bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoinitiated radical chains in solid polymeric methacrylates
Authors: Egerton P. L. , Reiser A. , Shaw W. , Wagner H. M.
Published: April 2003

Polymeric methacrylates functionalized with free methacryloyl groups are efficiently crosslinked in the presence of transition‐metal carbonyls on UV irradiation of the polymeric solid. The reaction proceeds by a radical chain mechanism with a kinetic chain length of about 10 in a solvent‐free polymer containing 10−3 mole of methacryloyl groups per cm3. The chain length increases steeply when the glass transition of the polymer is reached, either by plastification or by an increase in temperature. The temperature dependence of the crosslinking yield below the glass transition is consistent with an activation energy of about 9 kcal mole−1. The addition of acrylic monomers enhances chain propagation by up to an order of magnitude. Postirradiative crosslinking in the matrix comes to a standstill well before all acrylic groups or radicals have been exhausted: if, after cessation of the primary reaction, the matrix is briefly heated, a second crop of crosslinks is obtained without further exposure. The system behaves thus as if the radicals had been removed into traps from which they can be set free by thermal activation. From an analysis of the reaction kinetics it appears that in the glassy polymer 90% of the radicals are inactivated in this way. Radical recombination, however, is the principal mechanism of chain termination above the glass transition. From the kinetic data, diffusion coefficients for polymer‐bound groups are found to be in the range of 10−17–10−16 cm2 sec−1 in the glassy polymer at room temperature. They are of the order of 10−14 cm2 sec−1 in plasticized films above the glass transition.
Trifunctional polycondensation: A cumulative distribution function
Authors: Stafford J. W.
Published: April 2003

A trifunctional polycondensation, cumulative‐weight‐fraction distribution function has been derived. The equation is exact and yields cumulative‐weight fractions that are the same as those calculated by summation of the differential distribution function. The cumulative distribution function still contains factorials, which renders computation difficult for high values of i. The cumulative distribution function is derived in a form that allows inferences to be drawn on whether mass is conserved past an extent of reaction of p = 0.5 or whether a material loss to what is considered a gel phase occurs. The inferences that can be drawn indicate that mass is conserved up to p = 1. The discrepancy between this finding and the requirements of the Flory gel–sol theory are discussed.
Kinetics of styrene polymerization at ultrahigh conversion
Authors: Kwant P. W.
Published: April 2003

The radical‐initiated bulk polymerization of styrene at low conversion can be adequately described by a simple kinetic scheme that involves initiation by the decomposition of a radical initiator, propagation, and termination by combination of polystyryl radicals. An integrated equation can be derived that will describe the relationship between monomer concentration and time. We have investigated the validity of applying equations of this kind in the 98–99.999% conversion range. From our experimental work we conclude that the initial rates at 130°C, when starting the polymerization at that temperature at more than 98% conversion, can be described by an integrated equation over at least two decades of monomer concentration. Deviations from the simple kinetics at ultrahigh conversion were observed after a certain time at 130°C. These are discussed and explained in terms of the kinetic assumptions made and an extended model is suggested to allow for depolymerization reactions that cannot be neglected at ultrahigh conversion.
Methods of acrolein polymerization and investigation of structures of the polymers obtained
Authors: Andreeva I. V. , Artemyeva V. N. , Nesterov V. V. , Kukarkina N. V.
Published: April 2003

Two methods for the polymerization of acrolein are proposed: suspension polymerization in water with the redox system K2S2O8:AgNO3 = 1:0.1 with respect to the monomer and a static method with the system K2S2O8:PA–SO2 adduct. The dependencies of yield, molecular weight, and structure of polyacrolein under investigation on the following factors: the amount and the ratio of the initiator components, the pH of the medium, and the monomer:solvent ratio were investigated. The structure of polyacrolein was studied by infrared spectroscopy, thermogravimetric analysis, and chemical functional analysis. The molecular weight distribution of samples of static and suspension polyacroleins modified under identical conditions was determined by gel permeation chromatography.
Stereoregularity of poly(α‐methylvinyl alkyl ether)s determined by 1H‐ and 13C‐NMR spectroscopy
Authors: Matsuzaki Kei , Okuzono Shuichi , Kanai Taiichi
Published: April 2003

α‐Methylvinyl methyl ether, ethyl ether, and isobutyl ether were polymerized under various polymerization conditions and the structure of the polymers was determined by 1H‐ and 13C‐NMR spectroscopy. α‐Methyl and β‐methylene carbon spectra of poly(α‐methylvinyl isobutyl ether) showed splitting and were analyzed by triad and tetrad sequences. β‐Methylene carbon spectra of poly(α‐methylvinyl ethyl ether) also showed splitting. When Eu(fod)3 was added, α‐methyl and methoxy proton spectra in benzene of poly(α‐methylvinyl methyl ether) showed splitting assigned to triad tacticities. All the polymers obtained in polar solvents exhibited an increase in syndiotacticity. The polymerization mechanism is discussed.
Coupling of acrylic polymers and collagen by use of a water‐soluble carbodiimide. II. Investigations of the coupling mechanism
Authors: Lloyd Douglas R. , Burns Charles M.
Published: April 2003

The coupling mechanism involved in the coupling of acrylic polymers and collagen by a water‐soluble carbodiimide was investigated. By the use of a series of homopolymers of α‐amino acids, support was given to the postulate that a major proportion of the coupling takes place in the amino functional group. In light of the results presented the reaction is sterically controlled and the steric, stoichiometric, and kinetic aspects of the reaction are discussed.
Aromatic polyamides. IV. A novel synthesis of sulfonated poly(para‐phenyleneterephthalamide): Polymerization of terephthalic acid and para‐phenylenediamine in sulfur trioxide
Authors: Silver Frank M.
Published: April 2003

