bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of polymers containing pseudohalide groups by cationic polymerization, 3. Preliminary study of the polymerization and copolymerization of alkenyl monomers containing azide groups
Authors: Cheradame Hervé , Habimana Jean de la Croix , Rousset Eliane , Chen Frank 
Published: April 2003

AbstractThe cationic polymerization or copolymerization of various alkenyl monomers was investigated in the presence of azide groups. The monomers were either of the n‐π‐donor type, such as vinyl ethers, or π‐donors, such as isobutene (2‐methylpropene) or styrene. The azide groups were introduced by a suitable comonomer, such as 2‐azidoethyl vinyl ether (AEVE) or 4‐azidomethyl‐styrene (AMS). The initiator was TiCl4. 3‐Azido‐2‐methyl‐1‐propene (AMP) (methallyl azide) revealed to be not polymerizable. In the case of vinyl ethers, their cationic polymerization in the presence of azide groups requires high Lewis acid concentrations, according to the work previously carried out on oxetanes. In the case of the less nucleophilic monomers styrene and isobutene it was shown that cationic polymerization takes place provided that the initiator concentration is equal or higher than that of the azide group. This effect was assigned to a complexation between the Lewis acid and the azide group, and consequently the more nucleophilic the monomers (heterocyclics or vinyl ethers) are the lower the required Lewis acid concentration to observe cationic polymerization. Some evidence was found showing that the isobutene polymerization carried out in the presence of a molecular containing an azide group results in an azido‐endcapped polyisobutene while in the case of styrene and vinyl ethers cationic copolymerization with comonomers containing azide groups was observed.
The glass transition of blends of poly(2,6‐dimethylphenylene oxide) and polystyrene‐block‐poly(2,2‐dimethyltrimethylene carbonate)
Authors: Kummerlöwe Claudia , Kammer Hans‐Werner , Morgenstern Ute , Berger Werner , Keul Helmut , Höcker Hartwig 
Published: April 2003

AbstractThe miscibility of poly(2,6‐dimethylphenylene oxide) (PPO) with polystyrene‐block‐poly(2,2‐dimethyltrimethylene carbonate) (PS‐block‐PDTC) was studied and compared with the corresponding PPO/PS blends. PPO/PS‐block‐PDTC blends show two thermal transitions in the temperature range investigated; that is the melting of the DTC block and the glass transition of the mixed PPO/PS block phase. The Tg values obtained are discussed by means of the Fox and Gordon‐Taylor equation. The influence of the PDTC block leads to higher Tg values of the PPO/PS block mixture than of the corresponding homopolymer blend.
Copolymerization of 5‐norbornen‐2‐yl acetate with cycloalkenes by the metathesis catalyst WCl6/(CH3)4Sn
Authors: Balcar Hynek , Dosedlová Alena 
Published: April 2003

AbstractRing‐opening metathesis copolymerization of 5‐norbornen‐2‐ylSystem. name: bicyclo[2.2.1]hept‐5‐en‐2‐yl.
acetate (NBEAc; 80% endo) with cyclooctene (COE) and norborneneSystem. name: bicyclo[2.2.1]hept‐2‐ene.
(NBE) was studied using WCl6/(CH3)4Sn as catalytic system. The copolymerization parameters (r1 = r2 = 1 for the NBEAc/NBE system and r1 = 1/r2 = 132 for the NBEAc/COE system) show that the reactivity of the monomers is not affected by the presence of an ester substituent but that it depends on the structure of the hydrocarbon cycle. Thus the well known inhibition effect of the ester group may be concluded not to lie in the propagation step of the catalytic cycle.
Doped polymers by oxidative polymerization, 2. Synthesis and electrical conductivity of oxidized poly[trans‐1,2‐di(2‐furyl)ethylene]
Authors: Koßmehl Gerhard , Greczmiel Thomas 
Published: April 2003

