bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photodegradation of O‐methacryloyl ketone oxime‐methyl mechacrylate copolymers in the solid phase
Authors: Tsunooka Masahiro , Imono Syozo , Nakayama Kazuo , Kuwabara Hideaki , Tanaka Makoto 
Published: April 2003

AbstractSeveral kinds of copolymers bearing O‐acyloxyimino groups were prepared and their photodegradabilities were examined. Copolymers of O‐methacryloyl ketone (acetophenone, benzophenone, or 2‐acetonaphthone) oxime and methyl methacrylate (or styrene) were photodegradable even in the solid phase but in the case of copolymers of O‐acryloyl acetophenone oxime and methyl methacrylate (or styrene) both photodegradation and photocrosslinking were observed. From these results it was found that the photodegradability of the copolymers was not dependent on the comonomer (methyl methacrylate or styrene) but dependent on the structure of the monomer bearing O‐acyloxyimino groups. From detailed analysis of photodegradation of the copolymer of O‐methacyloyl acetophenone oxime and methyl methacrylate in the presence of benzophenone it was found that the benzophenone worked not only as a sensitizer for the decomposition of O‐acyloxyimino groups but also as a plasticizer to assist segment motions of polymer chains and the diffusion of oxygen in the film.
Evolution of H2O and CO2 during the copper‐catalyzed oxidation of isotactic polypropylene
Authors: Jellinek H. H. G. , Wei You Ching 
Published: April 2003

AbstractThe kinetics and mechanism of H2O and CO2 evolution during uncatalyzed and copper(oxide)‐catalyzed (Cu, CuO, CuO0.67) oxidation of isotactic polypropylene have been investigated in detail for various catalysts over a range of temperatures (90–150°C). These volatiles were determined chromatographically; H2O and CO2 represent the main volatiles of the oxidation, comprising about 80 mol % of all volatiles. Uncatalyzed oxidation evolves ca. 1 mol of H2O and 1 mol of CO2 for each unit mole of polymer oxidized, while catalyzed oxidation produces 2 mol of H2O and ca. 1.2 mol of CO2 for each unit mole of polymer. These results indicate that secondary as well as tertiary H atoms on the polymer chains are involved in hydroperoxide formation and decay. The oxidation mechanism has been formulated and evaluated on this basis. It consists essentially of two parallel oxidation reactions involving tertiary and secondary groups (H atoms and hydroperoxides), respectively. The mechanism can be represented by first‐ and pseudo‐first‐order reactions in series: (1) oxygen absorption showing induction periods; (2) hydroperoxide formation and decay (plateaus are reached); (3) H2O evolution from the decay of hydroperoxides; and (4) subsequent CO2 production involving chain scission. Arrhenius parameters for all oxidation reactions (uncatalyzed and catalyzed) are also presented. It appears that CuO0.67 is the most efficient catalyst of those investigated.
Block copolymers derived from azobiscyanopentanoic acid. VI. Synthesis of a polyethyleneglycol–polystyrene block copolymer
Authors: Ueda Akira , Nagai Susumu 
Published: April 2003

AbstractPolycondensations were carried out between azobiscyanopentanoly chloride (ACPC) and polyethyleneglycols (PEG) having average molecular weight of 600, 2000, 8400, and 21,500, resulting in the chain extended PEG of several times the original polymer chain length and containing scissile NN units of azobiscyanopentanoic acid (ACPA). The poly(polyethyleneglycol‐azobiscyanopentanoate), designated as \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} (PEG\rlap{--} )_n^*$\end{document} were thermally decomposed in the presence of styrene (St) to obtain PEG–PSt block copolymers. The amount of St consumed was proportional to [NN]0.5 and [St]1.2, whereas the chain length of the PSt segment was proportional to [NN]−0.5 and [St]0.8.
Preparation and properties of the polyester made from 2.2‐bis(4‐hydroxycyclohexyl)propane and adipic acid
Authors: Gaughan R. G. , Hill H. W. , Inda J. E. 
Published: April 2003

