bluuebunny/crossref_metadata_2025 huggingface dataset:
Oscillatory reactions in polymer systems
Authors: Ishiwatari Tsutomu , Kawagishi Mitsuru , Mitsuishi Masaru
Published: April 2003

Modified Belousov–Zhabotinskii (BZ) oscillation reactions were studied in the systems of ferroin or tris(2,2′‐bipyridyl)ruthenium(II) dichloride or the polymerized ruthenium complex as electron transfer agents and sulfuric acid or polyethylenesulfonic acid (HPES) as acidic media. HPES was a good acidic medium for the chemical oscillation in spite of a long induction period. Moreover, chemical oscillation was observed at low concentration of HPES, where no oscillation was observed in the solution of sulfuric acid. On the other hand, no oscillation was observed in the solution of polystyrenesulfonic acid (HPSS). These results were discussed from the standpoint of the nature of polyelectrolytes.
Synthesis of aromatic polyesters by direct polycondensation with triphenylphosphine dichloride
Authors: Kitayama Shinichiro , Sanui Kohei , Ogata Naoya
Published: April 2003

Aromatic polyesters of high molecular weights were prepared by the direct polycondensation reaction of dicarboxylic acids and bisphenols or hydroxybenzoic acids with triphenylphosphine dichloride as a new condensing agent. Reaction conditions, including the amount of reagents and the concentration of monomer, solvent, and acid acceptor, were investigated. The aromatic polyester with the solution viscosity of 1.66 dL/g was obtained from bisphenol. A and terephthalic and isophthalic acid in quantitative yield under the optimum condition. The principal advantage of this condensing agent is that, based on the recycling system, recovered triphenylphosphine oxide can be reconverted to the reactive triphenylphosphine dichloride by treating with phosgene or oxalyl chloride.
Photoinduced decomposition of the polybromostyryl carbanions
Authors: Königsberg Itzhak , Jagur‐Grodzinski Joseph
Published: April 2003

The photoinduced decay in THF of the sodium salt of the polybromostyryl carbanions (PSB̄) was investigated in vacuum at −78°C. Maximal rates of decay were obtained when the wavelength of the incident light corresponded to the absorption maximum of the PSB̄ at 495 nm. The quantum yield of the process was found to be 13 eq./Einstein. Products of the photostimulated decompositions at −78°C were found to be different from those obtained as result of the “dark” thermal decomposition at –20°C. Decomposition of the PSB̄ carbanions was accompanied by evolution of Br− anions and by formation of polyaryl carbanions absorbing in the 270‐ to 400‐nm range. The mechanism of the photoinduced decomposition of PSB̄, though basically analogous to the SRN1 reaction mechanism, was found to differ significantly from the latter. The intramolecular dissociative electron transfer was assumed to represent its initiation step. Its propagation was attributed to the addition of PSB̄ to the initially formed biradicals, ejection of Br− from the resulting radical anions, and intramolecular electron transfer yielding polybromostyryl radicals. Products of the photoinduced decomposition of PSB̄ remained soluble in THF when the intensity of the incident light was relatively weak, though their molecular weight distribution broadened. Insoluble, highly crosslinked polymers were obtained when the intensity of the incident light was very high.
A regenerable immobilized NADH model III. Reduction of N‐methylacridinium perchlorate by immobilized 1,4‐dihydronicotinamide
Authors: Eling B. , Hoogsteen W. , Challa G. , Pandit U. K.
Published: April 2003

A regenerable dihydropyridine, immobilized on a macroreticular polystyrene resin, reduces the N‐methylacridinium ion. The influence of the polymeric network on this hydride transfer reaction was studied. During the reaction charge was built up in the resin and the transport of substrate was hindered, due to electrostatic repulsion. As a result, the reaction rate decreased as the reduction proceeded. It was observed that the charge accumulation was dependent on the site location. Reutilization of the polymeric reagent for the reduction of the acridinium ion amounted to 93% per cycle and was better than that observed (earlier) for the reduction of the ketone trifluroacetophenone.
Preparation and properties of photocrosslinkable poly(2‐vinyloxyethyl cinnamate)
Authors: Watanabe Shoji , Kato Masao , Kosakai Shohei
Published: April 2003

Photocrosslinkable poly(2‐vinyloxyethyl cinnamate)'s with substituents in para position of cinnamoyl moieties were prepared cationically. Polymerizability of the monomers was markedly governed by the substituent and the glass transition temperatures of the polymers varied in the range of about 0 to 72°C. The photocrosslinking mechanism in relation to the photosensitivity of the polymers is discussed on the basis of spectroscopical studies.
Syntheses of monomethoxy polyethyleneglycol vinyl ether macromonomers and their radical copolymerization with maleic anhydride
Authors: Suzuki Tohru , Tomono Tsugikazu
Published: April 2003

In order to develop new biocompatible materials, monomethoxy polyethyleneglycol vinyl ethers (Me(EG)n VE, n = 1–39) were synthesized from the corresponding monomethoxy polyethyleneglycol with acetylene. Successful purification of the macromonomers was performed by some adsorption procedures such as charcoal and ion‐exchange resin treatments. The Me(EG)n VE macromonomers were easily copolymerized with maleic anhydride (MAn) to give alternating copolymers. The copolymerization rates significantly depended on the ethyleneglycol chain length of the Me(EG)n VE, resulting in relatively lower polymerization rate of higher MW macromonomer. The use of nonelectron donor solvent such as carbon tetrachloride led to higher yields and higher MW of copolymers.
Copolymers containing alternating sequences of nucleic acid–base pairs. I. Monomer synthesis
Authors: Aponte Maria A. , Butler George B.
Published: April 2003

