bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of p‐toluene sulfonyl ester and amino derivatives of tri‐ and poly(ethylene glycol)
Authors: Swamikannu A. Xavier , Litt Morton H. 
Published: April 2003

AbstractMethods described in the literature are inadequate for the preparation of pure polyethylene glycol (PEG) tosylate. Therefore an improved method is presented. The hydroxyl groups on PEG can be quantitatively converted into the tosylate and isolated from the reaction medium free from impurities with no chain cleavage or reduction in molecular weight. 1,2‐Di(N‐phenyl 2‐aminoethoxy) ethane, α,ω‐di(N‐phenyl 2‐aminoethyl) poly(oxyethylene), and α,ω‐di(N‐phenyl, N‐benzyl 2‐aminoethyl) poly(oxyethylene) were prepared from the tosylates of tri‐ and poly(ethylene glycol)s and the corresponding primary and secondary aromatic amines.
Polymerization initiated by ylide: Polymerization of ethyl methacrylate with the use of 4‐picolinium p‐chloro phenacylide as initiator
Authors: Tewari R. S. , Awasthi A. , Srivastava A. K. , Kumar M. 
Published: April 2003

AbstractThe ylide 4‐picolinium, p‐chloro phenacylide‐initiated thermal polymerization of ethyl methacrylate (EMA) was studied. 4‐Picolinium p‐chloro phenacylide induces the thermal polymerization of ethyl methacrylate at 65°C. The rate of polymerization (Rp) rose as the initiator concentration increased from 2 × 10−3 to 4 × 10−3 M and the initiating exponent was computed as 1.9. The Rp decreased as the concentration of ylide increased from 6 × 10−2 to 1M. The greater initiator concentration also affected the molecular weight inversely. The polymerization was carried out at different temperatures and the overall activation energy was computed as 4.08 Kcal/mol. Polymerization was inhibited in the presence of hydroquinone as a radical scavenger. Kinetic studies and other data show that the overall polymerization takes place in a radical mechanism. The various kinetic parameters, such as the rate and average degree of polymerization, molecular weight, and energy of activation of the present system, were evaluated.
Ring‐opening polymerization of anhydro‐deoxy‐sugar derivative and chemical synthesis of stereoregular 2‐deoxy‐(1 → 6)‐α‐D‐arabino‐hexopyranan
Authors: Hatanaka Kenichi , Kanazawa Shuji , Uryu Toshiyuki , Matsuzaki Kei 
Published: April 2003

AbstractThe cationic, ring‐opening polymerization of 1,6‐anhydro‐3,4‐di‐O‐benzyl‐2‐deoxy‐β‐D‐arabino‐hexopyranose (ABDA) (=1,6‐anhydro‐3,4‐di‐O‐benzyl‐2‐deoxy‐β‐D‐glucopyranose) was investigated with Lewis acid as catalyst. Phosphorus pentafluoride at −78°C caused polymerization to a highly stereoregular (1 → 6)‐α‐linked polysaccharide. Effects of C‐2 substituent on the polymerization of 1,6‐anhydro sugar are discussed. In addition, copolymerization of ABDA (M1) with 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose (LGTBE, M2) was studied. The monomer reactivity ratios calculated by the Kelen‐Tüdös method were r1 = 4.46 and r2 = 1.66. Debenzylation of the polymer produced 2‐deoxy‐(1 → 6)‐α‐D‐arabino‐hexopyranan in which every repeating unit contained two free hydroxyl groups.
Polymerization of vinylcarbazole on copper(II)‐13X molecular sieves: Role of copper(II) salts
Authors: Biswas Mukul , Banerjee Madhusudan , Maiti Mrinal M. 
Published: April 2003

AbstractCopper(II)‐exchanged‐13X molecular sieves, prepared from four copper(II) salts, namely, sulfate, nitrate, chloride, and acetate, and their activities in the polymerization of N‐vinylcarbazole at a fixed copper ion exchange level were studied. From the kinetic characteristics of polymerization it was established that the variation in activities of the Cu‐exchanged sieves is due primarily to the difference in the pH of the original salt solution, which is responsible for the varying degree of proton exchange with the zeolite during copper ion exchange. A first‐order dependence of the rate of polymerization was observed with respect to H+ ion concentration of the original copper‐salt solution. It was further established that the rate of polymerization of exchanged copper ion, at a hypothetical zero proton concentration, is low. A mechanism of polymerization of NVC on copper‐exchanged‐13X zeolite was suggested on the basis of the results obtained.
Differential scanning calorimetry studies of irradiated polyethylene: II. The effect of oxygen
Authors: Zoepfl F. J. , Markovic V. , Silverman Joseph 
Published: April 2003

