bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of spiropolymers by polycycloaddition of ketene dimer with dinitrile oxides
Authors: Kurita Keisuke , Hirakawa Nobuhiko , Dobashi Toshiaki , Iwakura Yoshio 
Published: April 2003

AbstractNovel spiropolymers containing biisoxazolinic units in the main chain were synthesized by polycycloaddition of ketene dimer with dinitrile oxides. Ketene dimer functioned as a difunctional monomer with loss of carbon dioxide, but use of 10% excess amount seemed to be the optimum condition in terms of viscosity of the resulting polymers. These spirocyclic polymers were white to pale yellow and had inherent viscosity of up to 0.34 dl/g. Thermogravimetric analysis of the polymers showed unusual abrupt reduction of weight at 279 or 298°C. Solubility was also studied.
Polylactide. II. Viscosity–molecular weight relationships and unperturbed chain dimensions
Authors: Schindler A. , Harper D. 
Published: April 2003

AbstractMark–Houwink equations for benzene and chloroform solutions of S‐polylactide and racemic polylactide were established by end‐group analysis of partly hydrolyzed polymers. Unperturbed chain dimensions calculated for both polymers reveal a considerable difference and suggest a helical conformation for S‐polylactide in solution. This finding supports 1H‐NMR observations that reveal chemical shift differences that appear when the same configurational sequence is present in two stable conformational states.
Interaction between dyes and polyelectrolytes. XI. Photoreduction of methylene blue bound to potassium polystyrenesulfonate
Authors: Shirai Masamitsu , Murakami Yoshihiro , Tanaka Makoto 
Published: April 2003

AbstractThe effect of potassium polystyrenesulfonate (PSSK) on the quantum yield (Φ) in the photoreduction of methylene blue (MB) by allylthiourea was investigated. MB was bound to PSSK in monomeric, dimeric, or slightly aggregated form, depending on the polyanion–dye ratio (P/D). At a relatively lower P/D in which most MB molecules were bound to PSSK in dimeric or slightly aggregated form, the value of Φ was smaller than that at a P/D of zero. On the other hand, at a higher P/D, in which most MB molecules were bound to PSSK in monomeric form, the value of Φ was larger than that at a P/D of zero. It was suggested that the lower reactivity of dimeric or slightly aggregated MB on PSSK was caused by the length of its lifetime which is shorter than that of the monomeric form. It was also suggested that the increase in Φ at higher P/D was caused by the decreased deactivation of the triplet excited MB by the ground‐state MB.
Synthesis of model molecules of functional isoprenic units
Authors: Clouet Françoise , Brossas Jean 
Published: April 2003

AbstractWe have prepared model molecules of monohydroxylic and monocarboxylic isoprenic units by initiating isoprene with sec.butyllithium in benzene and killing the living ends by oxygen or carbon dioxide; the monoadduct compounds have been isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry.
Investigations on equilibrium of poly(ethylene oxalate) and 1,4‐dioxane‐2,3‐dione
Authors: Alksnis A. , Deme Dz. 
Published: April 2003

AbstractBehavior of poly(ethylene oxalate) in a temperature range of 148–240°C was studied, and a new method of isolating 1,4‐dioxane‐2,3‐dione from the products of decomposition of poly(ethylene oxalate) was used. The process of decomposition was second order. Equilibrium of poly(ethylene oxalate) and 1,4‐dioxane‐2,3‐dione was registered at 148–240°C. The influence on this process of certain inorganic compounds as catalysts was investigated.
Functional monomers and polymers. LIII. Kinetic study on the oxidation of Cu(I)·polyvinylimidazole complexes by molecular oxygen
Authors: Sato M. , Kondo K. , Takemoto K. 
Published: April 2003

AbstractThe autoxidation of Cu(I) complexes with imidazole and polyvinylimidazole derivatives was studied by observing the formation of the corresponding Cu(II) complexes with a stopped‐flow technique. The reaction was second order and proportional to the concentrations of Cu(I) and oxygen. In the Cu(I)‐imidazole complex pH variation was without effect in the range of 7.5‐8.6. The oxidation rate of Cu(I).polyvinylimidazole complexes, on the other hand, decreased with a rise in pH. The activation parameters of the Cu(I)·polyvinylimidazole complexes, compared with those of the Cu(I).imidazole complex, were characterized by large enthalpic requirements coupled with favorable entropies of activation. This was explained by the fact that a conformational change in the polymeric ligands took place during oxidation.
Synthesis of polypyridazinophthalazinediones from diacetylphthalic acids and aromatic dihydrazines
Authors: Imai Yoshio , Ueda Mitsuru , Ohnuma Masakuni , Akashi Kuniaki 
Published: April 2003

