bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding of methyl orange and its homologs by polyion complex in ethylene glycol
Authors: Takagishi Toru , Kozuka Hiroshi , Kim Gong Ju , Kuroki Nobuhiko 
Published: April 2003

AbstractThe extent of binding of methyl orange, ethyl orange, propyl orange, and butyl orange by a polyion complex, which consists of equimolar sodium polymethacrylate and a piperidinium cationic polymer, was measured in ethylene glycol at 25, 30, and 35°C. The effects of aqueous and nonaqueous media on the binding of the dye by the polymer matrix were compared. In ethylene glycol only noncooperative binding (Langmuir type) was observed, whereas two modes of binding, noncooperative and cooperative, were involved in the aqueous environment. The first binding constants and the thermodynamic parameters associated with the binding in ethylene glycol were evaluated. The polymer matrix exhibited a higher affinity toward the dye in ethylene glycol than in water at low concentrations of free dye and bound these anionic cosolutes with different hydrophobicities but the same affinity as in ethylene glycol. These interactions are highly exothermic and characterized by relatively large negative entropy changes. Electrostatic forces are the principal contributors to the dye–polymer complex formation. The binding behavior observed in the nonaqueous solvent is reasonably accounted for in terms of disappearance of hydrophobic interactions between the dye and the polymer and an increase in electrostatic attraction between the anionic small molecule and the positively charged sites on the polyion complex.
Tribo‐ and photopolymerization of 9‐ethyl‐3‐vinylcarbazole crystals
Authors: Tazuke Shigeo , Supakorn Onusa , Inoue Takashi 
Published: April 2003

AbstractCrystals of 9‐ethyl‐3‐vinylcarbazole(I) were easily polymerized to high polymer under mechanical shear stress and photoirradiation without initiator. The degree of polymerization was higher for tribo‐ than for photopolymerization. It was concluded that the mechanism of polymerization was cationic for both polymerizations on the basis of additive effects. The polymerization behavior depended on the recrystallizing solvents. Ethanol crystals are less sensitive to tribo‐ and photo‐polymerization than those of n‐hexane or benzene. X‐ray diffraction patterns of I also differed, depending on the recrystallizing solvents. The reactive crystals were in a high energy state, as revealed by DSC analysis. Similarities of photo‐ and tribopolymerization and comparative studies of tribopolymerization with triboluminescence of I indicated that polymerizations are likely to be induced by an identical reactive intermediate tentatively considered as a zwitterionic species.
The degradation and stabilization of polyacrylonitrile. I. Evidence for β‐ketonitrile defect structures as initiators of degradation
Authors: Ayrey G. , Chadda S. K. , Poller R. C. 
Published: April 2003

AbstractThe theory that β‐ketonitrile structures initiate discoloration reactions in polyacrylonitrile has been tested by a number of methods. Using radiochemical techniques the numbers of carbonyl groups in various polymers have been measured as have the amounts of combined water. A model β‐keto compound, 1,3,7,‐tricyanoheptan‐4‐one was synthesized and its reactions studied. None of these experiments supported the idea that β‐ketonitrile structures are of primary importance in initiating the degradation of polyacrylonitrile.
Thermotropic liquid crystalline polymers. II. Further examples on their synthesis by the interaction of poly(acryloyl chloride) with mesogenic compounds
Authors: Paleos C. M. , Margomenou‐Leonidopoulou G. , Filippakis S. E. , Malliaris A. , Dais Photis 
Published: April 2003

AbstractA recently reported method for the synthesis of thermotropic liquid crystalline polymers by the interaction of reactive polymers with mesogenic compounds is further illustrated by the preparation of two mesomorphic polymers. Specifically, poly(acryloyl chloride) is esterified withp‐hydroxybiphenyl andp‐hydroxyazobenzene for the synthesis of poly(p‐biphenyl acrylate) and poly(p‐acryloyloxyazobenzene), respectively. The liquid crystalline character of both polymers was established by optical microscopy, x‐ray diffraction analysis, and differential scanning calorimetry.
Glow discharge polymerization of chlorine‐containing fluoromethane
Authors: Inagaki N. , Kimura K. , Minamidani T. , Katsuura K. 
Published: April 2003

AbstractGlow discharge polymerization in the CF2Cl2/CH4, CHF2Cl, and CHFCl2 systems was performed. The materials formed are not polymers but oligomers; they contain considerable chlorine and fluorine and their surface energies are not so low as those of the polymers from the CF4/CH4 mixture. These materials dissolved in organic solvents and their molecular weights were measured. In glow discharge polymerization of methylmethacrylate the addition of CHFCl2 caused formed polymers to be soluble in organic solvents. This polymerization is discussed.
Effect of quaternized poly(4‐vinyl pyridine) on the cleavage of threonine catalyzed by pyridoxal or pyridoxal phosphate
Authors: Nakano Hidehiko , Yamane Ryuji , Sangen Osamu , Yamamoto Yoshitake 
Published: April 2003

