bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo study of star‐branched polymers on the tetrahedral lattice. I. Conformation of the macromolecule
Authors: Kolinski Andrzej , Sikorski Andrzej
Published: April 2003

The star‐branched polymers on the tetrahedral lattice are studied by means of the Monte Carlo method. The influence of solvent quality on the dimensions of the coil is described for both linear and branched polymer systems of different functionality. It has been observed that the ratios of gyration radii 〈S2〉b/〈S2〉l are greater than those predicted theoretically for the random‐flight model. The fourth reduced moment of S2 distribution and the mean‐square separation of the branch ends from the center of gravity have been also computed. The changes in segment arrangement in the coil with increasing number of branches have been observed.
Polymerization of cyclohexene oxide with aluminum complex/silanol catalysts. V. A catalytic activity dependence on the aluminum chelate structure
Authors: Hayase S. , Onishi Y. , Yoshikiyo K. , Suzuki S. , Wada M.
Published: April 2003

The catalytic activity of an aluminum complex/silanol system was found to vary with the aluminum ligand as follows: β‐diketonate < β‐ketoester anion < ortho‐carbonylphenolate. Aluminum complexes with electron donating groups conjugated with a carbonyl group had higher catalytic activity. The catalyst activity correlated with the strength of interaction between the aluminum complex and the silanol; there were two such interaction mechanisms. Cyclohexene oxide was polymerized cationically by the activated proton of SiOH. The activated proton is considered to be similar to Brönsted acid on silica‐alumina catalyst; therefore, the catalyst would be a model of the silica‐alumina catalyst.
Poly(β‐pinenes) carrying one, two, and three functional end groups. II. Syntheses and characterization
Authors: Kennedy J. P. , Liao Tung‐Ping , Guhaniyogi Suhas , Chang Victor S. C.
Published: April 2003

Conditions for the convenient synthesis of linear poly(β‐pinenes) that carry one or two tert‐chloro end groups (∼Clt) and three‐arm star poly(β‐pinenes) that carry three termini have been worked out. Specifically, the polymer with one ∼Clt end group was prepared by the H2O/BCl3 system, whereas those with two and three ∼Clt termini were prepared by the use of p‐dicumyl chloride and sym‐tricumyl chloride/BCl3 inifer combinations. The ∼Clt‐terminated polymers were dehydro‐chlorinated to yield the corresponding olefins. The molecular weights of the products were low enough to permit infrared (IR) and quantitative 1H‐NMR investigations. Poly(β‐pinene‐b‐tetrahydrofuran) diblock copolymers have been synthesized by inducing the polymerization of tetrahydrofuran (THF) by the PβClt/AgCF3SO3 initiating system.
Properties of poly(p‐phenylene)s and the perdeuterated analog
Authors: Hsing Chih‐Fen , Khoury Issam , Bezoari Massimo D. , Kovacic Peter
Published: April 2003

ESR data for poly(p‐phenylene) (PPP) prepared from benzene and catalyst‐oxidant systems were compared with data for PPP obtained by a variety of other methods. The results were similar, except for the Yamamoto preparation, and comparable to the spin densities for heterocyclic polymers of thiophene, pyrrole, and selenophene. Deuterated PPP from C6D6 showed significant differences in properties, in comparison to ordinary PPP, in relation to molecular weight, color, solubility, and spins/g in electron spin resonance (ESR). The implications are discussed with regard to the mechanism of benzene polymerization by AlCl3‐CuCl2.
Condensation polymerization of oligomeric polydimethylsiloxanols in aqueous emulsion
Authors: Saam John C. , Huebner David J.
Published: April 2003

Polydimethylsiloxane oligomers with silanol ends condense in aqueous dispersion under mild conditions to form high polymers in the presence of sulfonic acid surfactants. The process follows a second‐order rate law in silanol if reversibility is taken into account. The second‐order rate constant is proportional to the area at the oil–water interface and is a complex function of surfactant concentration. The principal driving force is the heat of condensation of the water produced in the polymerization. A mechanism paralleling surface catalysis is offered in which a termolecular complex that consists of two surfactant molecules and one silanol end group reacts bimolecularly at the oil–water interface.
Phase‐transfer reactions catalyzed by phosphonium salts attached to polystyrene resins by spacer chains
Authors: Tomoi Masao , Ogawa Eiji , Hosokama Yasunori , Kakiuchi Hiroshi
Published: April 2003

The rate of reaction of 1‐halooctanes with aqueous sodium cyanide catalyzed by phosphonium salts attached to insoluble polystyrene resins by tetramethylene or heptamethylene spacers was studied as a function of catalyst particle size, degree of polymer crosslinking, percentage of ring substitution, and temperature. Rates of reaction of 1‐bromooctane with 17–38% ring‐substituted catalysts increased as spacer‐chain length increased. Rates of reaction of 1‐bromooctane decreased, whether the percentage of ring substitution increased or decreased from 17–19%. Rates of reaction of 1‐chlorooctane increased with increasing spacer‐chain length and decreasing percentage of ring substitution. Apparent activation energy for the reaction of 1‐bromooctane with 9% ring‐substituted, spacer‐modified catalysts was 9–10 kcal/mol and 13 kcal/mol with 17–19% ring‐substituted catalysts. The hydrophilicity of catalysts decreased with increasing spacer‐chain length and decreasing percentage of ring substitution. The mechanisms of reaction were discussed in terms of intrinsic reactivity and intraparticle diffusion limitations on the reaction rates.
Syntheses and characterization of N‐grafted poly(p‐phenylene terephthalamide)
Authors: Takayanagi Motowo , Katayose Teruo
Published: April 2003