A novel polyamide condensation reaction of aromatic diamines (usually as strong inorganic acid salts) and aromatic diacids in SO3 has been discovered. para‐Phenylenediamine was polymerized with terephthalic acid in SO3 at 20–47% polymer concentration to form highly anisotropic (liquid crystalline) sulfonated poly(p‐phenyleneterephthalamide) (SPT) solutions (dopes) with inherent viscosities as high as 1.6. Sulfonation of the aromatic diamine ring was a major side reaction. The effects of reaction variables such as temperature, time, monomer concentration, stoichiometry, and solvent acidity on molecular weight were studied. The dopes were spun to fiber, but tensile properties were limited by coagulation problems associated with hydrophilicity of the highly sulfonated polymer. Thermogravimetric analysis of SPT at 20°C/min showed weight loss only above 450°C.
Aromatic polyamides. VI. Synthesis of aromatic copolyamides and copolyamide–oxadiazoles in sulfur trioxide
Authors: Silver Frank M. , Black W. Bruce
Published: April 2003

Copolymerization of para‐phenylenediamine sulfate (PPD‐S), hydrazine sulfate (Hy‐S), and terephthalic acid (TA) in SO3 yielded solutions of poly[p‐(disulfonatophenylene)terephthalamide]–co‐poly(p‐phenylene‐1,3,4‐oxadiazole) (SPT‐co‐POx). Reaction of PPD‐S, TA, and 4,4′‐sulfonyldibenzoic acid (SDBA) in SO3 gave sulfonated copolyamide (SPT‐co‐SPSDB) solutions. Solutions of both SPT‐co‐POx (mole % ratios of 70:30 to 90:10) and SPT‐co‐SPSDB (75:25 to 90:10) were anisotropic, illustrating liquid crystalline behavior for polymeric structures containing significant amounts of noncoaxial backbone components.
Polysiloxane dizwitterionomers. III. Water sorption
Authors: Graiver D. , Litt M. , Baer E.
Published: April 2003

The interaction of water with the various polysiloxane dizwitterionomers and the model compound 4,7‐diazaheptyl‐4,7‐di(3‐propane‐sulfonate) heptamethyltrisiloxane was studied. The model compound is soluble in water but the polymers swell inhomogeneously when soaked in water. The initial sorption kinetics of these zwitterionomers indicate similar mechanisms of water uptake which is independent of ion concentration (D = 4.7 × 10−7 cm2/sec). The sorption isotherms reveal the high sorptive capacity of these ionomers. Furthermore, the linear relationship between the water uptake and the concentration of ions over a large relative humidity range (0.22 ≤ P/P0 ≤ 0.93) allowed us to treat each phase separately. It has been found that most of the absorbed water molecules are immobilized in the ionic domains. Their concentration in this phase is nearly identical to the sorptive capacity of the model compound.
Polymer particle formation in soapless emulsion polymerization
Authors: Arai Masahiko , Arai Kunio , Saito Shozaburo
Published: April 2003

Polymer particle formation in soapless emulsion polymerization for monomers that are soluble in diluent is studied theoretically and experimentally. A kinetic model is proposed assuming that polymer particles are formed by homogeneous nucleation of both growing radicals and dead polymer molecules above the critical size in solution. Based on this model, the dependence of the number of polymer particles on the concentration of initiator and monomer in solution is discussed for the polymerization system of methyl methacrylate–potassium persulfate–water. Experimental results of the number of polymer particles in this system can reasonably be interpreted by this model.
Polymerization of aromatic nuclei. XXII. Structure of the oligomer product from thiophene and trifluoroacetic acid: A reinvestigation
Authors: Margosian Daniel , Kovacic Peter
Published: April 2003

A reinvestigation was made of thiophene polymerization by trifluoroacetic acid with the aim of elucidating the structure of the oligomer product. Comparison of spectral and molecular weight data was made with corresponding data for thiophene polymer generated by means of aluminum chloride and for trimer prepared from thiophene–phosphoric acid. We conclude that the solid product from thiophene–trifluoroacetic acid is best represented by the following structure:
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In addition, the major product is the known liquid trimer:
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Our designation is in disagreement with that of Wassermann et al., who proposed a structure having aliphatic unsaturation.
Synthesis and characterization of copolyesters of PET and substituted p‐hydroxybenzoic acids
Authors: Balachandar M. , Balakrishnan T. , Kothandaraman H.
Published: April 2003

Random copolyesters of different compositions were synthesized by melt polycondensation of poly(ethylene terephthalate) and 3‐bromo ‐ and 3,5‐dibromo‐p‐hydroxybenzoic acids. The copolymer compositions were determined by proton nuclear magnetic resonance spectroscopy. The thermal behavior of these copolyesters was investigated by differential scanning calorimetry. The glass transition temperature, crystallization temperature, and decomposition temperature were found to increase with increase in the paraoxybenzoate content of the copolyesters. The limiting viscosity number and the weight‐average molecular weight were determined.
Photodegradation of polyvinylacetophenone. I. Long‐wave photolysis
Authors: Weir N. A. , Milkie T. H.
Published: April 2003

Polyvinylacetophenone (PVAP) films were exposed to long‐wave (λ ≥ 300 nm) ultraviolet radiation in the absence of oxygen. The gaseous products, determined quantitatively by mass spectrometry, were methane, ethane, carbon monoxide, and acetaldehyde. These indicated that the polymer was undergoing photodecomposition via a Norrish type I reaction. The polymer also undergoes crosslinking reactions, becoming insoluble after 100 hr irradiation, and the ultraviolet and phosphorescence spectra indicate loss of carbonyl chromophores. The mechanism of photolysis is discussed, and the implications of the effects of photodegradation on the efficiency of the polymer as a sunlight energy transfer agent are examined.
Synthesis, characterization, and polymerization of N‐vinylarylamines
Authors: Lin John W‐P.
Published: April 2003

