bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ring‐opening polymerization of nitrogen– and phosphorus‐containing monomers: Polymerization mechanism and polymer properties
Authors: Kobayashi Shiro , Saegusa Takeo 
Published: March 2011

AbstractThe first part of this paper describes cationic polymerizations of cyclic imino ethers, 2‐oxazolines and 5,6‐dihydro–4H–1,3–oxazines, which proceed via cyclic onium propagating species or via covalently bonded alkyl halide species. In an extreme case, both ionic and covalent species are present in equilibrium and propagate concurrently. The propagation rate constants due to the respective species were determined. A poly(cyclic imino ether) becomes hydrophilic or lipophilic dependent on the substituent of the monomer. Based on this principle, various types of nonionic polymer surfactants have been prepared, e.g., diblock and triblock copolymers, graft copolymers, and surfactants having one 2‐oxazoline chain. The second part is concerned with ring‐opening polymerizations of new eight cyclic trivalent phosphorus monomers. These polymerizations produced phosphorus‐containing functional polymers such as a chelating resin. 31P NMR analyses of polymerization of cyclic phosphinite monomers led to propose a new mechanism of “Electrophilic Ring‐Opening Polymerization”.
Synthesis of copolymers containing acetals
Authors: Reibel L. , Zouine H. , Franta E. 
Published: March 2011

AbstractThe polymerization of cyclic acetals such as dioxolane and dioxepane, initiated by triflic acid in the presence of poly(ethylene oxide)glycol (PEOG), exhibits special features: One can produce triblock copolymers of PEOG and of one cyclic acetal; the molecular weight of the copolymer increases linearly with time like in a living system; a hydroxyl group is found at both ends of the copolymer obtained; macrocycle formation, usually inevitable in large quantity when a classical onium mechanism operates, can be very much reduced and even practically suppressed depending on the experimental conditions. When we tried to prepare a pentablock from the triblock by adding a second acetal under similar conditions (after recovery and purification of the triblock copolymer) we obtained fast transacetalization instead, leading to random placements of the two cyclic acetals, while the PEOG remained as one block, and that only a very small amount of cycles was formed if any. These results are interpreted in terms of multiple transfer reactions of hydroxyl groups onto activated monomer molecules or onto small growing oligomers.
Regularities of cationic polymerization of substituted aziridines
Authors: Ponomarenko V.A. , Chekulaeva I.A. , Lapshina I.V. , Ignatenko A.V. 
Published: March 2011

AbstractThe cationic polymerization of some ordinary N‐ and C‐substituted aziridines, initiated by the methyl etherate of boron trifluoride, shows a typical “temporarily living” character. Kinetic and spectroscopic data on the polymerization of N‐methyl‐aziridine under conditions under consideration as well as molecular mass characteristics of the polymers obtained, testify to the zwitter‐ions as active centres of chain growth. This process is characterized by slow initiation, stationarity of propagation and slow termination with the participation of the polymer chain just after a monomer is used up. Such peculiarity of zwitter‐ion polymerization allows to obtain liniar functional polyaziridines of given molecular mass by termination of the system by means of appropriate nucleophilic compounds.
‘Immortal’ anionic ring‐opening polymerization by metalloporphyrin catalyst
Authors: Inoue Shohei 
Published: March 2011

AbstractRing‐opening polymerization of epoxide initiated by aluminium porphyrin gives polyether with narrow molecular weight distribution even in the presence of chain transfer agent such as alcohol. This is due to the rapid, reversible exchange between (porphinato)aluminium alkoxide as the growing species and alcohol. As a result, the growing polymer molecules never die, and the reaction may be called ‘immortal’ polymerization.
The active centres' nature in anionic polymerization of polar monomers
Authors: Berger Werner , Adler Hans‐Jürgen 
Published: March 2011

AbstractIn the anionic polymerization of polar monomers the nature of active centres is considerably influenced by the reaction conditions. In a survey, the present state of knowledge is represented and discussed for the polymerization of acrylonitrile. Analogous problems of methyl methacrylate and vinylpyridine polymerization are included in the considerations.
Functionalization of living polymers – results and problems
Authors: Weber Lothar 
Published: March 2011