N‐grafted poly(p‐phenylene terephthalamide)s (PPTA) were synthesized from PPTA and acrylonitrile or propylene oxide via metalation in a solution of the polymer in a sodium methylsulfinylcarbanion–dimethyl sulfoxide solvent at low temperatures. The introduction of these branches into the amide groups of PPTA increased solubility but decreased thermal stability. The effects of the branches on thermal properties and solubility are discussed. The structure of the graft copolymers is described on the basis of wide‐angle x‐ray diffraction, infrared spectra, and solubility.
Preparation of polysiloxanes from silicic acid. III. Preparation and properties of polysilicic acid butyl esters
Authors: Abe Yoshimoto , Misono Takahisa
Published: April 2003

Polysilicic acid butyl esters were prepared from 1‐butanol and silicic acid extracted from sodium metasilicate solution and water glass with tetrahydrofuran and hydrochloric acid. The properties of the esters were dependent on the degree of esterification (DE). The esters with a DE of less than ca. 60% could be isolated by precipitation with hexane and were highly liable to self‐condensation, whereas those with more than 60% DE were soluble in solvents and could not be precipitated easily. They underwent further condensation to form highly polymerized esters. Subsequent silylation allowed the isolation and characterization of these esters. The solvent‐soluble silylated esters had moderate thermal stability with decomposition points between 210 and 260°C and number‐average molecular weights of 10,000–30,000. From the evaluation of units structures of silylate it was suggested that polymer backbone was a pseudoladder structure.
Rigid‐ladder polymers: Polymers containing anthraquinone recurring units
Authors: Lee Byung H. , Marvel C. S.
Published: April 2003

In an attempt to synthesize some processable ladder or partial ladder polymers containing anthraquinone recurring units, leucoquinalizarin was treated with 3,3′‐diaminobenzidine. This polymer, which was a black powdery material, was slightly soluble in concentrated sulfuric acid and dimethylsulfoxide. Also, 1,5‐diamino‐2,6‐dimercaptoanthraquinone was condensed with 2,5‐dichloro‐p‐benzoquinone in pyridine to give a black powdery polymer. This was only partially soluble in concentrated sulfuric acid, but could be solubilized in alkali by reduction with sodium dithionite.
Carbon‐13 NMR microstructural characterization of dichlorocarbene adducts of polybutadiene
Authors: Komoroski Richard A. , Horne Samuel E. , Carman Charles J.
Published: April 2003

13C‐NMR has been used to examine a number of dichlorocarbene adducts of cis‐ and trans‐polybutadiene prepared in a two‐phase system. Dichlorocarbene was generated by reaction of aqueous or solid NaOH or KOH with CHCl3 in the presence of a phase transfer catalyst. Monomer compositions, comonomer sequence lengths, and stereochemical information were obtained for the resulting polymers. The polymers examined here were stereochemically pure and were treated as simple copolymers. Samples prepared using aqueous NaOH can be described as essentially random copolymers over the entire range of monomer composition. Samples prepared using solid alkali‐metal hydroxides contain a higher fraction of blocked units than a polymer of comparable composition prepared using aqueous NaOH. This blockiness can coincide with the presence of two glass transition temperatures and a two‐phase morphology as seen by transmission electron microscopy. Fractionation of a substantially blocked sample yielded a chlorine‐poor fraction which was a random copolymer and a chlorine‐rich fraction which was more blocked than the original unfractionated material.
Diaryliodonium salts as thermal initiators of cationic polymerization
Authors: Crivello J. V. , Lockhart T. P. , Lee J. L.
Published: April 2003

Diaryliodonium salts (I) undergo efficient thermal decomposition in the presence of copper (II) compounds. Such systems can be employed as a novel class of latent thermal initiators for cationic polymerization. An investigation of the mechanism of the reaction demonstrated that the copper (II) compound is first reduced to the corresponding copper (I) compound, which subsequently reduces the diaryliodonium salt. The cationic polymerization of some typical monomers using these new initiators was carried out to demonstrate the scope of their utility.
Synthesis and characterization of polymerizable bisphthalonitrile monomers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

The reactions of 4‐aminophthalonitrile (APN) with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BPTDA), and with 1,2,3,4‐benzenetetracarboxylic dianhydride (PMDA) have been studied to optimize the conditions for the synthesis of monomeric thermosetting bisphthalonitrile compound. Suitable procedures for the synthesis of the two monomers are presented. Elemental analyses, IR spectra, dynamic thermogravimetric analyses, differential scanning calorimetry, 1H‐NMR, and mass spectral studies have been used to characterize these compounds. Preliminary observations show that these materials can be polymerized to give high‐temperature‐resistant materials.
Investigation of the structure of polymeric microemulsions by proton magnetic resonance
Authors: Ballet François , Candau Françoise
Published: April 2003

