bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Rh(III) and Ru(II) complexes in the polymerization of vinyl monomers initiated by charge transfer mechanism
Authors: Dass N. N. , Sen S. R. 
Published: April 2003

AbstractThe initiation of polymerization of vinyl monomers such as methyl methacrylate (MMA) and methyl acrylate (MA) by a charge transfer complex formed between n‐butylamine(nBA) and carbon tetrachloride (CCl4) in dimethylsulfoxide (DMSO) at 30°C is slow. The effect of the dimethylsulfoxide complexes of Rh(III) and Ru(II) on the polymerization of MMA and MA in the presence of nBA, and CCl4 in DMSO has been studied. The rate of polymerization and percent conversion of the MMA and MA at 30°C are evaluated at the critical concentration of the metal complexes. At the critical range of the metal complex concentrations, both Rp, and percent conversion of MMA and MA were found to be highest. However, above and below the critical concentrations, Rp and percent conversion of the monomers were found to decrease. A suitable mechanism for the polymerization has been proposed.
Syntheses and polymerizations of some vinyl monomers containing nitro‐ or fluorophthalimides
Authors: Overberger C. G. , Shalati Mohamad D. 
Published: April 2003

Abstract4‐Nitro‐N‐vinylphthalimide (4) was synthesized by two different procedures. Compound4was not polymerizable or copolymerizable by AIBN. Poly(N‐vinylphthalimide) (17) was prepared and partially nitrated at 10–25°C.N,N′‐(1,2‐Ethanediyl)bis(4‐nitrophthalimide) (15) andN,N′‐(1,3‐propanediyl)bis(4‐nitrophthalimide) (16) were prepared by the condensation of the corresponding diamine with phthalic anhydride followed by nitration of the condensation products. 4‐Nitrophthalic anhydride was prepared by the hydrolysis of15. Four styrene‐substituted phthalimide monomers were synthesized. These includeN‐(4‐vinylphenyl)phthalimide (25a),N‐(4‐vinylphenyl)‐3‐fluorophthalimide (25b),N‐(4‐vinylphenyl)‐3‐nitrophthalimide (25c), andN‐(4‐vinylphenyl)‐4‐nitrophthalimide (25d). Monomers25aand25bwere polymerized by freeradical initiator (AIBN), whereas monomers25cand25dwere not polymerizable or copolymerizable by AIBN due to a strong inhibitive effect exerted by the nitrophthalimide group. Monomers25cand25dwere cationically polymerized (BF3·OEt2). Monomer25band styrene were copolymerized and their reactivity ratios werer1= 1.7 andr2= 0.55, respectively. The prepared polymers are useful as backbone polymers for grafting living anionic polymers.
Electron–proton and electron–methyl exchanges in pyrolysis of polyacetylene and polymethylacetylene
Authors: Fan J. L. , Chien James C. W. 
Published: April 2003

AbstractPyrolysis of polyacetylene is marked by high yields of proton‐enriched products methane, ethane, ethylene, propane, polypylene, butadiene, cyclopentadiene, 1,3‐pentadiene, and toluene in total amounts exceeding benzene. The activation energies for their formation are low. Polyacetylene doped with AsF5 and iodine produced these products in even higher yields of two to 17 times of undoped polymers. The dominant mechanism is thought to be random‐chain scission followed by electron–proton exchange reactions. Polymethylacetylene is thermally less stable than polyacetylene. Pyrolysis gave mesitylene as the expected main product. However, as in the case of polyacetylene, large amounts of proton‐enriched products were formed with moderate activation energies. (The yields of methane, propylene, and propane are nearly the same in the pyrolysis of polymethylacetylene as compared to that of polyacetylene at 923°K referenced to mesitylene and benzene, respectively.) By analogy, mechanisms involving both electron‐proton and electron–methyl exchange reactions were proposed to account for the formation of all the pyrolyzates of polymethylacetylene. These reactions, not observed in the pyrolysis of polypropylene and polyisoprene, are attributable to the conjugated backbone permitting facile migrations of electrons, protons, and methyl groups.
Thermal oxidation of polyacetylene
Authors: Will Fritz G. , McKee Douglas W. 
Published: April 2003