AbstractThe effect of absorbed doses of ionizing radiation up to 2MGy in the presence of air on the melting behavior of high‐ and low‐density polyethylene was analyzed from data obtained by differential scanning calorimetry. Thermal measurements were made during the first melting after irradiation. The first melting temperature of polyethylene irradiated in air decreased with increasing absorbed dose. Above approximately 0.6 MGy bimodal endotherms were observed for high‐density polyethylene. The heat of fusion remained unchanged after irradiation in air for absorbed doses of less than 2 MGy. Bimodal endotherms were not obtained for low density polyethylene samples irradiated in air. The changes in melting temperature and the appearance of bimodal endotherms are related to the radiation chemistry of polyethylene in the presence of oxygen.
Functional monomers and polymers. CIV. Synthesis and properties of oligomer models of polyethyleneimine derivatives with spacer‐separated nucleic acid bases
Authors: Sakuma Yo , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractA series of polyethyleneimine derivatives and their oligomer models with pendant thymine or adenine bases separated by β‐alanyl groups as spacers were prepared by an activated ester method. To elucidate the nature of intramolecular interaction of thymine and adenine bases ultraviolet (UV) spectrophotometric studies were undertaken for the series of compounds and the results were compared with those obtained for the corresponding oligomers without spacers. In the thymine derivatives, the nature of the intramolecular interaction resembled that of the corresponding compounds without β‐alanyl units, although larger hypochromicities were found in the series with β‐alanyl units. In the adenine derivatives, contrary to the corresponding thymine systems, UV hypochromicities of the compounds decreased by incorporation of the spacer group into side chains. It became evident that the intramolecular interaction of adenine bases was due to stacking neutral species, hydrogen bonding, and residual hypochromicity for the protonated species.
Reactive crystals. IV. Crystalline state photopolymerization of 5,5′‐1,4‐phenylene‐bis(2‐cyano‐2,4‐pentadienoic acid) derivatives
Authors: Nakanishi Fusae , Arai Masami , Nakanishi Hachiro 
Published: April 2003

Abstract5,5′‐1,4‐Phenylene‐bis(2‐cyano‐2,4‐pentadienoic acid) derivatives were prepared. Many of this series of compounds were found to be polymerizable in the crystalline state by irradiation with light of wavelength λ > 340 nm. The polymers obtained contain a benzene and a cyclobutane ring in the main chain and have a cyanoacrylate as the side chain. They are crystalline and some of them are soluble in organic solvents. Photopolymerization was found to follow a stepwise mechanism. The polymerization process is separable into an oligomerization and a subsequent polymerization by controlling the wavelength of the irradiating light; an oligomer was obtained by an irradiating light; an oligomer was obtained by an irradiating light of wavelength λ > 430 nm.
Core‐shell emulsion copolymerization of styrene and acrylonitrile on polystyrene seed particles
Authors: Dimonie Victoria , El‐Aasser Mohamed S. , Klein Andrew , Vanderhoff John W. 
Published: April 2003

AbstractSeeded emulsion copolymerization of an azeotropic composition of styrene (St) and an acrylinitrile (AN) comonomer mixture in polystyrene (PS) seed at different polymerization temperature of 55–75°C were investigated. The kinetic data showed a transition temperature at 65°C, above which the activation energy of polymerization is low, 6.1 Kcal/mol, compared with 9.8 Kcal/mol below it. The particle‐size results and thin layer chromatographic (TLC) data showed two types of particle of different composition and morphology in the final latex system: a smaller size of (St–AN) copolymer and a larger size of core‐PS and (St–AN) copolymer shell, with a zone of PS grafted (St–AN) copolymer in between. Various polymerization parameters, that is emulsifier concentration, type of seed particle and its size, and monomer/polymer ratio, were studied and their effects on particle size and particle morphology were examined. The percent of grafted core‐PS was 10% below a polymerization temperature of 65°C and 40% above that temperature. By adjusting the size and number of the seed particles, monomer‐polymer ratio, and emulsifier concentration conditions were established in which a final copolymer latex with “perfect” core‐shell morphology was achieved.
Insitu dehydro‐oligomerization of castor oil, fatty acid ester into esters of dimer and oligomer acids over molybdenum oxide on silica‐alumina catalyst
Authors: Kumar V. G. , Venkatachalam S. , Rao K. V. C. 
Published: April 2003