Several N‐vinylarylamines have been prepared by direct N‐vinylation of arylamine salts with acetylene at atmospheric pressure. Nuclear magnetic resonance (NMR) spectra of the various N‐vinylarylamines were recorded and chemical shift assignments were made for the first time. The vinyl protons of the enamines generally exhibit an ABX pattern. The electron‐rich monomers are sensitive to acid‐catalyzed hydrolysis in a wet solvent. Polymerizations of the monomers were carried out at low temperatures with phosphorous pentafluoride as an initiator. It was found that PF5 generated directly from thermal decomposition of p‐chlorobenzenediazonium hexafluorophosphate is useful in the preparation of an extremely high‐molecular‐weight poly(N‐vinylcarbazole) (Mw = 3 × 106) with a narrow molecular weight distribution (MWD = 2.1). The polymerizability of N‐vinylarylamines appears to vary with the amine functional groups of the monomers. N‐vinylarylamine containing a planar amine moiety such as carbazole forms a higher‐molecular‐weight polymer than the monomers with the nonplanar bulky amine groups.
Contribution to the mechanism of copolymerization of phenylvinyl alkyl ethers and thioethers with maleic anhydride
Authors: Vuković R. , Kurešević V. , Fleš D.
Published: April 2003

The equilibrium constants of the charge‐transfer complex monomers of phenylvinyl alkyl ethers (I) and thioethers (II) with maleic anhydride (MAn) were determined by the transformed Benessi—Hildebrand NMR method, and it was found that the bulkiness of alkyl groups had no significant influence on the equilibrium constant. The rate of copolymerization, however, was largely dependent on the bulkiness of the alkyl groups in the phenylvinyl alkyl ether series. The rate of copolymerization of I (R = Et; sec‐Bu) and II (R = Et; sec‐Bu) with MAn was proportional to the square root of AIBN concentration, and intrinsic viscosity of poly‐I (R = Et)‐co‐MAn was proportional to the reciprocal square root of AIBN concentration. Spontaneous copolymerization did not occur, but I (R = Et) copolymerizes with MAn in the presence of oxygen; II did not copolymerize with MAn in the presence of oxygen; nor in the presence of peroxide initiators. In the copolymerization of I (R = Et) and MAn, it was found that molecular weight increases with conversion. By applying the generalized model described by Shirota and co‐workers, the reactivity ratios k1c/k12 and k2c/21 for copolymerization of I (R = Et) and II (R = Et) with MAn were calculated from the change of copolymerization rate with monomer feed at constant total monomer concentration.
Quaternary ammonium polyelectrolytes. III. Kinetic studies of amination of chloromethylated polystyrene with tertiary amines
Authors: Luca Cornelia , Petrariu I. , Dima M.
Published: April 2003

The amination kinetics of benzyl chloride and chloromethylated polystyrene with three tertiary amines were studied: N‐2‐hydroxyethyl‐dimethylamine, N,N‐bis(2‐hydroxyethyl)‐methylamine, and triethylamine in N,N‐dimethylformamide. The amination of chloromethylated polystyrene takes place with two reaction rate constants K1 and K2. K2 is higher than K1; hence there is a self‐accelerating effect. This phenomenon is due to the influence of the positive electrostatic field of the macroion chain on amines that are nucleophilic reactants. The magnitude of the self‐accelerating effect given by the K2/K1 ratio depends on the substituent volume of the nitrogen atom of the amine molecule.
Coenzyme models. 19. Oxidation of furoin by a flavin immobilized in cationic polyelectrolytes: A flavoenzyme model
Authors: Shinkai Seiji
Published: April 2003

The rate constants for the oxidation of furoin by a flavin (vitamin B2 analog) immobilized in cationic polymers were evaluated under anaerobic conditions, and the influence of reaction environments was discussed in connection with the enzymatic reactivity. It was found that (1) proton abstraction from furoin which forms the carbanionic intermediate is rate determining in the initial stage of the reaction and is facilitated by the environment of cationic polymers, (2) proton abstraction is efficiently accelerated by added cationic surfactant (CTAB), and (3) N‐dodecylbenzohydroxamic acid in aqueous CTAB acts as an excellent proton‐abstracting reagent. The polymers with high dodecyl group content served, in all cases, as better oxidizing reagents. As a summary of these conclusions, the importance of hydrophobic environments in flavin‐mediated oxidation was emphasized.
Hydrolysis of dextrin in the presence of block copolymer of vinyl alcohol and styrenesulfonic acid
Authors: Arai Kenichiro , Ogiwara Yoshitaka
Published: April 2003

A block copolymer of vinyl alcohol and styrenesulfonic acid was prepared by a two‐step polymerization and subsequent modification, and its catalytic activity on the hydrolysis of dextrin was investigated. The hydrolysis rate in the presence of the copolymer containing more vinyl alcohol‐repeating units was found to follow Michaelis–Menten‐type kinetics, whereas that in the presence of a copolymer containing fewer vinyl alcohol units proceeded according to ordinary second‐order kinetics. The process of complex formation for the former system was characterized by pronounced decreases in enthalpy and entropy, although the enthalpy and the entropy of activation for the decomposition of the complex to product was comparable to that of a sulfuric acid‐catalyzed system. The maximum rate enhancement obtained in the present experiment was approximately fivefold on the basis of the reaction in the presence of sulfuric acid at 65°C. The results were compared with those obtained in the presence of a random copolymer catalyst, previously reported.
Polymerization of acetylene and its monosubstitutes in the presence of halides and oxohalides of molybdenum and tungsten
Authors: Voronkov M. G. , Pukhnarevich V. B. , Sushchinskaya S. P. , Annenkova V. Z. , Annenkova V. M. , Andreeva N. J.
Published: April 2003

