bluuebunny/crossref_metadata_2025 huggingface dataset:
Proton, phosphorus and carbon nuclear magnetic relaxation studies on the interaction of poly(riboadenylic acid) with Cu2+
Authors: Enmanji Koe
Published: April 2003

Interaction between poly(riboadenylic acid) (poly(A)) and Cu2+ in neutral aqueous (D2O) solution has been studied by 1H, 31P, and 13C nuclear magnetic resonance. electron‐nuclear hyperfine coupling constant and apparent electron‐nuclear distances were determined by measurement of T1 and T2 values as a function of temperature. The apparent distance from Cu2+ to H(2), H(8), H(1′), and phosphorus nuclei were estimated to be 4.1, 3.7, 5.1, and 3.1 Å from these results. Cu2+ was found to coordinate directly to the phosphate groups of poly(A) (Type I complex). Simultaneously there are bindings of Cu2+ directly to one of the nitrogen atoms of adenine ring, mainly to N(7) (Type II complex) and either N(1) or N(3) (Type III complex).
Assignment of proton NMR spectrum of triglycidylether of para‐aminophenol (TGPAP), using two‐dimensional techniques: SUPERCOSY and J‐resolved
Authors: Jagannathan N. R. , Herring F. G.
Published: April 2003

One‐ and two‐dimensional 400‐MHz proton NMR experiments are reported for the epoxy resin monomer, triglycidylether of para‐aminophenol (TGPAP). Assignment of the epoxy protons becomes difficult due to many overlapping signals from the glycidylamine and glycidylether regions. To solve this problem we employed the homonuclear proton shift‐correlated (SUPERCOSY) and J‐resolved two‐dimensional techniques. The combination of these methods permits the complete elucidation of the complex spectrum.
Preparation of poly(fumaric acid) from poly(di‐t‐butyl fumarate) and poly(di‐trimethylsilyl fumarate)
Authors: Kitano Toshiaki , Ishigaki Akemitsu , Uematsu Gen‐Ichi , Kawaguchi Seigou , Ito Koichi
Published: April 2003

Polymerization conditions of di‐t‐butyl fumarate and di‐trimethylsilyl fumarate were studied in detail. They cannot be polymerized by either anionic or coordination initiators, but radical and radiation polymerizations are successful. Characterization of poly(di‐t‐butyl fumarate), obtained thereby, with 1H‐NMR spectrum suggests that the backbone of the chain is stiff. From analysis of thermal properties of poly(di‐t‐butyl fumarate), it is found to be completely converted to poly(fumaric acid) by pyrolysis around 200°C. Poly(di‐trimethylsilyl fumarate), on the other hand, can be quantitatively hydrolyzed with acid to the same polyacid, too. The preliminary measurement of the dissociation behaviors of poly(fumaric acid) was done by potentiometric titration, which shows that the titration curves of poly(fumaric acid) are different from those of poly(acrylic acid) and poly(maleic acid).
Relationship between distribution of substituents and water solubility of O‐methyl cellulose
Authors: Takahashi Shin‐Ichi , Fujimoto Tetsuya , Miyamoto Takeaki , Inagaki Hiroshi
Published: April 2003

The solubility behavior of O‐methyl cellulose (MC) in water was investigated in terms of the distribution of substituents along the cellulose chain as well as in the anhydroglucose (AHG) units. For this purpose, three different types of MC samples were prepared by respective homogeneous reaction, i.e.. (i) methylation of cellulose acetate (CA) prepared from cellulose triacetate (CTA), followed by deacetylation, (ii) methylation of CA prepared by direct acetylation of cellulose in a 10% LiCl–dimethylacetamide (DMAc) solution, followed by deacetylation, and (iii) methylation of cellulose with dimethyl sulfate in a 10% LiCl–DMAc solution. Their water solubility was compared with that of MC samples prepared by the alkali cellulose process, i.e., by the heterogeneous reaction, including commercial products. It was found that water‐soluble MC samples prepared by the alkali cellulose process exhibit a thermally‐reversible sol‐gel transition in aqueous solution, but all of the MC samples preapred homogeneous reactions show a normal phase separation in aqueous solution. This result gives a direct support for the consideration that the highly substituted glucose sequences present in the commercial MC act as “crosslinking loci” on warming. The distribution of substituents in the AHG units was estimated by 13C‐NMR method. The results on the water solubility of MC were also discussed in terms of the distribution of substituents in the AHG units.
Catalysis of copper(II) chelate‐amine complexes in the oxidative coupling of 2,6‐dialkylphenols
Authors: Tsuruya Shigeru , Nakagawa Katsutoshi , Masai Mitsuo
Published: April 2003

The oxidative coupling reaction of 2,6‐dimethylphenol and 2,6‐di‐tert‐butylphenol with molecular oxygen was performed by using a series of copper(II) chelate complexes as a catalyst, derived from copper(II), β‐diketone, and some Shiff bases. Under the applied reaction conditions, the reaction products of 2,6‐dimethylphenol were poly(2,6‐dimethyl‐1,4‐phenylene oxide) (CO coupling product) and 3,3′,5‐5′‐tetramethyl‐4,4′‐diphenoquinone (CC coupling product), and that of 2,6‐di‐tert‐butylphenol oxidation was only 3,3′,5‐5′‐tetra‐tert‐butyl‐4,4′‐diphenoquinone (CC coupling product). The catalytic activity has been shown to be dependent on the properties of the copper(II) chelates used as catalysts and the mole ratios of amine ligand to copper(II) chelate (ligand ratio). The basicity and the steric bulkiness of the amine used as a ligand for copper(II) β‐diketonato catalysts were found to be two of the main factors that govern the oxidative coupling mode (CO and/or CC coupling) of 2,6‐dimethylphenol. The oxidative coupling activity of 2,6‐dialkylphenol is discussed in terms of both the stabilities of the copper(II) chelates and of the copper(II) chelate‐amine adducts. The rate of oxygen absorption for 2,6‐dimethylphenol catalyzed by the copper(II) acetylacetonato‐piperidine system is first order in oxygen partial pressure and zero order in 2,6‐dimethylphenol concentration, respectively. A Cu(II)‐oxygen, as an intermediate is suggested on the basis of the results obtained.
Magnesium chloride supported high mileage catalysts for olefin (decene‐1) polymerization XV. Termination and energetics
Authors: Chien James C. W. , Ang Tsunle
Published: April 2003

