bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractMethylthiomethyl 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

AbstractThermal 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

AbstractAcrylamide 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

AbstractRadiation‐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

Abstract9‐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

AbstractStarting 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.
Molten bisphenol‐A polycarbonate—poly(ethylene terephthalate) blends. II. Kinetics of the exchange reaction.
Authors: Godard P. , Dekoninck J. M. , Devlesaver V. , Devaux J. 
Published: April 2003

AbstractThe kinetic aspects of the bisphenol‐A polycarbonate‐polyethylene terephthalate exchange reaction are studied. Though the overall mechanism of transesterification is reversible, the kinetics can be treated from a more simple model of two consecutive reactions, due to the decomposition of the alkyl carbonate formed. The values of the kinetic parameters, similar to those obtained for the bisphenol‐A polycarbonate‐polybutylene terephthalate transesterification, suggest that the most likely mechanism is a direct ester–ester interchange reaction which can also be catalyzed by additives such as titanium derivatives.
Molecular orbital analysis of the XPS spectra of PMDA‐ODA polymide and its polyamic acid precursor
Authors: Silverman B. D. , Bartha J. W. , Clabes J. G. , Ho P. S. , Rossi A. R. 
Published: April 2003

AbstractThe calculated carbon 1s (C1s) core energy‐level positions of PMDA‐ODA polymide and of its polyamic acid precursor are compared with the level positions inferred from XPS measurements. For the polyamic acid, calculation and experiment both yield a difference of approximately 1 eV between the carboxylic acid and the amide carbonyl C1s level positions. The difference in shape between the main C1s XPS peaks of the polyamic acid and polyimide is shown to be related to the difference in C1s core energy‐level shifts of the carbon atoms composing the benzene ring adjacent to the amide or imide group. The planar imide or PMDA structure apparently yields larger core level shifts for these atoms. We have previously designated these atoms as “imide carbon atoms” (C‐Im) to distinguish them from the aromatic carbon atoms (C‐C) of the ODA part of the polymeric repeat unit. Comparison of the carbonyl XPS band intensities with the main peak intensities for the polyamic acid, as well as for the polyimide, suggests that there is a carbonyl deficiency at the surface of both of these materials.
Synthesis and characterization of adenine base grafted polyacrylamides as polynucleotide analogs
Authors: Overberger C. G. , Ferng W. 
Published: April 2003

AbstractThe adenine base grafted polyacrylamides and their corresponding monomer model compounds were prepared and examined. The results suggest that the monomer model compounds exist in a preferred conformation, whereas the adenine base grafted polyacrylamides exist in a limited ordered conformation in an aqueous medium.
Synthesis and characterization of poly(2‐amino‐2‐methylpropyl)acrylamide, poly(2‐amino‐2‐methylbutyl)acrylamide, and copolymers of polyacrylamide
Authors: Overberger C. G. , Ferng W. , Chi Minn‐Shong 
Published: April 2003

AbstractPolyacrylamides possessing an amino group at the terminus of the branch chain as the potential site for amino acid and/or nucleic acid base grafting have been prepared. This type of polyacrylamide would provide a substantial spacing distance between the polymer main chain and pendant groups. Poly(2‐amino‐2‐methylpropyl)acrylamide (PDMPA) and optically active poly(2‐amino‐2‐methylbutyl)acrylamide (PDMBA) were characterized using vapor phase osmometry (VPO), gel permeation chromatography (GPC), and dilute solution viscometry. In addition, copolymers of poly(2‐amino‐2‐methylpropyl)acrylamide with N‐vinylpyrrolidinone, N‐vinylimidazole, and H(5)‐vinylimidazole, were prepared.
Polymerization of styrene oxide by nitronium tetrafluoroborate
Authors: Velichkova Rumyana St. , Tsevi Rayna Al. 
Published: April 2003