AbstractPoly[2,2‐bis(4‐oxycyclohexyl)propane adipate] was formed by melt polymerizing adipic acid and 2,2‐bis(4‐hydroxycyclohexyl)propane in the presence of n‐butylhydroxyoxostannane. This polyester possessed a melting temperature (Tm) of 200°C and a glass transition temperature (Tg) of 75°C. An excellent notched impact strength of 22 ft. lbs./in. was its best physical property.
Functional polymers and sequential copolymers by phase transfer catalysis. XIX. Thermotropic polythioethers and copolythioethers based on 4,4′‐dithiolbiphenyl
Authors: Shaffer Timothy D. , Percec Virgil 
Published: April 2003

AbstractThermotropic liquid crystalline (LC) polythioethers and copolythioethers have been synthesized from 4,4′‐dithiolbiphenyl (TB) and α,ω‐dibromoalkanes having between two and twelve methylene units. Copolythioethers were prepared from TB and a 1:1 mol/mol ratio of 1,5‐dibromopentane and α,ω‐dibromoalkanes having nine to twelve methylene units. Peculiarities of the phase‐transfer catalyzed (PTC) polyetherification reaction in the preparation of these polymers have led to aliphatic‐ether structural units. This side reaction has been explained by a possible neighboring group effect with sulfur, through sulfonium formation, and is consistent with a mechanism previously proposed in PTC polyetherifications. While not significantly enhancing solubility, the copolymeric nature of these polymers have led to lower melting and isotropization temperatures with broad mesophase thermal stability ranges. Lastly, unique spherulitic textures resembling higher‐ordered smectic mesophases have been observed in all the prepared polymers.
Kinetics of reaction of methyl α‐eleostearate with phenol
Authors: Yoshimura Yukio 
Published: April 2003

AbstractThe kinetics of addition reactions between methyl α‐eleostearate which forms the main chain of tung oil and phenol when catalyzed by an acid, p‐toluene sulfonic acid, have been studied. The addition reactions, carried out with phenol was shown to be second order with regard to methyl α‐eleostearate concentration and first order with regard to phenol concentration. The reactions were additions of two phenol molecules to one methyl α‐eleostearate molecule, and it was presumed that they proceed in the two steps given below in which the first step is rate determining:

The apparent reaction rate constant (l/mol min) was found to be 0.036 and its value was nearly equal to that in the case of m‐cresol. The apparent activation energie (kcal/mol) was found to be 4.76 and its value was larger than that in the case of m‐cresol.
Polymerization by phase‐transfer catalysis 3: Poly(1,4‐oxylylene thioethers) synthesis
Authors: Tagle L. H. , Diaz F. R. , De La Maza M. P. , Vega J. C. 
Published: April 2003

AbstractPoly(1,4‐oxylylenethioethers) were synthesized from 2,5‐disubstituted‐1,4‐bis(chloromethyl)‐benzenes and sodium sulfide under phase‐transfer conditions. The polythioethers were characterized by elemental analysis and infrared spectroscopy. The effect of the catalyst, solvent, and temperature were studied. Their glass transition temperature and thermal decomposition were determined.
Synthesis and characterization of model compounds for carbazole‐substituted N‐acylated linear polyethylenimine (PEI). Synthesis and 1H‐NMR spectra of N‐acylated diethylamine and N,N′‐dimethyl‐1,2‐ethanediamine containing 9‐carbazolylacetyl, (R,S)‐ or (R)‐2‐(9‐carbazolyl)propanoyl groups
Authors: Arora Kartar S. , Overberger C. G. 
Published: April 2003

