bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative recalculation of the monomer reactivity ratios in copolymerization for styrene and methyl methacrylate
Authors: Leicht R. , Fuhrmann J. 
Published: April 2003

AbstractThe monomer reactivity ratios (MMRs) in radical copolymerization for styrene and methyl methacrylate were recalculated by five different methods using literature copolymerization data. The use of approximate 95% confidence limits and their visual inspection helps to separate possibly biased copolymer composition data. The recalculated mean MRR values were r1 (styrene) = 0.501 ± 0.031 and r2 = 0.472 ± 0.031. The results of the linear least‐squares calculation procedures seldom approach the quality of the nonlinear least‐squares analysis according to the method of Tidwell and Mortimer.
Coordination polymers. XV. Influence of diols on the reaction between unsaturated polyesters and Mg ions
Authors: Szilágyi Á. , Vancsó‐Szmercsányi I. 
Published: April 2003

AbstractAn increase in viscosity of reaction mixtures of low molecular mass, COOH, and alcoholic OH‐terminated polyesters with MgO is considerably reduced by the presence of diols in the system. This effect is analogous with that described for the presence of water. Joint presence of water and diol results in an additive effect. The mechanism of this effect can be interpreted by coordination chemistry. In this system both diol and water saturate the coordination sphere of Mg2+ ion (as ligands). Consequently, the coordination of donor groups of polyester (terminal OH and ester carbonyl groups) is suppressed by reducing the extent of linking the polyester molecules with coordination bonds; that is, the average molecular mass of the system. Moreover, coordination of low‐molecular ligands modifies the final molecular structure that occurs in the system. In addition, some kinetic effects are revealed in the process because the system is diffusion‐controlled by the ever‐increasing viscosity. This effect is also favorable to the coordination of low molecular mass ligands. All of these factors lead to a reduction in the increase of viscosity in the present system.
Preparation of polystyrene labeled with amino groups at specific sites
Authors: Worsfold D. J. 
Published: April 2003

AbstractThe preparation of monodisperse polystyrene substituted with single dimethylamino groups is described. Three methods are adopted. The first involves the use of a dimethylamino‐substituted initiator to give an end amino group. The second uses an ester coupling reaction with a dimethylamino‐substituted methyl valeric ester to give a central amino substituent. The third method, which is capable of giving an amino substituent at any selected place along the chain, uses a dimethyl‐amino‐substituted butadiene derivative as a comonomer in a sequential polymerization. This latter method takes advantage of the unusual reactivity ratios of styrene and dienes in anionic copolymerization.
Liquid‐crystalline copolyesters based on poly(p‐oxybenzoate) and poly(p,p‐biphenylene terephthalate)
Authors: Volksen W. , Lyerla J. R. , Economy J. , Dawson B. 
Published: April 2003

AbstractTwo copolymers composed of p‐hydroxybenzoate (PHB) and biphenylene terephthalate (BPT) with PHB/BPT ratios of 1/2 and 2/1 were characterized with respect to their tendency to exhibit liquid‐crystalline behavior in the melt phase. The BPT ‐rich copolyester, PHB/BPT = 1/2, displayed a birefringent melt phase of very high viscosity and no tendency to crystallize on cooling. The resulting fused material exhibited what apeared to be a second‐order transition at 170°C. The PHB‐rich composition, PHB/BPT = 2/1, also exhibited a highly birefringent melt phase of high viscosity which was quite shear sensitive. This polymer melt had little tendency to crystallize on cooling; however, on reheating no apparent second‐order transition could be detected. The observed phase changes were characterized by differential scanning calorimetry, hot‐stage microscopy, and wide‐angle x‐ray diffraction techniques. Additional data, pertaining to the compositional nature and apparent sequence distribution, were obtained by 13C‐NMR spectroscopy of the solid materials through magic‐angle spinning, dipolar decoupling, and cross‐polarization techniques.
Copolymerization of acrylonitrile with 3‐chloro, 2‐hydroxy‐propyl acrylate and methacrylate
Authors: Bajaj P. , Padmanaban M. 
Published: April 2003