AbstractIn spite of intensive research, work during the last 20–30 years, even today, the reaction products of living polymers are produced only in small quantities on industrial scale. The expected production of tyres from telechelic polymers was not reached, The difficulty is that the functionalization of living polymers does not result in only one type of functionalized polymer chain but always in a mixture of non‐, mono‐, di‐ and polyfunctionalized compounds. During the last years different technologies for functionalizing living polymers were developed in Buna. The results of these investigations are discussed. Likewise, we show that the functionalized living polymers of ∝‐methylstyrene are of great interest for different industrial uses. A complete technological scheme for the production of telechelic polymers has been developed, which is attached herewith.
Determination of the number of active centers in Ziegler‐Natta polymerizations of olefins
Authors: Mejzlík Jiří 
Published: March 2011

AbstractThe methods employed for determination of the number of active centers are classified according to their principles into the following categories: (i) labelling of an organometal component as an initiating species; (ii) labelling of growing chains based on the number of macromolecules, on the number of metal‐polymer bonds, and on selective tagging of the growing chain; (iii) inhibition (retardation) of polymerization by effective catalyst poisons and calculation of the number of active centers on the basis of the poison consumption data. Typical features of the above categories are presented and advantages, as well as shortcomings of the methods are discussed.
Oh the mechanism of stereoregulation in the allylnickel complex catalyzed butadiene polymerization
Authors: Taube Rudolf , Gehrke Jörg‐Peter , Schmidt Udo 
Published: March 2011

AbstractAfter a brief account of the present knowledge on the mechanism of the allylnickel complex catalyzed stereospecific butadiene polymerization, synthesis and catalytic properties of the cationic allylnickel(II) complexes, [C3H5NiL2]PF6 (L = P(OAlk)3, P(OAr)3, PPh3, AsPh3, SbPh3, MeCN, Me3CNC, 1,5–COD), are described. From kinetic and 31P‐NMR spectroscopic investigations, especially with [C3H5Ni(P(OPh)3)2]PF6 as a typical trans‐catalyst, the definite course of the catalytic stereoregulation has been elucidated.
Synthesis of polyheterocycles on the basis of poly‐functional monomers and study of their characteristics
Authors: Zhubanov B. A. 
Published: March 2011

AbstractApplication of polyfunctional monomers in the course of polycondensation allows to synthesize different types of polymers using different activity of functional groups. It is possible in this case to vary to a large extent the characteristics of the obtained polymers. The presence of functional groups of different activity in one monomer also allows to modify it by introduction of new fragments for subsequent use in polycondensation or polymerization reactions.The abovementioned is confirmed by the example of using trimellitic anhydride and a number of alicyclic tetracarbonic dianhydrides.Trimellitic anhydride is directly used for synthesis of polymers and also modified for preparation of new derivatives.The perspective of using alicyclic tetracarbonic dianhydrides for synthesis of heterocycles has been shown.Varying the monomer nature and conditions of a polycondensation reaction, polymers with different specific characteristics have been obtained: heat‐resistant, high‐ and low‐fusible, soluble, incombustible, film‐forming, fiber‐forming, binding for glass‐plastics.
Model reactions for crosslinking of poly(diolefin)s by cations
Authors: Hallensleben Manfred L. , Nimtz Fritz 
Published: March 2011

AbstractIn order to study the reactivity of polymer chain segments of different chemical structure, which are generated either by the chain propagation mechanisms or by isomerization reactions of the preformed polymer chain as a consequence of chemical or temperature influences, low‐molecular‐weight model reactions are of growing interest (1–3). With respect to cationically initiated crosslinking reactions of poly(diolefin)s, linear as well as cycloolefins may serve as model compounds to elucidate initiation and propagation steps in regard to network formation. Of particular interest are the number of individual polymer chains which are interconnected in the crosslink section.1‐Methylcyclohexene, a model for cis‐1,4‐poly(isoprene), reacts with protons as well as classical carbenium ions to yield the addition products and dimers only, which show structural varieties. Some of the isomers were separated by preparative HPLC and were identified by NMR and mass spectroscopy.
Topological aspects of structure and properties of highly crosslinked networks
Authors: Topolkaraev V. A. , Berlin A. A. , Oshmyan V. G. , Prut E. V. 
Published: March 2011

