bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of acetylene‐terminated aromatic amide resin precursors
Authors: Abraham Tonson , Soloski Edward J. , Benner Charles L. , Evers Robert C. 
Published: April 2003

AbstractA series of 10 acetylene‐terminated aromatic amide monomers was synthesized by the triethylamine‐promoted reaction of bis[p‐(m‐chlorocarbonylphenoxy)phenyl] sulfone or bis[p‐(m‐chlorocarbonylphenoxyl)phenyl]ketone witho‐ orp‐ethynyl‐ ando‐ orp‐trimethylsilylethynylaniline. Yields were essentially quantitative. Structures were verified by infrared and nuclear magnetic resonance spectroscopy and mass spectral data. Thermal characteristics of the monomers were investigated by means of differential scanning calorimetry and thermogravimetric analysis. The initial glass transition temperatures were generally well below the onset of cure which occurred in the 160–225°C range for the terminal ethynyl monomers and in the 260–295°C range for their trimethylsilylethynyl analogs. Onset of decomposition in air for the resinified terminal ethynyl monomers took place in the 400–485°C range, while resins from the trimethylsilylethynyl monomers underwent breakdown at substantially lower temperatures.
Syntheses and crosslinking reactions of polymers containing spiroorthoester moieties
Authors: Tagoshi Hirotaka , Endo Takeshi 
Published: April 2003

AbstractThe radical copolymerization of unsaturated spiroorthoesters such as 2‐methylene‐1,4,6‐trioxaspiro[4.6]undecane (SOE I) and 2‐methylene‐9‐methyl‐1,4,6‐trioxaspiro[4,5]decane (SOE II) with vinyl monomers was carried out to find that SOE I and SOE II were copolymerized with electron‐poor olefins such as methyl acrylate, acrylonitrile, and methyl methacrylate to obtain the corresponding copolymers containing spiroorthoester moieties, respectively. The obtained copolymers were treated with BF3.OEt2 or BzS+SbF to afford crosslinked polymers undergoing expansion in volume on crosslinking in those cases of copolymers of SOE I.
Preparation of cationic polyacrylamides by a modified Hofmann reaction: Fluorescent labeling of cationic polyacrylamides
Authors: Tanaka Hiroo , Ödberg Lars 
Published: April 2003

AbstractCationic polyacrylamides (C‐PAM) which contain both primary and quaternary amines were prepared according to the Hofmann reaction by adding choline chloride to a solution of polyacrylamide in water. The reaction was 90% complete after 60 min at 20°C. The degree of amination was over 70% and the proportion of primary and quaternary amines could be altered widely by controlling the relative concentrations of NaOH, NaOCl, and choline chloride.C‐PAM was dansylated (fluorescently labeled) in a homogeneous system using aqueous dimethylformamide as solvent. The optimum excitation wavelength for dansylated C‐PAM in water at room temperature (22 ± 1°C) was 333 nm and the corresponding emission wavelength 538 nm. The fluorescence intensity was almost constant at pH levels above 5, but decreased rapidly below pH 4 and was almost zero at pH 2.
Polymers from multifunctional isocyanates. II. Synthesis and polyaddition reactions of novel aliphatic diisocyanatoesters
Authors: Mormann Werner , Leukel Gabriele 
Published: April 2003

AbstractTrimethylsiloxyalkyl and ‐aryl isocyanates were reacted with alkanedioic acid dichlorides (oxalyl‐, adipoyl‐, suberoyl dichloride) or isocyanatoalkanoyl chlorides (3‐isocyanatopropanoyl‐, 6‐isocyanatohexanoyl chloride) to give liquid low viscous diisocyanatoesters and ‐diesters in high yield. From these and 1,4‐butanediol, polyurethanes were made having a regular sequence of ester and urethane groups. The properties of the polymers, especially their thermal stability, are discussed with respect to their structure. They are mostly crystalline materials (mp 100–240°C). Thermogravimetry data indicate that polyurethanes based on diisocyanatoalkyl oxalates decompose 50–80°C lower than those based on other acids.
Thermal analysis of chemically synthesized polyaniline and effects of thermal aging on conductivity
Authors: Wei Yen , Hsueh Kesyin F. 
Published: April 2003