Abstracttrans‐1,2‐Di(2‐furyl)ethylene (2) was oxidized with several inorganic oxidants such as FeCl3, CuCl2 and Na2S2O8 under varying conditions to give a “doped” polymer in a one‐step reaction. Such polymeric salts show typical semiconductor properties, and the electrical conductivity increases with increasing degree of oxidized units in the polymeric structure. The influence of the oxidizing agent and the conditions of the reaction on the composition and the electrical conductivity were studied. The black polymer, which was synthesized by oxidation with FeCl3 in a mole ratio monomer/oxidizing agent of 1 to 6 in acetonitrile for 16 h at 20°C, shows the highest electrical conductivity of 2,0 · 10−5 Ω−1 · cm−1.
An example of the thermal decomposition of a crystalline polymer — poly(l,6‐bis(N‐carbazolyl)‐2,4‐hexadiyne)
Authors: Bradner Friedrich P. , Shapiro Jacob S. 
Published: April 2003

AbstractThe thermal decomposition of poly(1,6‐bis(N‐carbazolyl)‐2,4‐hexadiyne) crystals, prepared by gamma radiation, was examined over a range of experimental conditions, the most important of which are temperature and crystal size. The only two significant products found were carbazole and to a lesser extent 9‐methylcarbazole. Decomposition kinetics, which applied to the two observed autoacceleratory regions, was best fitted to an Avrami‐Erofeyev equation with an exponent of two. The activation energy determined for the first autoacceleratory region was found to be higher than that determined for the second autoacceleratory region. A reaction mechanism is described based on stressinduced initiation, followed by either a molecular or a free‐radical non‐chain process. In an attempt to release stress, the polymer was observed to undergo sidegroup cleavage due to shearing of neighbouring polymer chains.
Analysis of the linear methods of determining copolymerization reactivity ratios, 12. Copolymerization of styrene or methyl methacrylate with N‐p‐tolylcitraconimide or fumarodinitrile
Authors: Braun Dietrich , Czerwinski Wojciech K. , Bednarski Ralf , Tüdős Ferenc , Kelen Tibor 
Published: April 2003

AbstractFor copolymerization of styrene or methyl methacrylate with N‐p‐tolylcitraconimide (in toluene) or fumarodinitrile (in benzene) at 60°C with 2,2′‐azoisobutyronitrile (AIBN) as initiator, the composition of the resulting copolymers was measured as a function of the monomer feed composition. To provide good accuracy of reaction modelling in terms of the terminal and penultimate models, the linearized forms of both models were applied assuring high sensitivity of the evaluation. Among the systems considered the styrene/fumarodinitrile system with r′1/r′1 ≈ 10 was found to copolymerize according to the penultimate mechanism to a significant degree.
Monomer‐isomerization polymerization, 35. Kinetics of monomer‐isomerization polymerization of 2‐butene with Ziegler‐Natta catalyst
Authors: Endo Kiyoshi , Ueda Ryuichi , Otsu Takayuki 
Published: April 2003

AbstractThe kinetics of monomer‐isomerization polymerizations of cis‐2‐butene with TiCl3/Al(C2H5)3 catalysts in the presence and absence of NiCl, was studied. Both the rate of isomerization and polymerization increased as a function of the concentrations of the monomer and catalyst. The apparent activation energies for the polymerization with TiCl3/Al(C2H5)3 and with TiCl3/NiCl2/Al(C2H5)3 were estimated to be 25,6 and 17,2 kJ/mol, respectively. This difference in the apparent activation energy for monomer‐isomerization polymerization may be accounted for by the rates of isomerization to 1‐butene. The reaction constants for the isomerization and polymerization were evaluated by simulation. The rate of polymerization with the TiCI3/Al(C2H5)3 catalyst was found to be about 40 times higher than that of isomerization, and in the presence of NiCl2, both rates become similar. From product analysis produced with TiCl3 and alkylaluminium compounds, it is concluded that the active sites for isomerization involve Ti2+ complexes and those for the polymerization involve Ti3+ complexes.
Structural and thermal investigations on aromatic polyoxadiazole/polyamide 6 blends
Authors: Calandrelli Luigi , Immirzi Barbara , Malinconico Mario , Martuscelli Ezio , Riva Fernando 
Published: April 2003