AbstractThe thermal oxidation of undoped trans‐polyacetylene powder in dry air has been studied and the principal features of the mechanism have been developed. Thermogravimetric and differential thermal analysis reveal an exothermic process that first leads to a weight increase, followed by precipitous weight loss above 240°C due to formation of volatile oxidation products. Isothermal weight gain studies between 25 and 142°C show first‐order kinetics below 90°C with a rate constant of 3.10−7 s−1 at 25°C and an apparent activation energy of 16 kcal/mol. A weight gain of more than 40% has been observed at 25°C after 2000 h of exposure to air. A change in first‐order kinetics occurs at temperatures above 90°C. Identification of solid oxidation products with photoacoustic infrared spectroscopy reveals that oxygen intercalates into the polymer structure in large concentrations, similar to other electron acceptors. However, oxidative attack on the polymer backbone occurs simultaneously. At elevated temperatures or for long‐term oxygen exposure, the concentration of dopant oxygen decreases, probably by intramolecular regrouping of hydrogen atoms, resulting in the formation of hydroxyl groups and enhanced polymer degradation. This mechanism is consistent with the finding of others that the conductivity of polyacetylene upon oxygen exposure increases initially before decreasing significantly with continued exposure, especially at elevated temperatures.
Reactive oligomers. II. Polymerization of glycol bis(allyl phthalate)s and glycol bis(allyl succinate)s
Authors: Matsumoto Akira , Kukimoto Yutaka , Aoki Kazuhiro , Oiwa Masayoshi 
Published: April 2003

AbstractSeven glycol bis(allyl phthalate)s (GBAP) and four glycol bis(allyl succinate)s (GBASu) as reactive oligomers were prepared and their polymerization behaviors were investigated in detail in terms of cyclopolymerization and gelation as compared with diallyl dicarboxylates. Thus, the rates of polymerization of GBAPs were reduced compared to diallyl phthalate, being attributed to the steric effect on the intermolecular propagation of the uncyclized radical, whereas those of GBASus were enhanced as a consequence of intermolecular association by dipole–dipole interaction in polar GBASu monomers. Cyclization was enhanced in the following order: diallyl aliphatic dicarboxylates series < GBASu series < GBAP series. Gelation was discussed according to Gordon's theory; the actual gel‐point conversions increased with an increase in the molecular weight of monomers, although the discrepancy between actual and theoretical gel‐point conversion inversely tended to be decreased. The decreased delay in gelation with an increase of the molecular weight of monomers is ascribed to the reduction of excluded volume effects on crosslinking.
Synthesis and reactivity of aromatic aldehyde functions based on crosslinked polystyrene
Authors: Geckeler K. , Zheng H. , Bayer E. 
Published: April 2003

AbstractCrosslinked polystyrene‐containing chloromethyl groups were transformed into an aldehyde‐containing arylether polymer by an one‐step reaction with 4‐hydroxybenzaldehyde. Further modification of the aldehydic derivative of polystyrene by reaction with hydroxylamine proved the chemical availability of the polymer‐bound aldehyde functions and also good conversions for the product. In contrast, 2,4‐dinitrophenylhydrazine did not react under comparable conditions but after swelling in dioxan. It could be shown that swelling is a prerequisite for this reaction. The aldehyde function of the polymer was oxidized to the carboxylic acid using crown ether‐solubilized potassium permanganate. The carboxylic acid was converted to the carboxylic acid chloride by reaction with thionyl chloride. Finally, kinetic aspects of the reaction of chloromethyl polystyrene and 4‐hydroxybenzaldehyde have been investigated and discussed.
Plasma polymerization. XI. A comparison of the plasma polymerization of the isomeric perfluorinated diazines
Authors: Clark D. T. , Abu‐shbak M. M. 
Published: April 2003

AbstractPlasma polymers synthesized by inductively coupled RF techniques have been investigated as a function of operating parameters for the isomeric perfluorinated diazines (pyrazine, pyrimidine, and pyridazine). A combination of ESCA and microanalytical studies shows that plasma polymers are produced by rearrangement mechanisms: the C/F and C/N stoichiometric ratios are similar to those of the starting monomers over a range of operating parameters. A comparison of rates of formation of plasma polymer films reveals distinctive differences between the isomeric diazines that suggest that equilibration of valence isomers occurs on a substantially slower time scale than for isomeric fluorinated benzenes5–9 which, in general, polymerize at essentially the same rates. In contrast to the remarkably low critical surface tension of plasma polymers based on perfluorobenzenes (ca. 20 dynes cm−2), the plasma polymer films from the perfluorinated diazines which are initially hydrophobic become hydrophilic in contact with water droplets. This is attributed to the hydrolytic instability of films associated with the labilizing influence of nitrogen on nucleophilic displacement of fluoride which is a feature of the chemistry of monomers.
Photoinitation of cationic polymerization. II. Laser flash photolysis of diphenyliodonium salts
Authors: Pappas S. Peter , Pappas Betty C. , Gatechair Leslie R. , Schnabel Wolfram 
Published: April 2003