To provide suitable monomers for a study designed to synthesize copolymers containing alternating sequences of nucleic acid base pairs, the following electron‐donor monomers were synthesized: 9‐(2‐vinyloxyethyl)adenine, 1‐(2‐vinyloxyethyl)thymine, and 1‐(2‐vinyloxyethyl)‐cytosine. The following electron‐acceptor monomers were also synthesized: 9‐(2‐maleimidoethyl)adenine, 1‐(2‐maleimidoethyl)thymine, and 1‐(2‐maleimidoethyl)cytosine. The methods of synthesis are described along with their characterization by the usual methods, and their physical properties are reported. A variety of novel compounds were required as intermediates in the above identified syntheses. This paper also includes characterization of these compounds and a report of their physical properties.
The use of organotin compounds in the thermal stabilization of poly(vinyl chloride). VI. An assessment of the relative importance of HCl‐scavenging, exchange, and addition reactions
Authors: Ayrey G. , Hsu S. Y. , Poller R. C.
Published: April 2003

Reactions of PVC with three representative stabilizers Bu2SnY2 (Y = OCOC11H23, SCH2COOCH2CH(Et)CH2CH2CH2CH3, OCOCH=CHCOOMe) in solution and under nitrogen were studied by two principal methods. First, using stabilizers with radioactive labels in the Y groups, the uptake of these groups by virgin and degraded polymer was measured. The UV‐visible absorption spectra of the stabilized polymers are discussed. Second, the effect of these three stabilizers on the rate of elimination of hydrogen chloride from heated PVC was studied. It is shown that the effects of HCI‐scavenging and of exchange reactions in suppressing the evolution of HCI can be separately evaluated. The thermal decomposition of dibutyltin bis(methyl maleate) to give maleic anhydride is reported. Interpretation of the observations is made in terms of assessing the relative importance of the various polymer–stabilizer reactions in promoting stabilization.
PVC miniemulsion polymerization. I. Origin of droplet families
Authors: Dewald R. C. , Hart L. H. , Carroll W. F.
Published: April 2003

A soap/alcohol miniemulsion in combination with an homogenized mixture of monomer and initiator is utilized to generate PVC plastisol. Droplet distributions generated consist of two distinct types. Judicious control of soap‐to‐alcohol ratio allows control of the number and size of the smaller droplet family; homogenization and initiator water solubility affect the other. Final latex particle distribution may be unimodal or bimodal depending upon manipulation of these factors.
Electroinitiated copolymerization of indene and α‐methylstyrene
Authors: Toppare L. , Eren S. , Akbulut U.
Published: April 2003

Electroinitiated cationic copolymerization of indene and α‐methylstyrene in dichloromethane has been investigated by constant potential electrolysis. The effects of copolymerization potential and the temperature on the copolymer composition was also studied. Constant potential electrolysis was found to be a suitable method to study the potential effects on copolymer compositions and the reactivity ratios of the monomers. The reactivity ratios were calculated according to integrated Lewis–Mayo equation.
Functionalization of polymeric organolithium compounds. Oxidation
Authors: Quirk Roderic P. , Chen Wei‐Chih
Published: April 2003

The oxidation of poly(styryl)lithium with molecular oxygen was investigated in the solid state (with and without N,N,N′, N′‐tetramethylethylenediamine) in benzene (with and without N,N,N′, N′‐tetramethylethylenediamine) and in benzene/tetrahydrofuran (THF) solutions. The oxidation products included the corresponding polystyrene dimer [(PS)2], the dimeric poly(styrene) peroxide (PSO2PS), poly(styrene) hydroperoxide (PSO2H), and the hydroxyl‐terminated polymer (PSOH). The hithertofore unreported macroperoxide (PSO2PS) accounts for approximately 50% of the dimeric product obtained from poly(styryl)lithium oxidations in the presence of Lewis bases. The total amount of peroxide products was determined by iodometric titration in the presence of a phase‐transfer catalyst, dicyclohexyl‐18‐crown‐6. On the basis of the effect of polar additives on the amount of dimeric products, it is concluded that dimer formation in the air termination of polymeric organolithium compounds results from oxidation and not carbonation reactions.
Salt effects in the binding of 4‐(1‐pyrenyl)‐butyltrimethylammonium to poly(vinylbenzo‐18‐crown‐6) and poly(vinylbenzoglyme) in water
Authors: Roland Bruno , Wakui Tadahiro , Smid Johannes , De Schryver Frans C.
Published: April 2003

The binding of 41‐(1‐pyrenyl)butyltrimethylammonium bromide (PN+) to the neutral poly‐soap‐type polymers poly(vinylbenzo‐18‐crown‐6) (P18C6) and poly(vinylbenzoglyme) (PVBG) was studied by optical spectroscopy and fluorescence in the presence and absence of salts. Measurements of the respective binding constants were based on distinct differences in the optical absorption spectra of free and polymer‐bound PN+. When crown ether‐compelxable cations (e.g., K+) were added the adsorption of PN+ to P18C6 decreased as the neutral polymer was converted to a polycation. No decrease was found with PVBG because alkali ions do not complex significantly to this polymer in water. PN+ adsorption to both polymers rose rapidly, however, as the salt concentration increased. This effect was strongly anion‐dependent and increased in the order of Cl− < Br− < I− < CNS− < BPh4−. The increased binding was reflected in a higher binding constant and also in a larger number of bound PN+ molecules per polymer chain under saturation conditions. It is argued that the formation of ion pairs or larger ion clusters in the aqueous phase when anions are added forces more PN+ molecules to adsorb on the surface of the polymer coil to which they are bound as ion pairs or higher aggregates. Under saturation conditions enough PN+ molecules are bound to convert the pyrene monomer fluorescence spectrum into that of the excimer. These results are compared with data obtained for the anionic solute 4‐(1‐pyrenyl)butanoate in the presence of salts.
Ethynyl‐terminated polyarylates: Synthesis and characterization
Authors: Havens S. J. , Hergenrother P. M.
Published: April 2003

