bluuebunny/crossref_metadata_2025 huggingface dataset:
Molten bisphenol‐A polycarbonate—poly(ethylene terephthalate) blends. II. Kinetics of the exchange reaction.
Authors: Godard P. , Dekoninck J. M. , Devlesaver V. , Devaux J.
Published: April 2003

The kinetic aspects of the bisphenol‐A polycarbonate‐polyethylene terephthalate exchange reaction are studied. Though the overall mechanism of transesterification is reversible, the kinetics can be treated from a more simple model of two consecutive reactions, due to the decomposition of the alkyl carbonate formed. The values of the kinetic parameters, similar to those obtained for the bisphenol‐A polycarbonate‐polybutylene terephthalate transesterification, suggest that the most likely mechanism is a direct ester–ester interchange reaction which can also be catalyzed by additives such as titanium derivatives.
Molecular orbital analysis of the XPS spectra of PMDA‐ODA polymide and its polyamic acid precursor
Authors: Silverman B. D. , Bartha J. W. , Clabes J. G. , Ho P. S. , Rossi A. R.
Published: April 2003

The calculated carbon 1s (C1s) core energy‐level positions of PMDA‐ODA polymide and of its polyamic acid precursor are compared with the level positions inferred from XPS measurements. For the polyamic acid, calculation and experiment both yield a difference of approximately 1 eV between the carboxylic acid and the amide carbonyl C1s level positions. The difference in shape between the main C1s XPS peaks of the polyamic acid and polyimide is shown to be related to the difference in C1s core energy‐level shifts of the carbon atoms composing the benzene ring adjacent to the amide or imide group. The planar imide or PMDA structure apparently yields larger core level shifts for these atoms. We have previously designated these atoms as “imide carbon atoms” (C‐Im) to distinguish them from the aromatic carbon atoms (C‐C) of the ODA part of the polymeric repeat unit. Comparison of the carbonyl XPS band intensities with the main peak intensities for the polyamic acid, as well as for the polyimide, suggests that there is a carbonyl deficiency at the surface of both of these materials.
Synthesis and characterization of adenine base grafted polyacrylamides as polynucleotide analogs
Authors: Overberger C. G. , Ferng W.
Published: April 2003

The adenine base grafted polyacrylamides and their corresponding monomer model compounds were prepared and examined. The results suggest that the monomer model compounds exist in a preferred conformation, whereas the adenine base grafted polyacrylamides exist in a limited ordered conformation in an aqueous medium.
Synthesis and characterization of poly(2‐amino‐2‐methylpropyl)acrylamide, poly(2‐amino‐2‐methylbutyl)acrylamide, and copolymers of polyacrylamide
Authors: Overberger C. G. , Ferng W. , Chi Minn‐Shong
Published: April 2003

Polyacrylamides possessing an amino group at the terminus of the branch chain as the potential site for amino acid and/or nucleic acid base grafting have been prepared. This type of polyacrylamide would provide a substantial spacing distance between the polymer main chain and pendant groups. Poly(2‐amino‐2‐methylpropyl)acrylamide (PDMPA) and optically active poly(2‐amino‐2‐methylbutyl)acrylamide (PDMBA) were characterized using vapor phase osmometry (VPO), gel permeation chromatography (GPC), and dilute solution viscometry. In addition, copolymers of poly(2‐amino‐2‐methylpropyl)acrylamide with N‐vinylpyrrolidinone, N‐vinylimidazole, and H(5)‐vinylimidazole, were prepared.
Polymerization of styrene oxide by nitronium tetrafluoroborate
Authors: Velichkova Rumyana St. , Tsevi Rayna Al.
Published: April 2003

The polymerization of styrene oxide by nitronium tetrafluoroborate in nitromethane and methylene chloride at 5, 20, and 50°C is investigated. GPC analyses of the products combined with isocyanate method show that both cyclic and linear oligomers are formed. In CH3NO2 the cyclic dimer and trimer are 2‐benzyl‐4‐phenyl‐1,3‐dioxolane and 1,3,5‐tribenzyl‐trioxane, respectively. In CH2Cl2 2,5‐diphenyldioxane is isolated. In nitromethane, mainly isomerized structures with acetal linkage are produced, while in methylene chloride isomerization does not proceed. By NMR and IR spectra the presence of CO and OH end groups in the linear oligomers is shown. There are indications that oligomers are formed both directly from the monomer and by degradation of the polymer.
Low surface energy polymers and surface active block polymers. I. t‐butylphenyl containing polymers
Authors: Litt Morton , Chen Tien‐Teh , Hsieh Bing R.
Published: April 2003

Two new monomers in the 2‐oxazoline series were synthesized and polymerized. These were 2‐[4‐(t‐butyl)phenyl]‐2‐oxazoline (I) and 2‐[(3‐(3,5‐di‐t‐butyl)phenoxy)propyl]‐2‐oxazoline (II). The polymer from I crystallized readily during bulk polymerization and showed Tm at 592 K (319°C). After annealing, the polymer showed a critical surface tension of 23.2 dyn/cm. Polymer from II was amorphous; hence, annealing showed little effect on contact angles. Block polymers were made with I (Xn = 10) and ethyl oxazoline (Xn = 6,20,60). Very sharp molecular weight distributions were obtained. All samples crystallized when annealed. The block polymer was an effective emulsifier for emulsion polymerization of butyl acrylate at 0.1%.
Peculiar temperature dependence of the binding of methyl orange and its homologs by 2‐diethylaminoethyl methacrylate‐N‐vinyl‐2‐pyrrolidone copolymers
Authors: Takagishi Toru , Hosokawa Toshitsugu , Okada Minoru , Kozuka Hiroshi
Published: April 2003