AbstractA process is described for the conversion of methylricinoleate, the major castor oil, fatty acid ester, directly into esters of dimer and oligomer acids by using molybdenum oxide on a silica–alumina catalyst. The dehydration of the methylricinoleate into a corresponding mixture of conjugated and nonconjugated olefins and the oligomerization reaction took place side by side in a continuous column, fixed‐bed reactor. The products are characterized by IR, 1H NMR, and MS. The fragmentation pattern in the mass spectrum of the dimeric species distilled from the mixture reveals that the product contains cyclic and acyclic isomeric structures. The mechanism of dimerization and oligomerization reactions to transition metal complexes and transition metal oxide catalyst systems is reviewed briefly and the possibility of a common mechanism for all similar systems is suggested. A general mechanism for oligomerization reactions to similar catalysts is proposed and the products of the present reaction are explained on the basis of the proposed mechanism.
Preparation and characterization of plasma‐polymerized styrene thin films
Authors: Prohaska G. W. , Johnson E. D. , Evans J. F. 
Published: April 2003

AbstractPlasma‐polymerized styrene (PPS) thin films (several hundred to several thousand Å thick) have been prepared under a variety of discharge conditions in a tubular reactor inductively coupled to a radio frequency (13.56 MHz) power supply. Studies have focussed on the correlation of deposited polymer structure, evidenced both at the film surface (via XPS analysis) and in the bulk polymer (via transmission FT–IR analysis) with controllable plasma parameters (coupled rf power, monomer flow rate, monomer pressure). It has been determined that the relative number of phenyl rings incorporated into the film intact is an inverse function of the power per styrene molecule ratio. Polymer deposition rate was found to be a strong function of styrene flow rate and substrate temperature. Plausible elements of the styrene plasma polymerization mechanism will be considered.
Dual functional catalysis for ethylene polymerization to branched polyethylene. I. Evaluation of catalytic systems
Authors: Beach David L. , Kissin Yury V. 
Published: April 2003

AbstractSynthesis of low‐density polyethylene, that is, a density of less than 0.925 g/cm3, has traditionally been accomplished by the use of free‐radical initiators at high ethylene pressures or of an alpha olefin comonomer such as 1‐butene at lower pressures. We investigated an alternative route to branched, low‐density polyethylene with a single monomer, ethylene, as the feed in conjunction with multicomponent catalyst systems capable of in situ dimerization of ethylene and subsequent copolymerization to produce low‐density polyethylene. This article discusses the details of the evaluation of a number of dual‐functional systems based on Ziegler‐Natta catalysts. Specific, well defined, dual‐functional catalyst systems which could easily produce branched, low‐density polyethylene with levels of 20–30 branches per 1000 carbon atoms were developed. Variations in the relative number of component catalysts resulted in systematic, predictable changes in the properties of the polyethylene produced, which demonstrated the utility of the dual‐functional catalyst concept.
Thermal stability of the silica‐aminopropylsilane‐polyimide interface
Authors: Linde H. G. , Gleason R. T. 
Published: April 2003

AbstractThermal degradation of the silica–aminopropylsilane–amic acid/imide interface was studied by modifying a high‐surface‐area, neutral silica gel with a number of substituted aminopropylsilanes (APS). These substrates were reacted further with phthalic anhydride or aromatic amic acid monomers and the thermal decomposition of the adsorbed/reacted materials was monitored by thermogravimetric analysis (TGA) and infrared (IR) spectroscopy. The 3‐aminopropyltriethoxysilane/poly[N,N′‐(p,p′‐oxydiphenylene)pyromellitimide] interface was also evaluated by this method.Comparison clearly distinguishes the thermal decomposition of surface‐bound APS from surface‐bound alkylphthalimides, the adhesion product of alkylamines and aromatic amic acids. Alkylamine imidization with the elimination of aromatic amine (analogous to polymer scission) and the decomposition of the surface‐bound imide are shown in the amic acid TGA profiles. This imidization and the accompanying aniline elimination begin at about 130°C, under nitrogen, to form the surface alkyl imide which slowly decomposes at 400°C. TGA analysis indicates that the surface‐bound imide undergoes minimal degradation under nitrogen at 370 ± 10°C; temperatures above this threshold range produce changes in the APS–imide interface.
Synthesis and characterization of nadimidized 1‐[(dialkoxyphosphinyl)methyl1]‐2,4‐ and ‐2,6‐ diaminobenzenes and their polymerization to fire‐resistant laminating resins
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractA series of nadimidized 1‐[(dialkoxyphosphinyl1)methyl]‐2,4‐ and ‐2,6‐diaminobenzenes was prepared and polymerized thermally to yield highly crosslinked fire‐resistant laminating resins. Bisnadimides were characterized by elemental analysis and Fourier‐transform‐infrared (FT–IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy. Curing behavior of the polymer precursors was studied by differential scanning calorimetry (DSC). Char yield of polymers at 700°C was 64–69% and 30–60% in nitrogen and air atmospheres, respectively. The pyrolysis behavior of some bisnadimides was investigated by gas chromatography–mass spectroscopy (GC–MS). Cyclopentadiene was evolved by retrograde Diels–Alder reaction during processing, but most was captured by copolymerization. The fire‐resistance of some polymers was evaluated by determining their limiting oxygen index and smoke evolution.
Preparation and luminescence properties of tris(bipyridine) ruthenium(II)‐containing vinyl polymers: Ru(bpy)2 (poly‐6‐vinyl‐2,2′‐bipyridine)Cl2 and Ru(bpy)2(poly‐4‐methyl‐4′‐vinyl‐,2,2′‐bipyridine)Cl2
Authors: Sumi Katsuhiro , Furue Masaoki , Nozakura Shun‐Ichi 
Published: April 2003