MoCl5, WCl6, and OMoCl4 were found to be effective initiators for the polymerization of acetylene and its monosubstituted derivatives RCCH. The polymerization proceeded in homogeneous and heterogeneous media and was carried out in nonpolar (chloroalkanes, aromatic hydrocarbons) and polar (THF, acetone, dioxane, carboxylic acids) solvents to give a high yield of polymers.
Polyimidines. VI. The comparison of polyimidines from bis(3,3‐diphenyl‐6‐phthalidyl) ketone
Authors: Cassidy Patrick E. , Doctor Shreenath V.
Published: April 2003

New thermally stable polyimidines have been synthesized from bis(3,3‐diphenyl‐6‐phthalidyl) ketone and five diamines: o‐phenylenediamine, m‐phenylenediamine, 1,5‐diaminonapthalene, 1,8‐diaminonapthalene, and benzidine. Polymers of low molecular weight (inherent viscosity up to 0.24 dl/g) were obtained by solution and sealed‐tube polymerizations. The structural differences of the amines provided information concerning the effects on the thermal stability properties of the resulting polyimidines. The yellow to black polymers exhibited a 10% loss ranging from 420–510°C in air and 460–555°C in nitrogen and were soluble in chloroform and dimethylformamide.
Photochemical reactions of N‐vinylcarbazole in the binary solvent of benzonitrile and nitrobenzene
Authors: Hamanoue Kumao , Teranishi Hiroshi , Okamoto Masami , Furukawa Yoh , Tagawa Seiichi , Tabata Yoneho
Published: April 2003

Photochemical reactions of N‐vinylcarbazole (VCZ) in the binary solvent of benzonitrile (ϕCN) and nitrobenzene (ϕNO2) were investigated. Both solvent and oxygen effects on the final products were examined. Benzonitrile and nitrobenzene behaved differently in the photochemical reaction of VCZ. At higher concentrations of benzonitrile in the aerated system, cyclodimerization was favored and it was inhibited by a cation scavenger and retarded by a radical scavenger. Polymerization occurred in the deaerated system and was inhibited by a radical scavenger and not by a cation scavenger. Using picosecond laser photolysis it was concluded that cyclodimerization occurs through the diffusion‐controlled encounter collision of the excited singlet state of VCZ with an oxygen molecule, producing the VCZ cation radical and oxygen anion radical, and that this oxygen anion radical plays a very important role in the cyclodimerization of VCZ. It was also suggested that radical polymerization in the deaerated system is initiated by the excited triplet state of VCZ. On the other hand, at higher concentrations of nitrobenzene, only cationic polymerization took place irrespective of the presence of oxygen, and it was suggested that a contact charge‐transfer complex is produced by the mixing of VCZ with ϕNO2 producing VCZ cation radical and NO2 anion radical by an excited‐state electron transfer.
Radiation degradation of methyl α‐chloroacrylate–methacrylonitrile copolymers
Authors: Chen Chi‐Yu , Pittman Charles U. , Helbert John N.
Published: April 2003

The radiation degradation behavior of methyl α‐chloroacrylate (MCA) and methacrylonitrile (MCN) copolymers has been investigated as part of a program to develop high‐sensitivity polymeric resists for integrated circuit manufacture. High‐molecular‐weight copolymers were prepared by emulsion techniques. Several different copolymer compositions were prepared varying from 19 to 68 mole % MCA. These copolymers were fractionated and then subjected to γ irradiation from a 60Co Source. The Gs ‐ Gs, Gs ‐ 4Gs values were determined from M̄;F>nk−1 and Gu−1 versus dose plots, and the Gfs and Gs Values were then calculated. Molecular weights of both unirradiated and irradiated polymers were analyzed by membrane osmometry and gel permeation chromatography. All copolymers exhibited higher degradation susceptibilities than that of poly(methyl methacrylate) (PPMA), which has Gx = 1.3. The individual Gx and Gx values of the copolymers were found to fall between those of the two homopolymers, poly(methyl α‐chloroacrylate) (Gx = 6.0) and polymethacrylonitrile (Gx ∼ 3.1). The dependence of Gx and Gx values on molecular weight was minor. The crosslinking susceptibility of the poly(methyl α‐chloroacrylate) (Gx ∼ 0.8), was greatly decreased by copolymerization with MCN. Relatively small amounts of MCN caused a large drop in Gx, i.e., Gx ∼ 0.15 at 32% MCN and Gx ∼ 0.03 at 51% MCN. The observation could be attributed to the decreasing probability that crosslinking sites, in the MCA monomer units on adjacent chains, would lie in close proximity.
Stereospecific polymerization of isobutyl vinyl ether catalyzed by calcined iron sulfate
Authors: Hino Makoto , Arata Kazushi
Published: April 2003

The polymerization of isobutyl vinyl ether was studied in a heterogeneous system using iron (II) sulfate calcined in air at various temperatures as a catalyst. The maximum activity was shown by the catalyst calcined at 700°C, which effected the polymerization at room temperature in a few seconds, while the sulfate treated at 750°C was totally inactive. Poly(vinyl ethyl ether) was also obtained by the FeSO4 (700°C) catalyst at room temperature. This catalyst formed the crystalline polymer (melting temperature 135–138°C) when the reaction was performed in toluene as solvent at room temperature. Poisoning experiments with Hammett indicators were carried out with the FeSO4 (700°C) catalyst. The treatment with n‐butylamine rendered it inactive in the reaction of isobutyl vinyl ether, while its catalytic activity was little affected by dicinnamalacetone. On the basis of the observed results, the nature of active sites of catalyst is discussed.
State of order in isotactic polyhexylethylene
Authors: Trafara Gundolf
Published: April 2003