AbstractThe effect of poly(4‐vinyl pyridine) quaternized with ethyl bromide (C2PVP) on the cleavage of threonine catalyzed by pyridoxal (PL) of pyridoxal phosphate (PLP) with metal ion was investigated. When PLP was used with Cu2+, Al3+, Fe3+, or VO2+C2+PVP showed marked stimulation, whereas the stimulation was small when PL was used with each of these metal ions. The stimulation by C2PVP was reduced in the presence of 0.1M KCI. To account for this stimulation we suggested the contribution of the electrostatic interaction between C2PVP and phosphate moiety of PLP. The introduction of hydrophobicity into the polymer by quaternizing partially with dodecyl bromide did not improve the stimulation. With Co2+ or Zn2+, or without multivalent cation, a similar effect of C2PVP on the catalysis of threonine cleavage by PLP was shown, although the reaction rate was low, but with Ni2+ C2PVP did not affect the reaction catalyzed by PL or PLP.
Aqueous polymerization of methyl methacrylate initiated by peroxydisulfate–citric acid redox system catalyzed by silver ion
Authors: Dash Sudhansu Bhusan , Baral Nilambar , Pati Nrusingha C. , Nayak Padma L. 
Published: April 2003

AbstractThe kinetics of the aqueous polymerization of methyl methacrylate initiated by potassium peroxydisulfate–citric acid catalyzed by silver ion was investigated in nitrogen atmosphere. The rate of polymerization is proportional to the square root of peroxydisulfate concentration. The initial rate increases with increasing citric acid concentration up to 15 × 10−3M, after which it decreases. The rate of polymerization also increases initially with monomer concentration and decreases at higher monomer concentration. The effects of temperature and the addition of some solvents and salts on the rate of polymerization have also been studied and a suitable kinetic scheme has been proposed for the reaction.
Synthesis of polymer intermediates containing the hexafluoroisopropylidene group via functionalization of 2,2‐diphenylhexafluoropropane
Authors: Lau K. S. Y. , Landis A. L. , Kelleghan W. J. , Beard C. D. 
Published: April 2003

AbstractThe title compound was synthesized by hydrogenolysis of its precursor 2,2‐bis(4‐trifluoromethanesulfonatophenyl)hexafluoropropane (2) in the presence of a base. 2,2‐Diphenylhexafluoropropane (6) can be appropriately functionalized at the 3,3′‐positions to give the diamino (7), dibromo (11), dicarboxaldehydo (13), 3‐ethynyl‐3′‐carboxaldehydo (14) derivatives which are important monomers in the synthesis of various high‐temperatures resistant polymers and oligomers containing the hexafluoroisopropylidene (6F) group. 2,2‐Bis(4‐triflatophenyl)hexafluoropropane (2) undergoes quantitative dinitration at the 3,3′‐positions to yield 2,2‐bis(3‐nitro‐4‐triflatophenyl)hexafluoropropane (3) which ultimately leads to the 3,3′‐diamino‐4,4′‐bis(arylamino) (5) and 3,3′‐diamino‐4,4′‐dihydroxy (8) derivatives which are specifically designed for phenylbenzimidazole, benzimidazoquinazoline, and benzoxazole polymers and oligomers.
The action of a benzotriazole light stabilizer in wool. I. A diffuse reflectance analysis of UV screening
Authors: Leaver Ian H. 
Published: April 2003

AbstractA procedure based on diffuse reflectance spectroscopy was developed to determine the UV screening effect of a benzotriazole light stabilizer in wool fabric. Expressions that enable the protective effect of the stabilizer to be calculated directly from reflectance data were derived. The dependence of the screening effect on additive concentration was deduced from measurements of fabric reflectivity in the wavelength range of 300–400 nm. Two reflectometers with quite different optical geometries were used to measure the reflectance spectra and the merits of the two systems are discussed. A theoretical expression for the optical screening phenomenon in highly scattering materials was evaluated for substrates of different reflectivity and the general implications of this relationship are considered.
Functional polymers. XIX. Biuret oligomers and polymers of biologically active primary aliphatic amines
Authors: Purgett Mark D. , Deits Walter , Vogl Otto 
Published: April 2003

