was successively followed by UV spectrometry. Diene‐type lipid liposomes were revealed for which a gamma‐ray dose of 0.8 Mrad was required for complete polymerization and which were polymerized more easily than triene‐type lipid liposomes. Triene‐type lipids required 2.3 Mrad gamma ray to polymerize them completely. Contrary to UV‐irradiation polymerization, there was no concentration dependence on the polymerization. Structure of the polymerized liposomes were confirmed by electron microscopy as small unilamellar liposomes. Study on the leakage of fluorescein from inner aqueous phase of the polymerized liposomes revealed that polymerized triene‐type liposomes were relatively more stable than the polymerized diene‐type liposomes.
Solid‐state thermolysis of poly(p‐t‐butoxycarbonyloxystyrene) catalyzed by polymeric phenol: Effect of phase separation
Authors: Ito Hiroshi
Published: April 2003

Thermolysis of poly(p‐t‐butoxycarbonyloxystyrene) (PBOCST) catalyzed by polymeric phenol in the solid state is very much dependent on the extent of phase separation. Poly(p‐hydroxystyrene) (PHOST, a thermolysis product of PBOCST) is not miscible with PBOCST. Therefore, this phenolic resin can not effectively catalyze the solid‐state thermolysis reaction when simply blended with PBOCST. However, if the phenolic functionality is forced to be in the vicinity of the t‐butoxycarbonyl (tBOC) group, the thermolysis takes place facilely at 130°C. The effect of casting solvent on thermolysis in PBOCST/Varcum films is also discussed.
Uniform polymer particles by dispersion polymerization in alcohol
Authors: Tseng C. M. , Lu Y. Y. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

Uniform polystyrene particles in 1–10 μm size range and up to 40% solid contents have been prepared by polymerizing styrene in ethyl alcohol with azo‐type initiators and a polymeric stabilizer polyvinylpyrrolidone along with an anionic, nonionic, or comonomeric co‐stabilizer. Effects of polymerization parameters, such as monomer concentration, type of co‐stabilizer, initiator type and concentration, crosslinking monomer, and diluent on average particle size and size distribution have been studied. Functional groups such as hydroxyl, carboxyl, amine, amide, silane, polydimethylsiloxane, and silacrown have been successfully incorporated onto the particles by copolymerization. A mechanism for particle formation and growth in dispersion polymerization is presented.
Synthesis and properties of eighteen‐arm polybutadienes
Authors: Toporowski P. M. , Roovers J.
Published: April 2003

A series of eighteen‐arm regular star polybutadienes with molecular weights between 9.9 × 104 and 1.9 × 106 were prepared and characterized. Evidence is presented for the expanded configuration of the large eighteen‐arm stars in a θ solvent. The intrinsic viscosities of the eighteen‐arm stars gave g′ = [η]/[η]l = 0.284 in dioxane at 27°C (θ solvent) and 0.225 in toluene at 35°C (good solvent). The linear viscoelastic properties of the melts were also determined. The plateau modulus, GN°, is the same as for linear polybutadiene. The zero‐shear viscosities (η0) and the longest relaxation times (Tmax) increase exponentially with the arm molecular weight Ma and are identical to those of four‐arm polybutadienes with the same Ma. The zero‐shear recoverable compliance (Je°) increases linearly with molecular weight. v′ in Je°GN° = v′Na, where Na is the number of entanglements per arm, is 0.95 slightly larger than 0.66 for four‐arm polybutadienes. Similarly, g2 is higher than calculated from the Rouse–Ham theory.
Kinetic study of the reaction between hydroxylated polybutadienes and isocyanates. II. Reaction with 3‐isocyanatomethyl‐3,5,5‐trimethylcyclohexylisocyanate (IPDI) and dimer diacid diisocyanate (DDI)
Authors: Coutinho Fernanda M. B. , Rezende Luiz Cláudio , Quijada Juan Raul
Published: April 2003

A comparative kinetic study of the reaction of three different hydroxylated liquid poly‐butadienes (M̄n ⋍ 3000)–R‐45M, R‐45HT and H‐034–with 3‐isocyanatomethyl–3,5,5‐trimethylclohexylisocyanate (IPDI) and dimer diacid diisocyanate (DDI) was carried out in toluene solution. An analytical method was used to follow the kinetics of the reactions, at four different temperatures. In the second‐order plots, a discontinuity was observed in the reaction with IPDI, in contrast to the reactions with DDI which showed straight‐line plots. In all studied reactions, the R‐45M polybutadiene was about twice as reactive as R‐45HT and H‐034. The latter hydroxylated polybutadienes (R‐45HT and H‐034) showed similar reactivities.
A positron annihilation lifetime study of isotactic polypropylene
Authors: Lind John H. , Jones Phillip L. , Pearsall George W.
Published: April 2003

