bluuebunny/crossref_metadata_2025_split huggingface dataset:
Living cationic polymerization of isobutyl propenyl ether as β‐substituted vinyl ether
Authors: Higashimura Toshinobu , Tanizaki Akio , Sawamoto Mitsuo 
Published: April 2003

AbstractIsobutyl 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

AbstractAromatic‐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

AbstractFour 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

AbstractCobaloxime, 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

AbstractPreparation 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

AbstractRutherford 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

AbstractTo 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

AbstractThe 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

AbstractNovel 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

AbstractThe 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

AbstractA 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

AbstractIt 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

AbstractIsotactic 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

AbstractThe 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

AbstractTwo 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

AbstractThe 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

AbstractThis 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

AbstractThree 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

Abstract14C‐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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractSolvent 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.