AbstractBiuret oligomers and polymers from primary aliphatic amines and aromatic or aliphatic diisocyanates have been synthesized. To demonstrate the feasibility of the synthesis of polybiurets, aliphatic primary amines with n‐propyl, n‐hexyl, n‐octyl, and n‐dodecyl groups have been incorporated. For the synthesis of biuret oligomers of biologically active primary aliphatic amines [8‐(4‐amino‐1‐methylbutylamino)‐6‐methoxyquinoline] (primaquine) and adamantanamine were selected. Primaquine was also incorporated into polyepichlorohydrin by nucleophilic substitution of the chlorine of the chloromethyl group by the primary aliphatic amino group of primaquine. The structure of the biuret polymers was established by elemental analysis, and by infrared 1H‐ and 13C‐NMR spectroscopic characterization. Several attempts to use primaquine as a diamine for the formation of condensation polymers, including reaction of primaquine with sebacoyl chloride (to form polyamides), or with diisocyanates (to form polyureas) were unsuccessful.
Radiation‐induced oxidation of polyethylene, ethylene–butene copolymer, and ethylene–propylene copolymer
Authors: Arakawa Kazuo , Seguchi Tadao , Watanabe Yuhei , Hayakawa Naohiro 
Published: April 2003

AbstractOxygen consumption and yield of oxidation products during γ‐irradiation were studied on five types of polyethylene (PE), ethylene–butene copolymer (EB), and ethylene–propylene copolymer (EPR) using gas chromatography, mass spectrography, and high‐resolution NMR. Samples were irradiated in oxygen under pressure from 0 to 500 torr by 60Co γ‐rays up to 20 Mrad at 22–25°C. In enough oxygen, oxygen consumption and yield of oxidation products are independent of oxygen pressure for low‐density PE, EB, and EPR. The G values of oxygen consumption were 14–18.4 for PE, 11.6 for EB at 1 × 106 rad/h, and 8.3 for EPR at 2 × 105 rad/h. The oxidation products determined were carboxylic acid (CH2COOH), H2O, CO2, and CO. The oxygen consumption and oxidation products for PE were found to increase with increasing crystallinity.
Phthalocyanine polymers. IV. Novel type of thermally stable polyimides derived from metal phthalocyanine tetramines and benzophenone tetracarboxylic dianhydride
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractPoly(metal phthalocyanine)imides of copper, cobalt, nickel, and zinc were synthesized by the reaction of metal phthalocyanino tetramines with benzophenone tetracarboxylic dianhydride. These polymers were characterized by elemental analyses and IR, TGA, and inherent viscosity studies. Noteworthy features of these phthalocyanine polymers are their remarkable thermal and thermooxidative stabilities with char yields at 800°C that range from 78 to 83% in a nitrogen atmosphere. The relative thermal stabilities of these polymers have been evaluated by activation energy measurements.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). XVIII. Epoxy and aldehyde telechelic polyisobutylenes
Authors: Kennedy J. P. , Chang V. S. C. , Francik W. P. 
Published: April 2003

AbstractThis article concerns the synthesis and characterization of new epoxy and aldehyde telechelic polyisobutylenes, that is,
magnified image
and . The synthesis of the epoxy derivative was achieved by quantitative epoxidation of α,ω‐di(isobutenyl) polyisobutylene with m‐chloroperoxybenzoic acid and that of the dialdehyde by quantitative isomerization of the epoxy termini with zinc bromide. Infrared (IR) and 1H‐NMR analysis of these new telechelic polymers and ultraviolet (UV) analysis of the 2,4‐dinitrophenylhydrazine derivative of the dialdehyde indicate quantitative conversions and yields, that is, essentially theoretical functionalization (Fn = 1.95 ± 0.05).
Radical‐initiated homo‐ and copolymerization of α‐methylene‐γ‐butyrolactone
Authors: Ueda Mitsuru , Takahashi Masami , Imai Yoshio , Pittman Charles U. 
Published: April 2003

AbstractThe kinetics of α‐methylene‐γ‐butyrolactone (α‐MBL) homopolymerization was investigated in N,N‐dimethylformamide (DMF) with azobis(isobutyronitrile) as initiator. The rate of polymerization (Rp) was expresed by Rp = k[AIBN]0.54[α‐MBL]1.1 and the overall activation energy was calculated as 76.1 kJ/mol. Kinetic constants for α‐MBL polymerization were obtained as follows: kp/kt1/2 = 0.161 L1/2 mol−1/2·s−1/2; 2fkd = 2.18 × 10−5 s−1. The relative reactivity ratios of α‐MBL(M2) copolymerization with styrene (r1 = 0.14, r2 = 0.87) were obtained. Applying the Q–e scheme led to Q = 2.2 and e = 0.65. These Q and e values for α‐MBL are higher than those for MMA
Radical‐initiated homo‐ and copolymerizations of methacryloyl fluoride
Authors: Ueda Mitsuru , Kumakura Toshihisa , Imai Yoshio , Pittman Charles U. 
Published: April 2003