Positron lifetime studies were performed on well‐characterized annealed and quenched samples of isotactic polypropylene. The positron experiments were conducted from −20 to 110°C as a function of both heating and cooling. Of the three decaying exponential components resolved from the lifetime spectra, only the long‐lifetime ortho‐positronium (o‐Ps) pickoff component was affected by the changes in temperature. The behavior of both the lifetime and intensity of the o‐Ps component was interpreted with the aid of x‐ray diffraction, densitometry, and optical microscopy examinations and results from previously reported investigations of the thermal transition behavior of polypropylene. The present experiments demonstrate that o‐Ps lifetimes were similar for both the annealed and quenched samples, independent of thermal cycling, while the o‐Ps component intensity was significantly larger for the quenched material during heating, with both sample types exhibiting a significant hysteresis upon cooling. These results suggest that the mean free‐volume cavity size is independent of prior thermal treatment, while the density of free‐volume sites is a sensitive function of structure and prior thermal history. The variations of lifetime and of intensity with temperature have provided insight into polypropylene's glass transition phenomena.
The nature and properties of giant‐orbital polymers
Authors: Pohl Herbert A.
Published: April 2003

In the course of studying the properties of highly conjugated polymers, we found that long‐range orbital delocalization conferred unexpected properties. The giant electronic orbitals made these materials electroactive yet very stable. A new mode of electronic polarizability, a giant nomadic polarization, resulted, making these organic polymers among the most polarizable materials ever observed. In addition, remanent magnetization, high conductivity, and unusual pressure sensitivity could be achieved. The giant‐orbital concept opens new vistas of materials properties.
Post‐gamma‐irradiation grafting of polypropylene. Part II. Butadiene: E.S.R. experiments
Authors: Busfield W. Ken , Buchanan Tracey Morley , Pomery Peter J.
Published: April 2003

ESR spectra of gamma irradiated annealed and quenched forms of polypropylene film have been studied at the temperatures used for post‐irradiation grafting experiments with butadiene, described in Part I. On warming from low temperature there is radical loss by termination and some radical transformation to radicals with optimum stability in annealed polypropylene at approximately 45°C. These radicals, which may be allyl type, are sited at the crystal faces, and decay more rapidly at higher temperatures in annealed polypropylene; in quenced polypropylene their concentration never exceeds one third the optimum observed in annealed polypropylene. Correlation with the grafting experiments suggests that allyl radicals are important for long‐term grafting. Effects on the ESR spectrum of adding butadiene to the system show that in the long‐term butadiene adds exclusively to the allyl radicals and that alkyl radicals still present at that stage are precursors to the allyl radicals. They do not react directly with butadiene presumably because they are sited in the inaccessible crystal core. Experiments at lower temperature show that butadiene does react with alkyl radicals in accessible regions.
Linear aminophenol polymers using the mannich reaction
Authors: Hodgkin Jonathan H.
Published: April 2003

Mannich reactions were used to prepare a series of low‐molecular‐weight linear polymers from substituted phenols, formaldehyde, and secondary diamines. The physical and spectroscopic properties of these new aminophenol polymers are described and compared with those of the bisphenolic diamines formed as an intermediate step in the polymerization process. The polymers were found to give coloured, water‐soluble, metal complexes with copper and iron salts.
Synthesis of block cotelomers involving a perfluorinated chain and a hydrophilic chain. Part I. Use of fluorinated telogens with trichloromethyl end groups
Authors: Boutevin B. , Diaf K. O. , Pietrasanta Y. , Taha M.
Published: April 2003

The synthesis of compounds involving a perfluorinated chain and a trichloromethyl group at the end of the chain is carried out by esterifying an alcohol with trichloracetic acid or by adding CCl4 to a perfluorinated alcohol acrylate. Cl3CCO2(CH2)2C6F13 and Cl3CCH2CHClCO2(CH2)2C6F13 are obtained, respectively. These telogens are both used to initiate a polyacrylamide chain, thus allowing the synthesis of new highly hydrosoluble surfactants. The transfer constant of ferric chloride to the polyacrylamide chain can be calculated by studying the kinetics of the telomerization reaction. We found C = 16 at 125°C. Telomers can be prepared in which the polymer chain contains between 10 to 1000 acrylamide units; the degree of polymerization can be precisely predicted according to the amounts of products allowed to react.
Radical‐Initiated homopolymerization and copolymerization of methylthiomethyl methacrylate
Authors: Ueda Mitsuru , Yazawa Masahiko , Suzuki Toshiyuki , Pittman Charles U.
Published: April 2003