AbstractThermal characteristics of chemically synthesized polyaniline with various dopants have been studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy, gel‐permeation chromatography (GPC), and chemical titration. The HCl‐doped polyaniline shows three major weight losses at around 100, 200, and 500°C which are assigned to removal of H2O and HCl, and decomposition of the polymer, respectively. Thermal aging of the HCl‐doped polyaniline performed at 100, 150, and 200°C for various periods of time results in a decrease in conductivity. After the thermal treatments, the polymer can be re‐doped with HCl to partially recover the conductivity. However, both the conductivity and the doping level cannot be restored to the level of the original materials owing probably to changes in morphology, crosslinking, or other chemical reactions.
Preparation and radical ring‐opening polymerization of 2‐substituted‐4‐methylene‐1,3‐dioxolanes
Authors: Hiraguri Yoichi , Endo Takeshi 
Published: April 2003

Abstract2‐Methyl‐2‐phenyl‐4‐methylene‐1,3‐dioxolane (IIa), 2‐ethyl‐2‐phenyl‐4‐methylene‐1,3‐dioxolane (IIb), 2‐phenyl‐2‐(n‐propyl)‐4‐methylene‐1,3‐dioxolane (IIc), 2‐phenyl‐2‐(i‐propyl)‐4‐methylene‐1,3‐dioxolane (IId), 2‐(n‐heptyl)‐2‐phenyl‐4‐methylene‐1,3‐dioxolane (IIe), 2‐methyl‐2‐(2‐naphthyl)‐4‐methylene‐1,3‐dioxolane (IIf), and 2,2‐diphenyl‐4‐methylene‐1,3‐dioxolane (IIg) were prepared and polymerized in the presence of a radical initiator. IIa–IIf were found to undergo vinyl polymerization with ring‐opening reaction accompanying the elimination of ketone groups in bulk. IIg was found to undergo the quantitative ring‐opening reaction accompanying the elimination of benzophenone in solution to obtain polyketone without any side reaction.
Synthesis of crown ether‐terminated poly(methyl methacrylate) by radical chain transfer polymerization
Authors: Chujo Yoshiki , Nakamura Tetsuya , Yamashita Yuya 
Published: April 2003

AbstractMercapto‐16‐crown‐5 was prepared starting from tetraethyleneglycol and 3‐chloro‐2‐chloromethyl‐1‐propene. Radical polymerization of methyl methacrylate was carried out in the presence of mercapto‐16‐crown‐5 as a chain transfer agent to give crown ether‐terminated poly(methyl methacrylate). The end crown group was characterized by IR and 1H‐NMR spectra. Sodium cation was selectively extracted by this crown‐containing polymer. The molecular weight of the obtained polymer had influence upon the ability of extraction of sodium cation.
Photoresponsive peptide and polypeptide systems. VIII. Synthesis and reversible photochromism of azo aromatic poly(L‐ornithine)
Authors: Yamamoto Hiroyuki , Nishida Ayako , Takimoto Tomoyuki , Nagai Akira 
Published: April 2003

AbstractPoly(L‐ornithine) having azo aromatic side chain was synthesized by the water‐soluble carbodiimide procedure. The photochemical properties of the azo polypeptide poly[Nδ‐p‐(phenylazo)benzoyl‐L‐ornithine] (PPABLO) was investigated by absorption and circular dichroism spectroscopy in hexafluoro‐2‐propanol (HFIP). The photochromism of the dichroic bands in the visible and ultraviolet wavelength regions was found to be reversible as a function of irradiation time at different wavelengths due to the photostationary state (about 70% trans)–cis photoisomerization of the azo aromatic moieties. The reversible photoinduced solubility change was also studied. On irradiation PPABLO is soluble under ultraviolet light (cis) and precipitate under visible light (70% trans) in HFIP–water. A discussion was presented that includes results on azo aromatic poly(L‐lysine).
Emulsifier‐free emulsion copolymerization of styrene and butyl acrylate. III. Kinetic studies in the presence of a surface active comonomer, the sodium acrylamido undecanoate
Authors: Guillaume J. L. , Pichot C. , Guillot J. 
Published: April 2003

AbstractEmulsion terpolymerization of styrene (S), butylacrylate (BuA) and sodium acrylamido undecanoate (AUNa), a surface active functional monomer have been carried out using a batch process in the presence of sodium 4‐4′‐azobiscyanopentanoate as initiator. Varying the AUNa concentration, stable particles bearing only carboxylic charges have been produced with diameters ranging from 200 to 500 nm at solids content as high as 40%. However a low AUNa yield at the particle surface has been found (30–35%), which could be explained by very unfavorable reactivity ratios of AUNa with S and BuA. Most of the AUNa seems to be wasted in the water phase (unpolymerized and forming hydrosoluble chains). Furthermore, a concentration of AUNa higher than 10−2 mol L−1 results in the latex destabilization, presumably caused by the formation of a large amount of polyelectrolytes. Kinetic studies of the AUNa consumption show that the AUNa is mainly fixed at the particle surface between 90 and 100% conversion, which indicates that the AUNa is mainly polymerized in the water phase and not at the particle surface. An attempt has been made to increase the surface charge density by polymerizing a shell of AUNa/S/BuA on a seed latex. It turned out to be unsuccessful (low surface yield, formation of new particles).
Anionic polymerization of N‐substituted maleimide. V. A study on the kinetic features of anionic polymerization of N‐phenylmaleimide
Authors: Hagiwara Tokio , Shimizu Takamasa , Uda Tomonori , Hamana Hiroshi , Narita Tadashi 
Published: April 2003