Polymerizations of decene‐1 were carried out from 0° to 70° at A/T = 167 and [M] = 0.75 M initiated by 0.17, 0.34, and 0.69 mM of Ti contained in the MgCl2/ethylbenzoate/p‐cresol/AlEt3/TiCl4‐AlEt3/methyl‐p‐toluate catalyst. The rate of polymerization is directly proportional to the catalyst concentration. About 12% of the Ti in the catalyst is initially active at 50°; they are 1.4%, 8.8%, and 9.4% at 0°, 25°, and 70°, respectively. The changes of Rp with temperature parallels the variations in the active site concentration. The decline of Rp with time has second‐order plots with slopes which are inversely proportional to the catalyst concentration, but the rate constants for these deactivations are nearly the same for decene and propylene polymerizations. These results strongly support a mechanism of deactivation involving two adjacent sites in the catalyst particle surfaces. The rate constants of propagation and of chain transfer to AlEt3, the energetics for these processes, and MW and MW distribution data have been obtained.
Photoelectrochemistry in particulate systems. 5. Visible light‐induced polymerization of 1‐vinylpyrene in semiconductor suspensions
Authors: Kamat Prashant V. , Todesco R. V.
Published: April 2003

Photoelectrochemical polymerization of 1‐vinylpyrene has been achieved in a semiconductor photocatalyst suspension under visible light irradiation (λ > 480 nm). Bandgap excitation of CdS, CdSe or Fe2O3 led to the oxidation of 1‐vinylpyrene, which initiated the polymerization process. A 25–47% yield of poly(1‐vinylpyrene) could be obtained upon irradiation of these semiconductor photocatalyst suspensions with 1‐vinylpyrene in acetonitrile. Dependence of the polymer yield on various experimental conditions is described.
ESCA and optical emission study of the inductively coupled RF plasma copolymerization of naphthalene and octafluoronaphthalene mixtures
Authors: Munro H. S. , Till C.
Published: April 2003

Plasma polymerization of octafluoronaphthalene, naphthalene, and 1 : 1 mixtures of the two yielded thin films which were then analyzed by ESCA. Optical emission was recorded during deposition and the resultant spectra are shown. Deposition of the copolymer at 150°C resulted in a film whose composition was different from that deposited at room temperature and from the single plasma polymers. Copolymerization resulted in a lowering of CF2 functionalities and an increased retention of the aromatic nature of the monomers. Optical emission of CF2 during copolymerization was greatly reduced as was a peak at about 510 nm.
Selective vinyl cationic polymerization of monomers with two cationically polymerizable groups. I. p‐isopropenylphenyl glycidyl ether: An epoxy‐functionalized α‐methylstyrene
Authors: Hashimoto Tamotsu , Sawamoto Mitsuo , Higashimura Toshinobu , Saito Noriaki
Published: April 2003

p‐Isopropenylphenyl glycidyl ether (IPGE), a monomer of dual cationic functionality (isopropenyl and epoxy), was polymerized by a variety of initiators, and optimum conditions were established for its selective vinyl cationic polymerization. The hydrogen iodide/iodine (HI/I2) initiating system or iodine polymerized selectively the isopropenyl group in CH2Cl2 at a low temperature (−78°C), to produce soluble poly(IPGE) with epoxy pendants. Under these conditions, the number‐average molecular weight of the polymers was inversely proportional to the initial initiator concentration, indicating the formation of long‐lived propagating species. Soluble poly(IPGE) was also obtained at −15 and −40°C by HI/I2 or iodine. However, at these higher temperatures, transfer and/or termination reactions took place to give olefin‐terminated polymers, in which some of the pendant epoxy groups were consumed. BF3OEt2 (a metal halide) and CF3SO3H (a strong protonic acid) polymerized both epoxy and isopropenyl groups of IPGE and yielded crosslinked insoluble polymers.
Polyimides containing carbonyl and ether connecting groups
Authors: Hergenrother P. M. , Wakelyn N. T. , Havens S. J.
Published: April 2003

Geveral new polyimides were prepared from the reaction of four aromatic dianhydrides with four new diamines containing carbonyl and ether connecting groups between the aromatic rings. The diamines were prepared from the reaction of 4‐aminophenol with activated aromatic difluoro compounds in the presence of potassium carbonate. Several of these polyimides were shown to be semicrystalline as evidenced by wide angle x‐ray diffraction and differential scanning calorimetry. Glass transition temperatures ranged between 192 and 247°C and crystalline melt temperatures were observed between 350 and 442°C. The polyimide from the reaction of 3,3′,4,4′‐benzophenonetetracarboxylic acid dianhydride and 1,3‐bis(4‐aminophenoxy‐4′‐benzoyl)benzene provided a semicrystalline solvent resistant transparent film with high tensile properties and compression molded compact tension specimens with high fracture toughness.
Inverse emulsion polymerization of acrylamide. II. Synthesis and characterization of copolymers with methacrylic acid
Authors: Glukhikh V. , Graillat C. , Pichot C.
Published: April 2003