2‐Diethylaminoethyl methacrylate (DEAEMA)–N‐vinyl‐2‐pyrrolidone (VPy) copolymers of various compositions have been synthesized. The resultant copolymers were examined for their ability to bind methyl orange and its homologs, in particular butyl orange, at 5, 15, 25, and 35°C in aqueous solutions. The amount of binding of butyl orange is much higher with the copolymers than with polyvinylpyrrolidone or with 2‐hydroxyethyl methacrylate–N‐vinyl‐2‐pyrrolidone copolymers. Introduction of only 3% of the hydrophobic DEAEMA residue increases markedly the binding affinity toward the cosolute. Maximal binding is obtained at 15°C in the temperature range measured. This peculiar temperature dependence of the extent of binding is explicable on the basis of hydrophobic effects involved in this binding. The peculiar temperature dependence disappeared in aqueous solution of NaSCN which acts as a water‐structure breaker: the extent of binding changes regularly with temperature. This is interpretable only in terms of reduction of hydrophobic contribution to the binding. With propyl orange, which is a less hydrophobic cosolute than butyl orange, the peculiarity of the binding was not detected.
Kinetics of successive seeding of monodisperse polystyrene latexes. I. Initiation via potassium persulfate
Authors: Sudol E. D. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

The polymerization kinetics of monodisperse polystyrene latexes prepared via successive seeding were studied in the region between Smith‐Ewart Case 2 (n̄ = 1/2) and Case 3 (n̄ ≫ 1). Potassium persulfate was used as the initiator. The kinetics were measured in a piston/cylinder dilatometer designed for microgravity experiments. A recipe formulation method was developed by which a constant emulsifier (Aerosol‐MA) surface coverage was maintained throughout a sequence, beginning with a 0.19 μm polystyrene seed. Monodisperse latexes up to 1 μm in size were prepared using 0.5 mM K2S2O8 with a 4% emulsifier surface coverage. The polymerizations were commenced in Interval III, the particles being swollen with twice their weight in monomer. The kinetics were characterized by the autoacceleration of the gel effect with the overall polymerization rate decreasing with increasing particle size (decreasing Np). The Case 2 to Case 3 kinetic transition was experienced in the first seeding step, however, independence of the rate on the number of particles was not evident even at high values of n̄ (n̄ > 10). This was attributed to a dependency of the free radical capture efficiency on the particle size (constant solids). Corroborating indirect evidence was supplied through surface charge analysis and detailed examination of the polymerization kinetics.
Complex forming properties of crosslinked poly (ethylene oxide). I. Interaction of linear and crosslinked poly(ethylene oxide) with molybdenum(vi) salts
Authors: Vassilev K. G. , Dimov D. K. , Stamenova R. T. , Boeva R. S. , Tsvetanov Ch. B.
Published: April 2003

Evidence was found of donor–acceptor complexation of molybdenum(VI) compounds by linear and crosslinked PEO. The interaction was studied by optical and NMR spectroscopy and conductivity measurements in organic medium. PEO networks were capable of binding molybdenum salts even in aqueous solution. The character of the interaction is considered to be essentially different from complex formation with alkali metal salts. This is manifested in the relatively low values of the stability constants of complexes with linear PEO. A remarkable effect of crosslinking on the binding capacity of PEO is registered resulting in an increase of complexation constants in chloroform by two orders of magnitude.
Polymerization of acenaphthylene by transition metal catalysts
Authors: Cho Hyun‐Nam , Choi Sam‐Kwon
Published: April 2003

The polymerization of acenaphthylene (ACN) was examined in the presence of the group V and VI transition metal salts such as WCl6, MoCl5, TaCl5, and NbCl5, as catalysts under various reaction conditions. These transition metal salts were found to be effective catalysts for the polymerization of ACN. The polymerization of ACN by WCl6 in chlorobenzene proceeded at a high initial rate when the monomer to catalyst mole ratio was 200. In addition, it was observed that aromatic solvents generally were found to be superior to aliphatic solvents for both conversion and molecular weight. The structure of the resulting polymers was characterized by means of NMR, IR, UV, and x‐ray diffraction. Emission properties were also investigated. Fluorescence emission spectra of the polymers obtained by WCl6 as a catalyst varied strongly depending on the polymerization solvent. Thus, it appears that the polyacenaphthylene produced by WCl6 was a different configuration dependent on the polymerization solvents used.
Preparation of plastic optical fibers for near‐IR region transmission
Authors: Kaino Toshikuni
Published: April 2003

Loss factors of PMMA and PS core plastic optical fibers (POFs) were analyzed, and it was revealed that the vibrational absorption owing to CH vibration plays the most significant role in reducing the near‐IR region attenuation loss. Conversion of the hydrogen of the CH bond in the core polymer to deuterium gives rise to a large reduction of the attenuation loss not only in the visible wavelength region but also in the near‐IR region.

The deuteration of styrene is not so effective as that of methyl methacrylate because of PS core POFs higher loss owing to imperfections in the wave guide structure and Rayleigh scattering. Using a perdeuterated PMMA as a POF core, a loss of 20 dB/km was attained in the 650–680 nm wavelength region. The loss limits of these deuterated polymer core POFs were also estimated.
Reverse osmosis and fine structure of decrystallized acrylic acid grafted nylon 6 membranes
Authors: Takigami Shoji , Kobayashi Fumihiko , Nakamura Yoshio
Published: April 2003