AbstractThe kinetic feature of the anionic polymerization of N‐PMI was investigated in THF. The polymerization system initiated with lithium tert‐butoxide was revealed to be so‐called “slow‐initiation” system. The rate constant of the initiation reaction, ki, was obtained to be 4.2 × 10−3 (L mol−1 s−1) at −72°C. The apparent rate constants of the propagation reaction, k, at −72°C were individually obtained from each slope of the first‐order plots in the later stages of the polymerizations for four different initiator concentrations. Each k is fairly close to that of initiation rate around 10−3. The propagation reaction was concluded to be dominated by ion‐pair mechanism from the analysis of the kinetic data and the results of the addition effects of crown ether and common salt.
Thermotropic liquid crystalline polymers with low thermal transitions. I. Low melting thermotropic liquid crystalline homo‐ and co‐polycarbonates
Authors: Mahabadi Hadi‐Kh , Alexandru Lupu 
Published: April 2003

AbstractDue to the particular rheological properties of thermotropic liquid crystalline polymers (TLCP), their application for imaging technology has been investigated. The first class of polymers investigated in this study are the thermotropic liquid crystalline polycarbonates prepared from the solution polycondensation of p,p‐dihydroxybiphenyl with bischloroformate as the aliphatic flexible spacer. From the variety of bischloroformates employed, smectic TLCP's were generally obtained with the possible presence of a nematic mesostate. The introduction of comonomers such as substituted hydroquinones or bisphenols were found to lower both the melting transitions and mesophasic range of the TLCP. From rheological characterization, the amount of nonmesogenic moieties present in the copolycarbonates were found to correlate with the increase in the melt viscosity of TLCP.
Thermotropic homopolyester. I. Synthesis and characterization of homopolyesters containing the mesogenic unit, bicyclo[2.2.2]oct‐2‐ene
Authors: Harruna Issifu I. , Polk Malcolm B. 
Published: April 2003

AbstractHomopolyesters based on bicyclo[2.2.2]oct‐2‐ene as a mesogenic group were prepared and characterized. The use of bicyclo[2.2.2]oct‐2‐ene in these homopolyesters lowered the symmetry of the resulting systems enough to lead to the observation of melting behavior.
Synthesis and radical copolymerization of new type pyridinum monomer and redox behavior of its polymers
Authors: Kitamura Naoya , Nambu Yoko , Endo Takeshi 
Published: April 2003

AbstractA new type pyridinium salt monomer, 1‐vinyl‐4‐carbamidopyridinium perchlorate, was prepared, and then homopolymerized and copolymerized with methyl methacrylate (MMA), 2‐hydroxyethyl methacrylate (HEMA), styrene, and acrylonitrile. Redox potentials of these pyridinium salt monomer and polymers were more positive than that of the model compound (1‐methyl‐4‐carbamidopyridinium salt). The copolymer with MMA showed an interesting redox behavior.
High molecular weight aromatic polymers by nickel coupling of aryl polychlorides
Authors: Colon I. , Kwiatkowski G. T. 
Published: April 2003

AbstractThis paper describes a totally new method for the formation of high molecular weight aromatic polymers. High molecular weight polyarylethersulfones are produced by nickel catalyzed coupling of aryl dichloride monomers. Metallic zinc is used to drive the polymerization reaction which takes place under relatively mild conditions in the presence of triphenylphosphine and a dipolar aprotic solvent. The versatility of the reaction is demonstrated, as well as the ability to provide a variety of high temperature polymers from readily available and inexpensive monomers. It is possible to use an integrated two‐step process to produce aryl dichlorides from inexpensive aryl chlorides, and then to couple these directly to polymer without need for isolation and purification. This process resulted from a fundamental understanding of the chemistry and the use of statistically designed experiments to identify the important reaction parameters and to optimize the degree of polymerization.
Crystallization of poly(ethylene oxide) in binary polymer blends: Influence of tacticity of poly(methyl methacrylate)
Authors: John Eunsook , Ree Taikyue 
Published: April 2003