Inverse emulsion copolymerization studies of acrylamide (Am) with methacrylic acid (MAA) are reported. Aqueous monomer solutions were emulsified in toluene with a blend of two surfactants (sorbitan sesquioleate and C18‐terminated acrylamide oligomers). Polymerization kinetics in presence of an oil‐soluble initiator (AIBN) were determined at 40°C as a function of methacrylic acid content and aqueous‐phase pH. Polymerization rates were found to be faster at basic pH than at acidic pH, which appeared to be related to the actual concentration of methacrylic acid in the aqueous phase. Monomer reactivity ratios have been derived as rA‐M = 0.58 ± 0.02 and rM‐A = 4.0 ± 0.10 at pH 4, rA‐M = 0.56 ± 0.005 and rM‐A = 0.15 ± 0.03 at pH 10. These differences were found to have an effect on the molecular characteristics of the copolymers. Initial emulsions and final inverse latexes displayed the same broad size distribution; under basic pH the particle size is relatively insensitive to the ionic comonomer concentration. Poor latex stability is characteristic of copolymer latexes prepared under acidic conditions. Based on these experimental results, some aspects of the polymerization mechanism are discussed.
Morphology and grafting reactions in core/shell latexes
Authors: Merkel M. P. , Dimonie V. L. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

The particle morphology and percent grafting were investigated as a function of the crosslink density of the seed latex in two systems of core/shell latexes of polybutadiene/polymethyl methacrylate (PB/PMMA) and styrene–butadiene rubber/polymethyl methacrylate (SBR/PMMA) prepared by seeded emulsion polymerization at 50°C. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to characterize the grafting efficiency of the core/shell latexes. The percent grafting of the shell polymer was found to decrease with increasing the crosslink density of the core material. The particle morphology and precent grafting were also investigated as a function of composition and structure of the core material in four core/shell latex systems: polybutadiene/styrene–acrylonitrile copolymer (PB/SAN), (styrene‐butadiene) random copolymer/styrene acrylonitrile copolymer (S:B/SAN), polystyrene : polybutadiene/styrene‐acrylonitrile copolymer (PS:PB/SAN) and Kraton/styrene‐acrylonitrile copolymer (Kraton/SAN), which were prepared by direct emulsification for the seed followed by emulsion polymerization at 70°C for the shell polymer. Grafting and crosslinking of the core material were found to be competitive reactions depending on the microstructure of the seed latex.
Product analyses and crosslink mechanism of plasma‐polymerized methyl methacrylate
Authors: Ohno Mikio , Ohno Keiichi , Sohma Junkichi
Published: April 2003

Plasma‐polymerized methyl methacrylate (PPMMA) film was produced by a radio‐frequency glow discharge of methyl methacrylate (MMA) gas with argon. PPMMA deposited under a plasma of mild energy was separated into a soluble fraction (sol‐PPMMA) and an insoluble matrix (insol‐PPMMA), which is highly crosslinked, by solvent‐extraction and filtration. The chemical structure of the sol‐PPMMA was determined by pyrolysis/gas chromatography, IR spectroscopy, 1H‐NMR, 13C‐NMR, and elemental analysis techniques. On the other hand, the structure of the insol‐PPMMA was examined with IR spectroscopy, 13C‐NMR with CP/MAS method, and elemental analysis. The crosslinking mechanism in the plasma polymerization of MMA is discussed on the basis of product analyses of the sol‐PPMMA and the insol‐PPMMA.
Structural changes in glassy polymers studied by thermal analysis and dynamic mechanical tests
Authors: Spathis G. , Kontou E. , Theocaris P. S.
Published: April 2003

Structural changes which take place in many amorphous polymers, when they are annealed at temperatures near the glass transition temperature, have important theoretical, physical, and mechanical consequences. In this paper the possible existence of some local ordering in highlycrosslinked epoxy resins is studied. Three kinds of tests—TMA, DSC, and dynamic experiments—are used for a type of epoxy resin, cured with six different amounts of curing agent. In order to study the effect of the thermal history on the behavior of the polymer at its transition region, as well as the morphology of the materials tested, three different thermal treatments have been followed. Interesting results were derived concerning the influence of these parameters to these parameters to the mechanical characterization of the polymer.
Plasma fluorination of polyolefins
Authors: Strobel Mark , Corn Stewart , Lyons Christopher S. , Korba Gary A.
Published: April 2003

ESCA and contact angle measurements were used to characterize the surfaces of Polyethylene and polypropylene films exposed to SF6, CF4, and C2F6 plasmas. None of these gases polymerized in the plasma. However, all plasma treatments grafted fluorinated functionalities directly to the polymer surfaces. SF6 plasmas graft fluorine atoms to a polyolefin surface. CF4 plasmas also react by a mechanism dominated by fluorine atoms, but with some contribution from CFx‐radical reactions. Although C2F6 does not polymerize, the mechanism of grafting is still dominated by the reactions of CFx radicals. For all gases studied, the lack of polymerization is attributed to competitive ablation and polymerization reactions occurring under conditions of ion bombardment.
Synthesis and polymerization of racemic and optically active β‐substituted β‐propiolactones. II: β‐monosubstituted and β‐disubstituted monomers and polymers with different optical purities
Authors: Lavallée Claude , Leborgne Alain , Spassky Nicolas , Prud'homme Robert E.
Published: April 2003