AbstractThe kinetics of methacryloyl fluoride (MAF) homopolymerization was investigated in methyl ethyl ketone (MEK) with azobis(isobutyronitrile) as initiator. The rate of polymerization (Rp) followed the expression Rp = k[AIBN]0.55[MAF]1.18. The overall activation energy was calculated as 74.4 kJ/mol. The relative reactivity ratios of MAF(M2) copolymerization with styrene (r1 = 0.083, r2 = 0.14), and methyl methacrylate (r1 = 0.48, r2 = 0.81) in methyl ethyl ketone were obtained. Application of the Q–e scheme (in styrene copolymerization) led to Q = 2.22 and e = 1.31. The glass transition temperature (Tg) of poly(MAF) was 90°C by thermomechanical analysis. Thermogravimetry of poly(MAF) showed a 10% weight loss of 228°C in air.
Effect of temperature conditions on the mechanism of formation, molecular structure, and properties of polyurethanes
Authors: Dorozhkin V. P. , Kimelblat V. I. 
Published: April 2003

AbstractThe formalized kinetic approach to the mechanism of urethane formation in the system of prepolymer with end NCO groups–1,4‐butanediol together with the dispersion analysis of kinetic curves have helped to establish that, at moderate temperatures, the mechanism may be represented by a scheme comprising a noncatalytic stage of urethane formation and a catalytic one including the formation of a double complex of a catalyst with an isocyanate or a hydroxyl group. As the temperature rises the proportion of the noncatalytic stage decreases significantly, while a mechanism, including the formation of the triple complex isocyanate group–catalyst–hydroxyl, becomes the most probable. It has been shown that the formation of a triple complex at elevated temperatures is thermodynamically more advantageous than the formation of double complexes; hence these changes of mechanism with temperature. It has been found that the temperature conditions of polyurethane production greatly affect the degree of its branching. Two crosslinked polyurethanes were obtained, one under the temperature conditions providing for the minimum degree of branching, the other under isothermal conditions. It has been discovered that the degree of branching of a prepolymer may greatly affect the density of chemical and physical bonds and a range of physical and chemical properties of the polyurethane.
Structure and polydispersity of some poly(methyl methacrylates) prepared by different methods
Authors: Moustafa A. B. , Badran A. S. , Ebdon J. R. , Hunt B. J. 
Published: April 2003

AbstractPoly(methyl methacrylate) has been prepared under various conditions of monomer, initiator, reaction medium, and temperature. All the 13C‐NMR spectra for the polymers obtained were those to be expected for radically initiated poly(methyl methacrylates) of conventional, slightly syndiotactic‐rich microstructures prepared at normal temperature. The spectra were found to be very similar to that for a radical poly(methyl methacrylate) first analyzed by Inoue et al.,8 and to those of poly(methyl methacrylates) prepared in earlier experiments of this general type. The ratios of isotactic (mm) to heterotactic (mr and rm) to syndiotactic (rr) triads were found to be close to 5:34:61. It can be concluded from the 13C‐NMR spectra that the propagation steps in these polymerizations are of conventional radical type, and are uninfluenced from the steric point of view by nature of the polymerization medium by the presence of the various additives. The polydispersity for some poly(methyl methacrylate) samples determined by gel permeation chromatography was found here to vary rather widely and ranges between 1.9 and 7.9.
The validity of the compound concentration scale for the interpretation of some crosslinked polyolefine properties
Authors: Kunert Krzysztof A. 
Published: April 2003

AbstractIn our earlier investigations of chemically crosslinked polyethylene and polypropylene we based our interpretation of the properties of these polymers on the compound concentration scale.1–4 To check the validity of this scale we performed some NMR experiments on crosslinked polypropylene and compared the results with the gel scale.
Kinetic models of homogeneous ionic polymerization
Authors: Chen Gan‐Tang 
Published: April 2003

AbstractBased on modern concepts of ionic polymerization, a system of kinetic models which covers various initiation and propagation mechanisms, all based on a pseudo‐steady‐state assumption, is proposed. Special attention is given to the effect of solvent on the rate‐controlling steps. Equations for reaction rate, degree of polymerization, and molecular weight distribution for 12 fundamental models are derived and fully discussed. The theory is also extended to more complicated systems such as the ion pair, free‐ion system.
Copolymerization of unsaturated spiro ortho esters with maleic acid derivatives
Authors: Fukuda Hiroyuki , Hirota Masahiro , Endo Takeshi , Okawara Makoto , Bailey William J. 
Published: April 2003