AbstractKinetics of the crystallization of poly(ethylene oxide) (PEO) from the PEO blends with syndiotactic, atactic, or isotactic poly(methyl methacrylate) (s‐, a‐, and i‐PMMA) was investigated. The isothermal spherulitic growth rates were measured with an optical microscope. The influence of the composition of the blends, the tacticity of PMMA, and temperature on the growth rates were studied. Linear growth rates were observed regardless of the tacticity. The growth rates of spherulites are markedly reduced by a‐PMMA and s‐PMMA. However the growth rates of PEO are hardly influenced by i‐PMMA. Such observations are interpreted by assuming that PEO forms miscible blends with a‐ and s‐PMMA in the molten states, whereas it does not from with i‐PMMA.
Synthesis and characterization of side‐chain liquid crystalline polysiloxanes containing oligooxyethylene spacers and benzyl ether based mesogenic groups
Authors: Hsieh Chang‐Jyh , Hsu Chain‐Shu , Hsiue Ging‐Ho , Percec Virgil 
Published: April 2003

AbstractThe synthesis of side‐chain liquid crystalline polysiloxanes containing oligooxyethylene spacers and 4‐methoxyphenyl benzyl ether and 6‐cyano‐2‐naphthyl benzyl ether based mesogenic groups is presented. The phase behavior of both monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarized microscopy. All synthesized polysiloxanes present smectic mesomorphism. The insertion of oxygen atoms into the flexible aliphatic spacers leads to decrease in both glass transition and isotropization temperatures of the resulting side‐chain liquid crystalline polymers.
The synthesis, characterization, and photoinitiated cationic polymerization of silicon‐containing epoxy resins
Authors: Crivello J. V. , Lee J. L. 
Published: April 2003

AbstractThe preparation of a variety of silicon‐containing epoxy monomers and oligomers is described and their reactivity in photoinitiated cationic polymerization examined. Monomers and oligomers having terminal cycloaliphatic epoxy groups were found to be especially reactive in cationic polymerization. These materials are attractive candidates for use in coatings, adhesives, and elastomers.
In situ formation of new crosslinking agents from acrylate derivatives and bisepoxides
Authors: Lee Soo , Thames Shelby F. , Mathias Lon J. 
Published: April 2003

AbstractThe synthesis of several newly available diacrylate crosslinking agents derived from hydroxy functional acrylates and bisepoxides is described. These crosslinking agents are synthesized via the acid catalyzed addition of hydroxyl‐containing acrylate monomers to bisepoxides derived from bisphenol‐A and its hexafluoropropyl analog. These materials are generated in an excess of the acrylate monomer and the reaction mixtures are then converted directly to highly crosslinked materials. The alcohol functional monomers include hydroxyethyl methacrylate (HEMA) and the butyl and ethyl esters of (α‐hydroxymethyl)acrylic acid. The latter are especially interesting for several reasons. First, they are readily available through the addition of the corresponding acrylate to formaldehyde. Second, these monomers react with the bisepoxides to give all‐ether‐linked connecting groups, in conrast to HEMA which yields a molecule with both ether and ester linkages between the two acrylate units. Third, the monomers are very different in solubility from HEMA and the polymers display very different chemical and physical properties. For example, while the crosslinked HEMA polymers are swellable in water, those of the (α‐hydroxymethyl)acrylates are insoluble in water but swellable in organic solvents such as chloroform. All monomers, crosslinking agents, and crosslinked polymers were characterized by FT‐IR, solution or solid state 13C‐NMR spectroscopy, and thermal analysis.
New gem‐dicyanocyclobutane‐containing hydroxyesters
Authors: Mori Shoji , Kakuchi Toyoji , Padias Anne Buyle , Hall H. K. 
Published: April 2003

AbstractSix new gem‐dicyanocyclobutanes containing carbomethoxy and hydroxyl/acetoxy functions were synthesized by cycloaddition of the appropriate vinyl ethers or alkoxystyrenes to methyl β,β‐dicyanoacrylate. They proved to be too thermally labile to allow polycondensation to potentially piezoelectric linear polyesters.
The polymerization of oxiranes with the α‐chlorobenzyl methyl sulfide–antimony pentachloride initiator system
Authors: Iijima Takao , Kakiuchi Hiroshi 
Published: April 2003

Abstractα‐Thiomethoxyphenylmethylium hexachloroantimonate was prepared from α‐chlorobenzyl methyl sulfide and antimony pentachloride and studied by visible spectroscopy. The salt is unstable at room temperature and used as in situ initiator for the polymerization of oxiranes in dichloromethane. Propylene oxide (PO) and cyclohexene oxide (CHO) were used as oxiranes. The microstructure of PO polymer is amorphous by 13C‐NMR. The initiator was more effective for the polymerization of CHO than for that of PO.
Model reactions of functionalization of polycarbonate. Reactions of phenyl chloroformate with nucleophiles and cationic polymerization behavior of bicyclo orthoesters containing carbonate group
Authors: Uno Hitomi , Nakazawa Akihiko , Takata Toshikazu , Endo Takeshi 
Published: April 2003