AbstractThe cyclopolycondensation of two diacetylphthalic acids with aromatic dihydrazines produced a series of new high‐molecular‐weight polypyridazinophthalazinediones with pendant methyl groups. The polymers were best prepared in m‐cresol at 100°C and, after isolation, were readily soluble in dichloroacetic acid and m‐cresol. Clear yellow films could be cast from m‐cresol solutions and thermogravimetric analysis of all the polymers showed a 10% weight loss at 455–;505°C in nitrogen.
Effect of water on the glass transition temperature of poly(hydroxy methylene)
Authors: Reimschuessel H. K. , Turi E. A. , Akkapeddi M. K. 
Published: April 2003

AbstractThe effect of moisture on the glass transition temperature of poly(hydroxy methylene) was investigated by thermal analysis which entailed combinations of DTA and DSC with TGA techniques. As the moisture content increased, the glass transition temperature (Tg) decreased monotonically from a value (Tgo) of 134°C for the dry polymer toward a finite value (Tgt) of about 39°C. This response of Tg to an increase in the moisture content (w) was adequately represented by the general relationship Tg = (ΔTg)0 exp{–[ln(ΔTg)0]w/τwl} + Tgl, recently developed for correlating Tg and moisture content of nylon 6 and and found generally applicable to hydrophilic polymers. With (ΔTg)0 = 95, τ = 0.555, and wl = 0.375, good agreement was found between experimental and calculated values for poly(hydroxy methylene).
The effects of overall composition and monomer sequence distribution on the infrared carbonyl stretching frequencies of ethylene–vinylacetate and styrene–vinylacetate copolymers
Authors: Ebdon J. R. , Kandil S. H. , Morgan K. J. 
Published: April 2003

AbstractThe vinyl acetate centered triad fractions of some free radically prepared ethylene–vinyl acetate and styrene–vinyl acetate copolymers have been determined from the patterns of vinyl acetate methine carbon peaks in their 13C nuclear magnetic resonance (NMR) spectra. The positions and shapes of the carbonyl bands in the infrared (IR) absorption spectra of the copolymers recorded in chloroform are shown to depend on the compositions of the copolymers and on the proportions of the various vinyl acetate centered triads. Infrared absorption measurements may thus be used in part to characterize the monomer sequence distributions of these copolymers.
Preparation and photolysis of poly‐4′‐acetylacrylophenone and its copolymers with styrene and methyl methacrylate
Authors: Lukáč I. , Chmela Š. , Hrdlovič P. 
Published: April 2003

AbstractPoly‐4′‐acetylacrylophenone (P4AcAP) and its copolymers with styrene (4AcAP/S) and methyl methacrylate (4AcAP/MMA) were prepared. Ultraviolet (UV) spectra of these polymers show an absorption band at 29,500 cm−1 (ϵ = 270) of n‐π* character. The low temperature emission spectra of films of copolymers studied exhibit a less resolved vibrational structure and are bathochromically shifted with respect to those of polyacrylophenone and its styrene and methyl methacrylate copolymers. The emission decay is slightly nonexponential and has a lifetime of about 0.02 sec. Quantum yields of main chain scission in solution with 366‐nm radiation are of the same order as those of the unsubstituted polyacrylophenone. Substitution by a strong electron‐accepting group, in comparison with polyacrylophenone, influences the value of the quantum yield only a little but prolongs the lifetime of the lowest triplet state. This is also evident in an increase in the Stern–Volmer constant in passing from polyacrylophenone–naphthalene in benzene (68 mole−1) to P4AcAP–naphthalene in dioxane (380 mole−1). With biphenyl as a triplet quencher, the Stern–Volmer constants are low because of back transfer:
Chemiluminescence study of PS–PVME compatible mixtures
Authors: Naito K. , Kwei T. K. 
Published: April 2003

AbstractThe oxidation of polystyrene (PS), poly(vinyl methyl ether) (PVME), and their mixtures has been studied by the chemiluminescence method. It was found that luminescence versus temperature curves had sharp inflections that shifted to higher temperatures with increasing PS content of the blends. A linear relationship was obtained between inflection temperatures and onsets of oxidation exotherms as measured by calorimetry. The inflection points for the mixtures also correlated linearly with the temperatures of thermally induced phase separation
Carboxylation of a polypentenamer and preparation of its hydrogenated derivatives
Authors: Tanaka H. , Macknight W. J. 
Published: April 2003