Nylon 6 film and acrylic acid grafted nylon 6 (GN) membrances were reacted with paraformaldehyde and lactic acid in the presence of acid catalysts. Decrystallized nylon 6 (DN) and decrystallized grafted nylon 6 (DGN) membranes were thus obtained. The cross sections of GN and DGN membranes were observed by a transmission electron microscope. Branch poly(acrylic acid) penetrated toward the center of the membrane and deposited homogeneously within the membrane as the extent of grafting exceeded about 100%. The reverse osmosis of DN and DGN membranes was investigated. The water permeability through the membranes was improved by the decrystallization reaction. DGN membranes with more than 100% grafting show high values of the salt rejection (Rs) as compared with DN and DGN membranes with about 50% grafting, especially at the region of the high hydraulic permeability coefficient of water (K). The relationships among Rs, K, and the volume fraction of water (H) are discussed by considering the results of the decrystallization reaction and electron microscopy.
Structure–property relationships of ionene polymers
Authors: Klun Thomas P. , Wendling Larry A. , Van Bogart John W. C. , Robbins Aida F.
Published: April 2003

The synthesis of new ionenes was accomplished by the reaction of novel diamines and dihalides. A new class of crosslinkable ionenes was made possible by the synthesis of tertiary diamines with acrylate functionality, generated ultimately from diepoxides and secondary amines. Other tertiary diamines were produced by endcapping of diols with tolylene diisocyanate, followed by reaction with N,N‐dimethylethanolamine and also termination of living poly(tetrahydrofuran) polymer with dimethylamine. New dihalides were produced by the opening of diepoxides with ω‐bromoacids.

These diamines and dihalides underwent Menschutkin reactions providing novel ionenes for structure–property relationship studies. Correlations were drawn concerning amine nucleophilicity, dihalide nucleofugascity, and molecular weight. Stress–strain and thermal data reflected the effects of ionic domains and large flexible segments in the polymers. Also considered were the electrical conductivity, moisture–vapor transmission, and oxygen permeability of these materials.
Temperature dependence of ESR spectra of methyl methacrylate radicals from 77 K to 300 K
Authors: Chen C. R. , Knight Randall L. , Pollock Lori
Published: April 2003

The radicals formed in poly(methyl methacrylate) (PMMA) under vacuum by UV irradiation at room temperature were carefully examined from 77 K to 300 K by electron spin resonance (ESR). The conventional nine‐line spectrum was observed with significant overall intensity changes in contrast to previous reports. The intensity decreases greatly as the temperature increases from 77 K to 100 K. The intensity of the ESR spectrum increases as the temperature increases gradually from 100 K to 260 K. The spectral changes were reversible at all temperatures. Three different models are considered to interpret the temperature dependence of the intensity of the ESR spectrum. The results indicate that the ESR spectrum depends on (1) the steady‐state concentration of the propagating radical in the polymer, (2) the conformational distributions of the radicals, and (3) the environmental structures of the polymer matrix.
Studies in the formation of poly(oxazolidones) I. Kinetics and mechanism of the model oxazolidone formation from phenyl isocyanate and phenylglycidyl ether. Selectivity of catalysts
Authors: Sendijarević Aiša , Sendijarević Vahid , Frisch Kurt C.
Published: April 2003

The reaction of phenyl isocyanate with phenylglycidyl ether in the presence of various catalysts served as a model reaction for the preparation of poly(oxazolidones). The type of catalyst used determines the mechanism of the oxazolidone synthesis. In addition to the basic product, oxazolidone, side products may be formed, the most frequent of which is the formation of isocyanurates, which depends upon the temperature and the type of catalyst. The most effective epoxide‐soluble catalysts evaluated so far in the preparation of oxazolidones were the complex catalyst AlCl3‐triphenylphosphine oxide and AlCl3‐hexamethylphosphoric triamide. The kinetic study of the oxazolidone formation was carried out by means of HPLC, and the isocyanate and epoxide were separately determined by means of the di‐n‐butylamine and the perchloric acid methods, respectively. The HPLC method also clearly demonstrated the presence of two isomers, 3‐phenyl‐5‐phenoxymethyloxazolidone‐2 and 3‐phenyl‐4‐phenoxymethyloxazolidone‐2. The distribution of these isomers, previously reported in the literature, was found to depend upon the temperature and the type of catalyst used.
Fractionation of partly hydrolyzed polyvinyl acetate
Authors: Lerner F. , Alon M.
Published: April 2003

Vinyl acetate–vinyl alcohol copolymers were fractionated in order to obtain their degree of hydrolysis distributions. In the method employed for fractionation, the differences in molecular weight of copolymer did not affect the fractional separation. Degree of hydrolysis distributions was found to be broad, with a pronounced maximum at a low degree of hydrolysis. Viscosity measurements were performed both for the precipitated fractions and unfractionated polymer. The Huggins constant was found to increase with a decrease in the degree of hydrolysis of polyvinyl acetate. These results were interpreted in terms of a polymer molecular association. From values of Huggins constants, comparative information about copolymer “blockiness” is also established.
Synthesis and microstructure of polymers from o‐methacryloyloxybenzoic acid
Authors: San Román J. , Madruga E. L. , Pargada L.
Published: April 2003

The free radical polymerization of o‐methacryloyloxybenzoic acid using acetone and benzene as solvents, in the interval 30–120°C, is investigated. The polymerization in benzene has a precipitant character. However, when acetone is used as solvent, at reaction temperatures higher than 60–70°C, the polymerization deviates from the classic free radical mechanism and, beside the addition of monomer molecules to growing chain ends, the release of salicylic acid and the formation of cyclic anhydride structures of glutaric type in the main chain has been detected. The microstructure of polymers obtained has also been studied by the transformation into the corresponding poly(methyl methacrylate)s.
Spectroscopic studies of photochemical reactions in organic solids: Photopolymerization of 1,4 bis[β‐pyridyl(2)vinyl] benzene
Authors: Ghosh Urmi , Chattopadhyaya S. , Misra T. N.
Published: April 2003

