bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of rate constants for elementary reactions in cyclopolymerization of N‐propyldimethacrylamide
Authors: Yamada Bunichiro , Saya Toshiaki , Otsu Takayuki 
Published: April 2003

AbstractRadical cyclopolymerization of N‐propyldimethacrylamide (PDMA) was investigated. Kinetic orders of polymerization rate with respect to the monomer and the initiator were 1,0 and 0,5, respectively, at a monomer concentration greater than 1,6 mol/l. Absolute values of rate constants of propagation and termination reactions were determined by the rotating sector method in bulk and in 50% propionitrile solution at 30°C. Poly(PDMA) consists of 5‐membered cyclic repeating units almost exclusively. The rate constants for addition of poly(PDMA) radical to vinyl monomers and those for addition of polymer radicals to PDMA were also evaluated. One the basis of the rate constants obtained, the rate determining step of PDMA propagation was deduced to be the intermolecular addition of the growing radical to PDMA monomer. The growing radical of PDMA, formed by intramolecular addition to the carbon‐carbon double bond of the same molecule, was found to be as reactive as polymer radicals from reasonance stabilized monomers. The 5‐membered ring formation was highly favored by the conformation of PDMA in which coplanarity of the newly formed bond and the semi‐occupied orbital of the new radical center is readily achieved. Relatively low reactivity of poly(PDMA) radical was accounted for by delocalization of the unpaired electron on the coplanar three carbon atoms. Radical addition of a 2‐tertiary thiol to PDMA solely yielded the substituted succinimide. The 5‐membered ring formation in PDMA polymerization and in the addition reaction was ascribable to the favorable conformation of PDMA.
Study of photopolymers, 15. Polymerization of ethylene glycol divinyl ether and photocrosslinking reaction of its polymer
Authors: Nishikubo Tadatomi , Iizawa Takashi , Yoshinaga Akira , Nitta Masayuki 
Published: April 2003

AbstractSoluble polymer with methylene‐1,4‐dioxane‐2,3‐diymethylene (75 − 65 mole‐%) and 2‐[(vinyloxy)ethoxy]ethylene structural units (25 − 35 mole‐%) were obtained in the radical polymerization of ethylene glycol divinly ether (EGVE) in benzene at conversions of about 30 – 45%. It was found that in the radical polymerization of EGVE the rate of polymerization is proportional to the 1,5th power of monomer concentration and to the 0, 6th power of initiator concentration. On the other hand, a soluble polymer with 1,4‐dioxepane‐5,7‐diylmethylene units was obtained from cationic polymerization of EGVE in dichloromethane by using iodine as as catalyst. Moreover, the photocrosslinking reactions by irradiation with UV light of the radically obtained polymer having pendant vinyloxy groups with dithiols or by diazonium tetrafluroborates were investigated.
Polymethacrylic acid derivatives, 2. Spectroscopic study of the compact conformation to coil transition
Authors: Morcellet‐Sauvage Joëlle , Morcellet Michel , Loucheux Claude 
Published: April 2003

AbstractThe compact → coil conformational transition of hydrophilic‐hydrophobic copolymers derived from poly(methacrylic acid) was studied by UV Spectroscopy. Two copolymers were used in this study: a Poly(N‐methacryloylalanine‐co‐N‐phenylmethacrylamide) (P50) and a poly(methacrylic acid‐co‐benzyl methacrylate) (S25). Both samples exhibit hypochromism in the absorption band of the aromatic chromophore when they are under the compact conformation: 7% and 30% hypochromism for P50 and S25, respectively. This difference is explained by differences in the hydrophobic side chain‐side chain interactions between the aromatic residues. Increasing the temperature was found to increase strongly the hypochromism of S25 and to have little effect on P50.
Odd‐even effects in polymeric liquid crystals
Authors: Roviello Antonio , Sirigu Augusto 
Published: April 2003