AbstractThe synthesis of N,N‐diethyl‐9‐carbazolylacetamide (6), (R,S)‐ and (R)‐N,N‐diethyl‐2‐(9‐carbazolyl)propanamide (7), N,N′‐dimethyl‐N,N′‐di‐(9‐carbazolylacetyl)‐1,2‐ethanediamine (11), and (R)‐N,N′‐dimethyl‐N,N′‐di[2‐(9‐carbazolyl)propanoyl]‐1,2‐ethanediamine (13) is reported. The racemic compound, (R,S)‐2‐(9‐carbazolyl)propanoic acid (2), was resolved by partial crystallization of the diastereomeric salts formed between 2 and (+)‐α‐methylbenzylamine. The 1H‐NMR spectra of 6 and 7 showed magnetic nonequivalence of the chemically equivalent protons of the methyl and methylene groups in 6 and 7 due to partial double bond character of the amide bond. The upfield resonances corresponding to the two sets of methyl and methylene protons were assigned by the aromatic solvent‐induced shift (ASIS) method to the protons anti to the carbonyl oxygen in the conformation of amide bond in 6 and 7. The 1H‐NMR spectra of 11 and (R)‐13 were used to determine the population of anti‐anti, anti‐syn (syn‐anti) and syn‐syn conformers in the structures of these dimer model compounds; the relative conformer populations were 0.45:0.47:0.08 and 0.28±0.02:0.29±0.01:0.43±0.01 in 11 and (R)‐13.
Synthesis of polyesters containing nucleic acid base derivatives as pending side chains
Authors: Lu C. X. , Li Qiang , Zhang Dehong , Ji Aixue 
Published: April 2003

AbstractPreparations of four diol monomers containing nucleic acid bases and the corresponding model polymers of polynucleotides with linear polyester backbone and nucleic acid base derivative as pending side chains are described. N‐(1′,3′‐Dihydroxy‐2′‐methyl‐2′‐propyl)‐2‐(thymin‐l‐yl)propionamide (Ia, HMPTPA), N‐(1′,3′‐dihydroxy‐2‐methyl‐2′‐propyl)‐2‐(uracil‐l‐yl)propionamide (Ib, HMPUPA), and their isomers, N‐(β,β′‐dihydroxyethyl)‐2‐(thynin‐1‐yl)propionamide (IIa, HETPA) and N‐(β,β′‐dihydroxyethyl)‐2‐(uracil‐1‐yl)propionamide (IIb, HEUPA) were synthesized through the selective N‐acylation of 2‐methyl‐2‐amino‐1,3‐propanediol and diethanolamine with 2‐(thymin‐1‐yl)propionic acid (TPA) and 2‐(uracil‐1‐yl)propionic acid (UPA), respectively, by the active amide‐benzotriazole method. Diol monomers I and II were polycondenzed with active amide of benzotriazole such as 1,1′‐(isophthaloyl)bisbenzotriazole (IPBBT) in the presence of triethylamine and in DMF at 60°C, giving polyesters containing thymine and uracil derivatives as the side group. Prior to polymer synthesis, an O‐acylation of Ia using the active monoamide l‐benzoylbenzotriazole was carried out as a model compound study.
Precipitation polymerization of acrylamide using vazo‐33 as an initiator and acetonitrile/water mixtures as the solvent
Authors: Tai Eva F. , Caskey Jerry A. , Allison Bruce D. 
Published: April 2003

AbstractPrecipitation polymerization of acrylamide initiated by a thermal initiator, Vazo‐33 (DuPont Vazo Initiator), was achieved at a solvent composition of acetonitrile/water = 4/6 (vol/vol). The polymerization kinetics were investigated in the acrylamide [M] concentration range 0.86–2.27M, Vazo‐33 [I] concentration range 1.4–11.0 × 10−4M, and temperature range 30–40°C. Polymerization was carried out in reaction ampules and the rate was determined gravimetrically. Number‐average molecular weight was obtained from intrinsic viscosity. The precipitation polymerization rate varied as [M]2.16 and [I]0.44. Number‐average molecular weight was proportional to [M]1.22 and inversely proportional to [I]0.31. The overall reaction activation energy was calculated as 17.3 kcal/mol in the temperature range studied. The optimal reaction conditions studied were: acetonitrile/water = 4/6, temperature = 40°C, [M] = 1.95M and [I] = 2.8 × 10−4M. One hundred percent conversion was achieved in 90 min and a polymer with a number‐average molecular weight of 1,200,000 was obtained.
Direct polyesterification promoted by a complex of phosphorus oxychloride with LiCl monohydrate
Authors: Higashi Fukuji , Fujiwara Yō‐Ichi , Yamada Yukiharu 
Published: April 2003