AbstractLaser flash photolysis of diphenyliodonium salts produces phenyliodinium radical cation (PhI+·), which was also generated independently by flash‐induced electron transfer from iodobenzene to a phenanthrolinium salt. Apparent second‐order rate constants were determined for reaction of the transient (PhI+·) with nucleophiles, including iodobenzene and cyclohexene oxide. Quantum yields of formation of acid from stationary photolysis of diphenyliodonium hexafluoroarsenate were found to be significantly higher than yields of iodobenzene. These results may be explained by facile reaction of PhI+· with PhI to yield a new iodonium salt together with a proton. High reactivity of PhI+· with cyclohexene oxide suggests that the transient may directly initiate cationic polymerization of epoxides.
Solvent effects on radical homo‐ and copolymerizations of methacryloyl fluroride
Authors: Ueda Mitsuru , Kumakura Toshihisa , Imai Yoshio , Pittman Charles U. , Wallace Easley 
Published: April 2003

AbstractThe effect of solvent in homo‐ and copolymerizations of methacryloyl fluoride (MAF) was investigated in various aromatic solvents. In these solvents, there is a significant effect on the rate of polymerization, on the tacticity of the resulting poly(methacryloyl fluoride), and on the copolymerization of MAF with methyl methacrylate (MMA). The equilibrium constants between MAF and aromatic solvents were determined from NMR spectroscopic measurements. These results indicated that the solvent effect on the MAF polymerization stems from changes in reactivity of MAF induced by the strong MAF–solvent interaction as well as stabilization of the MAF radical by solvents. Copolymerization of MAF with both p‐methoxystyrene (MSt) and p‐nitrostyrene (NSt) was also studied.
Monte carlo study of star‐branched polymers on the tetrahedral lattice. II. Statistical thermodynamics of single macromolecules
Authors: Sikorski Andrzej , Koliński Andrzej 
Published: April 2003

AbstractThe thermodynamical properties of the star‐branched polymers on the tetrahedral lattice are studied taking into account nearest‐neighbor interactions. The excess free energy and energy and heat capacities are computed for wide ranges of chain lengths, reduced potential ϵ/kT, and number of branches. A significant influence of the degree of branching on long‐range interactions in the polymer random coil is observed. The possibilities of phase transitions in both linear and branched systems are discussed on the basis of the Monte Carlo data.
Photoinduced swelling control of amphiphilic azoaromatic polymer membrane
Authors: Ishihara Kazuhiko , Hamada Naoshi , Kato Shinji , Shinohara Isao 
Published: April 2003

AbstractTo control the swelling of polymer membrane by photoirradiation amphiphilic azoaromatic polymer membranes were prepared and a photoinduced change in the swelling degree of water was investigated. The azobenzene moiety in the side chain of the polymer was isomerized from trans form to cis form by ultraviolet (UV) irradiation and reverse isomerization was found by visible light irradiation. The swelling degree of the polymer membrane for water in the dark was decreased by UV radiation, and when visible light irradiation was carried out in the polymer membrane the degree of swelling recovered to the original level. The swelling degree decreased with an increase in the mole fraction of the azobenzene moiety in the dark and under UV irradiation. The deswelling degree of the polymer membrane by UV irradiation also decreased with an increase in the mole fraction of the azobenzene moiety. This reversible change in the swelling degree was considered to be caused by the photoisomerization of the azobenzene moiety in the polymer membrane.
Organosilane polymers: Formable copolymers containing dimethylsilylene units
Authors: Zhang Xing‐Hua , West Robert 
Published: April 2003

AbstractFormable silane copolymers that contain dimethylsilylene units were synthesized and characterized. These polymers have high molecular weights and appreciable solubility in common solvents, can be molded or cast into films or drawn into fibers, and are photoactive.
Property relationships in dimer acid‐modified copolyesters of poly(1,4‐cyclohexylene dimethylene terephthalate) and poly(1,4‐cyclohexylene dimethylene 1,4‐cyclohexane dicarboxylate)
Authors: Fagerburg David R. 
Published: April 2003