AbstractStatistical model approach which allows to set the quantitative interrelation between the chemical structure of initial reagents, formation mechanism, topology and in the final analysis mechanical properties of highly crosslinked networks, is considered. The role of network topology in the formation of the main physico‐mechanical properties of polymer network is singled out. The analysis is carried out on the important class of highly crosslinked networks, formed by polyaddition reaction of diepoxides with aromatic diamines.
Thermal oxidation of polyorganosiloxanes
Authors: Zhdanov A. A. , Papkov V. S. 
Published: March 2011

AbstractThe kinetics of noninhibited and inhibited oxidation of poly[(diethyl)siloxane] oligomers (PDES) has been investigated. Phenyl‐ β ‐naphthylamine (PNA) and tris(triethylsiloxy)vanadate (TTESV) were used as antioxidants. It is shown that in the presence of PNA the oxidation of PDES proceeds with distinct induction periods. The activation energy of the initiation stage, estimated from temperature dependence of the induction periods, is about 230 kJ/mol. TTESV can act as inhibitor and catalyst in the oxidation of PDES, depending on temperature and content of oxygen in oxidizing mixture.
Role of metal ions in development of specific properties of polymer metal complexes
Authors: Rashidova S.S H. , Urinov E. U. , Khodjaev S. G. 
Published: March 2011

AbstractThe character of changing the hydrodynamic and conformational characteristics of vinylpyrrolidone copolymers with acrylic acid depending on solvent nature was studied. Peculiarities in changing the hydrodynamic, molecular characteristics and complex forming properties of equimolar vinylpyrrolidone copolymer with metal ions are revealed. Metal ions introduction in copolymer macromolecules gives rise to polymer‐specific, physiologically active properties.
High‐pressure absorption spectroscopy in polymerizing systems
Authors: Buback Michael , Vögele Hans‐Peter , Winkels Hermann‐Josef 
Published: March 2011

AbstractQuantitative high‐pressure absorption spectroscopy in the mid infrared, near infrared, and ultraviolet region enables direct and precise investigation of high‐pressure ethylene polymerizations with thermal, chemical, and laser‐photochemical initiation. The special advantages of kinetic studies via quantitative near infrared spectroscopy in an extended wavenumber range are outlined. Extensions of the method on copolymer systems are indicated. The spectroscopic technique is of general applicability in studies on reactions and equilibria in dense fluid states including liquids and compressed gases.
Fourier transform infrared study of orientation and relaxation in poly(methyl methacrylate)
Authors: Zhao Y. , Jasse B. , Monnerie L. 
Published: March 2011

AbstractInfrared measurements of the dicroic ratio of poly‐(methyl methacrylate) absorption bands provide a valuable method for determining the orientation as well as the relaxation of chains during stretching. Different strain rates and temperatures of stretching were used. Orientation relaxation was determined and a master curve was obtained at a reference temperature TO = 135°C. The master curve shows that orientation relaxation behaves similarly to mechanical relaxation.
Annealing of the β‐modification of polypropylene
Authors: Varga József , Tóth Ferenc , Hummel D.O. 
Published: March 2011

AbstractExpressive memory effect has been proven in the course of the annealing of the β‐modification of polypropylene (β‐PP). The character of the structural changes taking place in β‐PP during annealing strongly depends on the thermal history. In dependence on the thermal history βα or ββ‐recrystallization takes place during thermal treatment. In case the annealing starts from the crystallization temperature β‐PP is recrystallized into a more perfect structure with higher melting point ‐ similarly to thermodynamically stable modifications. The samples cooled below a certain temperature before subjected to annealing transform partly or fully into the α‐modification. The βα‐recrystallization tendency prevalent on the effect of recooling can be reduced or eliminated with the aid of stepwise annealing with decreasing temperature steps.
Reactivity of lactams in anionic polymerization
Authors: Sebenda Jan 
Published: March 2011