The laser Raman phonon spectroscopic technique has been used to study the photopolymerization reaction of 1,4 bis[β‐pyridyl(2)vinyl] benzene (P2VB). Raman and infrared spectroscopy have been used to study the intramolecular vibrations of the reactant and the product and to characterize them. Absence of any large Stokes' shift between absorption and emission bands of the monomer crystal shows that exciton–phonon coupling is weak, and the reaction is not likely to be phonon mediated. Phonon spectroscopy shows that the reaction proceeds by a heterogeneous mechanism. Sharp phonon bands of the product, however, suggests that the photopoly P2VB lattice is highly ordered.
Soapless emulsion polymerization of methyl methacrylate in water in the presence of barium sulfate
Authors: Konno Mikio , Shimizu Koichi , Arai Kunio , Saito Shozaburo
Published: April 2003

To investigate the kinetics of soapless emulsion polymerization in the presence of a solid phase, polymerization experiments were carried out for the methyl methacrylateK2S2O8H2O system using barium sulfate powder, which is assumed to be chemically inert. Reaction conditions were varied with respect to the ranges of initiator concentration, monomer concentration, agitation speed, and quantity of powder. Experimental results showed that the polymerization rate is greatly affected by the addition of powder. It is concluded that the physical circumstances of the polymerization are changed considerably with the addition of the powder. A conceptual model for the mechanism of the polymerization was proposed to explain the effects of the experimental variables.
Thermotropic polyesters with main chain isomeric naphthylene, trans‐1,4‐cyclohexylene, and 2,5‐pyridinediyl units: The importance of the order of ester linkages in the mesogenic units
Authors: Jin Jung‐Il , Choi E‐Joon , Ryu Seog‐Chul
Published: April 2003

Two new series of thermotropic polyesters were prepared and their mesomorphic properties were investigated. The polymers consist of triad aromatic ester‐type mesogenic units with decamethylene spacers. The mesogenic units of the first series are composed of isomeric dihydroxynaphthalene moieties as the central structure flanked by two p‐oxybenzoyl groups. In the second series the mesogenic units were of reversed ester linkages: the central moieties, derived from 1,4‐naphthalene dicarboxylic acid, trans‐1,4‐cyclohexanedicarboxylic acid, or 2,5‐pyridinedicarboxylic acid, are connected on both sides to p‐phenylene structures. Two low molecular weight model compounds with 1,4‐naphthylene unit at the center of the mesogenic unit were synthesized and their mesomorphic properties were compared with those of corresponding polymers. It was observed both for the model compounds and the polymers containing 1,4‐naphthylene units that the linking order of the ester group in the mesogenic unit exerted a decisive influence on the capability for the formation of a mesophase. Thermal and mesomorphic properties were investigated by DSC, on a polarizing microscope equipped with a hot‐stage, and by visual observation of stir‐opalescence of the melts.
Polyelectrolyte effects on the quenching of pyrene fluorescence in solutions of a pyrene substituted poly(acrylic acid)
Authors: Arora Kartar S. , Turro N. J.
Published: April 2003

The quenching of pyrene fluorescence by nitromethane, Tl+, Cu2+, I−, and 4‐dimethylaminopyridine (DMAP) in aqueous solutions of a pyrene substituted poly(acrylic acid) (1) was influenced by the “polyelectrolyte effect” of 1. The efficiency of quenching in solutions of 1 was measured in terms of the Stern–Volmer constants for dynamic and static quenching which were obtained from comparison of the intensity and lifetime of pyrene fluorescence in solutions of 1 and a monomer model compound. The efficiency of quenching in solutions of 1 was always greater at high pH (9) in comparison to that at low pH (4). The ionization of carboxylic groups in 1 caused an expansion of the polymer mainchain and concomitant exposure of the pyrene molecules to the aqueous phase and quencher. The polyanion domain of 1 favored the condensation of cationic quenchers and could account for very efficient quenching in case of Cu2+ and Tl+. A very efficient quenching of pyrene fluorescence in solutions of 1 by DMAP at high pH was attributed to the hydrophobic interactions of DMAP and pyrene moiety. The iodide ions were less efficient quenchers of pyrene fluorescence due to electrostatic repulsion from the polyanion. The efficiency of quenching by nitromethane was not significantly affected by ionization of the carboxylic groups in 1.
Electronic properties of the linear ladder polymer, poly[4‐(3‐pyridyl),8‐methyl,2,3–6,7‐quinolino] (PPMQ)
Authors: Ruan J. Z. , Litt M. H.
Published: April 2003

Electronic paramagnetic resonance (EPR) and conductivity of pristine and iodine‐doped PPMQ were studied. The pristine polymer EPR signal exhibited a Lorentzian line shape. Unpaired spin density measurements indicated that the spin concentrations of the undoped polymer lie in the range of one spin per 150–190 repeat units at room temperature. The peak‐to‐peak width doubled, the line shape became asymmetric and the spin concentration in the polymer increased slightly after doping with iodine. EPR saturation experiments show that the spin lattice relaxation time T1 is sensitive to trace impurity. Considerable reduction of T1 after doping with iodine shows strong coupling between the spin system and N‐iodonium nucleus. Conductivity increases up to 5 orders of magnitude by iodine doping; at room temperature, the best value found was 0.017 S/cm. The activation energy for conductance after doping is about half that of pristine polymer.
Alternating copolymerization of β‐methylstyrene and maleic anhydride
Authors: Vuković R. , Kurešević V. , Fleš D.
Published: April 2003