AbstractDimer acid (D) modified copolyesters based on 1,4‐cyclohexane dimethanol (CHDM) and either terephthalic acid (T) or trans‐1,4‐cyclohexane dicarboxylic acid (C) were examined. Both series produced clear, flexible materials with physical properties changing regularly with changing modifier levels. Yield stress, elongation at break, and Young's modulus showed linear correlations of log property versus volume fraction of CHDM‐D segments in accord with the logarithmic rule of mixtures. Annealing the CHDM‐T‐based copolyesters caused little or no change in properties. Annealing the CHDM‐C‐based copolyesters gave similar results except for a large decrease in the modulus—the higher the dimer acid level, the larger the decrease in modulus. The density measurements, the x‐ray pattern, and the dynamic mechanical analysis at 110 Hz before and after the annealing treatment supported the hypothesis that the modulus decrease resulted from domain perfection in the copolyester induced by the annealing process. Transmission electron‐microscope examination of osmium tetroxide‐stained films supported this hypothesis, although initial results were not repeatable.
On the reaction of linear and crosslinked polystyrene with 1,4‐bis(chloromethoxy)butane
Authors: Carpov Adrian , Luca Cornelia , Bărboiu Virgil 
Published: April 2003

AbstractThe chlorometylation of linear and crosslinked polystyrene with 1,4‐bis(chloromethoxy) butane was studied, and the behavior of 1,4‐bis(chloromethoxy)butane in the presence of chloromethylation catalysts was also established by 1H‐NMR spectroscopy.
Polyaromatic ether‐ketone sulfonamides prepared from polydiphenyl ether‐ketones by chlorosulfonation and treatment with secondary amines
Authors: Lee Jasun , Marvel C. S. 
Published: April 2003

AbstractPolyaromatic ether‐ketone sulfonamides with potentially open structures of interest for membranes were prepared from polyaromatic ether‐ketones by sulfonation with chlorosulfonic acid, followed by amination with various amines. Various degrees of substitution were achieved by controlling the reaction conditions of sulfonation. These polymers are soluble in solvents like dimethylformamide, dimethylacetamide, and chloroform and can be cast into transparent films.
Organic solid photochromism by photoreduction mechanism: Viologen embedded in solid polar aprotic polymer matrix
Authors: Kamogawa Hiroyoshi , Masui Toshiaki , Amemiya Suguru 
Published: April 2003

AbstractReversible photocolor developments of viologens embedded in poly(N‐vinyl‐2‐pyrrolidone) films, a typical polar aprotic solid matrix, were found to be affected by the kinds of viologen cation as well as the paired anion. The color developments in the corresponding low‐molecular‐weight solvents are connected closely to the solubility of viologens in these solvents; viologens are highly sensitive in the polar aprotic solvents in which they have poor solubilities, such as N‐methyl‐2‐pyrrolidone and hexamethyl phosphoric triamide. These facts confirm the color‐development mechanism consistings of electron transfer to the photoexcited viologen cation from the paired anion in polar aprotic solid matrices such as poly(N‐vinyl‐2‐pyrrolidone).
Solid‐state polymerization of butadienes. Polymerization of salts of 6‐amino‐2,4‐trans,trans‐hexadienoic acid
Authors: Tieke Bernd 
Published: April 2003

AbstractThe polymerization of 6‐amino‐2,4‐trans,trans‐hexadienoic acid and various of its salts was studied in the solid state. Crystals of the hydrochloride and organic inorganic double halides with cadmium chloride, manganese (II) chloride, and iron(II) chloride were found to polymerize rapidly upon UV or γ irradiation. An erythro‐diisotactic polymer is obtained in the form of extended chain crystals. The polymer behaves as an amphoteric polyelectrolyte. The kinetics and the mechanism of the polymerization as well as morphological changes during the solid state reaction are discussed.
Interaction between poly(N‐vinylpyrrolidone) and poly(acrylic acid)s: Influence of hydrogen and cupric ions on the adduct formation
Authors: Subramanian R. , Natarajan P. 
Published: April 2003