AbstractRuthenium (II) complex‐containing polymers were prepared and characterized by absorption and luminescence spectra, luminescence quantum yield, and luminescence lifetime. The polymers are Ru(bpy)2(poly‐6‐vinyl‐2,′2‐bipyridine)CI2 (1) and Ru(bpy)2(poly‐4‐methyl‐4′‐methyl‐4′ ‐vinyl‐2,2′‐bipyridine)CI2 (2). The absorption spectra and luminescence spectra of polymers 1 and 2 were substantially the same as that of Ru(bpy)3CI2. The lifetime of polymers 1 and 2 was similar to that of the respective monomer model compounds. The lifetime of polymer 1 was very short (ca. 13 ns) in comparison to Ru(bpy)3CI2 (660 ns), whereas the lifetime of polymer 2 (660 ns) was similar to that of Ru(bpy)3CI2. The temperature‐dependency of the lifetime was discussed in terms of Watts' model.
Polymerization of vinyl monomers in the water–1,4‐dioxane system containing peroxide and water‐soluble polymer
Authors: Nonaka Takamasa , Tagawa Rikiichi , Nishida Haruo , Egawa Hiroaki 
Published: April 2003

AbstractWater‐solube polymer (PST) containing triethylenetetramine side chain was prepared by the amination of chloromethylated polystyrene with triethylenetetramine in 1,4‐dioxane. The polymerization of vinyl monomers was carried out in the water–organic solvent system containing PST and a very small amount of peroxide. The polymerization of methyl methacrylate proceeded smoothly in the presence of both peroxide and PST. It was found that the polymerization was initiated with the radicals generated by the interaction between hydroperoxide and amino groups of PST. 1,4‐Dioxane hydroperoxide showed a high activity for the polymerization of methyl methacrylate. The maximum rate of the polymerization was observed at 60°C and in an approximately neutral solution. The addition of suitable amount of Cu(II) accelerated the polymerization of methyl methacrylate. The selective polymerization of vinyl monomers was observed in this system.
ESCA studies of metal‐containing plasma polymers. Part I. Incorporation of mercury into plasma‐polymerized perfluorobenzene
Authors: Munro H. S. , Till C. 
Published: April 2003

AbstractESCA was used to examine the structure and bonding of mercury‐containing, plasma‐polymerized perfluorobenzene. A maximum Hg:C stoichiometry, independent of distillation temperature and power but dependent on substrate temperature, was obtained. Comparison of the plasma polymers of perfluorobenzene and mercury‐containing perflurobenzene formed as a function of power, revealed that the C1s structure of the latter system was not due to the level of mercury incorporated but to sensitized reactions that developed from energy absorption by the mercury in the gas phase.
Hexakis(arylisocyano) derivatives of chromium(0) as initiators of vinyl polymerization: Steric effects
Authors: Hargreaves K. 
Published: April 2003

AbstractThe free radical polymerization of methyl methacrylate initiated by the hexakis (arylisocyano)chromium(0)‐CCl4 system has been studied for a number of derivatives in which both chlorine and methyl groups have been introduced into the benzene ring. It has been found that single substituents in the benzene ring, irrespective of position, have little effect on the activity of the system other than that which can be explained by the electronic effects of these substituents. However, where steric overcrowding occurs it has been shown that the rate of initiation is reduced considerably. This confirms the established mechanism of initiation for this type of derivative.
Radiation polymerization of acrolein at low temperatures
Authors: Kumakura Minoru , Kaetsu Isao 
Published: April 2003