AbstractAcrylonitrile (AN) was copolymerized with 3‐chloro, 2‐hydroxy propyl acrylate (CHPA) and 3‐chloro, 2‐hydroxy‐propyl methacrylate (CHPMA) in water and water‐acetone medium at 40°C with potassium persulfate and sodium metabisulfite as redox initiators. Copolymer composition was determined from the nitrogen content. The reactivity ratios for the AN‐CHPMA system were also calculated by the Kelen–Tudos method. The reactivity ratio r2 (CHPMA) was higher for the AN‐CHPMA system in both media, which indicated higher reactivity of CHPMA toward the propagation species. Addition of acetone decreases r2 and increases r1. It was found that the copolymers prepared in water medium were not completely soluble in dimethylformamide (DMF); the insoluble fraction was rich in CHPA/CHPMA and increased with increasing comonomer composition. The influence of the acrylate comonomer on properties such as solubility and intrinsic viscosity was also studied.
Synthesis and characterization of polyesters derived from aromatic 1,4‐dimethoxylated diacids
Authors: Diaz F. R. , Tagle L. H. , Olivares J. P. 
Published: April 2003

AbstractPolyesters were synthesized from the dichlorides of 2,5‐dimethoxyterephthalic and 2,5‐dimethoxy‐1,4‐benzenediacetic with dialcohols. The polymers were characterized by elemental analysis and infrared (IR) spectroscopy. Their intrinsic viscosity, glass transition temperature, and thermal decomposition were determined.
Synthesis and characterization of certain aromatic polyfumaramides
Authors: Sachindrapal P. , Nanjan M. J. 
Published: April 2003

AbstractTen polyfumaramides based on p,p′‐aromatic diamines and fumaric acid were synthesized by the phosphorylation method. The polymers were characterized by viscosity, solubility, infrared and UV‐visible spectroscopy, and thermogravimetry. The fluorescence spectra of one of the polymers were studied. A model compound, fumaroyldianilide, was synthesized and characterized.
Comparisons of glow discharge polymerization between hexamethyldisilazane and trimethylsilyldimethylamine
Authors: Inagaki N. , Kishi A. 
Published: April 2003

AbstractGlow discharge polymerization between hexamethyldisilazane (HMDSZ) and trimethylsilyldimethylamine (TMSDMA) was compared by means of infrared spectroscopy and ESCA analysis. Infrared spectra pointed out differences in chemical structure between the polymers prepared from the two monomers, although the two polymers were mainly composed of resembling units such as SiCH3, SiCH2, SiH, SiOSi, and SiOC groups: (i) The polymers prepared from TMSDMA contained N → O group, but the polymers from HMDSZ did not contain this group. (ii) Influences of the W/FM parameter (W is the input energy of rf power, F the flow rate of the monomer, and M the molecular weight of the monomer) appeared on decreasing the CN group and increasing the CO group in the TMSDMA system, but little influence appeared in the HMDSZ system. ESCA spectra (C1s, Si2p, and N1s core levels) supported the differences between the two polymers elucidated by infrared spectroscopy, and pointed out differences in susceptibility of the SiN bond to plasma: The NSi sequence of TMSDMA was completely ruptured in discharge to yield polymers, and the SiNHSi sequence of HMDSZ remained in considerable amount.
Unique hydrophobic interactions of pyrene in aqueous solution as effected by polyelectrolytes and surfactants
Authors: Herkstroeter W. G. , Martic P. A. , Hartman S. E. , Williams J. L. R. , Farid S. 
Published: April 2003

AbstractPyrene substituents covalently bounded to polyelectrolytes show not only excited‐state interactions but also unique ground‐state interactions in aqueous solution. The pyrene moieties in pyrenesubstituted ionic molecules also show these interactions when aqueous solutions of these molecules are treated with polyelectrolytes or surfactants well below their critical micelle concentrations. These hydrophobic interactions are revealed by changes in absorption, fluorescence, and excitation spectra. The well‐resolved vibrational bands in the absorption and excitation spectra of pyrene become somewhat diffuse, whereas monomer fluorescence is reduced and replaced by excimer fluorescence. The rationale for these results is that the pyrene moieties in these ionic solutions seek out hydrophobic locations on the polyelectrolytes or surfactants, where pyrene aggregation is responsible for these interactions and the corresponding changes in spectra.
Interpenetrating polymer networks from polyurethanes and methacrylate polymers. I. Effect of molecular weight of polyols and NCO/OH ratio of urethane prepolymers on properties and morphology of IPNs
Authors: Xiao H. X. , Frisch K. C. , Frisch H. L. 
Published: April 2003