AbstractThe reaction of benzoic acid and p‐chlorophenol with phosphorus oxychloride (POC) was significantly affected by the presence of metal salt hydrates or a mixture of metal salts and water sufficiently aged. Among metal salts examined, LiCl was most effective for the reaction to give quantitative yield of the benzoate. The reaction was assumed to proceed via a complexation of POC with LiCl monohydrate followed by selective hydrolysis of POC by water bound to LiCl. The reaction promoted by a complex derived from POC and LiCl monohydrate in pyridine was successfully used as a new condensing agent for the synthesis of aromatic polyesters by the direct polycondensation or aromatic dicarboxylic acids and bisphenols. Under favorable conditions for aging of POC with LiCl monohydrate and for addition of bisphenols, polymers of moderate to high molecular weights were obtained in quantitative yield. The reaction was applied with limited success to the preparation of a copolymer of high molecular weight from hydroxybenzoic acids.
Synthesis of soluble aromatic polyesteramides by stepwise copolycondensation of bisphenols and aromatic diamines with diphenyl chlorophosphate in pyridine
Authors: Higashi Fukuji , Ozawa Michihide , Mochizuki Akihiko 
Published: April 2003

AbstractThe reaction promoted by diphenyl chlorophosphate (DPCP) in pyridine was successfully applied to the preparation of soluble aromatic copolyesteramides of high molecular weights directly from aromatic dicarboxylic acids, bisphenols, and a wide range of mol % aromatic diamines. Dropwise addition of a mixture of bisphenols and diamines (more favorably of bisphenols and then diamines) to the mixture of dicarboxylic acids activated by DPCP led the reactions homogeneously even with high mol % of diamines to produce copolymers of good solubility. This improved copolymer solubility was roughly estimated by sequence distribution of polyamide and polyester units in the copolymers, which was studied in a model reaction and in the copolycondensations by simultaneous and stepwise addition of bisphenols and diamines.
The effects of oxidative reaction on ionic permeabilities through polypeptide membranes containing –SH groups in the side chains
Authors: Takizawa A. , Kinoshita T. , Ohtani A. , Tsujita Y. 
Published: April 2003

AbstractThe effects of the oxidative reaction on the ionic permeabilities through polypeptide membranes containing thiol groups in the side chains were investigated. Membranes were derived from poly(glutamyl‐cysteine) (PGC) containing 12% (in mol %) of SH groups in the side chains, and from poly(L‐cysteine) (PlCys) containing 26% of thiol groups in the side chains, respectively. On the basis of the polarographic analysis, it can be estimated that more than 80% of SH groups in the membranes could be oxidized by using 10 mM solution of iodine. The membrane potentials across the PGC membrane were increased by the iodine oxidation, indicating that SH groups of PGC were converted to highly dissociable groups, i.e., sulfonic acid derivatives. The decrease in the ionic permeabilities through the PGC membrane by the oxidation, therefore, was attributed to the decrease in ionic solubility into the membrane owing to the increase in fixed charge density of the membrane (Donnan exclusion effect). On the other hand, no influence of the oxidation on the membrane potentials of the PCys membrane suggests the possibility of oxidative S‐S cross linking in the membrane. The oxidation‐induced permeability decrease of the PCys membrane could be explained in terms of the decrease in ionic diffusibility associated with the formation of the side chain cross linkings between SH groups in the membrane.
Photoinduced membrane potential changes. Bi‐ionic potential across poly(vinyl chloride) membranes entrapping a photoresponsive bis(15‐crown‐5) derivative and the effects of photoirradiation
Authors: Anzai Jun‐Ichi , Sasaki Hiroshi , Ueno Akihiko , Osa Tetsuo 
Published: April 2003