AbstractCarboxylated three‐membered ring derivatives of a polypentenamer (PP) that contained 82% trans and 17% cis double bonds were prepared by carbene addition of ethyldiazoacetate with a copper catalyst to the double bonds and subsequent hydrogenation of the residual unsaturation. In this way derivatives that contained approximately either 5 or 10 mole % three‐membered rings with ester side groups were obtained. These side groups were further reacted by hydrolysis or neutralization to form carboxylic acid and cesium salts of carboxylic acid. Reaction conditions were chosen so that no backbone degradation occurred and side reactions that led to crosslinking were avoided. The derivatives were characterized by gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. It was found that an increase in substituent concentration decreased the melting point (Tm) in hydrogenated derivatives and increased the glass transition temperature (Tg) in unhydrogenated derivatives. The cesium salts of carboxylic acid were the least thermally stable among those studied and the hydrogenated derivatives were generally more stable than the unhydrogenated.
Polyimidines. IV. The synthesis and polymerization of 3,3‐diphenyl‐6‐aminophthalide
Authors: Fawcett Newton C. , Lohr Raymond A. , Cassidy Patrick E. 
Published: April 2003

AbstractThe monomer 3,3‐diphenyl‐6‐aminophthalide was synthesized in a 20% yield by the following sequence of reactions: nitration of phthalimide, hydrolysis and dehydration to 4‐nitrophthalic anhydride, Friedel–Crafts reaction with benzene to 2‐benzoyl‐5‐nitrobenzoic acid, cyclization with thionyl chloride to the pseudoacid chloride, Friedel–Crafts reaction with benzene, and, finally, reduction of the nitro group to the amino function with Adams catalyst. Although the five‐substituted isomer is also possible, it was obtained in yields of only one‐fifth to one‐tenth of those for the 6‐substituted isomer. The 3,3‐diphenyl‐6‐aminophthalide underwent polymerization with difficulty to yield low‐molecular‐weight polyimidines (inherent viscosity up to 0.68 dl/g) in reasonable yields (32−88%). Because of the rigid character of the backbone and steric crowding, conditions for polymerization were rather severe: 1–2 days at 180–225°C in nitrobenzene or polyphosphoric acid or 350°C in a sealed tube. The addition of sand to the reactants in the sealed tubes caused an increase in yield and molecular weight. The polymers were subjected to thermogravimetric analysis in air and nitrogen. The temperatures at which a 10% weight loss occurred were as high as 440°C in air and 510°C in nitrogen. These stabilities were similar to those encountered for previously synthesized all‐aromatic polyimidines.
Particle nucleation in emulsion polymerization. II. Nucleation in emulsifier‐free systems investigated by seed polymerization
Authors: Hansen F. K. , Ugelstad J. 
Published: April 2003

AbstractExperiments with seeded polymerization in emulsifier‐free systems were carried out with styrene in order to test the theory of particle nucleation presented in the first article in this series. The effect of amount, size, and surface charge density of the seed particles on the formation of new particles was investigated. An expression for the capture rate of oligomeric radicals from the water phase was evaluated in which the rate of capture was considered to be governed by the absorption of oligomers with chain length one less than the critical chain length for precipitation of the oligomer. Coagulation of primary particles was also included in the expression for the number of new particles obtained in the system. Limited coagulation of primary particles with already formed particles and with seed particles was found to play an important role in determining the final number of new particles found at the end of the runs.
Epoxy resins. III. Application of fourier transform IR to degradation studies of epoxy systems
Authors: Lin S. C. , Bulkin B. J. , Pearce E. M. 
Published: April 2003

AbstractThree cured epoxy resins were investigated under various degradation conditions by Fourier transform infrared (FTIR) spectroscopy for measurement. The epoxy resins were the diglyadyl ethers of bisphenol A (DGEBA), phenolphthalein (DGEPP), and 9,9‐bis(4‐hydroxyphenyl)fluorene (DGEBF). The thermal stability order of functional groups that incurred DGEBA was total methyl group ∼ total benzene ring > methylene > p‐phenylene > ether linkage > isopropylidene. The oxidative thermal and photodegradation processes were found to be related to the classical autocatalytical oxidation of aliphatic hydrocarbon segments. The Wieland rearrangement, Norrish‐type reaction, Claisen rearrangement, and other possible degradation mechanisms were suggested by the data.
Syntheses of polyimide copolymers based on N,N′‐(pyromellitoyl)diglycine
Authors: Yang Chin‐Ping 
Published: April 2003