AbstractSome model experiments for functionalization of a polycarbonate were carried out. At first, reactivity of phenyl chloroformate with a few nucleophiles was examined. Reaction with alkyl amines gave corresponding carbamates, but in the case of aniline, formation of a byproduct diarylurea was observed. Reactions with alcohols and phenols afforded carbonates in moderate yields, in which p‐nitrophenol and isopropyl alcohol were less reactive. On the basis of these results, 1‐ethyl‐4‐phenoxycarboxymethyl‐2,6,7‐trioxabicyclo[2.2.2]octane (2) and 1‐ethyl‐4‐ethoxycarboxymethyl‐2,6,7‐trioxabicyclo[2.2.2]octane (3) were prepared by the reaction of phenyl and ethyl chloroformates with 1‐ethyl‐4‐hydroxymethyl‐2,6,7‐trioxabicyclo[2.2.2]octane in the presence of tert‐amine. 2 polymerized cationically with BF3OEt2 at more than 80°C to give a polyether containing both ester and carbonate groups in the side chain, with contamination of a gelled polymer.
Lanthanide–imidazole complexes as latent curing agents for epoxy resins
Authors: Kaplan M. L. , Wayda A. L. , Lyons A. M. 
Published: April 2003

AbstractImidazoles have for some time been recognized as curing agents for epoxy resins. Once the resin and the imidazole compound are mixed there is a relatively short time in which the mixture can be used, since the polymerization (curing) reaction occurs to some extent even at room temperature causing the reaction mixture to thicken. In order to circumvent this problem we have found that imidazoles can be complexed with organo‐lanthanide compounds thereby tying up the imidazole and retarding its rate of reaction in the cure of epoxy materials at ambient temperatures. When it is desired to enhance the rate of cure the temperature of the mixture is simply raised. This paper concerns studies of the epoxy cure reaction with the M(THD)3–IM series. M represents the lanthanide metals Eu, Ho, Pr, Dy, Yb, and Gd, and THD is 2,2,6,6‐tetramethyl‐3,5‐heptanedione. Cure reactions were followed by differential scanning calorimetry and in some cases by infrared spectroscopy. We have demonstrated that these organo‐lanthanide–imidazole complexes are effective thermally latent curing agents for epoxy resins. At a temperature of 150°C cure is quite rapid. In the course of these studies it has also been determined that there is an inverse correlation between the lanthanide ionic radius in the complex and the temperature at which the cure reaction occurs. Thus the Yb compound, where the imidazole is most strongly bound, cures at the highest temperature and Pr, where imidazole is bound most weakly, at the lowest. Consistent with these facts is the observation that the Yb compound also gives the longest latency period when mixed with epoxy resin.
Polymeric amines and their copper(II) complexes: Catalysts for the hydrolysis of organophosphate esters
Authors: Bao Y. T. , Pitt C. G. 
Published: April 2003

AbstractCatalysis of the solvolysis of organophosphorus esters by polymers of aliphatic amines, imidazole, pyridine, 2,2′‐bipyridine, and their copper(II) complexes was studied using diisopropyl fluorophosphate (DEP) as a model substrate. The polymeric catalysts were synthesized either by (1) derivation of available polymers, including polyethylenimine, polyvinyl amine, polyvinyl alcohol, polystyrene, and poly‐4‐vinylpyridine or (2) by polymerization of functionalized monomers such as 4(5)‐vinylimidazole and 4‐vinyl‐4′‐methyl‐2,2′‐bipyridine. Polymer hydrophilicity was controlled by partial quaternization of amine groups with different alkyl halides. The greatest catalytic activity was exhibited by copper(II) complexes of polymers containing the 2,2′‐bipyridine group. At pH 7.6 and 3.7 × 10−3M, the most active of these catalysts reduced the half‐life of DFP from 800 to 9 min. The rate was largely independent of the pH in the range 6.5–8.5 but was limited by the aqueous solubility of the catalyst. Heterogeneous catalysis by some polymers was observed but was less effective. A Lineweaver‐Burk plot of V0−1 versus [DFP]−1 for a soluble polymeric 2,2′‐bipyridine‐copper(II) catalyst was linear. There was no correlation between catalysis of solvolysis of DFP and the carboxylic ester, p‐nitrophenyl acetate.