AbstractBi‐ionic potential (BIP) across poly(vinyl chloride) membranes containing azobenzene‐modified bis(15‐crown‐5) was measured in the presence of alkali‐metal chlorides. The BIP measurements revealed the cation selectivity sequence of the membranes (K+ > Rb+ > Cs+ ≫ Na+ > Li+), which agreed well with the potentiometric selectivity order of 15‐crown‐5–based ion‐selective electrodes developed so far. UV‐light irradiation induced the positive or negative shift of BIP. The magnitude and sign of the photoinduced potential shift depended considerably upon the kind and concentration of electrolytes and, as well, the direction from which the membrane was irradiated. The results were explained in terms of the surface‐potential changes induced by light irradiation.
Rigorous approach to kinetic parameters: polymerization of styrene with benzoyl peroxide in carbon tetrachloride
Authors: Ng S. C. , Chee K. K. 
Published: April 2003

AbstractBoth the rate constant of initiator dissociation, kd, and the chain transfer constant, Cx, are determined by monitoring the rates of monomer and transfer agent conversions in a chain polymerization. Statistical analysis that takes into account the errors of experimental variables has been used to treat the kinetic data for the polymerization of styrene initiated by benzoyl peroxide (Bz2O2) in carbon tetrachloride at 60°C. Values of kd and Cx produced by this error‐in‐variable method (EVM) are in accordance with those reported in literature. More important, the EVM algorithm always results in the smallest standard deviations of estimates, and hence, it is superior to the usual least‐squares calculations. Other distinct features of the method are outlined. The initiator efficiency for Bz2O2 is estimated to be 0.72 under the present conditions.
Direct polyamidation with thionyl chloride in N‐methyl‐pyrrolidone
Authors: Higashi Fukuji , Nishi Toshiharu 
Published: April 2003

AbstractMechanistic features of the reaction promoted by thionyl chloride and amides such as N‐methylpyrrolidone (NMP) were studied. The reaction was effective in the amidation of carboxylic acids, but not effective in the esterification. The amidation was affected by the kind and the amount of amides used, most favorably by two equivalents of NMP with respect to the acid. These amides were assumed to be involved in the intermediate formation, and the reaction was proposed to proceed via Vilsmeier adducts derived from thionyl chloride and the amides, and through activation of a carboxylic acid different from an acyl chloride. The reaction was successfully applied to the direct polycondensation of aromatic dicarboxylic acids and diamines in NMP at 70°C to produce polyamides with high molecular weights. Initial reaction of dicarboxylic acids with the adducts, additive effect of tertiary amines, and polycondensation temperatures were studied in terms of the inherent viscosity of the polymers produced.
Solution copolymerization of styrene and 2‐hydroxyethyl mechacrylate.
Authors: Lebduška Jan , Šnupárek Jaromîr , Kašpar Karel , Čermák Vladimír 
Published: April 2003

AbstractThe rate of solution copolymerization of styrene (M1) and 2‐hydroxyethyl methacrylate (M2) was investigated by dilatometry. N,N‐dimethyl formamide, toluene, isopropyl alcohol, and butyl alcohol were used as solvents. Polymerization was initiated by α,α′‐azobisisobutyronitrile at 60°C. The initial copolymerization rate increased nonlinearly with increasing 2‐hydroxyethyl methacrylate (HEMA)/styrene ratio. The copolymerization rate was promoted by solvents containing hydroxyl groups. Two different approaches were used for the prediction of copolymerization rates. The relationships proposed for the copolymerization rates calculation involve the effects of the total monomer concentration, mole fraction of HEMA, and of the solvent type. Different reactivity ratios were found in polar and nonpolar solvents: r1 = 0.53, r2 = 0.59 in N,N‐dimethyl formamide, isopropyl alcohol and n‐butyl alcohol; r1 = 0.50, r2 = 1.65 in toluene. The usability of these reactivity ratios was confirmed by batch experiments.
Inclusion polymerization in perhydrotriphenylene studied by ESR spectroscopy: Growing chain structure and conformation of methylsubstituted polybutadienes
Authors: Sozzani P. , di Silvestro G. , Gervasini A. 
Published: April 2003