AbstractInterpolymer adduct formation between poly(N‐vinylpyrrolidone) (PVP) and poly(methacrylic acid) (PMAA) is mainly due to hydrogen bonding. It is found that the interpolymer adduct formation is enhanced in the presence of Cu(II). A simple turbidity measurement making use of a spectrophotofluorometer is described for the study of the interpolymer adduct formation. Enhanced adduct formation in the presence of Cu(II) is described by the empirical relation d[PAd]/D[PVP] = k × 104α[Cu(II)]α, where PAd represents the interpolymer adduct and α and k are constants. Similar results have been obtained in the case of interpolymer adduct formation between poly(acrylic acid) (PAA) and PVP. In the above expression α signifies the influence of chelation on Cu(II)–PAA/PMAA–PVP‐type complex formation and k is the extent of PVP–PAA/PMAA interaction. The enhancement of adduct formation in the presence of Cu(II) is more in PAA than in PMAA. Turbidity and viscosity measurements further indicate that the influence of Cu(II) on interpolymer adduct formation between PVP and PMAA or PAA is more in the case of PAA than PMAA, as PAA is a better chelating ligand. But the extent of adduct formation is more in the case of PMAA in the absence of Cu(II) ions due to hydrophobic interactions exerted by methyl groups.
Mechanisms of polymer‐supported catalysis. 5. Solvation of quaternary onium ions in polystyrene gels by 13C‐NMR spectroscopy
Authors: Ford Warren T. 
Published: April 2003

Abstract13C‐NMR linewidths and spin‐lattice relaxation times have been determined for soluble and crosslinked polystyrenes containing quaternary phosphonium and ammonium ions. Solubilities and NMR linewidths show that the solvating abilities toward tri‐n‐butylphosphonium ions are CDCl3 > CH3OH > D2O > benzene, toluene, toward the trimethylammonium ions, CH3OH > CDCl3 > D2O > toluene, and toward the nonpolar polymer backbone, CDCl3, benzene > toluene > CH3OH > D2O.
Infrared study on the interaction of poly(vinyl chloride) and ketones. I. PVC‐MEK film system
Authors: Monteiro Elisabeth E. C. , Mano Eloisa B. 
Published: April 2003

AbstractIn a previous article we presented preliminary information on IR spectrometric evidence for the interaction between poly(vinyl chloride) and ketones by using films with residual solvent as samples for spectrometry. This article reports detailed information on PVC–MEK film systems as compared to model compounds. The results indicate that there are “specific” interactions which were observed by a frequency shift of the carbonyl absorption of the ketone and changes on intensities of the CCl vibrational modes of the polymer, which are similar to the effects observed for nonpolymeric systems.
Kinetic study of preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene–perfluorovinyl ether) copolymer
Authors: Hegazy El‐Sayed A. , El‐Assy Nasef B. , Rabie Abdel‐Gawad M. , Ishigaki Isao , Okamoto Jiro 
Published: April 2003

AbstractA kinetic study has been made on the preirradiation grafting of acrylic acid (AAc) onto poly(tetrafluoroethylene–perfluorovinyl ether) (PFA) film. The effect of grafting conditions was investigated. The dependences of the grafting rate on preirradiation dose and monomer concentration was found to be of the order of 0.5 and 1.3, respectively. The final degree of grafting was found to increase with dose and monomer concentration. However, it decreases as the grafting temperature increase. The overall activation energy for the graft polymerization was calculated from Arrhenius plots to be 5.6 kcal/mol. The activation energy for this grafting system was found to be independent of preirradiation dose used in the range from 10 to 100 kGy. The relationship between the grafting rate and film thickness gave a negative first‐order dependence. The results suggest that the grafting proceeds by radical mechanism with bimolecular termination of growing chain radicals. It was reasonable concluded that this grafting proceeds from the surface to the center of film with progressive monomer diffusion through the grafted layer which swells in the monomer solution.
Structure and immunological properties of polyacrolein formed by means of ionizing radiation and base catalysis
Authors: Rembaum A. , Chang M. , Richards G. , Li M. 
Published: April 2003

AbstractThe kinetics of the formation of polyacrolein microspheres by ionizing radiation (polymer I) were investigated. Their structure and reactivity were compared with polyacrolein microspheres prepared by base catalysis (polymer II). The study of Fourier infrared (IR) spectra of polymers I and II showed structural differences. The reaction of polyacrolein spheres with m‐aminophenol indicated the presence of conjugated groups. The reaction of antibodies with polyacrolein spheres was investigated as a function of pH and the number of reactive aldehyde groups was determined by nitrogen analysis of polyacrolein‐hydroxylamine adducts. Intensely fluorescent polyacrolein microspheres obtained by Co‐γ‐irradiation in sizes of 100 Å–4 μm have already found applications as immunoreagents for cell labeling and separation.