Cooling slowly from the melt and annealing at 250 K for a month isotactic polyhexylethylene becomes partially crystalline. The degree of crystallinity, calculated according to the method of Hermans and Weidinger, is 0.3. The wide‐angle x‐ray diffraction diagram shows seven reflections, not completely independent of one another. These x‐ray data do not allow an exact determination of the structure. The main chins possibly form quaternary helices (e. g., 4/1 or 7/2 helices) and the side chains are arranged in triclinic structure. The unit cell may be monoclinic: a ∼ 0.56 nm, b ∼ 3.8 nm, c ∼ 0.76 nm (in case of a 4/1 helix), β ≃ 97° The melting temperature is 278 K and the heat of fusion amounts to 30 J/g.
Chloromethylated polystyrene reaction with tris(2‐hydroxyethyl)amine. I. Crosslinked polymers prepared by chloromethylated polystyrene with tris(2‐hydroxyethyl)amine
Authors: Luca Cornelia , Drǎgan Stela , Bǎrboiu V. , Dima M.
Published: April 2003

A multifunctional crosslinked polymer resulted from a chloromethylated polystyrene reaction with tris(2‐hydroxyethyl)amine. A benzyl chloride reaction (chosen as a structural unit model) with tris(2‐hydroxyethyl)amine was investigated to explain the reasons for the crosslinking. Amino‐ethers and tris(2‐hydroxyethyl)amine hydrochloride in addition to ammonium quaternary salt were isolated from this reaction. The formation of amino‐ethers proved that an ammonium quaternary salt rearrangement also takes place during the quaternization reaction. This rearrangement leads to chloromethylated polystyrene during its reaction with tris(2‐hydroxyethyl)amine.
Cationic polyelectrolytes. I. Soluble polymers prepared from reaction of chloromethylated polystyrene with tris(2‐hydroxythyl)amine
Authors: Drǎgan Stela , Luca Cornelia , Petrariu I. , Dima M.
Published: April 2003

The reaction of chloromethylated polystyrene with tris(2‐hydroxyethyl)amine in N,N‐dimethylformamide is described for the conditions to prepare soluble reaction products. The groups of the quaternary ammonium salt, which appear in the first stage of the reaction, transpose to the amino‐ether groups. The reaction was followed by elementary analysis, IR and 1H‐NMR spectra, and viscosimetric measurements for nondialyzed and dialyzed samples. The presence of the tertiary amine groups on obtained polymers was also shown by titration. The polymers from the reaction of chloromethylated polystyrene with tris(2‐hydroxyethyl)amine reacted easily with benzyl chloride.
Relation between the thermal behavior of polyacrylonitrile and polymerization factors
Authors: Minagawa Masatomo , Iwamatsu Takashi
Published: April 2003

In order to clarify the mechanism to produce the large dispersion of the exothermic peak temperature (Tpk) of polyacrylonitrile, a systematic and quantitative study was made by means of the differential thermal analysis and the viscosity measurment. General tendency between Tpk and the polymerization methods was reconfirmed. Under a controlled condition (i.e., aqueous solution system), presence of N,N‐dimethyl formamide or isopropyl alcohol produced a lower Tpk of resulting polymer, while presence of activator produced a higher Tpk. Thus, the large dispersion of Tpk (250–300°C) can be explained inclusively in terms of a single reaction factor, i.e., chain transfer mechanism. Particularly in the above third case it was shown that owing to strong and rapid chain transfer to activator, some kind of secondary reaction (caused by propagating chain end radical), probably chain branching which deteriorates the higher thermal quantity of molecule, is restrained effectively. Furthermore, some specific behaviors (i.e., cooperativeness and dynamic character, etc.) were observed in this reaction of PAN in solid amorphous phase.
Polymerization ofN‐carboxy‐amino acid anhydrides in the solid state. I. Polymerizability of the various α‐amino acid NCAs in the solid state
Authors: Kanazawa Hitoshi , Kawai Tohru
Published: April 2003

The solid‐state polymerization of various α‐amino acid NCAs was investigated and the results were compared with those obtained by heterogeneous polymerization in acetonitrile. Essential differences were found in the polymerizability of the NCAs in these two systems. In the solid state, L‐leucine NCA was the most reactive among the NCAs examined, and its reactivity was even higher than in the precipitation polymerization of acetonitrile solutions. On the other hand, glycine NCA was the most inert among the NCAs examined in the solid state. The difference between the reactivities of glycine NCA and L‐alanine NCA was interpreted in terms of their crystal structures. Several kinetic features of the solid‐state polymerization were studied on γ‐benzyl‐L‐glutamate NCA.
Reactivity of 4‐vinylpyridine in the presence of Ziegler–Natta catalysts
Authors: Carlini Carlo
Published: April 2003

The homopolymerization of both free and aluminum alkyls complexed 4‐vinylpyridine (4VP) in the presence of Ziegler‐Natta catalysts, based on TiCl3“ARA” and aluminum or zinc alkyls, has been performed. The copolymerization of free or complexed 4VP with chiral α‐olefins or styrene (St), using the same catalysts, has also been investigated. Spectroscopic and solubility data of the polymers obtained are consistent with the presence in the above‐mentioned catalysts of several species having different reactivity and stereochemistry. Data, based on fractionation and composition of the resulting polymeric products, are reported supporting a polymerization mechanism different from that connected with a free radical initiation.
Wholly aromatic polyamides by the direct polycondensation reaction using triphenyl phosphite in the presence of poly(4‐vinylpyridine)
Authors: Higashi Fukuji , Goto Mitsuyoshi , Nakano Yoshimasa , Kakinoki Hideo
Published: April 2003