AbstractThe polymerization of styrene oxide by nitronium tetrafluoroborate in nitromethane and methylene chloride at 5, 20, and 50°C is investigated. GPC analyses of the products combined with isocyanate method show that both cyclic and linear oligomers are formed. In CH3NO2 the cyclic dimer and trimer are 2‐benzyl‐4‐phenyl‐1,3‐dioxolane and 1,3,5‐tribenzyl‐trioxane, respectively. In CH2Cl2 2,5‐diphenyldioxane is isolated. In nitromethane, mainly isomerized structures with acetal linkage are produced, while in methylene chloride isomerization does not proceed. By NMR and IR spectra the presence of CO and OH end groups in the linear oligomers is shown. There are indications that oligomers are formed both directly from the monomer and by degradation of the polymer.
Low surface energy polymers and surface active block polymers. I. t‐butylphenyl containing polymers
Authors: Litt Morton , Chen Tien‐Teh , Hsieh Bing R. 
Published: April 2003

AbstractTwo new monomers in the 2‐oxazoline series were synthesized and polymerized. These were 2‐[4‐(t‐butyl)phenyl]‐2‐oxazoline (I) and 2‐[(3‐(3,5‐di‐t‐butyl)phenoxy)propyl]‐2‐oxazoline (II). The polymer from I crystallized readily during bulk polymerization and showed Tm at 592 K (319°C). After annealing, the polymer showed a critical surface tension of 23.2 dyn/cm. Polymer from II was amorphous; hence, annealing showed little effect on contact angles. Block polymers were made with I (Xn = 10) and ethyl oxazoline (Xn = 6,20,60). Very sharp molecular weight distributions were obtained. All samples crystallized when annealed. The block polymer was an effective emulsifier for emulsion polymerization of butyl acrylate at 0.1%.
Peculiar temperature dependence of the binding of methyl orange and its homologs by 2‐diethylaminoethyl methacrylate‐N‐vinyl‐2‐pyrrolidone copolymers
Authors: Takagishi Toru , Hosokawa Toshitsugu , Okada Minoru , Kozuka Hiroshi 
Published: April 2003

Abstract2‐Diethylaminoethyl methacrylate (DEAEMA)–N‐vinyl‐2‐pyrrolidone (VPy) copolymers of various compositions have been synthesized. The resultant copolymers were examined for their ability to bind methyl orange and its homologs, in particular butyl orange, at 5, 15, 25, and 35°C in aqueous solutions. The amount of binding of butyl orange is much higher with the copolymers than with polyvinylpyrrolidone or with 2‐hydroxyethyl methacrylate–N‐vinyl‐2‐pyrrolidone copolymers. Introduction of only 3% of the hydrophobic DEAEMA residue increases markedly the binding affinity toward the cosolute. Maximal binding is obtained at 15°C in the temperature range measured. This peculiar temperature dependence of the extent of binding is explicable on the basis of hydrophobic effects involved in this binding. The peculiar temperature dependence disappeared in aqueous solution of NaSCN which acts as a water‐structure breaker: the extent of binding changes regularly with temperature. This is interpretable only in terms of reduction of hydrophobic contribution to the binding. With propyl orange, which is a less hydrophobic cosolute than butyl orange, the peculiarity of the binding was not detected.
Kinetics of successive seeding of monodisperse polystyrene latexes. I. Initiation via potassium persulfate
Authors: Sudol E. D. , El‐Aasser M. S. , Vanderhoff J. W. 
Published: April 2003

AbstractThe polymerization kinetics of monodisperse polystyrene latexes prepared via successive seeding were studied in the region between Smith‐Ewart Case 2 (n̄ = 1/2) and Case 3 (n̄ ≫ 1). Potassium persulfate was used as the initiator. The kinetics were measured in a piston/cylinder dilatometer designed for microgravity experiments. A recipe formulation method was developed by which a constant emulsifier (Aerosol‐MA) surface coverage was maintained throughout a sequence, beginning with a 0.19 μm polystyrene seed. Monodisperse latexes up to 1 μm in size were prepared using 0.5 mM K2S2O8 with a 4% emulsifier surface coverage. The polymerizations were commenced in Interval III, the particles being swollen with twice their weight in monomer. The kinetics were characterized by the autoacceleration of the gel effect with the overall polymerization rate decreasing with increasing particle size (decreasing Np). The Case 2 to Case 3 kinetic transition was experienced in the first seeding step, however, independence of the rate on the number of particles was not evident even at high values of n̄ (n̄ > 10). This was attributed to a dependency of the free radical capture efficiency on the particle size (constant solids). Corroborating indirect evidence was supplied through surface charge analysis and detailed examination of the polymerization kinetics.
Complex forming properties of crosslinked poly (ethylene oxide). I. Interaction of linear and crosslinked poly(ethylene oxide) with molybdenum(vi) salts
Authors: Vassilev K. G. , Dimov D. K. , Stamenova R. T. , Boeva R. S. , Tsvetanov Ch. B. 
Published: April 2003