β‐(trichloromethyl)‐β‐propiolactone (CCl3‐PL), β‐(trifluoromethyl,methyl)‐β‐propiolactone (CF3, Me‐PL) and β‐(trifluoromethyl,ethyl)‐β‐propiolactone (CF3,Et‐PL) have been obtained by the reaction of ketene with chloral, 1,1,1‐trifluoroacetone and 1,1,1‐trifluorobutanone, respectively. Chiral catalysis lead to optically active monomers. The enantiomeric excess of the lactones has been measured by 1H‐NMR spectroscopy, in the presence of 2,2,2‐trifluoro‐1‐(9‐anthryl)ethanol or an europium chiral shift reagent. Polymerizations have been carried out in bulk or in toluene, at 60°C or 80°C, using mainly organometallic initiators. The Polymers become insoluble and crystalline at enantiomeric excesses over 80% for CCl3‐PL and 70% for CF3,Me‐PL. Melting temperatures were recorded from 238 to 268°C for poly(CCl3‐PL) and from 78 to 100°C for poly(CF3,Me‐PL), depending upon the molecular weight and the enantiomeric excess. The 13C‐NMR specroscopy of poly(CCL3‐PL) indicates that the polymerization of the corresponding lactone leads to polymers of increasing degrees of isotacticity with the enantiomeric excess of the monomer.
Thermal decomposition behavior of bis‐aminimides and their application to polymerization of epoxide
Authors: Inubushi Shinzo , Ikeda Tomiki , Tazuke Shigeo , Satoh Tasuku
Published: April 2003

Bis‐aminimide compounds [bis‐N, N,‐dimethyl‐N,‐(2‐hydroxypropyl)‐amine‐N,′‐adipimide (1) and bis‐trimethylamine adipimide (2)] were found to exhibit different thermal decomposition behavior and polymerization efficiency for an epoxide (phenyl glycidyl ether, PGE). The thermal decomposition rate of 1 was much higher than that of 2. It seemed that hydrogen bonding enhanced the decomposition rate. Compound 1 was thermolyzed to give a diisocyanate and a tertiary aminoalcohol, which subsequently reacted with each other to give a urethane. When 2 was heated, the isocyanate generated from 2 remained unreacted. PGE reacted with thoseaminimides to give different products, depending on their thermolyzed products. Mixtures of diisocyanate, tertiary amine, and PGE were used in the model reactions, and the thermal reaction between the expected decomposition products of aminimides was investigated in the presence and absence of PGE. The amount of high molecular weight fraction in PGE + 2 is greater than that of PGE + 1. In the former, the free isocyanate groups may act as a chain extender to give higher molecular weight fractions.
Polyelectrolyte containing dihydronicotinamide. II. Interaction of polymer and substrate
Authors: Itoh Yoshihiro , Wakisaka Kazuyoshi , Abe Koji , Senoh Saburo
Published: April 2003

Reduction of crystal violet (CV) by poly(sodium styrene‐p,‐sulfonate) containing dihydronicotinamide (NAH) groups (PNAH) was compared with that by poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate) containing NAH groups (PNAH‐AMPS) in aqueous media. PNAH reduced CV far more effectively than PNAH‐AMPS, suggesting the presence of both hydrophobic and electrostatic interaction between PNAH and CV. An obvious color change was observed on addition of CV to the polyelectrolyte solutions, which was largely affected by the kind of polymers and the experimental conditions such as ionic strength and medium composition. These results imply that the location of CV within the macromolecular domain is an important factor for the polyelectrolyte‐induced metachromasy. Some correlations of the metachromatic behaviors of CV with the reduction were also discussed.
Phenyl thiazyl compounds: Synthesis and electrical conductivity
Authors: Ramakrishnan S. , Chien James C. W.
Published: April 2003

A series of substituted phenylene‐dithio‐bis(phenyldithiazyl) (PDBPD) and phenylthiophenyldithiazyl (PTPD) compounds have been synthesized utilizing the facile reaction between N‐trimethyl silylimides and aromatic sulfenyl chlorides. The compounds are insulators with conductivities of 10−8–10−12 (Ω cm)−1. However, they can be oxidized with Br2 to conductivities of 10−3–10−5 (Ω cm)−1 for pressed pellets. Electron donating and withdrawing substituents on the phenyl ring markedly alter the electrical transport properties. While PTPD compounds are soluble in many solvents, the PDBPD derivatives are only sparingly soluble.
Isoprene polymerization with cerium(III) acetylacetonate–diethylaluminum chloride in toluene: Effects of water concentration
Authors: Lee Dong‐Ho , Jang Jae‐Kwon , Ahn Tae‐Oan
Published: April 2003

Isoprene has been polymerized in toluene using a cerium(III) acetylacetonate–diethylaluminum chloride catalyst. The microstructure of obtained polyisoprene is predominantly trans‐1,4 structure. For this system the effects of water concentration on the conversion of isoprene to polymer, the microstructure and the molecular weight of polyisoprene have been examined. The conversion at a given polymerization time has a maximum at [H2O]/[DEAC] ratio of 1:0–1.1. The amounts of trans‐1,4 structure and the viscosity average molecular weights of polyisoprene are nearly independent of the water concentration. Although the conversion increases with the concentration of catalyst, the trans‐1,4 content is not affected by the catalyst concentration and the molecular weight of polyisoprene decreases slightly with increasing catalyst concentration.
Polyarylates (I): Investigation of the interfacial polycondensation reaction by UV
Authors: Tsai Hong‐Bing , Lee Yu‐Der
Published: April 2003

The interfacial polycondensation of bisphenol A with isophthaloyl chloride and terephthaloyl chloride in dichloromethane with triethylbenzylammonium chloride as the catalyst was described. A well‐defined two‐phase system had been observed, so the concentration of bisphenolate in the aqueous phase could be determined by UV spectrometer. The conversion was found to increase rapidly with reaction time, but the rate of increase in molecular weight was slow. At the initial stage with conversion up to 95%, the reaction proceeded similarly to that of solution polycon‐densation because the synthesized polyarylate could be dissolved in dichloromethane, and a polymer with a low molecular weight resulted. At the final stage of the reaction, the molecular weight was increased to a very high value due to the local concentration effect. The mole ratio of bisphenol A to diacid chlorides was found to affect the molecular weight very much. In the case of a mole ratio less than 1, the reaction remained in the initial stage mostly, and the molecular weight was low. However, for a mole ratio greater than 1, polyarylate with a very high molecular weight could be obtained because the local concentration effect was much more significant owing to the high concentration of bisphenolate that remained in the aqueous phase at the final stage.
Crosslinking reactions of 1,3,5‐tris(2‐methylaziridinyl‐1‐methyl)benzene (TRIMAM) with carboxyl terminated polybutadiene
Authors: Kishore K. , Dharumaraj G. Varghese , Rajalingam P.
Published: April 2003