AbstractSemiflexible mesophasic polymers of the general formula \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm OOC(CH}_{\rm 2} {\rm )}_{n - 2} - {\rm COO} - {\rm R}^1 \rlap{--} ]_{\rm X} ,n = 9,11,13,\rlap{--} [{\rm OOC(CH}_{\rm 2} )_{n - 2} - {\rm COO} - {\rm R}^2 \rlap{--} ]_{\rm X} ,n = 9,11,13,14, $\end{document}
and
\documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm OOCO} - {\rm (CH}_{\rm 2} {\rm )}_{n - 4} - {\rm OCOO} - {\rm R}^2 \rlap{--} ]_{\rm X} ,n = 9,11,13, $\end{document}
where
\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}^{\rm 1} = - {\rm C}_{\rm 6} {\rm H}_{\rm 5} - {\rm C}({\rm CH}_3 ) = {\rm CH} - {\rm C}_6 {\rm H}_5 - $\end{document}
and
\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}^{\rm 2} = {\rm C}_{\rm 6} {\rm H}_{\rm 5} - {\rm C}({\rm CH}_3 ) = {\rm N} - {\rm N} = ({\rm CH}_3 ){\rm C} - {\rm C}_6 {\rm H}_5 - $\end{document} are prepared and their solid and liquid crystalline behaviour examined and compared to that of the corresponding homologues with n even. Evidence is given of relevant odd‐even effects in the thermodynamic parameters of the clearing transition. The conclusion is drawn in favour of an anisotropic structuration also of the flexible parts of the polymer chain in the liquid crystal phase.
Modification des condensats phénoliques par des groupes phtalimides. Résines dérivées des phtalimidométhylphénols. Synthèse et caractérisation
Authors: Guyot Alain , Revillon André , Sallé Robert , Sillion Bernard 
Published: April 2003

AbstractBy reacting N‐hydroxymethylphthalimide (5a) or N‐chloromethylphthalimide (5b) with an excess of phenol, a mixture of 2‐phthalimidomethylphenol (6) and 4‐phthalimidomethylphenol (7) was obtained. The ratio 6/7 was found to be 2:3 for the reaction with 5a and 3:2 with 5b, as determined by 1H NMR at 250 MHz. The condensation of 6 with hexamethyleneteraamine (3) at the mole ratio 6/3 equal to 2 and 7,5 was performed at 190°C. The resulting resins (HPP) were compared to those prepared from o‐cresol and 3 (HOC), and GPC of the resulting products was made. A higher thermal stability of the resins HPP was evidenced by thermogravimetric analysis. This improvement of the thermal stability was also observed for the condensation products of the ortho and para isomers 6 and 7 with phenol and formaldehyde, leading to modified novolacs FPP, although the amount of incorporated 6 and 7 was found to be less than the original amount in the reaction mixture.
Estimation of chain molecular dimension of poly(2‐methylpent‐1‐ene sulfone) at critical polymer contents by dielectric measurements
Authors: Araki Kazuo , Imamura Yoshio 
Published: April 2003

AbstractDielectric measurements were made in the frequency range from 30 Hz to 3 MHz for a series of the solutions of poly(2‐methylpent‐1‐ene sulfone) (PMPS) having two different molecular weights in benzene at 30°C. The unperturbed chain molecular dimension was estimated from dielectric relaxation time at the critical polymer contents, Ccr. This value of the unperturbed dimension was much higher than that from the intrinsic viscosity measurement. The dielectric motion at Ccr involves simultaneous co‐operative reorientations of about three spheres. The number of the spheres of reorientation may be related to the flexibility of the molecular chain of the polymer. The ratio of two effective volumes of the polymer obtained from the unperturbed chain molecular dimension and from the dielectric relaxation time, τm agreed with that of the two effective volumes obtained from the K value in Onogi's treatment and from the τm value.
Absolute determination of molecular weights of standard polystyrenes by means of sedimentation‐diffusion measurements in toluene
Authors: Petrus Vladimír , Porsch Bedřich , Nyström Bo , Sundelöf Lars‐Olof 
Published: April 2003