The structure of polymeric microemulsions, viz. toluene/water/PS‐PEO graft copolymer/2‐propanol, has been studied by 1H‐NMR spectroscopy. Results show that at low water contents, the copolymer adopts a rather diffuse micellar structure in which the rotational mobility of the ethylene oxide units is little affected by the ternary solvent mixture. Above a critical water concentration (ca. 4%), a restriction in mobility of the ethylene oxide chains is observed which has been related to the formation of an inverse micellar structure with water solubilized within the particles. The study of the chemical shifts and linewidths of water protons indicates that initially most of the water is hydrogen bonded to the hydrophilic part of the copolymer, then is present in its free form in water aggregates. These results confirm previous data obtained by dialysis equilibrium experiments.
The aging of living α‐methylstyryl oligomers. II. The mechanism of aging
Authors: Comyn J. , Glasse M. D.
Published: April 2003

The living anions of oligomeric α‐methalystyrene in THF transform to a new anion in the presence of excess monomer and UV light. Kinetic results have demonstrated that one step in this process is the second‐order disappearance of monomer to form a dimeric intermediate. We have attempted to prepare this intermediate. Contrary to other reports, no hydrogen was liberated on terminating the reactions mixture with water, and an oily liquid which was identified as 1‐methyl‐1,3‐diphenyl‐cyclopentane was isolated. However, this is not the intermediate; the true intermediate is 2,5‐diphenylhex‐1‐ene and under the conditions of the reaction the former compound is formed from this by a cyclization reaction.
High‐temperature resins based on aromatic amine‐terminated bisaspartimides
Authors: Kumar Devendra , Fohlen George M. , Parker John A.
Published: April 2003

Various 4,4′‐bis{N2‐[4‐(4‐aminophenoxy)phenyl]aspartimido}diphenylmethane (APADM)‐type precursors were synthesized by Michael‐type reaction of an aromatic bismaleimide (1mol) with an aromatic diamine (2 mol) in an aprotic solvent. The structures of these materials were characterized by using Fourier‐transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR) and 13C‐NMR; their curing behaviors and thermal stabilities were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermal polymerization of APADM by heating it above its melting temperature produced a tough polymer. From these preimidized precursors, graphite‐fiber laminates were prepared and their mechanical properties evaluated. To elucidate the thermal curing mechanism and the structure of the polymer, a model compound, N‐[4‐(4′‐aminobenzyl) phenyl] aspartimidobenzene was synthesized. The gas‐chromatographic mass spectra of these compounds has suggested a mechanism for their decomposition. The structure of the polymer also was studied by using FT‐IR and 1H‐NMR.
The examination of bromine‐containing fire retardants in unsaturated polyester resins by means of pyrolysis residue analysis
Authors: Ravey M.
Published: April 2003

A method has been developed for following the bromine and weight losses of fire retarded UPE as a function of temperature. The results obtained by this method indicate that those bromine–containing fire retardants which exhibit a linear LOI–bromine concentration relation, the bromine concentration in the pyrolytically produced fuel remains more or less constant, while for those materials which deviate positively from the linear relation (that is they are more efficient), the bromine concentration in the fuel tends to peak at certain temperatures. When this effect is combined with variation in composition of the pyrolytic fuel, a situation can arise where a high bromine concentration coincides with a fuel particularly sensitive to flame quenching by bromine. Such a combined effect may be the reason why some brominated fire retardants are far more effective than others.
Radical polymerization of methyl methacrylate initiated by an enolizable ketone–carbon black system
Authors: Tsubokawa Norio , Shibata Naohiro , Sone Yasuo
Published: April 2003

The polymerization of methyl methacrylate (MMA) initiated by an enolizable ketone (R1COCH2COR2)‐carbon black system was investigated. Although enolizable ketone itself could not do so, the polymerization of MMA was initiated by enolizable ketone in the presence of carbon black. In addition, a chloranil‐enolizable ketone system was able to initiate the polymerization of MMA. It was found that the enol form of the ketone and quinonic oxygen groups on the carbon black surface played an important role in the initiation system; namely, it was considered that the polymerization was begun by the ketone radical (R1COCHCOR2) formed by a one‐electron transfer reaction from enolate ion to quinonic oxygen groups. The effect of solvent on the process was also studied. The rate of the polymerization increased, depending on the solvent used, in the following order: benzene < 1,4‐dioxane < dimethyl sulfoxide < N,N‐dimethylformamide < N‐methyl‐2‐pyrrolidone. Furthermore, it became apparent that during the polymerization poly(methyl methacrylate) was grafted onto the carbon black surface (grafting ratio was ca. 40% when benzene was used as solvent) and the carbon black obtained gave a stable colloidal dispersion in organic solvent.
Kinetcis and mechanism of HCN‐evolution from the oxidation of polyurethanes
Authors: Jellinek H. H. G. , Dunkle S. R.
Published: April 2003

The oxidative degradation of aliphatic, aromatic, and secondary polyurethanes was investigated over a range of temperatures of 440–1000°C as a function of time and oxygen concentration. The degradation was studied with special emphasis on HCN‐evolution; its rate constants and Arrhenius equations were determined. In some of the temperature ranges reactions were diffusion controlled. At relatively low temperatures the oxidative rate constant was a linear function of oxygen concentration, whereas at higher temperatures oxidation of the evolved HCN took place in passage through the hot zone of the furnace; in addition, at these higher temperatures thermal degradation of the polymers and thermal decomposition of HCN in the hot zone occurred simultaneously with oxidation to an appreciable extent. The kinetics and mechanism proposed and quantitatively evaluated account well for the experimental results.
Styrene and polystyrene microemulsions. I. Solubility in the W/O system
Authors: Gan Leong M. , Chew Chwee H. , Friberg Stig E.
Published: April 2003