AbstractThe formation of charge‐transfer (CT) complexes of unsaturated spiro ortho esters such as 2‐methylene‐1,4,6‐trioxaspiro[4.4]nonane(I) and 2‐methylene‐1,4,6‐trioxaspiro[4.6]undecane(II) with maleic acid derivatives such as maleic anhydride (Manh), dimethyl maleate (DMM), and N‐ethyl maleimide (NEM) was ascertained by ultraviolet (UV) and nuclear magnetic resonance (NMR) spectroscopy. The stoichiometries of these complexes were estimated as 1:1. The determination of their equilibrium constants (K) was attempted by using the Hanna‐Ashbough equation with NMR spectroscopy. Although K values for I‐DMM and II‐DMM were specified as 0.266 and 0.336 L/mol, respectively, those for the other systems could not be obtained but were assumed to be negligible small (K ≪ 1). Copolymerization of these systems which was carried out without an initiator determined that spontaneous copolymerization occurs in all cases but that the copolymerization rates of I‐DMM and II‐DMM systems are slow. The systems in which Manh or DMM was used as an acceptor monomer gave the alternating copolymers at various monomer to feed ratios. The terpolymerizaton of the I–Manh–DMM system established that DMM takes little part in giving the alternating copolymers I and Manh. Consequently, it was assumed that the reactivity of the CT complex monomer is dependent on the contribution of the dative structure to CT complex.
Synthesis of poly‐ϵ‐caprolactone via a free radical mechanism. Free radical ring‐opening polymerization of 2‐methylene‐1,3‐dioxepane
Authors: Bailey William J. , Ni Zhende , Wu Shang‐Ren 
Published: April 2003

Abstract2‐Methylene‐1,3‐dioxepane 6 polymerized with a quantitative ring opening to form poly‐ϵ‐caprolactone via a free radical mechanism. On the other hand, 2‐methylene‐1,3‐dioxolane (ethylene ketene acetal) 4 and 2‐methylene‐1,3‐dioxane 5, under the same conditions, generated polymers with mixed ring‐opened and nonring‐opened structures. In copolymerization monomer 6 also showed a high tendency toward ring opening by which the ester functionality could be conveniently introduced into the backbone of the addition polymers.
Ethynyl‐terminated polysulfones: Synthesis and characterization
Authors: Hergenrother P. M. 
Published: April 2003

AbstractHydroxy‐terminated polysulfones (PSs) of number‐average molecular weights from 3000 to 26,000 g/mol were converted to the corresponding 4‐ethynylbenzoate–terminated PS through a three‐step synthesis. The initial step involved the reaction of the hydroxy precursor with 4‐bromobenzoyl chloride followed by displacement of the bromo group with trimethylsilylacetylene using a palladium catalyst. The trimethylsilyl group was subsequently cleaved with a weak base to afford the ethynylbenzoate‐terminated PS. A more direct route to the ethynylbenzoate‐terminated PS involved the reaction of the hydroxy‐terminated PS with 4‐ethynylbenzoyl chloride. The trimethylsilylethynyl and ethynyl groups undergo a thermally induced reaction to provide modified PS with better solvent resistance and higher apparent glass transition temperatures than an unmodified linear PS. The physical properties of the modified PS are compared with those of a linear PS.
Molecular orbital study of the Q–e scheme in free radical copolymerization
Authors: Colthup Norman B. 
Published: April 2003

AbstractMolecular orbital calculations were used to study free radical polymerization. Calculations show that the monomer is activated during the reaction and the pi bond becomes a diradical. The radical on the carbon that is about to form the new bond is called the e radical in this article. The other is the Q radical. For different monomers it is shown indirectly that changes in the energies of formation of the Q and e radicals are related to changes in the Q and e terms in the empirical Q–e scheme of Alfrey and Price. The polar effect in the Q–e scheme involves the e‐radical, unpaired electron density. Specifically, the Q–e sum (ex + ey) is correlated with the e radical spin density. Also the e term is correlated with the electron density on the unsubstituted carbon of the monomer. The relationship of the Q radical to the adjacent substituent is shown by correlating ln Q values with the energy of addition of a hydrogen atom to a monomer. These relationships give theoretical meaning to the Q–e terms and allow calculation of Q and e values from molecular orbital properties for small monomers.