Hydroxy‐terminated polyarylates (HTPA) with number‐average molecular weights of approximately 2500, 5000, 7500, and 10,000 were synthesized and converted to corresponding 4‐ethynylbenzolyloxy‐terminated polyarylates (ETPA) by reaction with 4‐ethynylbenzoyl chloride. The terminal ethynyl groups were thermally reacted to provide chain extension and crosslinking. The cured ETPA exhibited higher glass transition temperatures (Tg) and better solvent resistance than a high molecular weight linear polyarylate. Solvent resistance was further improved by curing 2,2‐bis(4‐ethynylbenzoyloxy‐4′‐phenyl) propane, a coreactant, with ETPA at concentrations of approximately 10% (w/w).
Preparation and properties of polyamides containing p‐terphenyl units
Authors: Li Zao Bang , Ueda Mitsuru
Published: April 2003

Novel polyamides that contained p‐terphenyl units were prepared with inherent viscosities in the range of 0.4–1.7 dL/g by the polycondensation of 4,4″‐dichloroformyl‐p‐terphenyl with aromatic diamines and 4,4″‐diamino‐p‐terphenyl with aromatic dicarbonyl chlorides. Polyamides composed of only paraoriented phenylene units were insoluble in all solvents and showed a high degree of crystallinity. A series of polyamides that contained p‐terphenyl units were more thermostable than corresponding polymers with p‐phenylene or biphenylene linkages.
Isothermal pyrolysis of cellulose untreated and treated with some flame‐retardants
Authors: Hirata Toshimi , Okamoto Hajime
Published: April 2003

Linter cellulose, untreated and treated with boric acid, ammonium sulfamate, and guanidine sulfamate, was heated iosthermally in an imaging furnace thermal balance under a flow of helium gas to obtain kinetic parameters of the weight loss and changes in the elemental content and infrared (IR) spectra during pyrolysis. The weight, carbon, hydrogen, and oxygen losses of the untreated cellulose obey a zeroth‐order reaction at an early stage and a first‐order reaction at a later stage. The Arrhenius parameters for the weight and elemental losses are in agreement for both reactions. The activation energy and preexponential factor of the first‐order weight loss are 185 kJ/mol and 2.0 × 1013 s−1, respectively. The carbon, hydrogen, and oxygen losses of the samples treated with boric acid and guanidine sulfamate also obey a first‐order reaction at a later stage of pyrolysis. The results of the elemental and IR spectral analyses suggest that the zeroth‐ and first‐order reactions are caused mainly by the production of levoglucosan and that an initial rapid step, especially for the treated samples, is contributed by dehydration.
Effect solvatant des copolymères styrène–macromère a chaîne polyoxyéthylène. Influence du support polymère
Authors: Hamaide T. , Mariaggi N. , Foureys J. L. , Le Perchec P. , Guyot A.
Published: April 2003

Polyoxyethylene macromers were used to prepare functionalized linear and crosslinked copolymers with styrene and divinylbenzene. Gel or macroporous resins were prepared. These copolymers and resins were used as anionic activators for the Williamson reaction of potassium phenoxide and alkyl bromides under solid–liquid or solid–liquid–liquid (triphase) conditions. In contrast to similar resins obtained from chemical grafting of polyoxyethylene onto chloromethylated styrene–divinylbenzene polymers, the activity factors were strongly dependent on the composition of the resins and their morphology: an optimum activity was obtained for a 0.05M fraction of macromers in soluble copolymers and crosslinked resins. In addition, a macroporous resin with large pores was more efficient than a gel‐type resin of similar composition. These effects are discussed in terms of accessibility of the activating group and compatibility of the support with the medium.
Liquid‐crystal polymers with tolan units
Authors: Al‐Dujaili A. H. , Jenkins A. D. , Walton D. R. M.
Published: April 2003

A new series of liquid‐crystal polymers containing main‐chain mesogenic units is reported. The general repeating unit is
magnified image
where n = 4, 5, 6, 7, 8, 10, or 12.
Synthesis, charge transfer complexation, and photosensitivity of poly(N‐methyl‐3‐hydroxymethyl carbazolyl acrylate‐co‐acryloyl‐3′‐hydroxypropyl‐3,5‐dinitrobenzoate)
Authors: Natansohn Almeria
Published: April 2003

The synthesis of copolymers intrachain charge transfer complexes having as donor structural units N‐methyl‐3‐hydroxymethyl carbazolyl acrylate and as acceptor structural units acryloyl‐3′‐hydroxypropyl‐3,5‐dinitrobenzoate is presented. Charge transfer complexation in the copolymer and in the mixture of model compounds is analysed by NMR spectroscopy. Photosensitivity of the copolymers and of the corresponding mixture of model compounds is revealed by the increase of the ESR signal with illumination. Attempts to assign the ESR signal splitting to different radical structures are made. Besides an ESR signal increase dependent on light, a permanent increase in the number of spins is also noted as an effect of illumination.
Living cationic polymerization of isobutyl propenyl ether as β‐substituted vinyl ether
Authors: Higashimura Toshinobu , Tanizaki Akio , Sawamoto Mitsuo
Published: April 2003