The polycondensation reaction of aromatic dicarboxylic acids and diamines by using triphenyl phosphite were carried out in N‐methylpyrrolidone (NMP) in the presence of poly(4‐vinylpyridine) (P4VP). The reaction, especially of terephthalic acid (TPA), was markedly facilitated to give the absence of P4VP. The reaction promoted by P4VP was further favored by the addition of various pyridine derivatives; of the pyridines examined, pyridine was most effective, giving the best results at a high level (pyridine/P4VP values up to 26). P4VP of the molecular weight in the range of 1.3 × 104−3.0 × 105 did not affect the viscosity of the resulting polymer. These favorable additive effects of P4VP on the reaction of TPA were not observed in the reactions of isophthalic acid, and m ‐and p‐aminobenzoic acids.
Effect of simultaneous polyaddition reaction on the curing of epoxides
Authors: Bokare U. M. , Gandhi K. S.
Published: April 2003

Epoxy‐amine curing reactions were theoretically studied using expectation theory taking into account the different reactivities of (1) the primary and secondary amine hydrogens and (2) the secondary hydroxyl group generated when an amine reacts with an epoxy group. The curing compositions and the fractional conversions at the gel point were computed. Generally the hydroxyl groups react slower than the amines and user these conditions, the reactivity of the OH group has a significant effect only when there is an intial excess of epoxide over the amine. The hydroxyl activity effectively increases the functionality of the epoxides and gelation can occur where it may not be expected.
Intramolecular excimer formation in polyamides with widely separated naphthyl groups in the backbone
Authors: Ibemesi J. A. , Kinsinger J. B. , El‐Bayoumi M. Ashraf
Published: April 2003

The photophysical properties of a series of polyamides containing naphthalene groups in the backbone were investigated. The polyamides were synthesized by interfacial polycondensation involving 2,6‐bis(N‐methyl, methylamino)naphthalene and the following diacid chlorides:
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(x = 2, 4, 6, and 8). The polyers were designated P‐2, P‐4, P‐6, and P‐8. The monomer model compound (MC) was made by acylation of the diamine monomer wth acetyl chloride. The polyamides exhibited intramoleular excimer fluorescence in dilute solutions at room temperature. Excimer fluorescence quantum yields were in the following order: P‐2 ≈ P‐8 > P‐4 ≈ P‐6. This sequence was rationalized on the basis of neighboring and nonneighboring group excimeric interactions that are dependent on the length of the intervening methylee chain. Temperature measurements on P‐2 revealed a small energy of actvation (1.8 kcal mole−1) for the conformational transition involved in the formaton of the intramolecular excimer. Intramolecular excimer formation for a given polymer depended on the solvent. Nanosecond fluorescence depolarization measurements demonstrated the flexibility of the naphthalene moieties even though they were doubly bound in the polymer chain. Our results showed that intramolecular excimer formation could occur over long distances of separation (n > 3) between the nteracting chromophores provided that the connecting chain was sufficiently flexible.
Functional monomers and polymers. LXIII. A study on the polymer–polymer interaction between nucleic acid base‐substituted poly‐L‐lysines
Authors: Ishikawa T. , Inaki Y. , Takemoto K.
Published: April 2003

A study of polymer‐polymer interaction was made on several poly‐L‐lysines that contained pendant nucleic acid bases substituted on the N′ position. Conformation and interaction of these polypeptides were studied in solution by spectroscopic measurement. The results obtained suggest that the high‐molecular‐weight polymers form polymer complexes in a helical conformation by specific adenine‐thymine base pairing. On the other hand, no interaction could be observed for the low‐molecular‐weight polymers, which existed in a random coil structure.
Studies of the polymerization of diallyl compounds. XXVII. Copolymerization of diallyl tartrate with several vinyl monomers
Authors: Ohata Tetsuji , Fukumori Etsuro , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

The radical copolymerization of diallyl tartrate (DATa) (M1) with diallyl succinate (DASu), diallyl phthalate (DAP), allyl benzoate (ABz), vinyl acetate (VAc), or styrene (St) was investigated in order to disclose in more detail the characteristic hydroxyl group's effect observed in the homopolymerization of DATa. In the copolymerization with DASu or DAP as a typical diallyldicarboxylate, the dependence of the rate of copolymerization on monomer composition was different for different copolymerization systems and unusual values larger than unity for the product of monomer reactivity ratios, r1r2, were obtained. In the copolymerization with ABz or VAc (M2), the r1 and r2 values were estimated to be 1.50 and 0.64 for the DATa/ABz system and 0.76 and 2.34 for the DATa/VAc system, respectively; the product r1r2 for the latter copolymerization system was found again to be larger than unity. In the copolymerization with St, the largest effect due to DATa monomer of high polarity was observed. Solvent effects were tentatively examined to improve the copolymerizability of DATa. These results are discussed in terms of hydrogen‐bonding ability of DATa.
Temperature drop turbidity. IV. Polystyrene
Authors: Hay James N. , Fitzgerald Pauline A.
Published: April 2003

The molecular weight distribution of fractionated and unfractionated polystyrene samples has been determined by temperature drop turbidimetry, in which polymer is precipitated from dilute solutions in cyclohexanol by progressively cooling from 388 to 310 K. Estimates of the molecular weight averages and the polydispersities, obtained by calibration of the temperature of initial onset of precipitation, Ti, and the weight‐average molecular weight were low, but could be substantially improved by correcting for concentration changes during precipitation. An empirical procedure correlating the breadth of turbidity‐temperature curves to the logarithm of the polydispersity, as measured by gel permeation chromatography, appeared to be a simpler method of characterizing the polymer samples and as accurate as the computational methods above.
Effects of electron beam preirradiation on the γ radiolysis of polyethylene
Authors: Mitsui Hiroshi , Shimizu Yuichi
Published: April 2003