AbstractSedimentation coefficients, s0c, diffusion coefficients, Dc, and specific viscosities have been determined for eleven samples of commercial narrow‐molecular‐weight distribution polystyrenes Pressure Chemicals Co. and Waters Ass., 5 · 104 g · mol−1 < weight average molecular weight Mw < 2 · 106 g · mol−1 at different concentrations in toluene (25°C). From the Svedberg equation the values of the MsD averages have been calculated from the sedimentation and diffusion coefficients extrapolated to infinite dilution. The reproducibility of the measured values of s00, D0 and [η] was better than 3%. The parameters determined for the same samples in Prague and in Uppsala (using different instruments and different data evaluation techniques) were in good agreement (the maximum deviation 6%). The plots of log s00 vs. log D0 and log [η] vs. MsD are linear without any systematic deviations; all experimental hydrodynamic data are consistent within the interval of experimental error, i.e. ±3%. However, when plotted versus the nominal molecular weights the scatter is considerably increased. Furthermore, the calculated average molecular weights, MsD, differ in several instances from the nominal ones.
Polymer‐solvent interactions in mixed solvents, 4. Ethyl‐ and butyl vinyl ether‐maleic acid alternating copolymers in water/2‐chloroethanol mixtures
Authors: Apostolopoulos Michel , Morcellet Michel , Loucheux Claude 
Published: April 2003

AbstractViscosity and preferential solvation measurements were carried out on maleic acid‐ethyl‐ and ‐butyl vinyl ether alternating copolymers (MA‐EVE and MA‐BVE, respectively) in watermethanol and water‐2‐chloroethanol mixtures. The conformational transition of MA‐BVE was found to be strongly related to the solvation of the polymer by 2‐chloroethanol. Comparison of experimental results on MA‐BVE, MA‐EVE, and poly(methacrylic acid) (PMA) in water‐2‐chloroethanol mixtures indicates that the behaviour of MA‐EVE is different from that of MA‐BVE and PMA because it does not undergo any conformational transition.
Darstellung und eigenschaften von copolyamiden mit oxyethylengruppen in definierter sequenz
Authors: Iwabuchi Susumu , Nakahira Takayuki , Tsuchiya Atsushi , Kojima Kuniharu , Böhmer Volker 
Published: April 2003

AbstractThe polyamides 3–5 were synthesized from α,ω‐diamino‐substituted oligo(oxyethylene)s (1) and bis‐chlorides of dicarboxylic acids (2). As copolymers with defined sequences they contain up to five oxyethylene units per repeating unit. Hereby properties like solubility, thermal stability and complexing ability towards alkali metal cations are influenced.
Stereochemistry of the acetal addition of a β‐deuterated vinyl ether as a model reaction for the polymerization of vinyl ethers
Authors: Morii Hisayuki , Fujishige Shoei , Matsuzaki Kei , Uryu Toshiyuki 
Published: April 2003

AbstractAs a model reaction for the homogeneous cationic polymerization of vinyl ethers, cis‐ethyl vinyl ether‐β‐d (1a) was reacted with 1,1‐diethoxyethane in presence of BF3O(C2H5)2 as a catalyst. The steric structures of the adducts, mainly 1,1,3‐triethoxybutane‐2‐d (3a) and 1,1,3,5‐tetraethoxyhexane‐2, 4‐d2 (4a, equivalent to the dimer) were determined by means of 1H NMR spectroscopy, taking into account the conformational characteristics based on energy calculation. The predominant stereoisomer of 3a was proved to be the erythro‐form. The assignments of the methylene proton resonances to erythro‐ and threo‐configurations were applied to the analysis of the spectra of 4a which enabled us to elucidate the molecular aspects of the opening of the double bond and the mode of approach of the monomer to the cationic reactive site. It was also concluded that the stereospecific reaction might be attributed to the repulsive forces between the ethoxy group of vinyl ether and that of the carbonium ion derived from the acetal.
Stereoregularity of polystyrene derivatives, 4. Poly(α‐methylstyrene) obtained by anionic catalysts
Authors: Kawamura Tokiji , Uryu Toshiyuki , Seki Toshiyuki , Matsuzaki Kei 
Published: April 2003