Isobutyl propenyl ether [IBPE; CH3CH=CHOCH2CH(CH3)2] was polymerized with a mixture of hydrogen iodide and iodine (HI/I2 initiator) in n‐hexane at −40°C to yield living polymers with a nearly monodisperse molecular weight distribution (MWD) (M̄w/M̄n ≈ 1.1). The number‐average molecular weight (M̄n) of the polymers increased proportionally to IBPE conversion and further increased when a new monomer feed was added to a completely polymerized solution. The M̄n was controlled by the initial concentration of hydrogen iodide if the acid was charged in excess over iodine. In polymerization by iodine alone the M̄n of the polymers obtained in nonpolar solvents (n‐hexane and toluene) also increased with conversion, but their MWD was broader (M̄w/M̄n = 1.3–1.4) than in the HI/I2‐initiated systems under similar conditions. The iodine‐initiated polymerization in polar CH2Cl2 solvent, in contrast, led to nonliving polymers with a broad MWD (M̄n/M̄n = 1.6–1.8) and M̄n, independent of conversion. The living polymerization of IBPE was also compared with that of the corresponding isobutyl vinyl ether, to determine the effect of the β‐methyl group in IBPE.
Preparation and properties of polymides from 3,4′‐ and 4,4′‐oxydianiline and various aliphatic and aromatic diacids
Authors: Imai Yoshio , Kajiyama Mikio , Ogata Shin‐Ichi , Kakimoto Masaaki
Published: April 2003

Aromatic‐aliphatic polyamides of high molecular weight were prepared by the direct polycondensation of 3,4′‐ and 4,4′‐oxydianiline with aliphatic diacids with 4‐10 methylene groups in a triphenyl phosphite/pyridine system. Polyamides prepared from 3,4′‐oxydianiline are characterized by greater solubility, lower melt temperatures, and lower glass transition temperatures than are those from 4,4′‐oxydianiline. Aromatic polyamides from 3,4′‐ and 4,4′‐oxydianiline and isophthalic and terephthalic acids were also prepared and characterized.
Liquid crystal polymers. XVIII. Comparison of the properties of aromatic polyesters with different mesogenic units and a common flexible spacer
Authors: Chen Guoquan , Lenz Robert W.
Published: April 2003

Four closely related polyesters, with aromatic ester triads and decamethylene spacers, were prepared and characterized for their thermotropic liquid crystalline properties. Two of the polymers, which were based on linear biphenols, formed stable nematic phases, whereas one of the two based on nonlinear biphenols formed a poorly defined nematic phase; the other was not liquid crystalline. Several polymerization reactions and methods were evaluated and structure‐property relationships of the polymers are discussed. The concept of “degree of liquid crystallinity” for polymers with poorly defined thermotropic behavior is considered.
Cobaloxime as a catalytic chain transfer agent
Authors: Burczyk A. F. , O'Driscoll K. F. , Rempel G. L.
Published: April 2003

Cobaloxime, synthesized from CoII acetate and dimethylglyoxime, was used as a chain transfer agent in the free radical polymerization of methyl methacrylate. It proved to be a catalytic chain transfer agent analogous to work recently reported on cobalt porphyrins. Chain transfer constants ranged from 103–104 and were chain length dependent. Catalytic behavior was demonstrated by calculating turnover numbers which showed that each cobaloxime molecule participated in many hundreds of chain transfer reactions.
Synthesis and characterization of poly(phosphon acetal) derivatives of poly(vinyl alcohol)
Authors: Vofsi David , Yanai Shaul , Cabasso Israel
Published: April 2003

Preparation of poly(phosphonoacetals) (PPA) by transacetalation of poly(vinyl alcohol) with diethyl‐phosphonoacetal is described. PPA with a degree of substitution of 60% is an alcoholsoluble polymer with a glass transition temperature (Tg) of 67°C. High resolution 1H and 13C NMR spectra reveal the presence of hemiacetals alongside the six‐membered acetal ring with an approximate ratio of 2:8 of these substituents. A possible correlation between the microtacticity of the parent PVA and the structure of PPA is indicated; the syndiotactic and isotactic sequences on the parent polymer controls the relationship between the two pendant groups.
Monitoring polymer surface derivatization by RBS and ESCA
Authors: Valenty S. J. , Chera J. J. , Smith G. A. , Katz W. , Argani R. , Bakhru H.
Published: April 2003

Rutherford backscattering spectrometry (RBS) has been used to detect and quantitate the thallium concentration resulting from the thallous ethoxide derivatization of phenol and carboxylic acid groups contained in the surface region of bisphenol‐A polycarbonate (PC) sheet. Hydrolysis of the PC surface prior to derivatization leads to increased thallium levels, in which the chemical nature of the thallium is shown to be of the form R–O–Tl (R = alkyl or aromatic) by electron spectroscopy for chemical analysis (ESCA). Similar trends in thallium concentrations were observed by both RBS and ESCA for PC surfaces that had been exposed for increasing lengths of time to accelerated weathering and outdoor Florida conditions. The detection limit for thallium in PC using RBS is ca. 5 × 1013 atoms/cm2. The diffusion of thallous ethoxide and transesterification of the aromatic carbonate linkage led to a thallium‐containing layer 300–700 Å thick, which increased the experimental uncertainty when assaying residual uncapped polymer chains in unweathered material. During the course of the RBS analysis, the interaction of 2‐MeV 4He+ with the PC substrate caused dramatic chemical and physical changes. Microscopy and profilometry indicate that a crater was formed having the same cross‐sectional area as the incident ion beam with a depth (ca. 0.3–1.5 μ) that varied according to the beam energy and integrated charge. ESCA analysis provided evidence for the loss of the carbonate linkage and the appearance of carbonyl and ester groups. Infrared analysis of the crater bottom shows the appearance of O‐H stretch, carbonyl functionality other than aromatic carbonate, and enhanced aromatic ring stretch vibrations. Crosslinking and subsequent densification of the polymer matrix are though to be responsible for the observed morphological changes. It is suggested that this beam‐induced damage does not prohibit the use of RBS to measure high‐Z elements on a PC matrix since quantitation of 1000‐Å Au layers on silicon and PC gave identical results.
Polymerization of allyldimethyldodecylammonium bromide in micellar and isotropic media
Authors: Paleos C. M. , Dais Photis , Malliaris Angelos
Published: April 2003