AbstractTwo types of reinforced elastomeric interpentrating polymer network (IPN) were prepared by simultaneous polymerization and crosslinking in solution. The first type consisted of polyurethane‐poly(methyl methacrylate) (PU/PMMA), and the second, of polyurethane‐poly(methyl methacrylate‐methacrylic acid) PU/P(MMA–MAA) of constant composition (90/10) and (80/20) by weight, respectively. The members of each type differed in the NCO/OH ratio of the PU prepolymer and the molecular weight (MW) of the polyol in the PU component because we wished to investigate systematically the effect of changing the NCO/OH ratio and MW of the polyol on the mechanical properties and morphology of the resulting IPNs. The mechanical properties, particularly the modulus of both tyes of IPN, increased with increasing NCO/OH ratio and decreased with increasing MW of the polyol in the PU. The morphology of the IPNs was studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Improved phase compatibility and decreasing extent of phase separation was observed in both types of IPN with increasing NCO/OH ratio and decreasing MW of the polyol used in the PU. These results may imply that improved interpenetration results from increasing the NCO/OH ratio and decreasing the MW of the polyol in the PU component. The fact that the effect is more pronounced with the type of PU‐P(MMA–MAA) IPN can be rationalized as due to the additional hydrogen bonding between the carbonyl in the carboxyl groups and the urethane or urea groups in the PU component.
Graft polymerization of acrylic monomers onto starch fractions. I. Effect of reaction time on grafting methyl methacrylate onto amylose
Authors: Goñi I. , Gurruchaga M. , Valero M. , Guzman G. M. 
Published: April 2003

AbstractA study was made of the ceric‐ammonium‐nitrate‐initiated graft polymerization of methyl methacrylate (MMA) onto a lineal fraction of starch (amylose). Grafting yields were determined by extraction with appropriate solvents: 1,2‐dichloroethane for homo‐PMM, and 0.5N NaOH for ungrafted amylose. Percent grafting was calculated by acid hydrolysis with 1N HCl. Molecular weights of PMMA side chains were determined by gel permeation‐chromatography. Grafting efficiencies ranged from 72 to 83%, grafting, from 190 to 271%, and frequency of attachment of side chains, from 900–1250 glucose units per chain. The results observed are discussed.
Hydrogels préparés par le greffage radiochimique pour l'immobilisation des enzymes
Authors: Jendrychowska‐Bonamour A.‐M. 
Published: April 2003

AbstractThe direct method of radiation grafting was used to cover poly(methyl methacrylate) tubes and rings with a thin layer of poly(acrylic acid) hydrogel. The copolymer formed is used as a support for covalent immobilization of enzymes. The enzyme support coupling was realized with carbodimide or glutaraldehyde. The activity of the immobilized chymotrypsin and peroxidase was determined and the stability of the enzyme‐linked copolymers was tested.
Anionic polymerization and copolymerization of p‐bromostyrene
Authors: Königsberg Itzhak , Jagur‐Grodzinski Joseph 
Published: April 2003

AbstractMonodispersed poly(4‐bromostyrenes) (PBs) and their block copolymers with styrene, isoprene, and 3‐methylbutene were prepared and characterized by GPC and NMR. Polystyryl and α‐methylstyryl carbanions act as effective initiators of the anionic polymerization of Bs in THF. The undersirable side reactions, due to thermally or photochemically induced decomposition of the bromostyryl carbanions, PBs−, may be eliminated by conducting the reaction at −78°C and in the dark. Under such conditions, the rate constant of propagation, kp (−78°), is 1.5 × 103 M−1 s−1. Radical anions, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Bs}^{\mathop - \limits_ \cdot} $\end{document}, formed as result of electron transfer from sodium naphthalenide to Bs, may eject spontaneously bromine ions. This step and reactions involving the respective phenyl radicals compete at −78°C with the addition steps leading to polymer formation. Electron affinity of Bs seems to be much higher than that of styrene or isoprene, and PBs− carbanions do not add to the latter monomers. Addition of Bs to polyisoprenyl carbanions leads to formation of the BsIBs block copolymers. BsIBs, prepared in THF, may be converted by preferential hydrogenation of the 1–2 adducts into block copolymers of Bs with poly(2‐methylbutene) and isoprenyl segments. The effectiveness of Bs as a flame retarding constituent of polymeric systems seems to be much more pronounced when it is incorporated in a “block” than in a random fashion. A considerably larger fraction of PBs is required to achieve the same LOI value when the respective homopolymers are blended. Spatial distribution of the easily charred microdomains in the block copolymers is believed to be responsible for this phenomenon.
The effect of the radical structure in trialkylaluminums on cis polymerization of dienes on titanium catalyst systems
Authors: Rafikov S. R. , Monakov Yu. B. , Tolstikov G. A. , Marina N. G. , Minchenkova N. Kh. , Savelieva I. G. 
Published: April 2003