AbstractThe rate of anionic lactam polymerization is greatly affected by variation of the permittivity of lactams with ring size and substitution, as well as by changes of permittivity during polymerization. Therefore, an estimation of reactivities under comparable conditions is possible in solution only. The lack of any solvent permitting anionic lactam polymerization at low temperatures was circumvented by using living polymers soluble in aprotic solvents as carriers. Such polymers are able to remain in solution even after the addition of a few monomer units of a lactam, the polymer of which is insoluble. In this way, relative reactivities of a series of four‐membered lactams, as well as that of the five‐membered one were established.
Cyclic polysiloxanes
Authors: Semlyen J. A. 
Published: March 2011

AbstractThe preparation, fractionation and characterisation of synthetic cyclic polysiloxanes (R(CH3)SiO)x are reviewed. Particular emphasis is given to the cyclic poly(dimethylsiloxanes) (PDMS) (R is CH3) cyclic poly(phenylmethylsiloxanes)(PPMS) (R is C6H5) and cyclic poly(vinylmethylsiloxanes) (PVMS) (R is CH2=CH).The application of high performance liquid chromatography (HPLC) and analytical and preparative gel permeation chromatography (GPC) to the preparation and characterisation of cyclic polysiloxanes is discussed. The methods include preparation of sharp fractions of relatively high molar mass cyclic polymers (with heterogeneity indices typically ca. 1.05) and comparison of the GPC and retention volumes of cyclics with the corresponding linear polymers.Investigations of the cyclic polymers prepared have been made using a number of experimental methods and techniques. These include dilute solution viscometry and low angle neutron scattering. Comparisons are drawn between cyclic PDMS and other cyclic polysiloxanes and also between cyclic polysiloxanes and the corresponding commercially‐important linear polymers.
‘Immortal’ polymerization of epoxide with metalloporphyrin catalyst
Authors: Inoue Shohei , Aida Takuzo 
Published: March 2011

AbstractAluminum porphyrin is an excellent initiator for the polymerization of epoxides to give polyethers with narrow molecular weight distribution, even in the presence of protic compounds such as alcohols, carboxylic acids, and hydrogen chloride. The number of polymer molecules is higher than that of initiator molecules. By taking advantage of the “immortal” nature of this polymerization, a novel, efficient procedure for the synthesis of block copolymers and end‐reactive polymers with narrow molecular weight distribution is developed.
Synthesis of polyoxiranes and polythiiranes bearing a potential aldehyde group in the side chain
Authors: Goutte P. , Sepulchre M. , Spassky N. 
Published: March 2011

AbstractPolyoxiranes and polythiiranes with acetal group in the side chain are prepared by polymerization of 1,1‐diethoxy‐2,3‐epoxy‐propane (DEO) and of the corresponding thiirane (DET) using different chiral and achiral initiators. In the case of poly(DET) acetal groups can be removed leading to a polymer with an aldehyde content up to 64 %. In similar experimental conditions the extent of acetal hydrolysis does not exceed 23 % for poly(DEO).
Gas phase polymerization of cyclopentene
Authors: Ismail F. , Léonard J. 
Published: March 2011

AbstractPure gaseous cyclopentene is found to polymerize on a glass surface when the polymerization is initiated with tungsten hexachloride. The polymer thus formed is colourless and has a high molar mass with a narrow molecular mass distribution. Polymerizations are carried out in the 10 to 60° C temperature range. From kinetic measurements, an overall activation energy of 69,0 kJ is obtained for the conversion of gaseous monomer to condensed polymer. NMR analyses show a distribution of cis‐and trans‐configurations of the double bonds in the polymer and the absence of any detectable branching.
Synthesis of poly‐β‐(α‐benzyl‐L‐aspartate) from L‐aspartic β‐lactam benzyl ester (3(R)‐benzoxycarbonyl‐2‐azetidinone)
Authors: Rodriguez‐Galan A. , Muñoz‐Guerra S. , Subirana J.A. , Chuong Bui , Sekiguchi H. 
Published: March 2011