To study the effect of micellar aggregation upon polymerization and polymer products, the polymerization of the micelle forming monomer allyldimethyldodecylammonium bromide (I) was investigated under both micellar and isotropic conditions. NMR spectroscopy and fluorescence quenching were employed to elucidate the structural characteristics and molecular weight of the polymer obtained by γ‐ray irradiation. It was found that (I) undergoes effective polymerization in the micellar state, producing a polymer which consists of a mixture of head to tail and head to head configurations at the ratio 85/15, and has a mean molecular weight of 11,000 ± 1000 daltons.
Thermal‐ and UV‐induced cis/trans isomerization of undoped polyacetylene films. An ESR and IR investigation
Authors: Cernia E. , D'Ilario L. , Lupoli M. , Mantovani E. , Schwarz M. , Benni P. , Zanobi A.
Published: April 2003

The UV‐ and thermal‐induced cis→trans isomerization of undoped polyacetylene (PA) films has been investigated. The results have shown that temperature and UV light promote the isomerization of PA with a similar mechanism. We suggest that the formation of paramagnetic defects in trans PA takes place by bond rehybridization, in agreement with previous hypotheses, and that both spin concentration and spin delocalization depend on the temperature of isomerization. It was found that under UV irradiation thermal cis→trans isomerization of polyacetylene also takes place at temperatures at which the sole thermal treatment isomerization is much lower or nil, and we suggest that the possibility of preparing trans PA under relatively mild conditions may lead to a better material.
Studies on some newer polyhydrazides containing amide linkages. III
Authors: Shukla J. S. , Misra P. K.
Published: April 2003

Novel polyhydrazides having inherent viscosities in the range of 0.24–0.38 dL g−1 were prepared by polymerizing a series of hydrazides with different diacid chlorides in polar aprotic solvents. These polymers display a wide range of solubility in a number of solvents. They start decomposing at about 200°C in air. Results of differential thermal and thermogravimetric analysis show that a steep weight loss takes place mainly in the range of 300–440°C.
Hydrodynamic invariant of polymer molecules
Authors: Tsvetkov V. N. , Lavrenko P. N. , Bushin S. V.
Published: April 2003

The theories of hydrodynamic properties of macromolecules in solution leading to an invariant relationship between the values of the intrinsic viscosity, [η], the molecular weight,M, and the translational friction coefficient of the molecule,f, have been considered. The review of experimental data comprising as much as about 2000 fractions of various polymers suggests that for all flexible‐chain and moderately rigid‐chain molecules the hydrodynamic parameterA0=kη0(M[η]/100)1/3f−1is actually an invariant independent of the chain length and the thermodynamic strength of the solvent and for moderately polydisperse samples also independent of the degree of their polydispersity. For polymers with very rigid chains the parameterA0has a high value over the experimentally investigated range ofM. These conclusions make it possible to recommend the use of the following average experimental values of the invariantA0for the determination ofMof polymers from the values of [η] andf: for flexible‐chain and synthetic polymers with moderately high chain rigidity (3.2 ± 0.2) · 10−10, for polymers with high chain rigidity (3.7 ± 0.4) · 10−10, and for cellulose derivatives and other polysaccharides with molecular dispersity of nonelectrolyte solutions (3.30 ± 0.30) · 10−10erg deg−1mol−1/3. The fact that the experimental value ofA0= 3.2 · 10−10does not coincide with the value ofA∞= 3.8 · 10−10erg deg−1mol−1/3predicted by the theories of translational friction and viscosity of macromolecules implies that the theoretical values ofP∞= 5.11 and Φ∞= 2.8 · 1023mol−1are mutually incompatible and these theories require further development.
Kinetics of emulsion polymerization of styrene—simulation model with varying free radical capture efficiency
Authors: Kao C. I. , Gundlach D. P. , Nelsen R. T.
Published: April 2003

A kinetic model has been developed and successfully applied to describe the reaction profiles of the seeded emulsion polymerization of styrene. The model incorporated a mechanism for the capture of aqueous‐phase oligomeric free radicals by latex particles. Both the collision and diffusion mechanism were considered. The experimental data agreed well with the collision mechanism. The rate of the free radical capture by latex particles is proportional to latex particle surface area (D2p), and also is a strong function of the rate of free radical generation per latex particle. The model predicts that the rate of polymerization is dependent on the latex particle diameter to the 2.5 power in the gel region. This was demonstrated experimentally by J. W. Vanderhoff et al. (J. Polym. Sci., 20, 225 (1956)). Propagation and termination rate constants for styrene in the 70–90°C temperature range were also determined.
Nucleation of polypropylene by cyclic oligomers present in poly(ethylene terephthalate)
Authors: Huson M. G. , McGill W. J.
Published: April 2003

It is shown that cyclic oligomers present in poly(ethylene terephthalate) are excellent nucleating agents for the crystallization of polypropylene. However, rigorous purification of poly(ethylene terephthalate) showed that these oligomers are not responsible for the ability of the polymer to induce transcrystallinity when cooled in contact with polypropylene melts.
Dilute solution properties of tactic poly(2‐hydroxyethyl methacrylate)
Authors: Jeon Sang Il , Jhon Mu Shik
Published: April 2003

