bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly(1,5‐hexadiyne) films prepared using rhodium(i) catalysts
Authors: Cataldo Franco 
Published: April 2007

AbstractBis(1,5‐cyclooctadiene)dirhodium(I)dichloride and bis(norbornadiene)‐dirhodium(I)dichloride are effective catalysts for polymerization of 1,5‐hexadiyne. The structure of the polymer obtained and its behaviour towards oxidation and oxidizing agents has been elucidated by means of infrared and ultraviolet spectroscopy. It is proposed that polymerization proceeds with formation of a polymer having a five‐membered ring in each of its monomeric units. The polymer is highly conjugated and can be obtained directly during polymerization as film, which has a metallic lustre, is insoluble in common solvents, and shows good resistance to oxidation in air, if sufficiently thick.
Solid state polymerization of bis(trichlorophenoxo) cobalt(ii) complex to give poly(dichlorophenylene oxide)
Authors: Baştürkmen Meray , Işçi Hüseyin , Kisakürek Duygu 
Published: April 2007

AbstractSynthesis of four‐coordinated (tetrahedral) trichlorophenol cobalt(II) complex with neutral ligand pyridine was achieved from the aqueous solution and its characterization was performed by UV‐visible, IR spectral and CHN analysis. Solid state thermal polymerization of the complex was accomplished first at constant temperature employing different time intervals and secondly at constant decomposition time. The poly(dichlorophenylene oxide)s so synthesized were characterized by IR, 1H NMR and 13C NMR spectral analysis, Tg determination, as well as measurement of molecular weight by a viscometric method.
Sedimentation velocity studies of poly (sodium styrenesulfonate‐co‐2‐ vinylnaphthalene)
Authors: White Brian , Johnson Paley , Guillet James E. 
Published: April 2007

AbstractSedimentation velocity measurements have been employed to investigate the molecular conformation of poly(sodium styrenesulfonate‐co‐2‐vinylnaphtha‐lene) (PSSS‐VN) in aqueous solution. Single symmetrical boundaries were observed in the molecular weight range of 7‐2‐33‐6 104, indicating that PSSS‐VN exists as a single macromolecular coil and not as an aggregate in aqueous solution. Based on the value of the exponent in the power law which describes the dependence of the weight‐average molar mass on the sedimentation coefficient (S), PSSS‐VN behaves as a Gaussian coil dissolved in a solvent of moderate quality. Solubilization of eight molecules of 9‐methylanthracene within the core of PSSS‐VN produced no detectable change in the value of the sedimentation coefficient.
Influence of two‐step process and of different stoichiometric ratios on morphologies generated in castor oil epoxy resins
Authors: Sanchez Jorge L. , Riccardi Carmen C. 
Published: April 2007

AbstractPhase separation during polymerization was studied in a model system consisting of a diepoxide based on diglycidyl ether of bisphenol A (DGEBA), variable amounts of ethylenediamine (EDA) and the mass of castor oil (CO) necessary to obtain a mass fraction equal to 0‐15 in a final system where the stoichiometric ratio of amine to epoxy equivalents, r, was equal to 1. A two‐step polymerization process was performed by curing first a system with r = 0‐5, during variable times before phase separation, and then carrying the system to r = 1. Thermodynamic analysis of samples with different r values led to a linear relationship between the Flory‐Huggins interaction parameter and r. The concentration (P) and average size (D̄) of dispersed‐phase particles followed opposite trends, i.e. P increased while D̄ decreased, when either r was increased or the time of curing in the first step of a two‐step process was decreased. This was explained by assuming that the competition between nucleation and growth was determined by the viscosity at the cloud point, ηcp. Low values of ηcp favoured growth over nucleation and led to fewer but larger particles.
Water vapour permeability, diffusion and solubility in latex films
Authors: Richard Joél , Mignaud Catherine , Wong Kenneth 
Published: April 2007

AbstractWater vapour diffusion D, solubility S and permeability P coefficients have been determined for films obtained from carboxylated styrene‐butadiene (SB) copolymer latexes. The experimental method is water vapour sorption performed in the range 30–60d̀C. Using the small angle neutron scattering (SANS) method and a selective labelling with D2O vapour, it has been shown that water molecules mainly diffuse in the films through the particle‐particle interfaces, which consist of a polar carboxyl‐rich copolymer. It has been shown that the degree of cross‐linking of the particles does not significantly affect the values of D and S. Moreover, the effect of neutralization conditions, regarding both the pH value of the initial latex and the nature of the neutralizing agent, has also been investigated. It has been found that D does not depend on these parameters, whereas S appears to be very sensitive to them. The results have been interpreted on the basis of the structural modifications of the films induced by neutralization. Finally, the hydrophilicity (or hydrophobicity) of the neutralizing agent has been identified as one of the key features for controlling the affinity of the latex film for water vapour and hence its permeability properties.
Submicron particle size and polymerization excess surfactant analysis by capillary hydrodynamic fractionation (CHDF)
Authors: Dos Ramos Jose G. , Silebi Cesar A. 
Published: April 2007