Curing reactions of a new crosslinking agent, 1,3,5‐tris(2‐methylaziridinyl‐1‐methyl)benzene (TRIMAM) with carboxylterminated polybutadiene have been studied by dynamic differential thermal analysis and by IR spectroscopy. The crosslinking reactions are found to be faster for this new compound compared with the conventional tris‐1‐(2‐methyl) axiridinyl phosphine oxide (MAPO).
Polymerization of acrylic acid initiated by a hexavalent chromium‐organic sulfur compounds reducing agent system
Authors: Lenka Subasini , Nayak Padma L.
Published: April 2003

The kinetics of polymerization of acrylic acid initiated by Cr6+‐thiourea, Cr6+‐thioacetamide, Cr6+‐2‐aminoethane thiol, Cr6+‐cysteine, and Cr6+‐thioglycollic acid have been studied at 30, 35, and 40°C in nitrogen. The rates of polymerization were measured. Chromic acid alone did not initiate the polymerization under deaerated and un‐deaerated conditions. On the basis of the experimental observation of the dependence of the rate of polymerization Rp on various variables, a suitable kinetic scheme is proposed.
Interaction of triphenylmethyl salts with vinyl ethers
Authors: Velichkova R. S. , Doicheva J. B. , Panayotov I. M.
Published: April 2003

The initiation of isobutyl, n‐butyl, ethyl, and 2‐chloroethyl vinyl ethers polymerization by trityl ion salts was investigated. The oligomers formed and the reaction mixtures were analyzed by GPC and 1H‐NMR spectroscopy. It is concluded that the initiation proceeds via two competing reactions. The addition of the initiator to the monomer is determined as usual by the electrophilicity of the former and the nucleophilicity of the latter. In order to realize initiation by hydride transfer it is necessary for the monomer to possess a hydrogen atom with hydride mobility and that the cation obtained is sufficiently stable. The relative part of these initiation reactions is determined.
Preparation and properties of silicon containing polyamides
Authors: Kiyotsukuri Tsuyoshi , Tsutsumi Naoto , Ayama Koichi , Nagata Minoru
Published: April 2003

Silicon containing polyamides were prepared by melt polycondensation method with a 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane and aliphatic dicarboxylic acids having various numbers of methylene groups. Only one endothermic peak appeared in the DTA curve of the quenched sample for polyamides having an even number of methylene groups in the repeating unit. Two endothermic peaks, however, appeared for the sample kept for a week in dry air at ambient temperature after quenching: the peak at the higher temperature is called peak I; and the peak at the lower one, peak II. By heat treatment at the higher temperature, peak II shifted to a higher temperature and increased its peak area, and peak I decreased its peak area while keeping its temperature unchanged. This behavior suggests the existence of two types of crystalline states. The peak temperature of peak I alternatively decreased with the increase of the number of methylene groups. The Young's modulus and the tensile strength increased with increase of annealing time at ambient temperature. The solubilities in various solvents, the resistance to alkali solution, and the thermal stability were acceptable. Both the permeation coefficient of oxygen (P) and the separation ratio (P/P) increased with the increase of silicon content in the repeating unit.
Photophysics of a sulfonated 2‐hydroxyphenylbenzotriazole UV absorber in solution and in polymer substrates
Authors: Ghiggino K. P. , Scully A. D. , Bigger S. W. , Leaver I. H.
Published: April 2003

The total absorption spectrum of the UV absorber sodium 2‐(2′‐hydroxy‐5′‐methylphenyl) benzotriazole sulfonate (TINS) has been resolved into contributions by two ground‐state forms in acetonitrile‐water solvent mixtures and hydrogen bonding polymer and protein substrates. These two ground‐state species can be assigned to (i) a planar intramolecularly hydrogen bonded form which can undergo the efficient nonradiative energy dissipation process of excited‐state intramolecular proton transfer (ESIPT), and (ii) a fluorescent nonplanar species in which ESIPT is effectively prevented. The mole fractions of each contributing conformer in the polymeric substrates have been estimated. In all the polymer systems studied, a significant proportion of the TINS molecules exist in the nonplanar form and thus may not contribute to photostabilization of the substrate. The proportion of nonplanar molecules varied from 11 to 86% in synthetic polymers and 20 to 41% in protein substrates.
Highly wettable films plasma‐polymerized from ethylene oxide
Authors: Inagaki N. , Suzuki K.
Published: April 2003

Highly wettable films were prepared by plasma‐polymerization from ethylene oxide. The surface energy of the formed films is 65.6 dyn/cm, and the contact‐angle of water on the films is 12 degrees. The formation of highly wettable films is limited to the plasma‐polymerization conducted at low W/FM values of below 200 MJ/kg. Analyses by infrared spectroscopy and ESCA show that the formed films contain much oxygen residues such as CO, CO, and C(O)O groups. Such polar groups would contribute high wettability of the plasma‐films from ethylene oxide.
Free radical copolymerization of sulfur dioxide with phenylacetylene
Authors: Kim Seong‐Ju , Akiyama Fuminori , Matsuda Minoru
Published: April 2003