The solubility of styrene, its oligomers, and different molecular weight polymers was determined in W/O microemulsions stabilized by sodium dodecyl sulfate and pentanol. The results showed a complex pattern due to the interactions with pentanol, surfactant, and associated structures.
Behavior of antioxidant in polyethylene
Authors: Matsumoto Shiro
Published: April 2003

The changes in the oxidative induction period of polyethylene and the concentration of antioxidant, 4,4′‐thio‐bis(3‐methyl‐6‐t‐butyl phenol), in polyethylene during thermal aging were investigated. The concentration decreased following a first‐order kinetics. The induction period depended only on the antioxidant concentration and was independent of the aging conditions. The Arrhenius plot of the rate constants of the concentration decrease was linear above and below the polyethylene melting range, and an activation energy was obtained. The main factor in the concentration decrease was the evaporation of the antioxidant from the surface, and the evaporation rate constant of the antioxidant dissolved in polyethylene was obtained.
A new solid‐phase polymerization—metal phthalocyanine sheet polymers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

The thermal reactions of pure metal(11) 4,4′,4″,4′″‐phthalocyanine‐tetracarboxylic acids of copper, cobalt, and nickel at 350–400°C in vacuum have been studied using Fourier transform infrared spectrometry, gas chromatography, and mass spectrometry. Based on these observations, novel in situ reactions for the synthesis of heat‐resistant phthalocyanine “sheet” polymers are described. The poly(metal phthalocyanine) polymers of copper, cobalt, and nickel so synthesized have been characterized by elemental analysis, infrared spectroscopy, and dynamic thermogravimetric analysis. The most noteworthy property of these polymers is their extreme resistance to heat in an anaerobic atmosphere and their high char yields (89–93%) at 800°C in a nitrogen atmosphere.
Anionic polymerization of lactones initiated by alkali graphitides. I. Polymerization of ϵ‐caprolactone initiated by KC24
Authors: Rashkov Iliya B. , Gitsov Ivan , Panayotov Ivan M. , Pascault Jeanpierre
Published: April 2003

The influence of the reaction conditions (time, temperature, concentrations of the monomer, and the initiator) on the amount and composition of the oligomers and high molecular products formed during the heterogeneous anionic polymerization of ϵ‐caprolactone was investigated. The polymerization was initiated by KC24 in xylene or tetrahydrofuran. Conditions were found under which intra‐ and intermolecular transesterification was strongly suppressed, thus providing the opportunity for the formation of polyesters with viscometric molecular masses of more than 300,000 and good yields (80% and higher). The total quantity of products with a viscometric molecular mass below 2500 did not exceed 15%; that of the cyclic dimer was not in excess of 5%. Peculiar features of the KC24 initiated polymerization are the insignificant rise in the number of oligomers and the formation of high polymers even in strongly diluted solutions of ϵ‐caprolactone (0.2 mol/L and lower). The quantity and molecular mass of the polymers obtained decreased as the temperature increased. It was also established that the polymerization of the cyclic dimer of ϵ‐caprolactone is not initiated by KC24.
Long‐lived polymer radicals. IV. Reactions of poly(N‐methylacrylamide) and poly(N‐methylmethacrylamide) radicals with binary mixtures of vinyl monomers
Authors: Sato Tsuneyuki , Iwaki Takahiko , Otsu Takayuki
Published: April 2003

N‐methylacrylamide (NMAAm) and N‐methylmethacrylamide (NMMAm) were polymerized to give polymer microspheres containing living propagating radicals. The microsphere polymer radicals were allowed to react with some binary mixtures of vinyl monomers including alternating copolymerization combinations. The reaction processes were investigated by ESR spectroscopy. In the poly(NMMAm) radical/methyl methacrylate (MMA)/styrene (St) system, the propagating radical from MMA was mainly observed at the higher MMA concentration, while polySt radical prevailed at the lower MMA concentration. In the poly(NMMAm) radical/α‐methylstyrene (α‐MeSt)/diethyl fumarate system, the α‐MeSt radical was exclusively observed, while the maleic anhydride (MAn) radical was predominantly observed in the α‐MeSt/MAn system. In the MAn/diphenylethylene system, the propagating radicals from both monomers were observed at comparable concentrations. The poly(NMAAm) microsphere radical behaved differently in the reaction with the MMA/St mixture. The poly(NMAAm) microsphere was found to incorporate preferentially St, leading to formation of the St radical. The St preference was enhanced in the St/cyclohexyl methacrylate (CHMA) system. These results were in agreement with those of block copolymerization via the reaction of poly(NMAAm) radical with the MMA/St or CHMA/St mixture, where the compositions of the resulting polymers were analyzed by pyrolysis gas chromatography.
Preparation of polymer colloids by chemical reactions in aerosols. I. Poly(p‐tertiarybutylstyrene)
Authors: Partch Richard , Matijević Egon , Hodgson Anthony W. , Aiken Barlow E.
Published: April 2003