AbstractThe particle size distribution of a blend of two polymer latex monodisperse standards, 86 and 238 nm, has been measured by capillary hydrodynamic fractionation (CHDF). The particle size distributions obtained agreed well with the expected particle diameters. The relative amounts of the two standards in the blends were accurately measured at different blend ratios. The particle size distribution of a parenteral lipid sample was successfully measured. A soluble species was fractionated from latex standards smaller than 100nm. This soluble species appears to be excess surfactant used in the preparation of small size monodisperse latexes. The amount of excess surfactant increases as the particle diameter of the standard decreases.
The role of polyvinyl alcohol in emulsion polymerization
Authors: Yuki Ken , Sato Toshiaki , Maruyama Hitoshi , Yamauchi Junnosuke , Okaya Takuji 
Published: April 2007

AbstractEmulsion polymerization of styrene (St) and vinyl acetate (VAc) in the presence of conventional polyvinyl alcohol (PVA), PVA modified with a terminal alkyl group or PVA modified with a terminal thiol group (HS‐PVA) was compared. Whereas stable PVAc latexes were obtained, a stable PSt latex was obtained only in the case of HS‐PVA. From the adsorption isotherms of these PVAs on the surface of PVAc and PSt latex particles, as well as the grafting efficiencies of VAc and St onto HS‐PVA in relation to the stability of the polymerization process, the role of PVA in the emulsion polymerization was discussed.
Intramolecularly crosslinked macromolecules—Formation and structure, characterization and particle properties
Authors: Funke Werner , Bauer Harald , Joos Betina , Kaczun Jürgen , Kleiner Birgit , Leibelt Ulrich , Okay Oguz 
Published: April 2007

AbstractReactive intramolecularly crosslinked macromolecules (RICM) (reactive microgels) have been synthesized by emulsion copolymerization. Besides 1,4‐divinylbenzene (1,4‐DVB), self‐emulsifying unsaturated polyesters (EUP) were used. In copolymerization of EUP and comonomers the diffusion rate of the latter influences the copolymerization rate of the growing species, if the initiator concentration is high and the water solubility of the difunctional comonomer is low. The compact structure of RICM is indicated by low slopes of log [\eta]/logw. Values of [\eta] of RICM are low and their molar masses high. [\eta] depends on the structure of RICM, e.g. pendent chains and crosslink density. Structures with pendent EUP chains could be confirmed by hydrolytic degradation. RICM may be stabilized electrostatically or sterically. Network chains of RICM from 1,4‐DVB are immobile.
Determination of the distribution of interparticle contact angle in the binary mixture of microgels
Authors: Ma Guang Hui , Fukutomi Takashi 
Published: April 2007

AbstractThe films of the binary mixtures composed of poly(4‐vinylpyridine) (P4VP) and polystyrene (PSt) microgels were prepared by casting the deionized aqueous solutions of mixtures at room temperature. The regularity of the particle arrangement was evaluated from the distribution of interparticle contact angle (ICA) formed by three nearest neighbouring particles by using scanning electron micrographs (SEM). It was found that the particles showed hexagonal closed packing, and formed interesting alternating structures when the diameters of two compositions were almost the same. On the other hand, it was found from the distribution of ICA that the arrangements among the particles of same compositions (among P4VP microgels or among PSt microgels) became more ordered as the ratio of the diameters (large particle to small one) became larger while those among the particles of different compositions (among P4VP and PSt microgels) were relatively ordered and the effect of the ratio of the diameters was not so apparent.
Superlong‐range interactions of colloids
Authors: Yoshino Shigeo 
Published: April 2007

AbstractColloid particles have superlong‐range attractive and repulsive forces. The distance between the secondary minimum of the potential energy of the interaction and the surface of the colloid is of the order of several μm and several tens of μm. These interactions clearly appear in the distribution of order‐solution phase coexistence, in gathering particles to the ordered phase and in spontaneous pair formation. A new ‘Dynamic electrical multipole model and resonance effect’ is given. From this model, it is predicted that pairs will form in a shear field even in highly concentrated salt solution. Pair formation was observed after 24 hours as predicted.
Kinetics of emulsifier adsorption and nucleation of latex particles
Authors: Dunn Alexander S. 
Published: April 2007