AbstractThe stereoregularity of poly(α‐methylstyrene)s prepared by anionic initiators was determined from the peak area of α‐methyl proton absorptions and aromatic C1 carbon absorptions. Highly syndiotactic polymers were obtained at 0°C in both toluene and tetrahydrofuran (THF). Sodium, potassium, and cesium naphthalenes gave polymers with the same syndiotacticity in THF. The syndiotacticity of polymers prepared by sodium and potassium naphthalenes as catalyst in both toluene and THF decreased at low temperatures. This behavior is similar to that of o‐methylstyrene and m‐methylstyrene in THF. The stereoregulation mechanism in the anionic polymerization of α‐methylstyrene is discussed and compared with that of polystyrene and ring substituted polystyrenes.
Thermolyse einiger azoalkylacetate und azochloralkane
Authors: Nuyken Oskar , Schuster Herbert , Kerber Robert 
Published: April 2003

AbstractThe kinetic results (from DSC and 1H NMR) of the thermolysis of symmetric azochloroalkanes and azoalkyl acetates with the general structure R1 R2 (X) C—N=N—C(X) R1 R2 (X=OCOCH3, Cl; R1, R2=CH3, C6H5) and of asymmetric phenylazoalkyl acetates with the general structure R1 R2(H3COCO) C—N=N—C6H5(R1 R2=CH3, C6H5) are described. The suitability of the asymmetric compounds as initiators for radical polymerization is demonstrated with (diphenyl)phenylazomethyl acetate (7c). Quantitative measurements of the thermolysis products from 1,1′‐azo(methylethyl) diacetate (4a) showed that the ratio for the disproportionation to combination reaction of the resulting substituted alkyl radikals is 4,3.
Configurational statistics of poly(dimethylsiloxane) accounting for all rotational states
Authors: Brückner Sergio , Malpezzi Luciana 
Published: April 2003

AbstractSome configuration‐dependent properties of poly(dimethylsiloxane) are evaluated by taking into account the full rotational range around skeletal bounds (ars model). Allocation of fractional electronic charges to Si, O and C atoms and consequent coulombic interactions give an essential contribution to the interpretation of experimental data. A comparison is drawn with the rotational isomeric state (ris) model adopted by many authors. A substantial equivalence between the two models is detected in the study of long polymer chains while some detectable difference arises in the description of short sequences.
13C NMR sequence analysis, 22. Stereoselectivity of the polymerization of D,L‐leucine and D,L‐valine N‐Thiocarboxy anhydrides
Authors: Kricheldorf Hans R. , Mang Thomas 
Published: April 2003

AbstractTwo kinds of N‐thiocarboxyanhydrides of D,L‐L and D,L‐L were synthesized, 5‐oxo‐2‐thioxo‐1,3‐oxazolidones 1a, 1b and 1,3‐thiozolidine‐2,5‐diones 2a, 2b. Their polymerizations were conducted at 20°C with primary, secondary, and tertiary amines or with potassium tert‐butylate as initiators. The tacticity of the resulting poly(D,L‐L)s and poly(D,L‐L)s was investigated by means of 13C NMR spectra. It was found that under all conditions the formation of isotactic sequences is favoured. The stereoselectivities of all polymerizations were low; the average lengths of isotactic blocks never exceeded 6 monomeric units. The chain growth deviates slightly from the Bernoullian statistics favoring the formation of longer isotactic blocks. While D,L‐4‐isopropyl‐2,5‐thiazolidindione (2a) did not polymerize, the polymerization of D,L‐4‐isopropyl‐5‐oxo‐2‐thioxooxazolidine (1a) (D,L‐L‐NTA) showed under all conditions lower stereoselectivities than those of the two D,L‐L‐NTAs.
Immobilisierung von salmin an CNBr‐sepharose 4B
Authors: Zeitz Klaus , Schott Herbert 
Published: April 2003