A procedure was developed by which polymer colloids can be prepared by polymerizing aerosol droplets of monomers with an initiator in the vapor state. This work describes the formation of poly(p‐tertiarybutylstyrene) particles by exposing the corresponding monomer droplets to trifluoromethanesulfonic acid. It was found that the monomer‐to‐initiator mass ratio is the critical factor in determining the uniformity and morphology of the particles. Under ideal conditions spheres of narrow size distribution are obtained. Otherwise porous particles or soft particles with whiskers may develop. The aerosol was prepared in a falling film generator, but other procedures for producing monomer droplets may be used.
Photoconductivity and hole transport in polymers of aromatic amine‐containing methacrylates
Authors: Stolka Milan , Pai Damodar M. , Renfer Dale S. , Yanus John F.
Published: April 2003

Substantial hole transport can be achieved in organic polymers simply by incorporating aromatic amine groups into the monomer. Hole mobilities similar to or greater than those in poly(N‐vinyl‐carbazole) (PVK) were measured in a series of high molecular weight arylamine‐substituted polymethacrylates. The hole transport in these polymers is electric‐field‐dependent as in PVK, varying between E and E2 within a range of 4 × 104 − ∼9 × 105 V/cm. The polymers also exhibit carrier generation in ultraviolet (UV) light in the range of absorption. Synthesis of the monomers, their polymerization, and the general properties of these polymers are discussed.
Heat‐resistant metal phthalocyanine imide copolymers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

Thermally stable poly(metal phthalocyanine)imide copolymers were prepared with metal(11) 4,4′,4″,4‴ ‐phthalocyanine tetraamines, 4,4′ ‐diamino diphenyl ether, and 3,3′,4,4′ ‐benzophenone tetracarboxylic dianhydride. Variables such as molar concentrations of the reagents, solvents, and temperature were investigated to optimize the conditions of the polymerization. Inherent viscosity, and infrared (IR) spectral and thermogravimetric analysis (TGA) studies were done to characterize the polymers. These polymers are stable and thier decomposition temperatures both in air and nitrogen are greater than 500°C. Their char yields at 800°C in nitrogen varied between 60 and 76%, depending on the type and concentrations of the metal phthalocyanine tetraamines. These polymers can be used to produce heat‐stable films, fibers, varnishes, and adhesives.
Reactivities of N‐alkylitaconimides in radical copolymerizations with styrene or methyl methacrylate
Authors: Oishi Tsutomu , Momoi Masaaki , Fujimoto Minoru , Kimura Tadashi
Published: April 2003

The radical copolymerizations of N‐alkylitaconimide (RII, R = CH3, C2H5, n‐C3H7, i‐C3H7, n‐C4H9, i‐C4H9, CH2CH2Cl, CH2C6H5) (M1) with styrene (ST) (M2) or methyl methacrylate (MMA)‐(M2) were carried out at 60°C, using azobisisobutyronitrile as an initiator in tetrahydrofuran in order to clarify the substituent effect on the copolymerizations. The monomer reactivity ratios r1, r2 and the Q1 and e1 values were determined from the results obtained. It was found that the relative reactivities 1/r2 of RII toward an attack by a poloystyryl radical could be correlated not by the steric‐substituent constant Es of the alkyl group in RII but by the polar‐substituent constant σ* in Taft's equation: log(1/r2) = ρ*σ* + δ Es. According to the above equation, the ρ* and δ values were obtained as 0.55 and 0, respectively, in the RII‐ST system, while in the RII‐MMA system, the ρ* and δ values were obtained as 0.49 and 0, respectively. It was also observed that the Q1values for RII were proportional to σ* constants and that the e1 values for RII were independent of σ* substituent constant. It was also found that the weight‐average molecular weights of the copolymers are between 8.5 × 104 and 32.5 × 104.
Stereochemistry of photoinitiated emulsion polymerization
Authors: Turro Nicholas J. , Pierola Ines F. , Chung Chao‐Jen
Published: April 2003

The tacticity of poly(methyl methacrylate) (PMMA) samples made by emulsion polymerization (EP) has been determined by NMR spectroscopy at higher resolution than any previous study. When photoinitiation is employed at room temperature, the polymer obtained is highly syndiotactic and more stereoregular than that obtained in homogeneous radical polymerization under the same conditions. The percentage of racemic dyads and the length of racemic sequences vary significantly with the degree of conversion and the temperature, but not with variation of the hydrophobic or the hydrophilic part of the detergent molecules. A magnetic field of 5 kG or less accelerates the polymerization reaction and increases the polymer molecular weight when dibenzyl ketone is employed as oil‐soluble photoinitiator, and has an indirect influence on the polymer tacticity. From measurements of the temperature dependence of the polymer steric composition, the difference of activation enthalphy and entropy of the meso and racemic additions have been calculated. The values do not follow the correlations from precedent literature for radical polymerization in solution if the reaction is considered a first‐order Markov process. The persistence ratio p depends on the detergent and the temperature of the EP; in some cases its difference from unity exceeds the experimental error. These results are interpreted as a conformational effect of the locus of the polymerization in the first stage of the EP (when micelles are present) that favors the racemic addition more than is expected in a homologous solvent such as an alkane, e.g., at the same temperature.
A regenerable immobilized NADH model. Reduction of α,α,α‐trifluoroacetophenone by 1, 4‐dihydronicotinamide anchored to macroreticular polystyrene
Authors: Eling Berend , Challa Ger , Pandit Upendra K.
Published: April 2003