Alternating copolymers of β‐methylstyrene and maleic anhydride were prepared by free‐radical‐initiated polymerization in bulk and in toluene as a solvent. The reactivity ratios k1c/k12 and k2c/k21 were calculated from the change of copolymerization rate with a monomer feed at a constant total monomer concentration according to the generalized model of Shirota and coworkers. From the equation Rp = Rp(f) + Rp(CT) were calculated Rp(f) and Rp(CT), and it was found that in toluene the copolymerization proceeds predominantly by the addition of CT‐complex monomers. Termination occurs predominantly by homotermination of β‐methyl‐styrene macro free radicals, kt22, but the cross termination kt21 is also operative.
High resolution 13C‐NMR spectroscopy of sodium carboxy methyl cellulose
Authors: Chaudhari S. N. K. , Gounden K. C. , Srinivasan G. , Ekkundi Vadiraj S.
Published: April 2003

Results of NMR studies on intact sodium carboxy methyl cellulose (SCMC) are presented. Similar studies in the literature are all on partially depolymerized SCMC. The degree of substitution and the relative distribution of substituents at OH‐2, OH‐3, and OH‐6 of anhydro D‐glucose residue in intact SCMC were determined by high resolution 13C‐NMR spectroscopy (125 MHz). It is observed that the degree of substitution at OH‐6 is almost equal to that at OH‐3. In two SCMC samples, which are widely different in molecular weight and degree of substitution (ds), the relative reactivity order of the hydroxyl groups was found to be OH‐2 > OH‐6 ≃ OH‐3. The NMR assignments were based on calculated shifts of carbons of anhydroglucose moiety in an oligosaccharide due to substitution.
Grafting of optically active nucleic acid base derivatives onto poly(vinylamine) as polynucleotide analogs
Authors: Overberger C. G. , Chen C. C.
Published: April 2003

Polynucleotide analogs consisting of poly(vinylamine) as the backbone and optically active thymine and adenine derivatives as the pendants were synthesized. The pendants were prepared by the addition reaction of the nucleic acid base to ethyl crotonate followed by hydrolysis. The pendants were resolved using brucine as the resolving agent and an acetone‐water mixture as the fractional crystallization solvent. The active esters of the pendants also were prepared. Poly(vinylamine) was isolated from water employing a weak acid, N‐hydroxysuccinimide (HOSu), to protect the amino group of the poly(vinylamine). Model reactions for grafting were examined. Grafting reactions were carried out by reacting the active esters with the PVAm.6HOSu complex at room temperature.
On the photoreactivity of diacetylene containing thermoplastic block copolymers
Authors: Liang Rong‐Chang , Reiser Arnost
Published: April 2003

A group of block copolymers containing diacetylenes as chain extenders in their hard segments was prepared, based on urethanes, esters, ureas, and amides as hard segments and polybutadienes, polyethers, polyesters, and polysiloxanes as soft segments. Almost all block copolymers were photoreactive, but there was a wide range of sensitivities. The photoreactivity of the copolymers was found to depend on the reactivity of the monomer unit, on the width of the diacetylene stacks in the hard segments, and on the degree of phase separation in the solid films.

To explore the range of monomer reactivities we prepared 15 crystalline monomers. Urethanes were in general the most reactive, and this was attributed in part to the specific effect of hydrogen bonding which brings about a shortening of the C1 to C4 distance between diacetylenes tend to reduce the photoreactivity.

The behavior of identical diacetylene units in the monomer crystal, in the homopolymer, and in the block copolymer is discussed in this paper.
Conformational properties of isotactic poly(2‐hyroxyethyl methacrylate) in the mixed water‐alcohol solvents
Authors: Kim Whan Gun , Jeon Sang Il , Jhon Mu Shik
Published: April 2003

Conformational properties of isotactic poly(2‐hydroxyethyl methacrylate) (PHEMA) have been studied in mixtures of water and several aliphatic alcohols by viscometry and fluorometry. The highest fluorescence intensity of auramine has been detected in aqueous isotactic PHEMA solution compared with several aliphatic alcohol systems. Upon aliphatic alcohol addition, there was the decrease of fluorescence intensity of auramine. As the number of aliphatic group of alcohol increases, the decrease of fluorescence intensity of auramine has been pronounced. And the sharp increases of the reduced viscosity of isotactic PHEMA in water‐alcohol solvents were observed in the lower region of alcohol volume percentage with the increasing number of aliphatic group of alcohol. Nevertheless, the sharp increase of the reduced viscosity of isotactic PHEMA in ethyleneglycol‐water solvent was obtained even at a low‐volume percentage region of ethyleneglycol at which compact structures exist. Therefore, we consider that the increase of viscosity at this region is due to the hydrophilic side group of polymer‐solvent interaction, forming hydrogen bonds. The experimental results suggest that compact structures of isotactic PHEMA in aqueous solution are caused by hydrophobic interactions by methyl group of polymer backbone, and the hydrophobic interaction by adding alcohols. Finally, our study brings the fact that the solvating sites of alcohols on the isotactic PHEMA molecule are strongly influenced by the number of hydroxyl and aliphatic group in alcohols.
Thermal decomposition processes in aliphatic polysulfides investigated by mass spectrometry
Authors: Montaudo G. , Scamporrino E. , Puglisi C. , Vitalini D.
Published: April 2003

The thermal degradation of four aliphatic polysulfides (polythiomethylene, polythiotrimethylene, polythioethylene, and polythiohexamethylene) was investigated by direct pyrolysis in the ion soruce of a mass spectrometer (DPMS) operating both in electron impact (E.I.) and chemical ionization (C. I.) modes. Flash‐pyrolysis GCMS was also used in the case of polythiomethylene(polysulfide I) to confirm the DPMS results. The overall evidence indicates that the primary thermal decomposition of these polymers yields cyclic sulfides by an intramolecular exchange process. A β‐CH hydrogen transfer reaction, occurring in parallel with the former process, produces primary pyrolysis compounds with SH end‐groups.
Kinetics of polyesterification III: Solid‐state polymerization of polyethylene terephthalate
Authors: Chen Show‐An , Chen Fu‐Lung
Published: April 2003