AbstractEvidence was found of donor–acceptor complexation of molybdenum(VI) compounds by linear and crosslinked PEO. The interaction was studied by optical and NMR spectroscopy and conductivity measurements in organic medium. PEO networks were capable of binding molybdenum salts even in aqueous solution. The character of the interaction is considered to be essentially different from complex formation with alkali metal salts. This is manifested in the relatively low values of the stability constants of complexes with linear PEO. A remarkable effect of crosslinking on the binding capacity of PEO is registered resulting in an increase of complexation constants in chloroform by two orders of magnitude.
Polymerization of acenaphthylene by transition metal catalysts
Authors: Cho Hyun‐Nam , Choi Sam‐Kwon 
Published: April 2003

AbstractThe polymerization of acenaphthylene (ACN) was examined in the presence of the group V and VI transition metal salts such as WCl6, MoCl5, TaCl5, and NbCl5, as catalysts under various reaction conditions. These transition metal salts were found to be effective catalysts for the polymerization of ACN. The polymerization of ACN by WCl6 in chlorobenzene proceeded at a high initial rate when the monomer to catalyst mole ratio was 200. In addition, it was observed that aromatic solvents generally were found to be superior to aliphatic solvents for both conversion and molecular weight. The structure of the resulting polymers was characterized by means of NMR, IR, UV, and x‐ray diffraction. Emission properties were also investigated. Fluorescence emission spectra of the polymers obtained by WCl6 as a catalyst varied strongly depending on the polymerization solvent. Thus, it appears that the polyacenaphthylene produced by WCl6 was a different configuration dependent on the polymerization solvents used.
Preparation of plastic optical fibers for near‐IR region transmission
Authors: Kaino Toshikuni 
Published: April 2003

AbstractLoss factors of PMMA and PS core plastic optical fibers (POFs) were analyzed, and it was revealed that the vibrational absorption owing to CH vibration plays the most significant role in reducing the near‐IR region attenuation loss. Conversion of the hydrogen of the CH bond in the core polymer to deuterium gives rise to a large reduction of the attenuation loss not only in the visible wavelength region but also in the near‐IR region.The deuteration of styrene is not so effective as that of methyl methacrylate because of PS core POFs higher loss owing to imperfections in the wave guide structure and Rayleigh scattering. Using a perdeuterated PMMA as a POF core, a loss of 20 dB/km was attained in the 650–680 nm wavelength region. The loss limits of these deuterated polymer core POFs were also estimated.
Reverse osmosis and fine structure of decrystallized acrylic acid grafted nylon 6 membranes
Authors: Takigami Shoji , Kobayashi Fumihiko , Nakamura Yoshio 
Published: April 2003

AbstractNylon 6 film and acrylic acid grafted nylon 6 (GN) membrances were reacted with paraformaldehyde and lactic acid in the presence of acid catalysts. Decrystallized nylon 6 (DN) and decrystallized grafted nylon 6 (DGN) membranes were thus obtained. The cross sections of GN and DGN membranes were observed by a transmission electron microscope. Branch poly(acrylic acid) penetrated toward the center of the membrane and deposited homogeneously within the membrane as the extent of grafting exceeded about 100%. The reverse osmosis of DN and DGN membranes was investigated. The water permeability through the membranes was improved by the decrystallization reaction. DGN membranes with more than 100% grafting show high values of the salt rejection (Rs) as compared with DN and DGN membranes with about 50% grafting, especially at the region of the high hydraulic permeability coefficient of water (K). The relationships among Rs, K, and the volume fraction of water (H) are discussed by considering the results of the decrystallization reaction and electron microscopy.
Structure–property relationships of ionene polymers
Authors: Klun Thomas P. , Wendling Larry A. , Van Bogart John W. C. , Robbins Aida F. 
Published: April 2003