Abstract1,4‐cis‐polymerizations of 1,3‐dienes of TiCl4‐AIR3 catalyst systems for isoprene and on TiI2Cl2‐AIR3 caltalyst systems for butadiene have been investigated. AIR3 denotes herein an organoaluminum compound (OAC) containing hydrocarbon radicals, linear of different lengths or cyclic, both saturated and unsaturated, as well as those containing O, N, or Si atoms. Neither the OAC radical structure nor the Al/Ti ratios in the range investigated have been found to influence the stereospecificities and reactivities (chain propagation constant) of the active centers. Differing activities of the catalyst systems have been established to result from the variations in the concentrations of the active centers involving <1–5% of all the Ti species. The nature of the OAC radical does not change the mode of the molecular weight distribution in the polymers obtained. An increase in the molecular weight (MW) of the polydienes produced with the use of higher‐MW trialkylaluminums was provoked by an increase in the macromolecules propagation period owing to the lower constant of chain transfer to the higher‐MW OAC.
Terpolymerization of acrylonitrile, styrene, and 2,4,6‐tribromophenyl acrylate
Authors: Janović Zvonimir , Sarić Karla , Vogl Otto 
Published: April 2003

AbstractAcrylonitrile was terpolymerized with styrene and 2,4,6‐tribromophenyl acrylate in aqueous emulsion and dimethylformamide solution. Experimental terpolymerization data agreed well with calculations based on the Alfrey–Goldfinger equation. Triangular coordinate graphs show the feed/terpolymer relationships; the lines of unique and binary azeotropic compositions were identified. No points of true azeotropic composition were found but a “pseudo‐azeotropic” region was recognized. The experimental data of the emulsion terpolymerization experiment agreed well with the theoretical curves over a wide range of monomer compositions up to high conversions. Incorporation of 2,4,6‐tribromophenyl acrylate in the terpolymer decreased the thermal stability but improved the flame retardancy of the terpolymers.
Characterization of polyacetylene/low density polyethylene composites prepared by in‐situ polymerization
Authors: Galvin Mary E. , Wnek Gary E. 
Published: April 2003

AbstractThe results of thermal, mechanical, and conductivity studies of polymer composites prepared by polymerization of acetylene in low‐density polyethylene (LDPE) films impregnated with a Ziegler–Natta catalyst are presented and discussed. The enthalpy of melting of the LDPE component decreases as the amount of polyacetylene (CH)x grown in the matrix increases and is rationalized as being due to entanglement effects, although grafting cannot be unequivocally ruled out. Composites prepared well below the melting point of the LDPE matrix possess enhanced tensile moduli and tensile strengths at break, compared with pristine LDPE; this suggests reinforcement of the LDPE amorphous regions by the (CH)x chains. Measurements of electrical conductivity as a function of (CH)x content for a series of iodine‐doped composites reveal an apparent percolation threshold at ca. 3 wt % (CH)x.
Synthesis of poly(vinyl alcohol)‐based poly(crown ether)s and permeability of their polymeric membranes
Authors: Kimura Keiichi , Yoshinaga Masanobu , Kitazawa Sadaya , Shono Toshiyuki 
Published: April 2003

AbstractPolymers that contain crown ether moieties at the side chain and are capable of forming rather tough film were synthesized by the polymer reaction of poly(vinyl alcohol) with formyl derivatives of aliphatic crown ethers such as 12‐crown‐4, 15‐crown‐5, and 18‐crown‐6. In the passive transport of alkali metal picrates across the poly(crown ether) membranes the permeation, particularly of alkali metals which tend to form intramolecular sandwich‐type complexes with the crown ether rings, was retarded, compared with a poly(vinyl alcohol) membrane. The cation selectivities in the permeation of poly(crown ether) membranes differed significantly from those of poly(vinyl alcohol).
Glow discharge polymerization of tetramethylgermanium
Authors: Inagaki N. , Mitsuuchi M. 
Published: April 2003