AbstractThe protamine salmine was immobilized on CNBr‐Sepharose 4B without involving the arginine side‐groups. The optimum conditions for the immobilization on a preparative scale were investigated in a series of analytical experiments. A Maximum yield (206 mg salmine/g dry salmine‐sepharose) was achieved at a pH‐value of 8, a gel concentration of 10 mg/ml suspension volume and a salmine sulfate concentration of 5 mg/ml reaction solution. An equation was developed to calculate the maximum immobilization of peptides on CNBr‐Sepharose 4B assuming known molecular weights of the ligand.
Polysiloxane‐based activators in the anionic block copolymerization of ϵ‐caprolactam
Authors: Lefebvre Pierre Marie , Jerome Robert , Teyssié Philippe 
Published: April 2003

AbstractThe activator used in the anionic polymerization of ϵ‐caprolactam is systematically anchored onto the growing polyamide chain. The use of a macromolecular activator, as an isocyanate‐terminated polymer, provides an attractive pathway to block copolymerization. However, this procedure is not compatible with a polysiloxane activator, because of the degradtion of the siloxane backbone under conditions needed for ϵ‐caprolactam polymerization. The degradation process was unambiguously evidenced through model‐reactions. This conclusion is in contradiction with a previously published report on this subject.
Über ternäre azeotrope — zur frage der existenz eines ternären azeotroppunktes ohne binäres azeotrop
Authors: Quella Ferdinand , Braun Dietrich 
Published: April 2003

AbstractThe terpolymerization equations of Alfrey‐Goldfinger and Ring for calculation of ternary azeotropes are compared. It is shown that the equation of Alfrey and Goldfinger can be transformed into that of Ring. Possible copolymerization ratios for the existence of ternary azeotropes without a binary one are discussed. Copolymerization ratios taken from literature show that there is a chance to find such and azeotrope, but and existing example was not found. So copolymerization ratios were arbitrarily chosen to give a range wherein such and azeotrope could exist.
Configurational characteristics of the polysulfides, . Dipole moments and gauche effects in poly (1,3‐dithiocane)
Authors: Welsh W. J. , Mark J. E. , Guzman J. , Riande E. 
Published: April 2003

AbstractSeveral earlier studies of poly(alkylene sulfides) have not yielded evidence for a sulfur gauche effect, in contrast to the large attractive gauche effect found particularly in the lower members of the poly(alkylene oxides). In this study the dipole moments at 25°C and the corresponding temperature coefficient of poly(1,3‐dithiocane)Structure based name: poly(thiomethylonethiopentamethylene).
[SCH2S(CH2)5]x are calculated in the rotational isomeric‐state approximation, and the results compared to the values determined by experiment. In the calculations the energy Eσ′ = [Eg± − Et] associated with S. . .CH2 interactions in the SCH2SCH2 segment is adjusted to attain agreement between theory and experiment. The results indicate that an extra stabilization energy of ca. 0,9 kcal . mol−1 must be added to these gauche states relative to the trans state (beyond that determined by conformational energy calculations based on semiempirical potential energy functions). This provides the first evidence of a large attractive sulfur gauche effect in the polysulfides, about equal in magnitude to that found for the analogous poly(methylene oxide).
The copolymerization of unsaturated carboxylic acids with styrene and an unsaturated tertiary amine in benzene
Authors: Harbák František , Bezděk Milan , Hynková Vlasta , Svobodová Jarmila 
Published: April 2003

AbstractThe copolymerization parameters of 2‐acryloyoxybenzoic (AOB) and 2‐methacryloyloxybenzoic (MOB) acids, methyl 2‐methacryloyloxybenzoate (MMOB), and N‐methyl‐N‐phenyl‐2‐aminoethyl methacrylate (MPAM) with styrene in benzene solution were determined and used in the calculation of the Alfrey‐Price copolymerization constants e and Q for AOB, MOB, MMOB, and MPAM. Using e Q thus determined and the corresponding tabulated values for methacrylic acid (MAA), the copolymerization parameters of pairs AOB‐MPAM, MOB‐MPAM, MMOB‐MPAM, and MAA‐MPAM were calculated. They are compared with those determined by the copolymerization of these pairs in which the interaction of functional groups on comonomers plays a role.
Miscibility of poly(vinyl chloride) with ethylene/N,N‐dimethylacrylamide copolymers.
Authors: Matzner M. , Robeson L. M. , Wise E. W. , McGrath J. E. 
Published: April 2003