Isotactic and syndiotactic poly(2‐hydroxyethyl methacrylate) (PHEMA) have been prepared. Intrinsic viscosity–molecular weight relationships were established for the isotactic and syndiotactic PHEMA in N,N‐dimethylformamide (DMF) at 25°C by solution viscometry and light scattering. The unperturbed dimensions and interaction parameters were examined in DMF, water, methanol, ethanol, and water–methanol (1:7 by volume) mixture for isotactic PHEMA and in DMF, methanol, and water–methanol (1:7 by volume) mixture for syndiotactic PHEMA using the Stockmayer–Fixman representation. The results suggest that the compact random coil structure for isotactic PHEMA occurs in water solvent and the isotactic PHEMA is more highly extended in polar solvents.
Water‐soluble copolymers. IX. Copolymers of acrylamide with N‐(1,1‐dimethyl‐3‐oxybutyl)acrylamide and N,N‐dimethylacrylamide: Synthesis and characterization
Authors: McCormick C. L. , Chen G. S.
Published: April 2003

The copolymerizations of acrylamide (AM) with N‐(1,1‐dimethyl‐3‐oxybutyl)acrylamide (DAAM) and with N,N‐dimethylacrylamide (DMAM) have been studied. The values of r1,r2 have been determined to be 0.75 for the AM‐DAAM pair and 0.86 for the AM‐DMAM pair. The molecular weights of the copolymers were found to decrease with an increase in the feed composition of DAAM or DMAM. The microstructure was predicted for a wide range of feed compositions through a knowledge of reactivity ratios. These model structures are utilized for assessment of structure/dilute solution relationships reported in a subsequent paper in this series.
Dependence of computed copolymer reactivity ratios on the calculation method. II. Effects of experimental design and error structure
Authors: Hautus F. L. M. , Linssen H. N. , German A. L.
Published: April 2003

Two calculation methods for estimating reactivity ratios, one method based on the differential Alfrey‐Mayo equation and one based on the integrated form of this model, are compared with respect to precision and bias. Both methods are characterized by the use of information about the monomer feed composition only and are assumed to be valid up to high conversion. As only monomer feed composition has to be analyzed, several sampling designs are feasible. Two extreme designs can be distinguished. One consists of repetitive sampling of the initial and final monomer feed mixture, whereas the other consists of sequential sampling during the course of the reaction. The influence of both designs of the calculatedr‐values is investigated by means of simulation. In the present paper the second calculation method, based on the integrated form, is solved by a nonlinear least squares method considering errors in both variables. This method required additional information about the errorstructure of the data. As this information is mostly of approximate nature, the influence of misspecification of this error structure on the calculatedr‐values is also examined.
Copolymers containing alternating sequences of nucleic acid base pairs. II. Polymerization studies
Authors: Aponte Maria A. , Butler George B.
Published: April 2003

The objective of this project was to utilize the alternating copolymerizability of electrondonor monomers with electron‐acceptor monomers to selectively introduce nucleic acid bases into copolymers in a controlled sequence distribution. To this end, maleimide monomers containing the adenine, thymine, cytosine, and 6‐chloropurine moieties were converted to their hompolymers. The homopolymer of 1‐(vinyloxyethoxy)thymine was also prepared. Alternating copolymers of the adenine maleimide monomer and the corresponding 6‐chloropurine maleimide monomer with 1‐(vinyloxyethoxy)thymine were prepared. The latter copolymer was converted to the alternating adenine–thymine copolymer by reaction with ammonia. Characterization of the polymers and copolymers via spectroscopic methods and physical measurements confirm their proposed structures. Monomer syntheses and characterization, as well as studies designed to establish the extent and nature of adenine–thymine interactions in the copolymers, are reported in accompanying papers.
Compositional and molecular weight analysis of polyether macromonomers by chromatographic techniques
Authors: Schulz W. W. , Kaladas J. , Schulz D. N.
Published: April 2003

This paper critically examines the scope and limitations of state‐of‐the‐art chromatographic techniques (GPC, GC, HPLC) for separating and analyzing the composition, molecular weight, and molecular weight distribution of acrylate and styrene based polyether macromonomers. Of the three chromatrographic techniques investigated, HPLC is found to be the most useful technique for macromonomer analysis, being applicable over a wide molecular weight range and having favorable selectivities towards the many macromonomer components. Macromonomer purity, n‐mer distribution, and molecular weight can be derived from a single chromatographic run. In addition, conformational information can be obtained.
Synthesis and properties of miscible epoxy/acrylic interpenetrating polymer networks
Authors: Allard Danielle , Fontanille Michel , Prud'Homme Robert E.
Published: April 2003

Three series of epoxy/acrylic interpenetrating polymer networks were prepared by the simultaneous polymerization of diglycidyl ether of bisphenol A, crosslinked with an aliphatic diamine, diglycidyl ether of bisphenol A dimethacrylate, bisphenol A dimethacrylate, and diethoxy bisphenol A dimethacrylate. Under the conditions provided it is believed that the two networks form simultaneously but independently. Differential scanning calorimetry and dielectric measurements indicate that these polymer networks are miscible because they exhibit a single, sharp glass transition temperature, the values of which, however, are lower than predicted by the law of mixture. This decrease may be due in part to the dilution of one network by the other and to the resulting breakage of intramolecular interactions. It is also due, in part or in whole, to the presence of solvent and/or monomer impurities that act as plasticizers.
Model cationic flocculants from the Mannich reaction of polyacrylamide
Authors: Pelton R. H.
Published: April 2003