The γ radiolysis of polyethylene preirradiated with electron beams to 3 Mrad was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 105 rad/hr. The hydrogen formation in the γ radiolysis was little affected by the preirradiation of electron beams, whereas the formation of trans‐vinylene unsaturation and gel was somewhat retarded. The rates of the formation of hydrogen and trans‐vinylene unsaturation were described by the zero‐order formation kinetics with respect to each concentration combined with the first‐order disappearance. The apparent rate constants and activation energies for the formation and disappearance of hydrogen and trans‐vinylene unsaturation were almost independent of the preirradiation. The gel fraction was analyzed by using the Charlesby–Pinner equation. The G values of crosslinking and main chain scission were increased by the preirradiation, whereas their activation energies remained unaltered. On the basis of these results the effects of preirradiation on the reactions induced by γ rays in polyethylene were discussed.
Synthesis and optical properties of polyethylenimine containing L‐proline and optically active thymine derivatives
Authors: Overberger C. G. , Morishima Yotaro
Published: April 2003

Preparation and optical properties of linear polyethylenimine (PEI) containing L‐(−)‐N‐[(−)‐2‐(thymin‐1‐yl) propionyl] prolyl group as grafting pendant, [P‐(−)Pro‐(−)T], and its related monomer and dimer model compounds are described. Hypochromic effects and circular dichroism of these compounds were compared with those of PEI containing (−)‐2‐(thymin‐1‐yl) propionyl group as grafting pendant, [P‐(−)T], which has no L‐proline ring as a spacing group. P‐(−)Pro‐(−)T showed no exciton coupling of B2u π‐π* transition although it showed large hypochromicity in neutral aqueous solution, implying that the stacking of the bases has no screw sense.
Electrochemical and chemical polymerization of acrylamide
Authors: Bhadani Suraj N. , Prasad Yugal K. , Kundu Swapna
Published: April 2003

The electrochemical and chemical polymerization of acrylamide (AA) has been studied. The electrolysis of the monomer in N,N‐dimethylformamide (DMF) containing (C4H9)4NClO4 as the supporting electrolyte leads to polymer formation in both anode and cathode compartments. The cathodic polymer dissolves in the reaction mixture and the anodic polymer precipitates during the course of polymerization. A plausible mechanism for the anodic and cathodic initiation reaction has been given. The chemical polymerization of acrylamide that has been initiated by HClO4 is analogous to its anodic polymerization. The polymer yield increases with an increase in concentration of the monomer and HClO4. Raising the reaction temperature also enhances the polymerization rate. The overall apparent activation energy of the polymerization was determined to be ca. 19 kcal/mole. The copolymerization of acrylamide was carried out with methyl methacrylate (MMA) in a solution of HClO4 in DMF. The reactivity ratios are r1 (AA) = 0.25 and r2 = 2.50. The polymerization with HClO4 appears to be by a free radical mechanism. When the polymerization of acrylamide is carried out with HClO4 in H2O, a crosslinked water‐insoluble gel formation takes place.
Evolution of HCN by thermal oxidative degradation from nylon 66 at high temperatures including burning
Authors: Jellinek H. H. G. , Dunkle S.
Published: April 2003

Work on the evolution of HCN from nylon 66 was extended to temperatures from ca. 300 to 695°C. Below ca. 300°C the evolution of HCN is governed by chemical decomposition, and above 300°C the evolution is controlled by diffusion. Above 530°C oxidation of HCN becomes noticeable and ignition occurs at 590°C. The rate constants for all of the temperature ranges and for the oxidation of HCN are given in terms of Arrhenius equations. The activation energy for the oxidation of HCN before ignition (590°C) is reached is 47 kcal/mole, and beyond this point, the oxidation is controlled by diffusion. The rate constants increase linearly with oxygen concentration as long as HCN oxidation is negligible; however, they pass through maxima if HCN oxidation is appreciable (some HCN is evolved even in the absence of oxygen). A new flash degradation apparatus has been constructed for these high‐temperature ranges and a degradation mechanism has been proposed which is in satisfactory agreement with the experimental results.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). II. Synthesis and characterization of α,ω‐di(tert‐chloro)polyisobutylenes
Authors: Kennedy Joseph P. , Smith Robert Alan
Published: April 2003

Detailed understanding of the mechanism of initiation and chain transfer in BCl3‐coinitiated isobutylene polymerization led to the efficient synthesis of symmetric telechelic polyisobutylenes carrying ∼CH2C(CH3)2Cl groups at either end of the molecule Cl‐PIB‐Cl. The synthesis is based on the use of inifers, i.e., bifunctional initiator‐transfer agents that effect controlled initiation and propagation in the absence of chain transfer to a monomer. Specifically, the synthesis of Cl‐PIB‐Cl was achieved by the p‐dicumyl chloride/BCl3/isobutylene/CH2Cl2 system. According to the inifer mechanism each Cl‐PIB‐Cl contains two terminal tertiary chlorines and one phenyl group at the interior of the chains. The structure of this new symmetric telechelic polymer has been established by detailed characterization studies including a sensitive new gel permeation chromatography (UV plus RI) analysis method, 1H‐NMR, kinetic experiments, and chemical derivatization. The Cl‐PIB‐Cl molecule is a key intermediate for the synthesis of hosts of new materials, e.g., triblock copolymers, α,ω‐diolefins, and α,ω‐difunctional polymers.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). III. Synthesis and characterization of poly(α‐methylstyrene‐b‐isobutylene‐b‐α‐methylstyrene)
Authors: Kennedy Joseph P. , Smith Robert Alan
Published: April 2003