A regenerable dihydronicotinamide immobilized on a macroreticular polystyrene carrier was developed and used in an aqueous medium for the reduction of trifluoroacetophenone to the corresponding alcohol. It was shown that the second‐order rate constant for the polymer‐bound reagent is significantly lower than that of the low‐molecular‐weight analog 1‐benzyldihydronicotinamide. The observed reaction rate, however, was of the same order of magnitude as that due to enrichment of substrate in the polymeric pores. It was possible to depress the undesired side reactions to 10–15% per reaction cycle, thereby allowing reutilization of the functionalized polymer.
Copolymerization parameters of substituted aniline monomers
Authors: Chatterjee S. K. , Singh B. P. , Pachauri L. S.
Published: April 2003

The Kelen‐Tüdös linear graphical method was used to determine the copolymerization parameters of some halogen‐substituted (e.g., Cl, Br, I) aniline monomers. It was found during copolymerization with p‐aminobenzoic acid or p‐aminophenol that the reactivity of these monomers followed the order of their basic strength. The order of their basic strength. The order of their reactivity, however, was reversed if they copolymerized with sulfanilic acid (SA). This reversal has been interpreted in terms of the resonance stabilization of monomers, the nature of the acidic functional groups present in the comonomer, and the influence of electron‐accepting or electron‐donating groups present in the comonomers.
Radiation‐induced oxidation of polymers. Effect of antioxidant and antirad agent on oxygen consumption and gas evolution
Authors: Arakawa Kazuo , Seguchi Tadao , Hayakawa Naohiro , Machi Sueo
Published: April 2003

The effects of antioxidants and of an antirad agent mixed in polyethylene and ethylene‐propylene copolymer were investigated by means of oxygen consumption and gas evolution. The antioxidants were NBC, Irganox 1010, and DPPD, and the antirad agent was propyl fluoranthene (PFR). A small amount of the antioxidant (0.5 phr) in polymer decreased oxygen consumption by one‐half or one‐third compared with pure polymer, but the activity was lost with increasing irradiation. The antirad agent also decreased oxygen consumption and it was assumed to act as the energy transfer agent in the polymer matrix.
Cis‐trans isomerization of polybutadiene double bonds during olefin metathesis
Authors: Kumar V. G. , Hummel K.
Published: April 2003

The cis‐trans isomerization of polybutadiene double bonds during metathesis degradation using WCl6/(CH3)4Sn catalyst system has been estimated kinetically along with productive metathesis. The isomerization was followed both for noncrosslinked and for crosslinked polybutadiene. Ninety‐six percent cis‐1, 4 units are found to isomerize into ca. 75% trans‐1, 4 units. The rate of stereomutation is found to be different in the presence and absence of a low‐molecular‐weight olefin. The results are explained with the help of a stereo model originally proposed by Katz (Advances in Organometallic Chemistry, Academic, New York, 1977, Vol. 16.)
Photocleavage of the acetate of a hydroxyphenyl benzotriazole UV absorber: The search for a photo‐Fries rearrangement product
Authors: Li Xiao‐Bai , Winnik Mitchell A. , Guillet James E.
Published: April 2003

The acetate ester of 2‐(2H‐benzotriazol‐2‐yl)‐4‐methyl phenol [Tinuvin P] upon irradiation, either in methylene chloride solution or in poly(methyl methacrylate) films, undergoes a photocleavage reaction to regenerate Tinuvin P. No photo‐Fries rearrangement product can be detected.
Preparation of AB polyacylthioureas and related copolyacylthioureas
Authors: Shimano Yasuo , Sasaki Shoichi
Published: April 2003

Reaction of sulfinylaminobenzoyl chlorides with lead thiocyanate gave sulfinylaminobenzoyl isothiocyanates (SBIs), from which were derived aminobenzoyl isothiocyanate hydrochlorides (ABIHs). AB polyacylthioureas (PATUs) with inherent viscosities of up to 0.28 dL/g were obtained by treating the SBI with an equivalent of water in N‐methyl‐2‐pyrrolidone (NMP). Low‐temperature solution polyaddition of the ABIH afforded AB PATU with inherent viscosities of up to 0.66 dL/g, which were further increased to as high as 0.75 dL/g by adding lithium bases to the polymerization mixtures. Polyaddition of isophthaloyl diisothiocyanate with intermediate diamines formed by hydrolyzing the adducts of SBI and aromatic diamines afforded copolyacylthioureas with inherent viscosities of up to 1.15dL/g. The copolymers were generally soluble in NMP, whereas solubilities of the AB PATU in analogous solvents were relatively low. Thermogravimetric analyses in both air and nitrogen exhibited weight losses of 5% at 204–236°C for AB PATU and at 170–192°C for the copolymers.
An investigation of some aspects of the photodegradation of plasticized PVC
Authors: Williams G. E. , Gerrard D. L.
Published: April 2003

Poly(vinyl chloride) (PVC) plasticized with a phthalate ester was photodegraded with both farultraviolet (λ mainly 254 nm) and near‐ultraviolet (λ > 280nm) light. Multiple changes in the infrared spectra of the films were thus induced. The PVC underwent oxidation, dehydrochlorination, and simultaneous chain scission and crosslinking. Some of the phthalate ester was split along the aliphatic side chains, leading to lower‐molecular‐weight analogs, while a further fraction became firmly bound to the crosslinked part of the PVC. Reaction sequences to account for this complicated series of changes are suggested.
Direct mass spectrometry of polymers. VII. Primary thermal fragmentation processes in polycarbonates
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio
Published: April 2003