AbstractRadiation polymerization of acrolein in the presence of the additives such as 2‐hydroxyethyl methacrylate, acrylic acid, and water at low temperatures (0–78°C) was studied. The polyacrolein resulting from the polymerization gave a small particlelike microsphere (0.5–5 μm in diameter). The rate of the polymerization reaction of acrolein appeared to be accelerated by the addition of a small amount of 2‐hydroxyethyl methacrylate or acrylic acid. The particle size of the polyacrolein particle varied with the condition of the polymerization and increased or decreased with an increase in the addition concentration of 2‐hydroxyethyl methacrylate or acrylic acid.
ESCA studies of metal‐containing plasma polymers. II. Plasma polymerization of ferrocene, vinylferrocene, and dimethylaminomethylferrocene
Authors: Munro H. S. , Eaves J. G. 
Published: April 2003

AbstractThe surface aspects of plasma polymers derived from ferrocene, dimethylaminomethylferrocene, and vinylferrocene were studied by electron spectroscopy for chemical applications. From a consideration of the ESCA peak area ratios it is apparent that ferrocene and vinylferrocene maintain a carbon‐to‐iron ratio characteristic of the “monomer”, whereas dimethylaminomethylferrocene plasma polymer is richer in iron than its monomer.
Thermally stable polymers from 1,4,5‐naphthalene–tricarboxylic acid and aromatic tetramines
Authors: Korshak V. V. , Mognonov D. M. , Izyneev A. A. , Doroshenko Yu. E. 
Published: April 2003

AbstractNew thermally stable polymers that contained benzimidazole and benzimidazobenzoisoquinoline fragments in polymer chains were synthesized by one‐stage cyclopolycondensation of aromatic tetramines (3,3′, 4,4′‐tetraminodiphenyl ether, 3,3′,4,4′‐tetraminodiphenyl methane, 3,3′,4,4′‐tetraminodiphenyl sylfone, and 3,3′‐diaminobenzidine) with 1,4,5‐naphthalene tricarboxylic acid 4:5–anhydride in polyphosphoric acid and with 1,4,5‐naphthalene tricarboxylic acid 4:5–anhydride 1‐phenyl ester. All polymers obtained were soluble in concentrated sulfuric acid, 85% phosphoric acid, polyphosphoric acid, methane sylfonic acid. Some were soluble in formic acid. Thermogravimetric analyses indicated that these polymers were stable up to 450–500°C in air. The polymers had good hydrolytic stability.
Solid matrix polymerization and stereoisomeric complexes of poly(methyl methacrylate)
Authors: Yau H. , Stupp S. I. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate within solid matrices of stereoregular poly(methyl methacrylate) has been studied by proton NMR and wide angle X‐ray diffraction. The semi‐crystalline isotactic (i‐) PMMA matrix was synthesized in the laboratory by anionic polymerization initiated by phenylmagnesium bromide, and the syndiotactic (s‐) PMMA matrix was synthesized through a Ziegler–Natta reaction. Matrix polymerization of the monomer was initiated through the redox activation of benzoyl peroxide with N,N‐dimethyl‐p‐toluidine. NMR measurements of triad distributions in matrix‐polymerized chains suggest that the well‐known stereospecific replica polymerization in PMMA (syndiotactic sequences promote isotactic sequences and vice versa) plays only a limited role in the systems studied. Experimental results indicate that chains grown within the i‐PMMA or s‐PMMA solid matrices have greater degrees of configurational disorder. The greater concentration of atactic triads in these chains could be the result of limited free volume or steric effects during polymerization in a highly condensed environment. X‐ray diffraction studies of solution cast blends of isotactic PMMA and PMMA with conventional tacticity reveal some crystallinity with a structure characteristic of the stereocomplex formed by isotactic and syndiotactic PMMA from suitable solvents. Evidence was obtained for the presence of this complex in solidified mixtures of the i‐PMMA solid matrix and liquid monomer. This observation is an example of special intermolecular structures that can form under conditions of in situ growth of chains within a pre‐polymerized matrix.
Effect of stirring on cellulose graft copolymerization. IV. Grafting of styrene by initiator systems involving potassium persulfate
Authors: Graczyk Tomasz , Hornof Vladimir 
Published: April 2003

AbstractDissolving pulp and its partially xanthated derivative were grafted with styrene, using either the Fe2+−K2S2O8 redox system of potassium persulfate alone as initiators. The conversion of styrene to both copolymer and homopolymer was found to be influenced by agitator speed. The effect of stirring was much more pronounced with the xanthated substrate in that a welldefined conversion maximum was observed at the same agitation speed for both total polymer and copolymer. Grafting onto dissolving pulp with the redox initiator also showed a maximum, but a maximum total polymer and maximum copolymer were located at different agitator speeds. Grafting of styrene onto dissolving pulp initiated by potassium persulfate was almost independent of stirring in the 0–910 rpm range.