AbstractThe incorporation of N,N‐dimethylacrylamide (DMA) as a comonomer in polyethylene yields a material possessing dramatically improved mechanical compatibility with poly(vinyl chloride) (PVC). At increased levels of DMA (25–30 wt.‐%) miscibility with PVC is achieved. This behavior is believed to be due to the specific interaction of the tertiary hydrogen of poly(vinyl chloride) (weak “acid” or proton donor) with the disubstituted amide in the ethylene copolymer (weak “base” or proton acceptor). Dynamic mechanical characterization of the ethylene/DMA copolymer (EDMA)/PVC blends reveals separate glass transitions temperatures at DMA levels below 20 wt.‐%; they merge into a single Tg when the DMA content reaches a value above 25 wt.‐% in the ethylene copolymer. The secondary loss transition for PVC (−40°C) is lowered in temperature and greatly suppressed in magnitude. This is further evidence of molecular miscibility. Mechanical property data obtained on the EDMA/PVC blends are consistent with the foregoing considerations.
Grafting of styrene onto carbon fibers having pendant thiol groups
Authors: Fujisawa Takao , Tanaka Akira , Yosomiya Ryutoku 
Published: April 2003

AbstractCarbon fibers containing thiol groups were produced by reacting carbon fiber oxidized by nitric acid, with excess thiirane. Then, graft polymerization with styrene was carried out in a sealed tube under nitrogen. The following order of initiating ability of the investigated initiators was found: di‐tert‐butyl peroxide > p‐cumenyl hydroperoxide (CHPO) > dodecyl peroxide > benzoyl peroxide > 2,2′‐azoisobutyronitrile. When CHPO was used as initiator, the rate of graft polymerization was maximum at [CHPO] = 0,01 mol/1. Chain transfer constant and grafting efficiency, both calculated from the equations of Fox and others, were compared with the experimental results.
Limiting viscosity number and sedimentation coefficient of solutions of cellulose acetates
Authors: Ishida Shin‐Ichiro , Komatsu Hideki , Katoh Hiroyuki , Saito Masatoshi , Miyazaki Yukio , Kamide Kenji 
Published: April 2003

AbstractViscosity and sedimentation experiments were made for fractions of cellulose acetate CA (degree of substitution, D.S. = 2,46) in acetone and CA (D.S. = 2,92) in N,N‐dimethylacetamide (DMAc) at 25°C. The following empirical relations were established between the sedimentation coefficient at infinite dilution s0 and the weight average molecular weight M̄w: s0 = 1,02 · 10−14 M̄w0,39 (s) for CA (D.S. = 2,46) in acetone and s0 = 1,83 · 10−14 M̄0,24w (s) for CA (D.S. = 2,92) in DMAc. From the analysis of the molecular weight dependence of s0 and the limiting viscosity number [η] (method 1B) and the concentration‐dependence parameter ks and [η] (method 1E), the solvent draining parameter X was estimated to be less than 1, indicating that the free draining effect cannot be ignored. The unperturbed chain dimension parameter A was determined from data on s0 and M̄w to be between 1,72 · 10−8 and 1,80 · 10−8 cm for CA (D.S. = 2,46) in acetone and between 1,63 · 10−8 and 1,68 · 10−8 cm for CA (D.S. = 2,92) in DMAc. These values are in good agreement with those estimated by thermodynamic and viscometric approaches.
Studies of siloxane‐acid model system: Hexamethyldisiloxane‐trifluoroacetic acid
Authors: Wilczek L. , Chojnowski J. 
Published: April 2003

AbstractThe equilibrium in the system containing hexamethyldisiloxane, trifluoroacetic acid, and the inert solvent methylene chloride is studied. The system may serve as a model of reactions which play an important role in the cationic polymerization of cyclic siloxanes. The kinetic studies confirm that analogous reactions control the concentrations of silanol and silyl ester end groups as well as of acid and water during the polymerization. Allowing for some hydrogen bonding formation in the analysis of these equilibria the respective equilibrium constants can be obtained preserving almost constant values in the total range of concentrations studied.