AbstractInclusion polymerization of diene monomers promoted by γ rays and performed in perhydrotriphenylene was studied by ESR techniques. During polymerization of butadiene, 1,3‐pentadiene, isoprene, 2,3‐dimethylbutadiene, 2‐methylpentadiene, and 2,4‐hexadiene, spectra attributable to allyl‐type radicals were collected. It was demonstrated they actually represent the propagating radicals and they do not vary over a long period of time. They are not temperature dependent in the range −150°/ +60°C, apart from the radical of polybutadiene, suggesting that the included methyl‐substituted polybutadienes are conformationally fixed. When the two opposite insertions of monomers 1,4 and 4,1 are distinguishable, the radicals bearing the higher number of methyl groups at the ends of allyl system prevail.
Solvation of polymeric organolithium compounds. Heats of interaction of tetrahydrofurans and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) with poly(butadienyl)lithium
Authors: Quirk Roderic P. , McFay Dennis 
Published: April 2003

AbstractThe enthalpies of interaction of tetrahydrofuran, 2,5‐dimethyltetrahydrofuran and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) with 0.02M benzene solutions of poly(butadienyl)lithium (MN∼4,000) were measured as a function of R([base]/[Li]) using highdilution, solution calorimetry at 25°C. At low R values (ca. 0.2) the enthalpy of interaction of THF ( — 6.1 kcal/mol) is only 1.5 kcal/mol more exothermic than with 2,5‐dimethyltetrahydrofuran and both decrease rapidly with increasing R value. These results indicate that this coordination process is much less sensitive to the steric requirements of the base than analogous processes for poly(isoprenyl)lithium and poly(styryl)lithium. The concentration dependence for the enthalpy of interaction with TMEDA falls off precipitously with increasing R values from an initial value of −12.4 kcal/mol at R = 0.14. These results suggest either a higher degree of association or a less favorable dissociation equilibrium constant for poly(butadienyl)lithium versus poly(isoprenyl)lithium.
Stereochemistry and dynamic behavior of some synthetic “angular” profisetinidin tetraflavanoid derivatives
Authors: Young Desmond A. , Ferreira Daneel , Roux David G. 
Published: April 2003

AbstractThe structure and stereochemistry of four synthetic “angular” tetraflavanoid‐condensed tannin derivatives are examined by high‐resolution variable temperature 1H NMR. spectroscopy, and hence correlated with their dynamic behavior. Three “angular” oligomers exist as stable rotational isomers at ambient temperatures, thus contrasting with the mobility about their interflavanoid bonds of most natural profisetinidin “trimeric” and “tetrameric” homologs. A “linear” tetraflavanoid analog results from one of these regioselectively controlled condensations.
On the copolymerization model and microstructure of methyl acrylate ‐ styrene radical copolymer. Influence of ZnCl2
Authors: Simionescu Cristofor I. , Bǎrboiu Virgil , Simionescu Bogdan C. , Talmaciu Viorica , Sava Corina 
Published: April 2003

AbstractBulk radical copolymerization of methyl acrylate (MeA, M1) with styrene (St, M2) in presence and absence of ZnCl2 as complexing agent was studied. 1H‐NMR spectra were used to establish copolymer composition and sequence distribution. The methoxy group signal was observed to be split due to pentads, but the analysis of sequence distribution is possible only at triad level. Both composition and sequence distribution data confirmed that bulk radical copolymerization respects quite well the terminal addition model; the values of r1 = 0.14 ± 0.02 (from composition data) and r1 = 0.25 ± 0.03 (from sequence distribution data) and r2 = 0.83 ± 0.10 (from composition data) were found. The presence of ZnCl2 increases the probability of alternating addition, e.g., for [ZnCl2]/[MeA] = 0.2, r1 = 0.03 ± 0.02 and r2 = 0.17 ± 0.03. The radical copolymer obtained in bulk in the absence of ZnCl2 presents a coisotactic configuration with σ = 0.75 ± 0.03, but the presence of the complexing agent reduces the probability of coisotactic addition, e.g., for [ZnCl2]/[MeA] = 0.2, σ = 0.52 ± 0.03.