Free radical copolymerization of sulfur dioxide with phenylacetylene (PA) in o‐dichlorobenzene was studied in a range of temperatures from 30 to 80oC as a function of total monomer concentration ([SO2] + [PA]). PA content in the copolymers increases with decreasing total monomer concentration and increasing temperature. Mw/Mn becomes sharper with decreasing the total monomer concentration, but does not depend upon feed compositions which are changed keeping total monomer concentration constant at 2, 4, and 6 mol/L, respectively. These results strongly indicate the existence of depropagation. Thermal decomposition of the copolymers happens more easily than PA homopolymer and the carbon‐centered free radicals are detected during the decomposition. Reactivity of ∼ CHĊ(Ph) free radical (∼ PA · ) is also discussed.
Conductivity of polydiacetylene with π‐conjugation between polymer backbone and substituents
Authors: Matsuda Hiro , Nakanishi Hachiro , Kato Shin‐Ichi , Kato Masao
Published: April 2003

Poly‐1,4‐bis(3‐acetamidephenyl)‐1,3‐butadiyne, i.e., a topochemically obtained polydiacetylene for which one can expect π‐conjugation between polymer backbone and substituents, has been examined as a candidate of conducting polymers. Upon iodine doping, the polymer film attained the conductivity of 4.8 × 10−2 S/cm, i.e., about three orders of magnitude greater than those of other polydiacetylene films which have no such π‐conjugation.
Preparation of polysiloxanes from silicic acid. IX. Partially silylated silicic acid and its spinnability
Authors: Abe Yoshimoto , Kaijou Akira , Shintani Nobuhiro , Nagao Yukinori , Misono Takahisa
Published: April 2003

The reaction in different molar ratios of trimethylchlorosilane to silicic acid offered partially silylated silicic acids PSSX (X = OH) with various degrees of silylation. Esterification and acetylation of PSSX (X = OH) with 1‐butanol or acetylchloride gave polysiloxanes PSSX (X = OBun and OCOCH3). Some of them showed an excellent spinnability and provided a fine fiber with a length of about 250 cm. A fiber drawing test from concentrated PSSX solutions of various solvents revealed that spinnability markedly depended on the DS, functional group X of PSSX, and solvent. Spinnability may also be correlated to solubility parameter of PSSX and solvent.
Polymerization and copolymerization of an isocyanate blocking agent. N‐(1,1′‐dimethyl‐3‐oxobutyl) acrylamide oxime. Mechanical and thermal properties
Authors: Michaud P. , Camberlin Y.
Published: April 2003

The bulk polymerization and copolymerization of N‐(1,1′‐dimethyl‐3‐oxobutyl) acrylamide oxime have been studied. Polymerization of diacetone acrylamide oxime was carried out with different initiating systems. The rate of polymerization of diacetone acrylamide oxime with azoisobutyronitrile as the initiating system was much higher than with peroxides. However, in the case of perester initiating systems (t‐butyl perbenzoate and t‐butyl per ethyl‐2‐hexanoate), cobalt salt promoted the polymerization rate markedly. Diacetone acrylamide oxime readily formed copolymers with a variety of comonomers (crosslinking agents and reactive diluents). Gel permeation chromatography has shown a higher reactivity of diacetone acrylamide oxime with trimethylol propane trimethacrylate as crosslinking agent and N‐vinyl‐pyrrolidone as reactive diluent. Therefore, the dynamic mechanical analyses presented an increase in Tg with trimethylolpropane trimethacrylate and N‐vinyl‐pyrrolidone as comonomers. The terpolymer formed with diacetone acrylamide oxime, trinethylolpropane trimethacrylate, and N‐vinyl‐pyrrolidone exhibited interesting mechanical properties and high temperature behavior.
Synthesis of poly(alkylene phosphate)s with N‐containing bases in the side chains. II. 9‐N‐oxoethyleneadenine on the poly(trimethylene phosphate) chain
Authors: Łapienis Grzegorz , Penczek Stanisław , Aleksiuk Gennadij P. , Kropachev Viktor A.
Published: April 2003

Poly(2‐hydro‐2‐oxo‐1,3,2‐dioxaphosphorinane) was quantitatively chlorinated, the resulting polymer was reacted with excess of imidazole giving the highly reactive polyesteramide. This polymer, treated with N‐hydroxyethyladenine with blocked amino group, gave polyphosphates with N‐oxoethyleneadenine in the side chains. The final polymers (Mn > 104) as well as the intermediate products were characterized by 1H‐, 13C‐, and 31P‐NMR spectroscopy. According to the spectra and analytical data the quantitative conversion: (A = adenine) was achieved.
Characterization of plasma polymers from tetramethylsilane, octamethylcyclotetrasiloxane, and methyltrimethoxysilane
Authors: Tajima Ichiro , Yamamoto Minoru
Published: April 2003

The products in inductively coupled plasma excited in organosilicic compounds were studied on chemical structures by spectroscopic methods. Plasma‐polymerized tetramethylsilane (PA) contains not only SiCH3 groups but also SiH groups on IR and 29Si‐NMR analyses. 13C‐NMR spectrum of PA reveals that the crosslinked structure of PA is mainly constructed of Ch2 and CH groups. Plasma‐polymerized octamethyleyclotetrasiloxane (PD4) is composed of SiCH3 and SiO groups. 13C‐ and 29Si‐NMR spectra of PD4 point out the highly preservation of the structural units similar to the monomer. These data of PD4 suggest that PD4 is formed from the ring‐opening polymerization by cleavages of SiO bonds. 13C‐NMR spectrum of poly[methyltrimethoxysilane] (PT) indicates the existence of CH3O groups, meanwhile its 29Si‐NMR analysis concludes that PT is chiefly composed of the structural units similar to the monomer. The surface analyses by XPS of PA, PD4 and PT suggest that these organosilicic plasma polymers resemble their starting materials.
Process parameters and their effect on grafting reactions in core/shell latexes
Authors: Merkel M. P. , Dimonie V. L. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