The primary fragmentation mechanisms in the thermal decomposition of several polycarbonates were studied by direct pyrolysis into the mass spectrometer. Our results indicate that ester exchange reactions predominate in the primary thermal fragmentation process of polycarbonates, causing the formation of cyclic oligomers.
Direct mass spectrometry of polymers. VIII. Primary thermal fragmentation processes in polyurethanes
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio
Published: April 2003

The primary fragmentation mechanisms in the thermal decomposition of several polyurethanes were studied by direct pyrolysis into the mass spectrometer. Ester exchange reactions predominate in the primary thermal fragmentation process, causing the formation of cyclic oligomers, which are subsequently cleaved to open‐chain oligomers containing hydroxyl end groups.
Direct mass spectrometry of polymers. IX. Copoly(carbonate‐urethanes) prepared by reorganization of polycarbonates with piperazine
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio
Published: April 2003

A detailed analysis of the reaction products generated by reorganization of polycarbonates with piperazine, performed by direct mass spectrometry methods, has shown that this reaction actually follows the pathway postulated and that, at 50% piperazine incorporation level, urethanediphenol compounds are almost exclusively produced. This allowed us to obtain, by repolymerization with phosgene, alternating copoly(carbonate‐urethanes) with thermal stabilities comparable to those of the parent polyurethanes. The primary fragmentation mechanisms in the thermal decomposition of these copolymers were studied by direct pyrolysis into the mass spectrometer. Ester exchange reactions predominate here, causing the formation of cyclic oligomers, which are subsequently cleaved to open‐chain oligomers containing hydroxyl end groups.
Some aspects of tailoring flame retardancy in HET‐acid‐based flame retardants
Authors: Vijayakumar Chinnasamy Thangavel , Fink Johannes Karl
Published: April 2003

HET acid was condensed with either ethylene glycol or 1,4‐butanediol to yield the respective oligoesters. These oligoesters were characterized by molecular weight, measured by vapor‐pressure osmometry. The degradation mechanism of oligoesters of HET acid with either ethylene glycol or 1,4‐butanediol was elucidated. The thermal properties of these polyesters were studied using differential thermal analysis and thermal volatilization analysis. The mechanism of degradation was proposed on the basis of pyrolysis–gas chromatography studies, the degradation products being subsequently identified by mass spectrometry. It turned out that in the course of decomposition, hexachlorocyclopentadiene was formed, which is believed to be the active substance for flame retardance in these systems. The aspect of tailoring flame retardancy by changing the chemical environment, i.e., by using different diols, is discussed.
Polystyrene degradation during combustion
Authors: Brauman S. K. , Chen I. J. , Matzinger D. P.
Published: April 2003

A novel driven‐rod, radiant pyrolysis technique has been used to study steady‐state linear regression of vertically mounted polystyrene rods degrading under high‐flux, nonflaming conditions that simulate those of combustion. With this technique a reliable, reproducible temperature‐depth profile (identical for combustion and radiant pyrolysis) for polystyrene has been obtained and used to successfully calculate the observed mass loss rate. Residues and volatiles have been analyzed. Mechanistic treatment of these results indicates that degradation of polystyrene under these rapid‐heating conditions is similar to that under more conventional slow‐heating conditions in the absence of oxygen. Oxidation is unimportant in the condensed‐phase degradation of polystyrene in this configuration. This radiant pyrolysis technique has also been used to obtain the heat of gasification of polystyrene.
Terpolymerization of acrylonitrile, styrene, and 2,3‐dibromopropyl acrylate
Authors: Saric Karla , Janovic Zvonimir , Vogl Otto
Published: April 2003

The terpolymerization of acrylonitrile with styrene and 2,3‐dibromopropyl acrylate in emulsion and dimethyl formamide solution was investigated. Polymerizations, when stopped at low conversions, yielded terpolymers that showed good agreement between experimental and theoretical copolymerization composition data, calculated from the Alfrey‐Goldfinger equation. The relationship between monomer feed and terpolymer compositions is displayed on triangular coordinate graphs proposed by Slocombe. By using a computer program the lines of unique composition and binary azeotropic composition for both systems were established. In the case of emulsion polymerization the azeotropic ternary point was determined at a molar ratio for acrylonitrile/styrene/2,3‐dibromopropyl acrylate of 0.27/0.61/0.12. The experimental results of emulsion terpolymerization fit the calculated curves satisfactorily over a wide range of monomer compositions up to high conversions. The influence of 2,3‐dibromopropyl acrylate on the thermal and flammability characteristics of the terpolymers is described.
Preparation and polymerization of thyroxine methacrylate monomers
Authors: Burdick Brent A.
Published: April 2003

Thyroxine methyl ester amides of mono‐, di‐, and tri‐glycyl methacrylates have been prepared. Water‐soluble polymers formed from thyroxine methacrylate monomers by free‐radical copolymerization with acrylamide had molecular weights of (2–4) × 104 (by viscometry). A fluorescent polymer was prepared by copolymerization with a fluorescein methacrylate monomer. Similarly, a polymeric thyroxine material was prepared with amine functionality by copolymerization with N‐3‐aminopropylmethacrylamide. These polymers may have interesting biological and immunochemical properties.
Phosphorus‐containing imide resins. III
Authors: Varma Indra K. , Fohlen George M. , Parker John A.
Published: April 2003