AbstractEvidence suggesting that the ultimate latex particles formed in the emulsion polymerisation of styrene are formed by the coalescence of unstable primary particles appears incompatible with the usual assumption that latex particles are predominantly nucleated from monomer‐swollen micelles in this system. However, this is not necessarily the case if the rate of emulsifier adsorption is not always sufficient to maintain a saturated monolayer of adsorbed emulsifier at the surface of growing latex particles so long as emulsifier micelles remain in the system. This appears to be the situation particularly when non‐ionic emulsifiers are used. Even with ionic emulsifiers abnormally high emulsifier/monomer ratios are needed to prevent the coalescence of primary latex particles. Some very high molecular weight polymer (controlled by the transfer constant to monomer) would be expected in the initial stage of styrene emulsion polymerisation if the micellar nucleation of latex particles is dominant.
Phase study of nylon 6/poly (acrylic acid) blends cast from solutions in aqueous formic acid
Authors: Nishio Yoshiyuki , Suzuki Hidematsu , Morisaki Kazue 
Published: April 2007

AbstractBlends of nylon 6 (Ny6) with poly(acrylic acid) (PAA) were prepared in film form from solutions in a mixture of formic acid and water by evaporating the solvent. The miscibility and phase constitution of the binary blends obtained over a wide composition range (5/95–95/5) were examined by wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and dynamic mechanical measurements. A Ny6 homopolymer film and Ny6/PAA blends with PAA concentrations ≥ 50 wt% exhibited a WAXD profile stemmed from the coexistence of two different crystalline modifications of Ny6, i.e. the α and γ forms. Above 50 wt% PAA content, the solution‐cast blends showed no definite crystallinity. It was found by DSC thermal analysis that the polymer pair is substantially miscible in the non‐crystalline state, since a single glass transition temperature (Tg) was situated between the Tgs of the two homopolymers at every composition; however, the Tg versus composition plots did not follow a monotonic function but yielded a peak maximum at a PAA concentration of c. 25 wt%. In order to interpret this phenomenon, attention was given to the following point revealed by dynamic mechanical measurements: at the compositions of Ny6/PAA = 100/0–50/50, a phase of low regularity such as a nematic structure is formed in the cast films.
Anionic difunctionalization with 1,1‐bis(4‐t‐butyldimethylsiloxyphenyl) ethylene. Synthesis of ω,ω‐bis(phenol)‐functionalized polystyrene condensation macromonomers
Authors: Quirk Roderic P. , Wang Yuechuan 
Published: April 2007

Abstractω,ω‐Diphenolpolystyrenes (6) can be synthesized in quantitative yields by reacting poly(styryl)lithium with 1,1‐bis(4‐t‐butyldimethylsiloxyphenyl)ethylene (1), followed by methanol termination and hydrolysis with dilute acid. The initially formed 1,1‐bis(4‐t‐butyldimethylsiloxyphenyl)alkyllithium can be reacted with additional styrene monomer to form a polystyrene internally substituted with two in‐chain phenol groups after methanol termination and acid hydrolysis. The diphenol‐substituted polystyrene condensation macromonomers have been characterized by end‐group titration, size exclusion chromatography, thin‐layer chromatography, and ultraviolet‐visible, 1H and 13C NMR spectroscopy. Chain‐extension reactions of 6 (Mn = 2.6 × 103g mol−1) with bis(trichloromethyl)carbonate produced the corresponding comb‐type, branched polymer with estimated Mn(SEC, polystyrene standards) = 1.2 × 104g mol−1 and no detectable residual condensation macromonomer. The second order rate constants for the addition reaction of excess poly(styryl)lithium with 1 and with 1‐(4‐t‐butyldimethylsiloxy‐phenyl)‐1‐phenylethylene (3) have been estimated to be 1.7 × 10−3M−1/2S−1 and 3.2 × 10−3M−1/2S−1 respectively. A sigma value (σ) of −0.46 has been estimated for the t‐butyldimethylsiloxy substituent.
Haloaldehyde polymers 60. Co‐oligomerization of chloral and bromal
Authors: Kruger F. W. Hein , Simonsick William J. , Asada Takeshi , Ute Koichi , Hatada Koichi , Vogl Otto 
Published: April 2007