Experimental studies on the solid‐state polymerization (SSP) of polyethylene terephthalate (PET) for the particle sizes of 14–16 mesh at 170–200°C and for the particle sizes of 14–18 mesh at 210–240°C are carried out under a vacuum of about 60 mtorr. Analysis of the data of the concentrations of hydroxyl and carboxyl groups and the number average molecular weight during the SSP allows determinations of the rates of esterification and ester interchange separately. It is found that at the temperature 170–200°C and the particle size 80–100 mesh the SSP is end‐group diffusion limiting, and that at the temperature 210–240°C and the particle size 14–16 mesh the ester interchange is ethylene glycol diffusion limiting and the esterification is predominantely end‐group diffusion limiting due to higher diffusion rate of water. These phenomena are explored by an assistance of the proposed rate expressions for the end‐group diffusion limited reactions and diffusion models for the by‐products, water, and ethylene glycol.
Liquid crystal polymers. VIII. Liquid crystalline polyesters of trans‐4,4′‐stilbenedicarboxylic acid and 1,3‐propanediol
Authors: Jackson W. J. , Morris J. C.
Published: April 2003

In our recent overview of liquid crystalline polyesters of trans‐4,4′‐stilbenedicarboxylic acid (SDA) and aliphatic glycols,1 we reported that “… the 1,3‐propanediol polyester did not exhibit thermotropic liquid crystallinity (no stir opalescence or DSC endotherm above Tm), perhaps because of the relatively high Tm (303°C) for a polymer of a glycol having an odd number of carbon atoms.” We now have studied the melting characteristics of another sample of this polymer more carefully and have concluded that it does exhibit a liquid crystalline mesophase over a very narrow temperature range. In this Note we give the thermal properties of this polymer and the thermal and mechanical properties of an SDA/1,3‐propanediol copolyester which we also injection molded. These properties are compared and contrasted with those of the similar polyester and copolyester prepared with 1,4‐butanediol instead of 1,3‐propanediol.
Isotopic effects in H‐atom abstraction from matrix molecules by methyl radicals in poly(methyl methacrylate). Determination of the scale of relative reagent motions
Authors: Bagryansky V. A. , Tolkatchev V. A.
Published: April 2003

The H‐abstraction by ĊH3 and ĊD3 radicals from PMMA molecules is investigated at 77 and 120 K. The film samples are prepared from the mixture of normal and deuterated PMMA. The reaction is of the first order with respect to radical concentration. Its rate is retarded in time as compared to the exponential law. An analysis of the molecular product ratio for the reaction allows the primary isotopic effect to be estimated. The initial reaction rate depends nonmonotonously on the proportion of the deuterated polymer in the matrix. Namely, there exists a range of isotopic compositions, with the reaction rate increasing with the portion of a deuteropolymer in the mixture. At 77 K the reaction rate of ĊD3 is lower than that of ĊH3 in PMMA of a mixed isotopic composition. This results from the proximity of ĊD3 with unreactive parental macromolecules, which reduces the local H concentrations around ĊD3 as compared to the mean concentration. At 120 K the radical decay rates do not differ. This fact cannot be explained by unfrozen mobilities of radicals at high temperatures or by their migration from parental macromolecules. The phenomenon is interpreted in terms of thermal fluctuations involving a great area around a radical and ensuring its migration within this area. The electron spin echo method is used to estimate the distance between a radical and its parental macromolecule, a ≥ 9.6 Å. This is the lower limit of the reaction accessibility.
Graft copolymerization of methyl methacrylate onto wool initiated by ceric ammonium nitrate–thioglycolic acid redox couple in presence of air. IV
Authors: Shukla J. S. , Sharma G. K.
Published: April 2003

The graft copolymerization of methyl methacrylate (MMA) onto wool initiated by ceric ammonium nitrate (CAN)–thioglycolic acid (TGA) redox couple has been studied at 55 ± 0.2°C under atmospheric oxygen. Grafted copolymer was characterized by IR spectroscopy, scanning electron micrographs, and thermogravimetric analysis. Effect of amines, acid, alkali, oxidizing, and reducing agents were determined experimentally. The molecular weights of grafted poly(methyl methacrylate) and homopolymer was also evaluated.
Polymerization in nonuniform latex particles: Distribution of free radicals
Authors: Chern Chorng‐Shyan , Poehlein Gary W.
Published: April 2003

Previous kinetic studies in emulsion polymerization have almost always involved an assumption of uniform distribution of free radicals in the latex particle. Such an assumption is not likely to reflect reality in many systems that employ water‐soluble initiators because the hydrophilic end‐group of the oligomeric free radical will preferentially stay in the surface layer of the particle. This constrained end‐group location would result in nonuniform distribution of free radicals in the polymerizing latex particles. A Monte Carlo simulation of the growth of a single polymer chain within the latex particle supports this hypothesis. Such a nonuniform distribution of free radicals in the latex particle is expected to have an influence on reaction kinetics and product properties. The mechanism for transport of free radicals out of polymerizing latex particles is reexamined based on the proposed concept, and a modified expression for the desorption rate constant is presented.
Kinetic and ESR studies on the radical polymerization of Di‐n‐butyl itaconate in benzene
Authors: Sato Tsuneyuki , Inui Shukei , Tanaka Hitoshi , Ota Tadatoshi , Kamachi Mikiharu , Tanaka Kohji
Published: April 2003