Three imide monomers were prepared by reacting maleic anhydride; 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride, bis(m‐aminophenyl) methyl phosphine oxide, and tris(m‐aminophenyl) methyl phosphine oxide, and tris (m‐aminophenyl) phosphine oxide. The characterization was done by elemental analysis and infrared spectroscopy (IR). These monomers were soluble in acetone. Their thermal polymerization was investigated by differential scanning calorimetry (DSC). The temperature of the exothermic peak position was influenced by the presence of free amino group in the monomer and was about 50°C higher in monomers that did not contain amino group. Anaerobic char yield of imide monomers cured at 270 ± 2°C for 30 min ranged from 58 to 64%. Graphite cloth laminate fabricated from one of these resins had a limiting oxygen index of 100.
Dielectric investigation on mercerized cotton and some of its hydrolysis residues
Authors: Elshafee E. , Moteleb M. M. Abdel , Kinawi A. , Shinouda H. G. , Rizk H. A.
Published: April 2003

The dielectric behavior of samples of mercerized and hydromercerized cotton was studied in a temperature range of 10–60°C at frequencies of 0.1–10,000 kc/s. The effects of mercerization of medicated cotton and mild hydrolysis of mercerized cotton on the two loss peaks γ and β, found in medicated cotton in this frequency‐temperature range, 1 were explored. Mercerization lowers the height of both peaks and, in addition, reveals another β relaxation process in a higher frequency range. Hydrolysis of mercerized cotton removes the γ process, causes variations in the levels of the first β maximum, depending on the time of hydrolysis, and enhances the second β process. These absorption peaks and the effects of various variables are discussed in terms of molecular structure and possible molecular motions responsible for their occurrence.
Ceric‐initiated polymerization onto polyacrylonitrile with carbohydrate end groups. Graft versus block copolymer formation
Authors: Fanta George F. , Burr Robert C. , Doane W. M.
Published: April 2003

Starch‐g‐polyacrylonitrile (starch‐g‐PAN) copolymers were prepared by ceric ammonium nitrate initiation, and the major portion of the starch in these graft copolymers was then removed by acid hydrolysis to yield PAN with oligosaccharide end groups. Although these PAN‐oligosaccharide samples reacted with methyl methacrylate in the presence of ceric ammonium nitrate, the resulting products were largely graft copolymers rather than the expected PAN‐poly(methyl methacrylate) (PMMA) block copolymers. The following evidence is presented for a PAN‐g‐PMMA structure: (i) PAN without oligosaccharide end groups also produced a copolymer with methyl methacrylate under our reaction conditions. (ii) Starch‐g‐PAN (51 or 37% add‐on) was a less reactive substrate toward ceric‐initiated polymerization than PAN with oligosaccharide end groups. (iii) Low‐add‐on (18%) starch‐g‐PAN reacted with methyl methacrylate to give a final graft copolymer in which a large percentage of PMMA was grafted to the PAN component rather than to starch.
Decomposition rate studies of azo initiators in solution
Authors: Idage B. B. , Vernekar S. P. , Ghatge N. D.
Published: April 2003

Rates of decomposition of di(3‐hydroxybutyl)‐2,2′‐azobisisobutyrate, di(4‐hydroxybutyl)‐2,2′‐azobisisobutyrate, di(2‐hydroxyethyl)‐2,2′‐azobisisobutyrate, di(2‐chloroethyl)‐2,2′‐azobisisobutyrate, and di(2‐hydroxypropyl)‐2,2, all of which are useful in the polymerization of butadiene and isoprene, were measured by nitrogen evolution technique at 60, 70, and 80°C, respectively, in each of the three solvents, namely, toluene, dioxane, and N,N‐dimethylformamide. The thermal decompositions of these azo compounds in solution were first order, and the Arrhenius equation was used to calculate their activation energies.
Photoinitiated polymerization: Effect of the initiator absorbance
Authors: Lissi E. A. , Zanocco A.
Published: April 2003

The dependence of the polymerization rate and average chain length on the absorbance of the initiator in the photoinitiated polymerization of vinyl monomers has been evaluated. It is found that a simple model taking into account the spatially inhomogeneous free‐radical distribution predicts an order in initiator that changes from 0.5 at low concentration to −0.5 at high concentration. The maximum rate is obtained, irrespective to any other condition, when the absorbance of the initiator is 2.51.
Comparative recalculation of the monomer reactivity ratios in copolymerization for styrene and methyl methacrylate
Authors: Leicht R. , Fuhrmann J.
Published: April 2003

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

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

The preparation of monodisperse polystyrene substituted with single dimethylamino groups is described. Three methods are adopted. The first involves the use of a dimethylamino‐substituted initiator to give an end amino group. The second uses an ester coupling reaction with a dimethylamino‐substituted methyl valeric ester to give a central amino substituent. The third method, which is capable of giving an amino substituent at any selected place along the chain, uses a dimethyl‐amino‐substituted butadiene derivative as a comonomer in a sequential polymerization. This latter method takes advantage of the unusual reactivity ratios of styrene and dienes in anionic copolymerization.