AbstractThe synthesis of new ionenes was accomplished by the reaction of novel diamines and dihalides. A new class of crosslinkable ionenes was made possible by the synthesis of tertiary diamines with acrylate functionality, generated ultimately from diepoxides and secondary amines. Other tertiary diamines were produced by endcapping of diols with tolylene diisocyanate, followed by reaction with N,N‐dimethylethanolamine and also termination of living poly(tetrahydrofuran) polymer with dimethylamine. New dihalides were produced by the opening of diepoxides with ω‐bromoacids.These diamines and dihalides underwent Menschutkin reactions providing novel ionenes for structure–property relationship studies. Correlations were drawn concerning amine nucleophilicity, dihalide nucleofugascity, and molecular weight. Stress–strain and thermal data reflected the effects of ionic domains and large flexible segments in the polymers. Also considered were the electrical conductivity, moisture–vapor transmission, and oxygen permeability of these materials.
Temperature dependence of ESR spectra of methyl methacrylate radicals from 77 K to 300 K
Authors: Chen C. R. , Knight Randall L. , Pollock Lori 
Published: April 2003

AbstractThe radicals formed in poly(methyl methacrylate) (PMMA) under vacuum by UV irradiation at room temperature were carefully examined from 77 K to 300 K by electron spin resonance (ESR). The conventional nine‐line spectrum was observed with significant overall intensity changes in contrast to previous reports. The intensity decreases greatly as the temperature increases from 77 K to 100 K. The intensity of the ESR spectrum increases as the temperature increases gradually from 100 K to 260 K. The spectral changes were reversible at all temperatures. Three different models are considered to interpret the temperature dependence of the intensity of the ESR spectrum. The results indicate that the ESR spectrum depends on (1) the steady‐state concentration of the propagating radical in the polymer, (2) the conformational distributions of the radicals, and (3) the environmental structures of the polymer matrix.
Studies in the formation of poly(oxazolidones) I. Kinetics and mechanism of the model oxazolidone formation from phenyl isocyanate and phenylglycidyl ether. Selectivity of catalysts
Authors: Sendijarević Aiša , Sendijarević Vahid , Frisch Kurt C. 
Published: April 2003

AbstractThe reaction of phenyl isocyanate with phenylglycidyl ether in the presence of various catalysts served as a model reaction for the preparation of poly(oxazolidones). The type of catalyst used determines the mechanism of the oxazolidone synthesis. In addition to the basic product, oxazolidone, side products may be formed, the most frequent of which is the formation of isocyanurates, which depends upon the temperature and the type of catalyst. The most effective epoxide‐soluble catalysts evaluated so far in the preparation of oxazolidones were the complex catalyst AlCl3‐triphenylphosphine oxide and AlCl3‐hexamethylphosphoric triamide. The kinetic study of the oxazolidone formation was carried out by means of HPLC, and the isocyanate and epoxide were separately determined by means of the di‐n‐butylamine and the perchloric acid methods, respectively. The HPLC method also clearly demonstrated the presence of two isomers, 3‐phenyl‐5‐phenoxymethyloxazolidone‐2 and 3‐phenyl‐4‐phenoxymethyloxazolidone‐2. The distribution of these isomers, previously reported in the literature, was found to depend upon the temperature and the type of catalyst used.
Fractionation of partly hydrolyzed polyvinyl acetate
Authors: Lerner F. , Alon M. 
Published: April 2003

AbstractVinyl acetate–vinyl alcohol copolymers were fractionated in order to obtain their degree of hydrolysis distributions. In the method employed for fractionation, the differences in molecular weight of copolymer did not affect the fractional separation. Degree of hydrolysis distributions was found to be broad, with a pronounced maximum at a low degree of hydrolysis. Viscosity measurements were performed both for the precipitated fractions and unfractionated polymer. The Huggins constant was found to increase with a decrease in the degree of hydrolysis of polyvinyl acetate. These results were interpreted in terms of a polymer molecular association. From values of Huggins constants, comparative information about copolymer “blockiness” is also established.