The polymerization of di‐n‐butyl itaconate (DBI) intiated with AIBN was kinetically investigated in benezene. The polymerization rate (Rp) was expressed by: Rp = k[AIBN]0.5[DBI]1.7. The polymerization showed a considerably low overall activation energy of 15.3 kcal/mol. The initiator efficiency of AIBN in this system decreased with increasing DBI concentration, ranging from 0.34 to 0.55°C, which is ascribable to viscosity effect due to the monomer. From an ESR study, the polymerization system was found to involve two kinds of persistent radicals, namely, primary propagating (III) and propagating (I) radicals. The relative concentration of III to I increased with decreasing monomer concentration. Azo‐nitrile initiators such as AVN and ACN similarly produced two persistent radicals, while MAIB, DBPO, and PBO yielded only propagating radical I as persistent. The MAIB‐initiated polymerization of DBI was also performed in benzene. Similar kinetic features were observed, that is, a higher dependence of Rp on the DBI concentration and a low overall activation energy (14.4 kcal/mol). The following rate equation was obtained at 50°C:Rp = k[MAIB]0.5[DBI]1.6. The initiator efficiency of MAIB decreased with increasing DBI concentration, ranging from 0.32 to 0.53 at 50°C. The concentration of propagating radical I was determined by ESR at 50 and 61°C, from which kp and kt were estimated. The kp value increased with increasing monomer concentration, while the kt one decreased with the DBI concentration. These values are much lower compared with those of MMA.
Ethylene–propylene copolymerization initiated with solubilized Ziegler–Natta macromolecular complexes. I. Determination of kinetic parameters
Authors: Cansell François , Siove Alain , Fontanille Michel
Published: April 2003

Copolymerization of ethylene with propylene (E–P) was initiated with soluble polystyrene –butadiene–Li/TiCl4 complexes in toluene leading to vinylic‐olefinic based block copolymers. The activity of the system was measured at a constant ratio r = Li/Ti for different feed compositions. From measurements of the amount of copolymers produced, a direct determination of the efficiency of the catalytic system was made. This efficiency was found to be close to that obtained for homopolymerizations of C2H4 and C3H6 initiated with the same catalytic complex (≃ 80% with respect to the concentration of “carbon‐titanium” bonds).

Both the measured values of the efficiency and the determination of the molar masses of the polyolefinic block are consistent with a living character of the system involved in the E–P copolymerization. In such conditions well‐defined linear [styrene]‐b‐[ethylene‐co‐propylene] copolymers were obtained. Furthermore, 13C NMR analyses allowed determination of the comonomer reactivity ratios, the values of which indicate an E–P random copolymerization.

From both these values and those of the absolute rate constants of propagation determined for the homopolymerization of C2H4 and C3H6 initiated with the same catalytic system, the absolute rate constants of cross‐propagation were deduced.
Photopolymerization initiated by charge–transfer complex. X. Photopolymerization of methyl methacrylate with the use of isoquinoline–sulphur dioxide charge–transfer complex
Authors: Lenka Subasini , Nayak Padma L. , Nayak Sanjay K.
Published: April 2003

Aqueous polymerization of methyl methacrylate in visible light was studied using isoquinoline–sulphur dioxide (IQ–SO2) charge–transfer complex as the photoinitiator. Analysis of kinetic and other data indicate that the polymerization proceed via a radical mechanism and the termination is dependent on the initiator concentration. Chain–termination via degradative chain (initiator) transfer appears to be predominant here.
Alternating copolymerization of maleic anhydride with allyl chloroacetate
Authors: Mamedova S. G. , Rasulov N. Sh. , Rzaev Z. M.
Published: April 2003

Some regularities of radical alternating copolymerization of maleic anhydride with allyl chloroacetate are studied. The formation of donor–acceptor complexes between comonomers with complexing constant Kc = 0.052 L/mol is found using 1H NMR spectroscopy. The kinetic parameters for this copolymerization reaction are found and the quantitative contribution of monomer complexes to chain‐growth radical reactions is calculated. It is shown that either a “free‐monomer” mechanism (dilute solutions) or a “mixed” mechanism (concentrated solutions) prevails for chain growth during radical copolymerization depending on total monomer concentration. It is found that inhibition of degradative chain transfer in the course of the reaction studied takes place owing to the presence of α‐chlorine atom in the allyl chloracetate molecule and formation of charge transfer complex.
Polyelectrolytes containing dihyronicotiamide I. Electrostatic effect on the reduction in aqueous solution
Authors: Itoh Yoshihiro , Wakisaka Kazuyoshi , Matsuda Yutaka , Abe Koji , Senoh Saburo
Published: April 2003

Reduction of charged or uncharged substrates by a copolymer of N‐(p‐vinylbenzyl)‐1,4‐dihydronicotinamide and sodium styrene‐p‐sulfonate (PNAH) in aqueous solutions was investigated. Electrostatic interaction of PNAH with charged substrates led to a far more effective reduction of crystalviolet (CV) and a far less effective reduction of potassium ferricyanide (FeC) than the monomer model [N‐benzyl‐1,4‐dihydronicotinamide (BNAH)] system. In the PNAH‐CV system, in particular, a rapid reduction occurs by a first‐order process because of the remarkable concentration effect of the polymer. Furthermore, this reduction was not appreciably affected by an added salt, suggesting the presence of hydrophobic interaction between PNAH and CV.
Photopolymerization of cyclohexene oxide by use of o‐nitrobenzyl triphenylsilyl ether/aluminum compound catalyst. Dependence of catalyst activity on the structure of the silyl ether
Authors: Hayase Shuzi , Onishi Yasunobu , Suzuki Shuichi , Wada Moriyasu , Kurita Atushi
Published: April 2003