The grafting of methyl methacrylate (MMA) onto polybutadiene (PB) latexes prepared by seeded emulsion polymerization at 50°C was investigated as a function of: (a) initiator concentration used in the secondary polymerization, (b) monomer‐to‐polymer ratio, (c) the specific surface area of the seed latex, and (d) the degree of conversion. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to determine the proportion of graft copolymer in the core/shell latex, It was found that grafting PMMA onto PB depended upon the concentration of initiator, decreasing as the concentration was increased. The amount of grafting increased with increasing specific surface area of the seed latex, while the molecular weight of the acetone‐soluble graft copolymer decreased. The amount of graft copolymer was found to decrease concurrently with increasing monomer‐to‐polymer ratio and degree of conversion. These results suggest a hydrogen abstraction mechanism in the formation of graft PB–PMMA through a chain transfer process.
Polymerization of N‐vinylcarbazole by transition metal salts
Authors: Cho Hyun‐Nam , Choi Sam‐Kwon
Published: April 2003

The polymerization of N‐vinylcarbazole (NVC) in the presence of transition metal salts such as WCI6, MoCI5, TaCl5 and NbCl5 under different reaction conditions was studied. In general, aromatic solvents were found to be superior to aliphatic solvents in the polymerization of NVC, i. e., both conversion and molecular weight were higher in aromatic solvents. It was observed that the polymerization reaction proceeds rapidly and almost quantitatively, even at low monomer concentration (< 5 × 10−2M) and at low catalyst to monomer mole ratio (10−5) in aromatic solvents. The copolymerization of NVC with acenaphthylene (ACN) was also investigated in solution at room temperature. The resulting homo‐ and copolymer were characterized by IR, NMR, x‐ray diffraction, and elemental analysis. Thermal and photophysical properties are also reported. From the spectral data, the polymerization solvent was found to have a strong influence upon the polymer stereoregularity.
Synthesis and properties of polyurethanes and polyureas containing 2,5‐thiophenylene linkage
Authors: Kwon Soon‐Ki , Choi Kil‐Yeong , Choi Sam‐Kwon
Published: April 2003

A novel diisocyanate monomer, thiophene‐2,5‐diisocyanate (ThDI) was prepared from readily available adipic acid via the intermediate formation of thiophene‐2,5‐dicarboxylic acid chloride (ThDAC) and thiophene‐2,5‐dicarboxylic acid azide (ThDAA) which was subjected to a Curtius rearrangement. Polyurethanes and polyureas containing 2,5‐thiophenylene linkage were synthesized by the polycondensation of thiophene‐2,5‐diisocyanate with various diols and diamines, respectively, in N,N‐dimethylformamide. Polymerization conditions were optimized and the high yields of polymers were obtained. The identity of ThDI, model compounds, and the resulting polymers was confirmed by elemental analysis and spectroscopic methods. These polyurethanes and polyureas were found to have inherent viscosities in the range of 0.33–0.68 dL/g. Some physical properties of these polymers were also investigated.
Novel polyamides with acyclic and cyclic bipyridinediyl diamino structures in the polymer backbone: Synthesis and complexation with transition metals
Authors: Pappalardo S. , Bottino F. , Finocchiaro P. , Mamo A.
Published: April 2003

The synthesis of two novel polyamide ligands 3 and 4, containing 2,17‐diaza[3.3](6,6′)‐2,2′‐bipyridinophane or 6,6′‐bis(2‐picolylaminomethyl)‐2,2′‐bipyridine units as part of the polymer backbone, respectively, and of the appropriate diamide model compounds 1c and 2c is described. 1H‐NMR and IR spectral data support the ligand structures; furthermore, 1H‐VTNMR analysis on macrocyclic diamide 1c indicates a restricted rotation of the amide bonds at ambient temperature and suggests for this molecule a fixed syn conformation in solution, with a “face to face” arrangement of the dipyridinyl moieties. Model compound 2c and polyamide 4 form stable 1:1 complexes with transition metals Co(II), Ni(II), and Cu(II). Conversely, macrocyclic model 1c and polyamide 3 exhibit the unique property to specifically complex Cu(II), even in the presence of sizeable amounts of Co(II) and Ni(II). The IR spectral changes related to the ligands upon complexation are briefly discussed.
Plasma polymers containing sulfonate groups
Authors: Inagaki N. , Hirao H.
Published: April 2003

Modification of plasma‐polymers prepared from phenylsilane with sulfur trioxide was investigated by FT/IR spectroscopy and ESCA. The sulfonation of phenyl groups in the plasma‐polymers occurred rapidly within 1 min when exposed to SO3 gas. The S/C and O/C atomic ratios determined by ESCA for the modified polymers were 0.138 and 0.418, respectively. The sulfonation made the plasma‐polymers electrically conductive. The conductivity was sensitive to moist atmosphere. The logarithm of the impedance at 120 Hz decreased linearly with increasing the relative humidity. The plasma‐films containing sulfonate groups may be a new material for moisture sensor devices.
Alkali cation binding of polymers with different sized crown ethers and photodimerizable units
Authors: Shirai Masamitsu , Ueda Akihiko , Tanaka Makoto
Published: April 2003

The polymers which have different sized crown ethers as alkali cation binding sites and photodimerizable cinnamoyl units were prepared by the cationic copolymerization of corresponding monomers. The crown–cation complexation ratio (1:1 or 2:1) was investigated by measuring quantum yields ϕ of the photodimerization of the crown‐connected cinnamoyl units in the presence of alkali metal chlorides and also by measuring the shift of λmax of alkali metal picrates in THF on addition of the crown polymers. A significant 1:2 complex formation of alkali cations with two different sized crown ether units in the side chain of the polymers was confirmed. The alkali metal cation binding ability and selectivity of the polymers, which were studied by a method of picrate salts extraction, were markedly different from those expected from the combination of polymers of same ring‐size crown ether units. When irradiated with ultraviolet (UV) light, the cinnamic acid ester groups of the polymers caused dimerization even in dilute solutions. The cation binding ability of the polymers was largely enhanced by the photodimerization of the cinnamoyl moieties with suitable template cations.
Thermal degradation of polyacrylamide and poly(acrylamide‐co‐acrylate)
Authors: Leung W. M. , Axelson D. E. , Van Dyke J. D.
Published: April 2003