AbstractA study on the anionic‐assisted polymerization of L‐aspartic β‐lactam benzyl ester in solution has been carried out in order to prepare an improved poly‐β‐(α‐benzyl‐L‐aspartate). We have found that both imide formation (with appreciable racemization) and size of the resulting polymers are highly dependent on the nature of reaction medium. A high molecular weight poly‐β‐aspartate without detectable branching could thus be obtained by using solvents with low polarity. The mechanism of side reactions is discussed.
Ab‐initio electrostatic molecular potential contour maps for initiation step and Ab‐Initio MRD‐CI calculations for propagation step of cationic polymerization of oxetanes
Authors: Kaufman Joyce J. , Hariharan P. C. , Roszak S. , Keegstra P. B. 
Published: March 2011

AbstractThe initiation step in the cationic polymerization of cyclic ethers is influenced by basicity and ring strain. We carried out ab‐initio MODPOT/VRDDO/MERGE calculations on a variety of substituted oxetanes and generated electrostatic molecular potential contour (EMPC) maps in three‐dimensions around the molecules. The size of the negative EMPC map region around the oxygen enabled us to predict the propensity to polymerize prior to the syntheses of the actual monomers themselves. We carried out ab‐initio MODPOT/VRDDO/MERGE MRD‐CI calculations for the propagation step of oxetane reacting with protonated oxetanes to cause ring opening of protonated oxetane. Similar MRD‐CI calculations on variously substituted oxetanes will shed insight into relative copolymerization preferences.
On several aspects of network formation and plastic deformation of tightly crosslinked epoxies
Authors: Oleinik E. P. , Bulatov V. V. 
Published: March 2011

AbstractThe article considers several features of the epoxy polymer network glassy state. Attention is paid to the “liquid‐glass” transition during cure, influence of the transition on the properties of network polymer, theoretical description of joint kinetics of network formation reaction and structural relaxation in tightly crosslinked polymer networks, and mechanism of plastic deformation of crosslinked epoxies in the glassy state.
Graphite intercalation compounds electrochemistry as a model for synthetic metals
Authors: Métrot André 
Published: March 2011

AbstractAfter an introductory description of the chemical and crystallographic properties of Graphite Intercalation Compounds, their general electrochemical behavior is examined. The reversible intercalation/de‐intercalation process leading to graphite salts is more specifically described based on the author's view of interlayer capacitive electroadsorption.
Preparation and electrochemistry of modified polypyrrole films by anodic copolymerization techniques
Authors: Merz A. , Baumann R. , Haimerl A. 
Published: March 2011

AbstractThe anodic copolymerization of pyrrole and N‐(ω‐ferrocenylalkyl)pyrroles, FcPy‐n, at platinum electrodes in an electrolyte consisting of tributylammonium benzenesulfonate in moist acetonitrile is optimized with respect to the absolute and relative concentrations of the monomers and the spacer length of FcPy‐n. The copolymer composition is estimated from cyclic voltammograms of the polymer films. Only films with less than 20% FcPy‐n content show the typical polypyrrole voltammograms. Free standing copolymer films with a conductivity of ca. 10 S cm−1 can be prepared.
Soluble conducting polymers: The poly(3–alkylthienylene)s
Authors: Rughooputh S.D.D.V. , Nowak M. , Hotta S. , Heeger A. J. , Wudl F. 
Published: March 2011

AbstractThe conjugated poly(3‐alkylthienylene)s, P3ATs, can be processed from solution and subsequently used as semiconducting and metallic polymers. Both as‐synthesized and solution‐cast films can be readily doped with resulting electrical conductivities which are quite high, σ‐30–100 S/cm.
Modification of carbon electrodes by vitamin B12‐polymers
Authors: Ruhe Annette , Walder Lorenz , Scheffold Rolf 
Published: March 2011

AbstractNew types of electroactive polymers consisting of derivatives of vitamin B12 and epoxy resins have been synthesized. Surface modification of carbon (carbon felt or basal plane pyrolytic graphite) has been achieved by thermal curing of the monomers on the electrodes. Electrochemical response from the Co (II)/Co (I) redox couple has been observed from sub‐mono to multilayer coverages. The influence of the size of the epoxy spacer on charge propagation in the polymer has been studied. The B12‐modified electrodes have been applied to electrosynthesis and electroanalysis: They catalyze the reductive cross‐coupling of alkyl halides and activated olefins and they are efficient sensors for alkylating agents.