Methylthiomethyl methacrylate (MtMA) was synthesized and homopolymerized in solution. The poly(MtMA) is readily soluble in benzene, acetone, tetrahydrofuran, and methylene chloride at room temperature. The values of K and a in the Mark–Houwink equation, [η] = KMa, were found to be K = 2.88 × 10–5 and a = 0.75 when M = Mw. The glass transition temperature of poly(MtMA) was observed to be 72°C by thermomechanical analysis. Intramolecular anhydride formation occurred when poly(MtMA) was heated to 250–300°C. The kinetics of MtMA homopolymerization was investigated in benzene, using azobisisobutyronitrile as initiator. The rate of polymerization Rp was expressed by Rp = k[AIBN]0.5[MtMA]1.05 and the overall activation energy was calculated to be 75.7 kJ/mol. The relative reactivity ratios of MtMA in styrene copolymerizations (r1 = 0.33, r2 = 0.55) were obtained. Applying the Q‐e scheme led to Q = 1.07 and e = 0.51 for MtMA.
Thermal oxidation of poly(ethylene‐co‐carbon monoxide) and polyethylene
Authors: Gooden R. , Hellman M. Y. , Winslow F. H.
Published: April 2003

Thermal oxidations at 101°C of ethylene‐carbon monoxide (E/CO) copolymer and low‐density polyethylene (DYNK) were studied over the range of 0–30 mL oxygen absorbed per gram of polymer. Relative changes in reaction rates, chemical composition, and molecular weights of the polymers were observed using oxygen uptake, infrared spectroscopy, and gel permeation chromatography. At comparable oxidation rates, differences in concentrations of most functional groups appeared to be small, except for the IR peak attributed to non‐hydrogen‐bonded hydroperoxide which was absent in the spectrum of E/CO copolymer. The extent of scission at comparable oxygen absorption was greater in E/CO than DYNK, since ketonic carbonyl groups were oxidized faster than methylene groups.
Functional monomers and polymers. CXXXI.. Synthesis and interaction studies on polyacrylamide and polymethacrylamide derivatives containing nucleic acid bases
Authors: Inaki Yoshiaki , Sugita Shin‐Ichi , Takahara Tohru , Takemoto Kiichi
Published: April 2003

Acrylamide and methacrylamide derivatives of nucleic acid bases were prepared from the corresponding aminoethyl derivatives. Free‐radical polymerization of these monomers in water or in organic solvents gave their polymers. From the studies of the polymer complex formation by UV spectroscopy, it was found that extremely stable polymer complexes were formed between complementary polymers containing nucleic acid bases.
Polymerization of 1,2‐epoxy‐4‐epoxyethylcyclohexane
Authors: Usanmaz Ali , Asaid Ahmad
Published: April 2003

Radiation‐induced polymerization of 1,2‐epoxy‐4‐epoxyethylcyclohexane (EECH) has been carried out at different temperatures in solid and liquid states. Activation energy was calculated from Arrhenius plot and ionic mechanism was proposed. Molecular weights for some polymer samples were determined by cryscopic method and compared with their intrinsic viscosities. Cationic polymerization of EECH initiated by BF3 · O(C2H5)2 and anionic polymerization initiated by NaOH are also studied. Two epoxy rings can be opened for polymerization selectively by radiation, but not by chemical initiators. The expected polyether structure was observed from the IR spectrum. Polymers obtained were shown to be amorphous from X‐ray photographs.
Characteristics and initiation ability of 9‐anthranylmethyl hexafluorophosphate
Authors: Skorokhodov S. S. , Stepanov V. V. , Toncheva V. D. , Velichkova R. S. , Panayotov I. M.
Published: April 2003

9‐Anthranylmethyl hexafluorophosphate–a stable primary carbenium salt–is prepared and characterized by UV, VIS, and NMR spectroscopy and by conductometric measurements in methylene chloride. 9‐Anthranylmethyl hexafluorophosphate initiates the polymerization of vinyl and heterocyclic monomers. This initiator has higher reactivity than trityl and diphenylmethyl salts. The initiation mechanism of the polymerization of some monomers is investigated.
Characterization of polyurethane network chains by gel permeation chromatography
Authors: Furukawa Mutsuhisa , Yokoyama Tetsuo
Published: April 2003

Starting materials, prepolymers, chain‐extended oligomers, and polyurethane network chains were characterized by gel permeation chromatography in order to make clear the change of molecular distribution in the formation of polyurethane networks. The polyurethane networks were prepared from poly(oxypropylene)glycol (PPG 1000, Mn = 997, Mw/Mn = 1.04), 2,4‐tolylene diisocyanate, and 1,4‐butanediol by the prepolymer method. Polyurethane networks were degraded by the amine degradation method, by which allophanate groups as crosslinking sites were decomposed selectively. The prepolymer had four species. The polydispersity index of the prepolymer (Mw/Mn) was about 2, that is, the most probable distribution. The product of the chain‐extending reaction of prepolymer with BD had five species. The molecular‐weight distribution of this product was narrower than that of the prepolymer. The polydispersity of the interstitial chains between crosslinking sites was also narrower than that of the chain‐extended product. The polyaddition mechanism in the formation of PPG–TDI–BD polyurethane networks was discussed.