AbstractN,N′‐(pyromellitoyl)diglycine (1) was synthesized by reacting pyromellitic anhydride with glycine in polar solvents such as DMAC, NMP, or DMF at 60°C and then refluxed azeotropically with toluene. Among these solvents, it is easy to form DMF‐insoluble salt (1″) in DMF, but this salt can be converted to 1 by treating first with NaHCO3 and then with HCl. Reacting monomer N,N′‐(pyromellitoyl)diaminoacetyl chloride (2) can be obtained by treating with thionyl chloride, and N,N′‐(pyromellitoyl)dimethyl aminoacetate (3) can be obtained by treating 2 with methanol. As 2 reacts with aromatic diamine in polar solvents, such as DMAC, DMF, or NMP, a series of copolypyromellitimide amides (5a–h) can be obtained. These copolymers can be processed by using DMAC + LiCl (5%) as solvent to produce flexible film of good weather resistivity and heat resistivity. Monomer 2 can also react with aromatic dihydrazides in polar solvents to produce copolypyromellitimide hydrazides (6a–c), and 6a–b can be condensated again to produce copolypyromellitimide oxadiazoles (7a–b) in polyphosphoric acid (PPA). Besides, 3 reacts with aromatic tetraamine by carrying out polycondensation in PPA to produce copolypyromellitimide benzimidazole (8). Structures of copolymers mentioned above were identified by comparing IR spectra with those of model compounds. Heat resistivity was measured by the thermogravimetric method, and their solubilities in various solvents were also investigated.
Asymmetric induction radical copolymerization of optically active l‐menthyl vinyl ether with vinylene carbonate and indene
Authors: Kurokawa Masahiro , Minoura Yuji 
Published: April 2003

AbstractThe copolymerizations of l‐menthyl vinyl ether (l‐MVE) with the monomers vinylene carbonate (VCA) and indene (IN) were carried out in benzene with azobisisobutyronitrile (AIBN) as an initiator to obtain optically active copolymers. The optically active l‐menthyl residue from the copolymer main chain was removed using dry hydrogen bromide gas. After the ether cleavage reaction, the copolymers prepared (VA–VCA and VA–IN) were still optically active, and hence it was found that asymmetric induction had taken place in the copolymer main chain. The optical rotatory dispersion (ORD) and circular dichroism (CD) data of the original and ether‐cloven copolymers were also determined.
Vapor‐phase graft copolymerization of binary solid monomers onto poly(ethylene‐co‐vinyl acetate) film by ultraviolet irradiation
Authors: Hayakawa Kiyoshi , Kawase Kaoru , Yamakita Hiromi 
Published: April 2003

AbstractVapor‐phase graft copolymerizations of acenaphthylene–maleimide or acenaphthylene–maleic anhydride binary solid monomers onto poly(ethylene‐co‐vinyl acetate) films were carried out under ultraviolet irradiation. The extent of sorption of single or binary monomers increased with the increasing vinyl acetate content in the backbone polymers. The sorbed binary monomers were mainly composed of acenaphthylene, but the maleimide or maleic anhydride fraction increased with the increasing vinyl acetate content of the films and the composition was little affected by surface hydrolysis. In all series of graft polymerization of single or binary monomers the overall extent of grafting increased with the vinyl acetate content and was suppressed by the surface hydrolysis of the backbone film. The composition of the grafted copolymer, however, differed markedly, depending on the combination of binary monomers. The grafted copolymer in the acenaphthylene–maleimide system was composed mainly of acenaphthylene units, whereas that in the acenaphthylene–maleic anhydride system was composed mainly of maleic anhydride units. The results were compared with those of γ‐ray grafting, and it was suggested that the contribution of a direct supply of monomers from vapor phase and the existence of an acetoxy group on the surface of the film should play an important role in the grafting reaction.
Synthesis and properties of optically active polyurea by interfacial polyaddition
Authors: Yasuzawa Takashi , Yamaguchi Hidemasa , Minoura Yuji 
Published: April 2003