AbstractA glow discharge polymerization technique was applied in the preparation of germanium‐containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by the rupture of bonds between Ge and CH3 groups which led to mixtures of polymers that consisted of CH3, CH2, GeCH3, GeOC, and GeOGe groups and germanium metal. Most Ge species present at the outermost layers of the films were oxidized subsequently by air, whereas the Ge species at the inner layers still existed as Ge metal. This film‐forming process can be explained by the concept of atomic polymerization proposed by Yasuda.See H. Yasuda, J. Polym. Sci. Macromol. Rev., 16, 199 (1981).
Preparation of monodisperse reactive styrene‐glycidyl methacrylate latexes by the emulsifier‐free dispersion copolymerization technique
Authors: Z̆ůrková E. , Bouchal K. , Zden̆ková D. , Pelzbauer Z. , S̆vec F. , Kálal J. , Batz H. G. 
Published: April 2003

AbstractLatexes based on styrene‐glycidyl methacrylate copolymers were prepared by the emulsifier‐free dispersion copolymerization technique. The main factors affecting the size and morphology of the latex particles and their distribution are the initiator concentration (K2S2O8), the total ionic strength of the aqueous phase, and the total monomer concentration. The existence of critical values for these variables was demonstrated. In the range in which these factors had values below the critical, the synthesized latex particles were spherical, homogeneous, and in varied sizes, depending on the abovementioned parameters in the range of 220–500 nm. Above the critical values of these variables the latex particles consisted of spherical aggregates of smaller particles. The reactive oxirane groups of the latex particles were modified later by hydrolysis, ammonolysis, reaction with Na2S, or periodic acid oxidation of the hydrolyzed or ammonolyzed forms of the latex particles.
Linear polythioesters. VI. Products of interfacial polycondensation of bis/4‐mercaptophenyl/ether with some aliphatic acid dichlorides
Authors: Podkościelny Wawrzyniec , Wdowicka Danuta 
Published: April 2003

AbstractNew polythioesters by interfacial polycondensation of bis/4‐mercaptophenyl/ether with oxalyl, succinyl, adipoyl, suberoyl, or sebacoyl chlorides were obtained. To define the optimal conditions of the process, the polythioesters of dithiol and adipoyl or sebacoyl chlorides were chosen as a model system. Yield for all reaction products and reduced viscosity were found. The following factors were studied: organic phase, contribution of catalyst, concentration and molar ratio of reagents, rate of addition of acid chloride, temperature of reaction, contribution of emulsifier, and concentration of hydrochloride acceptor. The structure of all polythioesters was determined by elementary analysis, infrared spectra, and x‐ray. Initial decomposition and initial intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Some mechanical and electrical properties of polythioesters from dithiol and adipoyl or sebacoyl chlorides were studied. The molecular weights for these polymers were also determined by gel‐chromatography.
Synthesis, characterization, and Diels–Alder extension of cyclopentadiene telechelic polyisobutylene. III. Silylcyclopentadiene‐telechelic polyisobutylene
Authors: Kennedy J. P. , Carlson G. M. 
Published: April 2003

AbstractTelechelic polyisobutylenes with silylcyclopentadiene termini (CpSi‐PIB‐SiCp) were prepared, starting with α,ω‐di(t‐chloro)polyisobutylene and followed by dehydrochlorination, hydrosilylation, and cyclopentadienylation. The prepolymer was characterized and found to have a terminal functionality close to 2.0. Thermal chain extension by Diels–Alder addition of the end groups did not occur, most likely because of fluxional isomerization of the silylcyclopentadiene end groups, confirmed by model studies. Chain coupling of CpSi‐PIB‐SiCp prepolymers with stoichiometric amounts of bismaleimide gave rise to degrees of extension of more than 11.
Structure and sorption properties of the polyion complex between poly(acrylic acid) and poly(4‐vinylpyridine)
Authors: Oyama Hideko Tamaru , Nakajima Toshinari 
Published: April 2003

AbstractA polyion complex was formed from poly(acrylic acid) (PAA) and poly(4‐vinylpyridine) (PVP). Its structure and composition were examined by means of infrared spectroscopy (IR), x‐ray photoelectron spectroscopy (XPS), and elemental analysis. The polyion complex was obtained by dissolving PAA and PVP together in methanol. The composition of the polyion complex was independent of stirring speed, mixing sequence, and standing time after mixing. However, the composition depended on the concentrations and the ratio of the components in the reaction mixture. Excess of PAA in the product was observed when concentrated solutions (2.0 × 10−1M) were used for the preparation or when an excess of PAA was added to PVP. The sorption of water vapor by an equimolar PAA/PVP complex at 293 and 303 K was higher than that by the pure components, especially in the low‐ and middle‐pressure regions. In the high‐pressure region, however, the uptake was not affected by the complex formation. While hydrogen bond interactions in general decrease sorption, Coulombic interactions between polymer chains increased the sorption capacity.