14C‐Labeled cationic derivatives of polyacrylamide were prepared by the reaction of polyacrylamide with 14C‐labeled formaldehyde and dimethylamine hydrochloride. The resulting Mannich base was reacted with dimethyl sulfate. Both reactions produced a yield of about 50% and the final product was a substituted polyacrylamide with tertiary and quaternary amine groups. Extensive dialysis removed the tertiary groups to give a stable radio‐labeled polymer that was an effective flocculant. Treatment with mixed‐bed ion exchange resin was effective in purifying polyacrylamide derivatives; however, counterions for the quanternary amine groups were not quantitatively exchanged for hydroxide groups.
O‐nitrobenzyl photochemistry: Solution vs. solid‐state behavior
Authors: Reichmanis E. , Smith B. C. , Gooden R.
Published: April 2003

The efficiency of various 2‐nitrobenzyl groups in the photogeneration of carboxylic acid from nitrobenzyl esters has been determined, and the solution vs. solid polymer matrix photochemistry is compared. Generally, the quantum yield for photoreaction is lower in the solid state, probably due to decreased conformational mobility. The substitution that affords the largest increase in quantum yield (ϕ) is at the α‐carbon atom. The value of ϕ for α‐methyl‐2‐nitrobenzyl trimethylacetate in solution is 0.65 vs. 0.13 for the parent 2‐nitrobenzyl ester.
Interfacial polymerization of an isocyanate and a diol
Authors: Pearson R. G. , Williams E. L.
Published: April 2003

The interfacial reaction between a liquid polyfunctional aromatic isocyanate and a diol was studied using infrared spectroscopy to follow the reduction in concentration of the isocyanate group. It was shown that the product polyurethane formed a gel layer around dispersed isocyanate droplets which were swollen by the diol but not by the isocyanate. A model for the process is suggested based on the reaction occuring at the interface of a diminishing droplet surface. It is suggested that the reaction is controlled by the reaction kinetic parameters and the mass transfer by diffusion of the diol through the product layer. Quantitative evaluation is based on steady and nonsteady state diffusion theories.
Specific interaction between polyethylenimine and azo dyes carrying hydroxyl groups
Authors: Takagishi Toru , Yoshikawa Kiyoaki , Hamano Hiromitsu , Kuroki Nobuhiko , Kozuka Hiroshi
Published: April 2003

The binding of acid azo dyes having phenolic hydroxyl groups such as orange I (I), orange II (II), chrome violet (III), 4‐hydroxyazobenzene‐4′‐sulfonate (IV), and 2,4‐dihydroxyazobenzene‐4′‐sulfonate (V) by polyethylenimine was studied by equilibrium dialysis and spectroscopic methods. The results obtained indicate that dyes (III) and (V) with two OH groups are bound much more strongly than dyes (I), (II), and (IV) with one OH group. Also polyethylenimine is far superior to any other polymers which have been examined, including bovine serum albumin, polyvinylpyrrolidone, and poly‐L‐lysine, in its ability to form complexes with these dyes (III) and (V). The OH groups involved participate preferentially in complex formation with polyethylenimine. The unusual affinity of polyethylenimine for the dyes carrying OH groups is discussed.
Solvent effects in phase‐transfer reactions prompted by polymer‐supported phosphonium salts
Authors: Tomoi Masao , Nakamura Eiji , Hosokawa Yasunori , Kakiuchi Hiroshi
Published: April 2003

Solvent effects on the intrinsic activity of, the ion‐exchange rate of, and the overall activity of polymer‐supported phosphonium salts under tri‐phase conditions were studied. The intrinsic activity of the catalysts as well as of soluble phosphonium salts was dependent only slightly on organic solvents. The exchange rate of the chloride ion in the catalysts against the acetate ion dependent on the solvents when the degree of ring substitution was ≤ 16%. With the ca. 30% ring‐substituted catalysts the rate increased and hardly depended on the solvents. The overall reactivity of the catalysts for the reaction of organic halides with NaCN was a function of substrate structure and organic solvents. For alkyl halides such as bromooctane the catalysts were more reactive in good solvents such as toluene or chlorobenzene than in poor solvents such as octane. For arylalkyl halides such as benzyl chloride the catalysts exhibited the opposite effect. In poor solvents the arylalkyl halides are absorbed preferentially into the catalysts.
Direct polyesterification promoted by a complex of diphenyl chlorophosphate with LiBr
Authors: Higashi Fukuji , Hoshio Atsushi , Yamada Yukiharu , Ozawa Michihide
Published: April 2003

The diphenyl chlorophosphate (DPCP)‐promoted polycondensation reaction between aromatic dicarboxylic acids and bisphenols was largely improved by carrying out the reaction in the presence of lithium halides to give high molecular weight aromatic polyesters. Among the halides LiBr, which is capable of forming a complex with hexamethylphosphoramide, was most effective, suggesting that a similar complexation of DPCP with LiBr in pyridine facilitates the complete reaction of DPCP with carboxyl groups. The complex could selectively activate carboxyl groups of hydroxybenzoic acids to give high molecular weight copolyesters from several combinations of aromatic hydroxy acids. The reaction could also be adaptable to the copolycondensations of a mixture of the dicarboxylic acids, bisphenols, and hydroxybenzoic acids.
On the anionic polymerization of cyanogen
Authors: Skarda V. , Ivkovich D. , Labes M. M.
Published: April 2003