The synthesis of a new glassy‐rubbery‐glassy triblock copolymer poly(α‐methylstyrene‐b‐isobutylene‐b‐α‐methylstyrene) has been demonstrated. The key to the synthesis was the preparation by inifer method of a perfectly bifunctional polyisobutylene which carries tert‐chlorine end groups Cl‐PIB‐Cl. In conjunction with Et2AlCl coinitiator, the telechelic Cl‐PIB‐Cl molecule initiates the polymerization of α‐methylstyrene at both ends of the prepolymer. Triblock composition can be controlled by the judicious selection of synthesis conditions; that is, Cl‐PIB‐Cl molecular weight, α‐methylstyrene concentration, and solvent polarity. Theoretical triblock Mn calculated from Mn of Cl‐PIB‐Cl and triblock overall composition is in excellent agreement with experimental Mn which indicates negligible homopolymer contamination. Extraction with a series of hydrocarbon solvents reveals broad composition distribution. The stress‐strain profile of a triblock is similar to that of a poly(styrene‐b‐butadiene‐b‐styrene) thermoplastic elastomer of similar composition.
Monte Carlo‐studium der reversiblen copolymerisation. I. Theorie, memøry‐6 programm, anwendungen
Authors: Motoc I. , Vancea R.
Published: April 2003

The binary reversible copolymerization, taking into account the length of the terminal sequence, are studied by the Monte Carlo method. We discuss the theoretical model, the algorithm, and a FR̃RAN program. Finally, the α‐methylstyrene‐methyl methacrylate copolymerization is studied by means of the proposed Monte Carlo model, and the results obtained are compared with those obtained using the Markov chain model and Wittmer's equations.
Characterization of polychloroprenes and cationically modified polychloroprenes by thermal dehydrochlorination
Authors: Iván Béla , Kennedy Joseph P. , Plamthottam Sebastian S. , Kelen Tibor , Tüdos Ferenc
Published: April 2003

Thermal dehydrochlorination of polychloroprenes and modified polychloroprenes was studied and was found to be rapid, readily reproducible, and reliable for the characterization of these rubbers. The rates of thermal dehydrochlorination of polychloroprenes and modified polychloroprenes are first order at 190°C under nitrogen. Significantly, the plot of dehydrochlorination rate (VHCl) versus dehydrochlorination extent (ζHCl) for polychloroprenes shows three regions. These data may be attributed to three dehydrochlorination regimes associated with four contributing repeat structures that have been identified by 13C‐NMR spectroscopy:
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In contrast to polychloroprene, VHCl vs. ζHCl plots for modified (cyclopentadienylated and grafted) polychloroprenes, i.e., polychloroprenes that do not contain allylic chlorines, exhibit only one region suggesting only one dehydrochlorination mechanism in these materials. The slopes of the VHCl vs. ζHCl plots of the modified polychloroprenes are virtually identical. Moreover, the slopes of the VHCl vs. ζHCl plots for modified polychloroprenes and that of the latest of the three regions for unmodified polychloroprene are indistinguishable. This similarity in the VHCl vs. ζHCl curves suggests dehydrochlorination by a fundamentally similar mechanism in these materials, most likely one involving the CH2C(Cl)CHCH2 structure common to all of them. Concentration of labile chlorines in polychloroprene may be estimated by the differences in the dehydrochlorination kinetics of polychloroprene and modified polychloroprenes.
Synthesis of polyamides by a new direct polycondensation reaction using triphenyl phosphite and lithium chloride
Authors: Higashi Fukuji , Goto Mitsuyoshi , Kakinoki Hideo
Published: April 2003

Metal salts such as lithium chloride were found to facilitate significantly the reaction of carboxylic acids and amines promoted by triphenyl phosphite, and the reaction was applied successfully to the direct polycondensation reaction of dicarboxylic acids and diamines and of p‐aminobenzoic acid. Among metal salts tested, lithium chloride was most effective to the reaction; the chloride was involved catalytically in the reaction, its addition of about twice equivalent to triphenyl phosphite giving the most favorable results. Triphenyl phosphite was most effective, whereas diphenyl phosphite was less effective, and alkyl esters gave no polymers. The reaction was also markedly affected by solvents, the most favorable results being given in N‐methylpyrrolidone (NMP). Various polyamides of high molecular weight were obtained in quantitative yield.
Polymidines. V. Poly[(3,3‐diphenyl‐2,6‐phthalimidinediyl)‐carbonyl(3,3‐diphenyl‐6,2‐phthalimidine)]s
Authors: Lohr Raymond A. , Cassidy Patrick E. , Kutac Andrew
Published: April 2003

A new diphthalide monomer, bis(3,3‐diphenyl‐6‐phthalidyl) ketone, was polymerized with six diamines: 1,6‐diaminohexane, benzidine, p‐phenylene diamine, p,p′‐diaminodiphenyl ether, p,p′‐diaminodiphenylmethane, and 4,4′‐diaminodiphenylsulfone. Solution polymerization in benzhydrol, biphenyl, or p‐phenylphenol solvents gave low‐molecular‐weight polymers (inherent viscosity 0.13 dl/g or less) which were soluble in chloroform and dimethylformamide. TGA data showed 10% weight losses at 445–525°C in air and 475–540°C in nitrogen for the aromatic backbones. Yields ranged from 47 to 78%. The application of continuous vacuum to the polymerization allowed the removal of water by‐product and resulted in a light‐colored polymer.
A new universal GPC calibration method
Authors: Hester R. D. , Mitchell P. H.
Published: April 2003

A model of GPC separation phenomenon with a new calibration method has been developed based on the probability of molecular size exclusion from a porous packing material. The model was shown to give a theoretical explanation of instrument range and sensitivity. With data from the literature, the new calibration method was shown to be statistically superior to the standard method suggested by Grubisic.