AbstractCo‐oligomers of chloral and bromal were synthesized by initiating a 1:1 mixture of chloral and bromal with about 20mol% of lithium tertiary‐butoxide or lithium bornyl oxide followed by acetate endcapping. The co‐oligomer compositions were analyzed by GC, capillary GC, high resolution NMR spectroscopy and HPLC. Co‐oligomers up to the pentamers were characterized by potassium ionization of desorbed species (K+IDS) mass spectrometry.
Synthesis of new polymers via Diels–Alder reaction. III. Biscyclohexadienephthalimides as dienes
Authors: Kuhrau Martin , Stadler Reimund 
Published: April 2007

AbstractDifunctional cyclohexadienes with dihydrophthalimide central units and phenyl side groups to increase solubility are used as bisdienes in repetitive Diels‐Alder polyadditions with bis(4‐(1,2,4,‐triazoline‐3,5‐dione‐4‐yl)phenyl)methane as a difunctional dienophile. The polymers show good solubility in CH2CI2 and CHCI3. Non‐stoichiometric Diels‐Alder polyaddition with slight excess of the bistriazo‐linedione provides the possibility of synthesizing telechelics with highly reactive triazolinedione end groups.
An investigation into the preparation of polyorganosiloxane materials from olivine
Authors: Bains Raghbir S. , Kendrick Dafydd Ap , Parsonage John R. 
Published: April 2007

AbstractModification of the Lentz trimethylsilylation technique was used to synthesize QxMy and QxMy(OH)2 polyorganosiloxanes from olivine (Q = SiO4/2, M = (Me3SiO1/2). The products ranged from viscous mobile liquids to hydrophobic insoluble solids with a molecular weight distribution between 3 × 103 and 400 × 103 depending on the time of addition of silylating agent, hexamethyldisiloxane (MM), to the preformed silicic acids. The stabilisation of the silicic acids leached from olivine was controlled by varying the period of silicic acid condensation‐polymerisation reactions and their solution concentration. The absence of the phase transfer agent propan‐2‐ol from the modified trimethylsilylation reaction resulted in the formation of silica gel. Propan‐2‐ol, by associating with silicic acids leached from olivine, produced a stable pre‐polymer suspension consisting of partially capped silicic acids.
A study of the thermal and dynamic mechanical properties of functionalized aryl cyanate esters and their polymers
Authors: Barton John M. , Hamerton Ian , Jones John R. 
Published: April 2007

AbstractDifferential scanning calorimetry (DSC) was employed to examine the thermally initiated and catalysed polymerizations of a number of cyanate ester monomers. Rigorous purification by preparative HPLC was found to have marked effects on the thermal polymerization characteristics of these compounds as determined by DSC. The effects on the thermal behaviour of varying the heating rate and level of catalysis were also examined. The thermal polymerization of the cyanate ester monomers was found to obey a first order model over wide apparent conversion limits. Functionalized cyanate ester/bis‐maleimide copolymers were prepared and the thermal stabilities of these were evaluated by thermogravimetric analysis (TGA) alongside a variety of commercial blends and homopolymers. The dynamic mechanical properties of the cured neat resins were also investigated.
Estimation of the equation of state exchange energy and entropy parameters of a polymer‐solvent pair by intrinsic viscosity measurements
Authors: Yilmaz Ferdane , Baysal Bahattin M. 
Published: April 2007

AbstractThe intrinsic viscosity data of linear poly(4‐chlorostyrene) in n‐propylbenzene and isopropylbenzene were used to estimate the equation of state exchange energy (X12) and entropy (Q12) parameters. The quantities estimated for X12 were 6.7 and 8.1 J cm−3 and those of Q12 were −0.069 and −0.063 J cm−3 deg−1 in n‐propylbenzene and isopropylbenzene, respectively. The average values of the chain unperturbed dimension constant (Ko) and the characteristic ratio (Cx) were found to be 0.55 × 10−3 dl mol1/2g−3/2 and 10.54, respectively, from the intrinsic viscosities measured at the corresponding θ‐temperatures.
Formation of cross‐links during prepolymerisation reaction of methylene‐bis (4‐phenylisocyanate) with poly (tetramethyleneoxide) in N,N‐Dimethylacetamide
Authors: Kamide Kenji , Hanahata Hiroyuki 
Published: April 2007