The reaction of anionic initiators with cyanogen was investigated by ultraviolet, visible, and infrared spectroscopy. It is argued that the reaction proceeds via formation of an analog of the heterocyclic anion C7N7− previously known from the reaction of KCN with (CN)2. The analytical results and spectra of the final black product were indicative of the possible formation of open‐structured C7N7− dimers. A molecular model of the dimer suggests why the polymerization might terminate at the dimer stage. The pyrolysis of the cyclic acid HC7N7 was studied with the aim of determining the structure and mechanism of the formation of the resulting black product. It is suggested that this thermally induced polymerization reaction probably proceeds via formation of azomethine‐type intermolecular crosslinks and may serve as a model for the investigation of the mechanism of nitrile polymerization in pyrolyzed acrylonitrile polymers.
Sequence‐length distribution in bulk and DMSO‐derived acrylic acid/methylmethacrylate copolymers
Authors: Ekpenyong Kieran I.
Published: April 2003

The mean sequence lengths (l̄) and probabilities (W) in the formation of various structural units were estimated for acrylic acid (AA) and methylmethacrylate (MMA) copolymers obtained in bulk and solution (DMSO) copolymerization. The results show that, although l1:l2 in bulk polymerization ranges from about 1:5 to about 5:1 when moving from lower to higher M1 feeds in DMSO polymerization, the corresponding ranges is 1:25 to about 1:2, all in favor of the monomer M2. The probability of the formation of structural units of a kind (e.g., doublets and triplets) that in bulk polymerization favors M1 more than M2 swings drastically in favor of M2 when the polymerization is carried out in DMSO.
Oligomerization of vinyl monomers 18. Stereochemistry of anionic oligomerization of 4‐vinylpyridine
Authors: Meverden Craig C. , Hogen‐Esch Thieo E.
Published: April 2003

Oligomers of 4‐vinylpyridine were prepared by reaction in vacuo of 4‐vinylpyridine with lithio‐4‐ethylpyridine at −78°C, followed by reaction with CH3I(13CH3I) or CH3OH. The stereochemistry was studied by NMR and GC. Methylation and the addition of 4‐vinylpyridine occurred in a stereochemically nonselective manner. The data also indicated that in contrast to the oligomerization of 2‐vinylpyridine the stereoisomeric meso and racemic 4‐pyridyl carbanions propagated with equal reaction rates. The stereochemistry was readily explained by an absence of coordination of the Li ion by the nitrogen of the penultimate pyridine ring observed in the corresponding oligomerization of 2‐vinylpyridine.
Moisture effects in lithium‐doped polyimide films
Authors: Khor Eugene , Gay M. Sandra , Taylor Larry T. , Wightman James P.
Published: April 2003

The interaction of lithium‐doped polyimide films with water has been investigated. Contact angle and water absorption/desorption measurements have been performed to obtain an idea of the hygroscopic nature of these lithium‐doped films. Contact angles were found to decrease as the amount of surface lithium increased. Film water content was also found to increase as the weight percent of total lithium content in the film increased. This phenomenon has been used to rationalize the electrical resistivity–temperature profile of certain lithium films which display an increase in electrical resistivity upon drying.
Kinetic study of the polymerization of acrylamide in inverse microemulsion
Authors: Candau Françoise , Leong Yee Sing , Fitch Robert M.
Published: April 2003

The polymerization of acrylamide in inverse microemulsions stabilized by Aerosol OT emulsifier and initiated with azobisisobutyronitrile (AIBN) or potassium persulfate (K2S2O8) has been investigated. The inverse polyacrylamide latexes formed are clear and highly stable. A dilatometric technique was used to follow the conversion of monomer at T = 45°C. The rate of polymerization is first order with respect to initial monomer concentration in the presence of AIBN, and is 1.5 order with K2S2O8. An inverse relationship between molecular weight and emulsifier concentration is found which suggests participation of the emulsifier in the initiation reaction. This is confirmed by the independence of the molecular weight of polyacrylamide on the concentration of the initiators. High values of the rate of polymerization are obtained combined with high molecular weights (up to 107). An important and novel feature of this microemulsion process is that each final latex particle consists of one single molecule of polyacrylamide in a collapsed state. This suggests kinetics which do not follow the Smith and Ewart theory but are characterized by continuous particle nucleation.
Molecular dimensions of polypeptides in helicogenic solvents
Authors: Kim Jong Ryul , Ree Taikyue
Published: April 2003

The dependence of the molecular dimension of polypeptides in helicogenic solvents on molecular weight was calculated by using the Zimm‐Bragg‐Nagai theory in collaboration with the broken‐rod model, in which the excluded volume effect was taken into account by setting the equivalent chain to be a nonintersecting chain. Our calculated results for PBLG in helicogenic solvents were compared with experiment with good agreement. The flexibility of the helices of PCBL and PELG as broken rods corresponded to that of PBLG without excluded volume effect (i.e., the broken rod of a self‐intersecting chain) in a comparison of their experimental data with our calculated results for PBLG of self‐intersecting and nonintersecting chains. Over a wide range of molecular weights M our theory explains the dependence of the length per monomeric residue h on M, even for short chains in which h > 1.5 Å.
The relative reactivity of primary and secondary amine hydrogen atoms of aromatic amines with epichlorohydrin and N‐ and O‐glycidyl compounds
Authors: Johncock P. , Porecha L. , Tudgey G. F.
Published: April 2003

The relative value of the rate constants for the reactions between the secondary and primary amine hydrogen atoms of 3‐trifluoromethylaniline with epichlorohydrin, and of aniline with phenyl glycidyl ether and with some N‐alkyl‐N‐glycidylanilines were determined by HPLC analysis. Values ranged from 0.14 to 0.24 and are in agreement with the findings of earlier workers for the reactions of aromatic amines with O‐glycidyl compounds but in direct conflict with the claim of a recent publication. The value for the reaction between 3‐trifluoromethylaniline and epichlorohydrin was unaffected by the nature of the catalyst, which covered a wide range of strengths and steric requirements.