The thermal degradation behavior of polyacrylamide and poly(acrylamide‐co‐acrylate) was studied by differential scanning calorimetry, thermogravimetric analysis, gas chromatography/mass spectrometry, and carbon‐13 solid state nuclear magnetic resonance. The degradation products over the temperature range of 115–450°C were characterized. Mechanisms are proposed for the degradation processes involved.
Living carbocationic polymerization. IV. Living polymerization of isobutylene
Authors: Faust R. , Kennedy J. P.
Published: April 2003

Truly living polymerization of isobutylene (IB) has been achieved for the first time by the use of new initiating systems comprising organic acetate‐BCl3 complexes under conventional laboratory conditions in various solvents from −10 to −50°C. The overall rates of polymerization are very high, which necessitated the development of the incremental monomer addition (IMA) technique to demonstrate living systems. The living nature of the polymerizations was demonstrated by linear Mn versus grams polyisobutylene (PIB) formed plots starting at the origin and horizontal number of polymer molecules formed versus amount of polymer formed plots. DPn obeys [IB]/[CH3COORt · BCl3]. Molecular weight distributions (MWD) are very narrow in homogeneous systems (Mw/Mn = 1.2–1.3) whereas somewhat broader values are obtained when the polymer precipitates out of solution (Mw/Mn = 1.4–3.0). The MWDs tend to narrow with increasing molecular weights, i.e., with the accumulation of precipitated polymer in the reactor. Traces of moisture do not affect the outcome of living polymerizations. In the presence of monomer both first and second order chain transfer to monomer are avoided even at −10°C. The diagnosis of first and second order chain transfer has been accomplished, and the first order process seems to dominate. Forced termination can be effected either by thermally decomposing the propagating complexes or by nucleophiles. In either case the end groups will be tertiary chlorides. The living polymerization of isobutylene initiated by ester. BCl3 complexes most likely proceeds by a two‐component group transfer polymerization.
Spectroscopic examination of linear poly(ethylenimine) containing nucleic acid pendants as polynucleotide analogs
Authors: Lan Ming‐Jye , Overberger C. G.
Published: April 2003

The NMR spectra and UV absorptions of polynucleotide analogs with a poly(ethylenimine) (PEI) backbone containing adenine, cytosine, and hypoxanthine pendants have been examined. As has been shown in single‐stranded polynucleotides, these polymers also exhibited base stacking behavior in aqueous solution as well as in 2,2,2‐trifluoroethanol. Such stacking resulted in significant UV hypochromicities and observed differences in the NMR spectra compared to the corresponding model compounds. From continuous variation mixing experiments, well‐defined base pairing interactions were observed between complementary graft polymers in aqueous solutions. Enhanced UV hypochromicity due to such interactions was also observed.
Synthesis of linear poly(ethylenimine) containing nucleic acid pendants as polynucleotide analogs
Authors: Lan Ming‐Jye , Overberger C. G.
Published: April 2003

Polynucleotide analogs with a linear poly(ethylenimine) (PEI) backbone and adenine, cytosine, and hypoxanthine pendants were synthesized. Linear PEI was synthesized by the cationic ring‐opening polymerization of 2‐H‐2‐oxazoline, followed by acid hydrolysis. 2‐(Adenin‐9‐yl)‐ and 2‐(N6‐benzyladenin‐9‐yl)‐, 2‐(cytosin‐1‐yl)propanoic acids in addition to 2‐(adenin‐9‐yl)‐3‐methyland 3‐(cytosin‐1‐yl)butanoic acids were synthesized from their respective nucleic acid bases. 2‐(Hypoxanthin‐9‐yl)propanoic acid and 3‐(hypoxanthin‐9‐yl)butanoic acid were converted from the corresponding adenine derivatives by reaction with nitrous acid. Grafting reactions of pendant groups onto various molecular weight PEI backbones were carried out at room temperature, using the coupling agent norborn‐5‐ene‐2,3‐carboximido diphenyl phosphate (PPONB), generally resulting in percent graft values greater than 90%. PPONB showed selectivity against the amino group of adenine and cytosine rings. The appropriate model compounds were also prepared.
Functional polymers and sequential copolymers by phase transfer catalysis. 24. The influence of molecular weight on the thermotropic properties of a random copolyether based on 1,5‐dibromopentane, 1,7‐dibromoheptane, and 4,4′‐dihydroxy‐α‐methylstilbene
Authors: Percec Virgil , Nava Hildeberto , Jonsson Håkan
Published: April 2003

The influence of molecular weight on thermal transitions and on their thermodynamic parameters is discussed for a random thermotropic liquid crystalline copolyether based on the reaction of a 1:1 molar mixture of 1,5‐dibromopentane and 1,7‐dibromoheptane with 4,4′‐dihydroxy‐α‐methylstilbene. Optimum phase transfer catalyzed polyetherification reaction conditions were established for the synthesis of polymers containing bromoalkane chain ends only over a wide variety of molecular weights. All these copolyethers present a crystalline and an enantiotropic nematic mesophase over the entire range of molecular weights studied. Both the thermal transitions and their thermodynamic parameters are strongly molecular weight‐dependent up to Mn = 10,000–12,000, after which they remain constant. The enthalpies and entropies of isotropization of the copolyethers are higher than those of melting. This is in contrast to the same thermodynamic parameters of the corresponding homopolyethers. The enthalpies and entropies of isotropization of both homopolymers and copolymers present similar values, suggesting that copolymerization does decrease the degree of order in the crystalline phase but does not significantly change the alignment degree of the mesogenic units in the nematic mesophase.