o‐Nitrobenzyl triphenylsilyl ehther/aluminum compound has been previously shown by the authors to act as catalyst in the photopolymerization of epoxides. The dependence of the structure of the silyl ether on the catalyst activity was examined. There were two steps in the photopolymerization. The first step (“Step 1”) is photodecomposition of the silyl ether to silanol. The second step (“Step 2”) is the initiation of polymerization by silanol and the aluminum compound. The introduction of an electron withdrawing group, Cl, CF3, on the benzene ring bonded to Si made the quantum yield of Step 1 low, however, the rate of Step 2 was increased. The low quantum yield of Step 1 was explained in terms of the rate of electron transfer that is controlled by the relative electron density between the CH2 and NO2 in the o‐nitrobenzyl group. The acceleration of Step 2 was explained in terms of an increase in silanol acidity that was promoted by the introduction of an electron withdrawing group. The overall rate of the photopolymerizatiol depends to a greater degree on the rate of Step 2 than on that of Step 1.
The dependence of cyclopolymerizability of acrylic and methacrylic anhydrides on various conditions: New interpretation of temperature dependency of cyclization constant in radical cyclopolymerization of nonconjugated dienes
Authors: Matsumoto Akira , Terada Tsunehiko , Oiwa Masayoshi
Published: April 2003

The cyclization constant Kc in the radical cyclopolymerization of acrylic and methacrylic anhydrides was evaluated in detail under various conditions. No linear relationship between in Kc and 1/T was observed; cyclization was acceleratively enhanced at elevated temperatures. The Kc values also increased with decreased monomer concentration and increased solvent polarity. These increasing dependencies of Kc are ascribed to the increased significance of depropagation, demonstrating a new interpretation of the temperature dependence of the cyclization constant in the radical cyclopolymerization of nonconjugated dienes.
Functional polymers and sequential copolymers by phase transfer catalysis. XXII. Vinylidene fluoride–trifluoroethylene copolymers by surface modification of polyvinylidene fluoride
Authors: Hahn Bruce , Percec Virgil
Published: April 2003

Polyvinylidene fluoride films and powders have been used to synthesize vinylidene fluoride‐trifluoroethylene copolymers. The synthetic procedure involves a phase transfer catalyzed heterogenous dehydrofluorination, followed by electrophilic chlorination or bromination. A phase transfer catalyzed displacement of bromine or chlorine by fluoride ion completes the synthesis. Dehydrofluorinations were up to 40% complete at room temperature and up to 100% complete at 90°C. Electrophilic chlorination of the resulting carbon–carbon double bonds were complete on both powder or films. The bromination of dehydrohalogenated polymers does not go to completion even when the reaction is carried out in solution. Displacement reactions were incomplete and resulted in further dehydrohalogenation when tetrabutylammonium hydrogen sulfate (TBAH) or 18‐crown‐6 and KF were used in organic solvents. Using TBAH, KHF2, and water, high degrees of displacement were achieved only on the brominated compounds. The chlorinated products gave both displacement and elimination.
Polymerization using palladium (II) salts. III. Polymerization of 4‐bromo‐4′‐ethynyl biphenyl
Authors: Trumbo D. L. , Marvel C. S.
Published: April 2003

The monomer 4‐bromo‐4′‐ethynyl biphenyl was synthesized and subsequently polymerized utilizing a bis (triphenylphosphine) palladium (II) chloride, copper (I) iodide, triphenylphosphine catalyst system in an organic amine solvent(s). The polymers produced were predominantly insoluble materials with reasonable thermal stability.
Synthesis of acetylene‐terminated polymers using supported palladium (II) catalysts
Authors: Trumbo D. L. , Marvel C. S.
Published: April 2003

A polymer‐bound palladium catalyst was synthesized from palladium diacetate and a single crystal polyethylene having 2,2′‐bipyridyl moieties as pendant groups. The resulting material was used in place of a free palladium catalyst in the synthesis of acetylene‐terminated resins. Supports other than polyethylen were also tested for their ability to bind palladium and their subsequent activity as catalysts in the synthesis of acetylene‐terminated polymers.
13C‐NMR study of chlorinated ethylene–vinyl acetate copolymers
Authors: Willman J. R. Schneider , Peat I. R.
Published: April 2003

13C‐NMR has been used to analyze the microstructures of a series of experimental chlorinated ethylene–vinyl acetate copolymers (15–56% CI). Previously established line assignments for EVA copolymers and substituent effect parameters for chlorine have enabled us to tentatively assign partial structures up to five carbon atoms in length. The 13C‐NMR analyses of a commercial vinyl chloride–vinyl acetate copolymer, a commercial vinyl chloride–vinyl acetate–ethylene terpolymer, and a commercial chlorinated polyethylene support the structural assignments. Data obtained for the experimental resins indicate that the acetate groups influence the way in which chlorine is added to the polymer chain. furthermore, the data indicate the acetate groups undergo little, if any, chlorination.
Secondary and tertiary oxonium ions in the polymerization of 1,3‐dioxolane initiated with HOSO2 CF3: 1H‐NMR studies
Authors: Kubisa Przemysław
Published: April 2003

In the polymerization of 1,3‐dioxolane (DXL) initiated with trifluoromethanesulfonic acid (TFAc) the proton originated from acid [underlined in the scheme (1)] may form either the hydroxy end‐group or the secondary oxonium ion:

equation image

where is a part of linear or cyclic macromolecule (or monomer). In 1H‐NMR spectra, due to the fast exchange, only one averaged signal of proton is observed, its chemical shift reflecting the relative concentration of both species. The chemical shift of proton, measured at different monomer and initiator concentrations changes, indicating that the proportion of macromolecules bearing OH end‐groups increases with increasing [monomer]o/[initiator]o ratio. This observation is fully consistent with a mechanism, according to which secondary oxonium ions are formed by inter‐or intramolecular reaction between growing species and OH end‐groups of linear macromolecules.