AbstractOptically active polyureas were prepared from optically active diisocyanate (L‐lysinediisocyanatemethylester) and optically inactive linear diamine [H2N(CH2)nNH2, n = 2,3,4,5,6, and 9]. Polymerization was carried out by the interfacial polyaddition technique using the benzene–water system and by solution polyaddition. The values of optical rotation of obtained polyureas were dependent on the methylene number of diamines. Asymmetric selective polyaddition of L‐lysinediisocyanatemethylester for racemic 1,2‐diaminopropane was unsuccessful.
Equilibrium study of polymer–polymer complexation of poly(methacrylic acid) and poly(acrylic acid) with complementary polymers through cooperative hydrogen bonding
Authors: Osada Yoshihito 
Published: April 2003

AbstractThe degree of linkage, θ, defined as the ratio of the binding groups to the total of potentially interacting groups and the stability constant K of the polymer–polymer complexes in the systems poly(methacrylic acid)–poly(ethylene glycol), poly(acrylic acid)–poly(ethylene glycol), and poly‐(methacrylic acid)–poly(vinyl pyrrolidone) in aqueous and aqueous alcohol media were determined as a function of temperature by potentiometric titration. It was found that θ and K are strongly dependent on chain length, temperature, and medium and that hydrophobic interaction is a significant factor in the stabilization of the complexes. The enthalpy and entropy changes and the cooperativeness parameter of the systems were calculated. A mechanism for the complexation in terms of cooperative interaction was proposed.
The preparation of α‐substituted acrylic esters
Authors: Ponticello I. S. 
Published: April 2003

AbstractTreatment of the lithium enolates of cyclopentadiene‐blocked acrylates with various electrophilic reagents, such as alkyl chloroformates, α,β‐unsaturated carbonyl compounds, epoxides, episulfides, and α‐halocarbonyl compounds, has led to a convenient synthetic method for the preparation of α‐substituted acrylic esters.
Polysiloxane zwitterionomers and related model compounds. I. Synthesis
Authors: Graiver D. , Baer E. , Litt M. , Baney R. H. 
Published: April 2003

AbstractPolymers containing zwitterions were prepared by reacting γ‐propanesultone with polydimethylsiloxane‐co‐(4,7‐diazaheptylmethylsiloxane), which generated substituted di(ammonium‐3‐propane‐sulfonate) groups pendant from the siloxane chain. Their concentration in the polymers varied from 0.5 to 10 mole %. Two model compounds were also prepared in order to (1) characterize the reaction leading to the formation of these zwitterions and (2) characterize the ionic forces in solutions (tetrahydrofuran and benzene were used as solvents). The degree of aggregation of these model compounds was higher in tetrahydrofuran and increased in both solutions with the concentration. No rearrangements of siloxane bonds were observed in the presence of these zwitterions or γ‐propanesultone.
Theoretical aspects of the radiation effects of polymers
Authors: Tsuda Minoru , Oikawa Setsuko 
Published: April 2003

AbstractThe Millar–Wall–Charlesby empirical rule of radiation effects on polymers was theoretically examined. The theoretically calculated adiabatic potential curves of the main chain scission and side chain cleavage revealed that the effects of radiation on polymers are clearly interpreted as chemical reactions in the excited states; namely, that degradation occurs when little or no activation energy is required in the main chain cleavage reaction in the excited states, or, in other words, stabilization of the excited polymer molecule leads to the main chain cleavage. Crosslinking occurs when moderate or large activation energy is required in the main chain cleavage reaction in any electronic state and little or no activation energy is needed in the CH bond cleavage reaction in the excited states. Therefore stabilization of the excited polymer molecule leads to the formation of a polymer radical that crosslinks. It was concluded that Millar–Wall–Charlesby's rule is exact only when the shape of the adiabatic potential curve in the ground state reflects those in the excited states.
Photosensitive polymers containing diaryliodonium salt groups in the main chain
Authors: Crivello J. V. , Lam J. H. W. 
Published: April 2003

AbstractPhotosensitive polyimidothioethers were prepared by the base‐catalyzed condensation of bisthiols with 4,4′‐(N‐maleimido)diphenyliodonium chloride. Copolymers with other bismaleimide monomers were also prepared. The ultraviolet‐induced degradation of two of the copolymers was studied and the effects of light intensity on the rate of photolysis determined. It was also demonstrated that the range of spectral sensitivity of these polymers can be extended into the visible region through the use of dye sensitizers.