AbstractAn attempt was made to investigate the cross‐linking reaction which occurs as a side reaction when an excess of methylene‐bis(4‐phenylisocyanate) (MDI) is reacted with polytetramethyleneoxide (PTMO) (number‐average molecular weight 2010) in N,N‐dimethylacetamide (DMAc) prepolymerisation reaction) to give an isocyanate‐terminated prepolymer having urethane groups. Cross‐links existing in the prepolymer were shown to be of the biuret type by high performance liquid chromatography (HPLC) analysis on a product prepared by the raction of excess phenylisocyanate with n‐butanol in DMAc. The biuret‐forming reaction, as well as the urethane reaction (i.e. the main reaction), is accelerated remarkably by an N,N‐dimethyl‐N'‐phenyl(phenylcarbamoyl)acetamidine derivative formed from a side reaction of MDI with DMAc, and the former reaction is suppressed dratically by neutralising the corresponding amidine with, for ecample, H2SO4. A novel kinetic model of the prepolymerisation reaction is proposed and reaction orders and rate constants are derived. Three heterocompetitive reactions are involved: (1) urethane groups formed from MDI with PRMOin the prepolymer, and subsequent formation of (2) biuret type cross‐links between isocyanates and urea groups formed from MDI with DMAc as a side reaction, and (3) the corresponding amidine derivative.
A novel synthesis of polymers with anthracene and dihydroanthracene subunits in the main chain
Authors: Bartz Thomas , Klapper Markus , Müllen Klaus , Schulz Rolf C. 
Published: April 2007

AbstractA new polycondensation method to connect redox‐active and chromophoric subunits by forming a C‐C bond and leading to a polyhydrocarbon is described. 1,ω‐bis(9,10‐Dihydro‐9‐anthry)alkanes with various alkylene spacers can be deprotonated by butyllithium to afford a monoanion in each dihydroanthracene moiety. Alkylation with dielectrophiles such as dibromoalkanes yields soluble polymers with dihydroanthracene units in the main chain. The reaction proceeds regioselectively in the 9,10‐position. Aromatization generates a polymer with anthracene units. The molecular weights are determined by GPC up to M̄n = 10 000. To prove the structure and to calibrate the GPC, suitable model compounds were synthesized.
Miscibility and enthalpy relaxations in polysulfone—Carboxylated polysulfone blends
Authors: Lau Wayne W. Y. , Jiang Y. Q. , Tan Pedro P. K. 
Published: April 2007

AbstractPhase behavior in polysulfone‐carboxylated polysulfone (PSf‐CPSf) blends was studied by glass transition observations in conjunction with enthalpy relaxation technique. Miscibility in all proportions was detected in blends where CPSf has a degree of carboxylation (DC, i.e. number of carboxyl groups per repeat unit) less than about 1.3. Partial miscibility was detected in blends for DC > 1.4 and up to DC = 1.9, probably as a result of decreasing intermolecular interactions with increase in DC.
Polymerization of isoprene initiated by α, ω‐dilithiopolyisoprene: 7Li NMR study of lonic species
Authors: Madani Abdelaziz El , Belleney Joël , Favier Jean‐Claude , Hémery Patrick , Sigwalt Pierre 
Published: April 2007

Abstract7Li nuclear magnetic resonance (NMR) of dilute solutions in hexane of α, ω‐dilithiopolyisoprenes with two degrees of polymerization (DP) values was studied at several temperatures. For DP ≈ 500, the spectrum is similar to that of monofunctional poly(isoprenyl)lithium. When the DP is low (e.g. 80) new resonances appear upfield, showing the existence of more aggregated species. Their formation was attributed to the ability of dilithio compounds to undergo cyclization by intramolecular association. These observations and a computer simulation permit us to explain the kinetics of polymerization.
Solution properties of poly(fluorostyrene‐co‐chlorostyrene) copolymers. I. Light scattering, differential refractometry and viscometry
Authors: Segudovic Nikola , Vukovic Radivoje , Kuresevic Vjera , Karasz Frank E. , Macknight William J. 
Published: April 2007

AbstractThe weight‐average molecular weights (M̄w) of nominally random, unfractionated copolymers of ortho‐ and para‐fluorostyrene and ortho‐ and para‐chlorostyrene were determined by light scattering measurements in tetrahydro‐furan, toluene, carbon tetrachloride and chloroform. It was shown that there is no significant variation in measured M̄w in the various solvents, a finding indicating that the copolymers are not compositionally heterogeneous. Intrinsic viscosity measurements in the same solvents established a consistent relationship between [n] and M̄w despite the differences in copolymer compositions. It was not possible to establish a similar relationship between the second virial coefficient A2 and M̄w. It was concluded that measurements of the specific refractive index increment could be used for determining copolymer composition if the measurements were performed in thermodynamically poorer solvents. The results established for the Mark‐Houwink constant α, intrinsic viscosity, and A2 values indicated that these solvated copolymer molecules are in a less expanded conformation than are polystyrene molecules of similar molecular weights in a given solvent.