AbstractBlends of poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) (PODZ) and polyamide 6 (PA6) were obtained by a coagulation process from sulfuric acid solution. The resulting blends were studied by means of X‐ray diffraction and calorimetry using a DSC and a thermogravimetric apparatus. The PA6 crystallinity was found to be strongly influenced by the presence of PODZ and is dependent on the blend compositions. Below 30 wt.‐% of PA6 crystallinity disappeared completely. A preliminary investigation of morphology and mechanical properties was also carried out.
Synthesis of degradable terpolymers responding to external stimuli such as pH, ionic strength and temperature
Authors: Imasaka Kazumichi , Nagai Tsuneji , Yoshida Masaru , Fukuzaki Hironobu , Asano Masaharu , Kumakura Minoru 
Published: April 2003

AbstractDegradable copolymers which respond to external stimuli such as pH, ionic strength, and temperature were successfully prepared by direct polycondensation of L‐lactic acid (LA), D,L‐mandelic acid (MA), and 3‐(p‐hydroxyphenyl)propionic acid (HPPA) without the use of a catalyst at 200°C by bubbling nitrogen through the solution. The molecular weights of the copolymers obtained were relatively low because of the low polymerizability of MA and HPPA, e. g., number‐average molecular weight M̄n ≦ 2100 and weight‐average molecular weight M̄w ≦ 4100. Poly{(L‐lactic acid)‐co‐(D,L‐mandelic acid)‐co‐[3‐(p‐hydroxyphenyl)propionic acid]} (poly(LA/MA/HPPA)) with a composition of the monomeric units (in mol‐%) LA:MA:HPPA = 80:10:10 showed rapid degradation after a lag time of 5 h within 48 h from the start of the test, in M/15 phosphate buffer solution (pH 7,2) at 37°C. With increasing pH and temperature, the rate of degradation was markedly accelerated.
A simplified wittig synthesis using polyacrylates with a terminal triphenylphosphonium group and polymerization of the macromonomers
Authors: Shen Wei‐ping , Jin Hong‐mei 
Published: April 2003

AbstractIn the presence of zinc halide, triphenylphosphine and chlorotrimethylsilane can be used directly to initiate group transfer polymerization of acrylate monomers. The resulting polymers with terminal triphenylphosphonium groups can be converted to the corresponding vinyl‐macromonomers by means of the Wittig reaction. We found that the vinyl‐macromonomers can be smoothly prepared with very good yields from the macromolecular phosphonium salts and aqueous formaldehyde in tetrahydrofuran/potassium hydroxide applying the phase transfer catalysed Wittig synthesis. The macromonomers were polymerized and copolymerized with styrene in butanone.
Copolymerization of N‐chlorophenylmaleimides with vinyl acetate
Authors: Konsulov Vitan B. , Grozeva Zoya S. , Kelen Tibor , Borbély János 
Published: April 2003

AbstractBy radical copolymerization, thermostable copolymers of N‐(2‐chlorophenyl)maleimide (2CPMI), N‐(3‐chlorophenyl)maleimide (3CPMI) and N‐(4‐chlorophenyl)maleimide (4CPMI) with vinyl acetate were prepared. The values of reactivity ratios determined according to the Kelen‐Tüdős method are: r2CPMI = 0,148 and rVA = 0,049; r3CPMI = 0,221 and rVA = 0,032; r4CPMI = 0,655 and rVA = 0,0. The position of the Cl atom in the phenyl ring of CPMI influences the copolymerization kinetics. 2CPMI exhibits the strongest tendency for cross propagation, 4CPMI has the highest ability for homopolymerization. Vinyl acetate in all the three systems forms inactive radicals. The thermostability of all three copolymers is higher than that of the vinyl acetate homopolymer and decreases in the order poly(3CPMI‐co‐VA) > poly(4‐CPMI‐co‐VA) > poly(2CPMI‐co‐VA).
Modifizierung von homo‐ und copolymeren des epichlorhydrins durch polymeranaloge umsetzungen
Authors: Nuyken Oskar , Lattermann Günter , Dannhorn Wolfgang , Vogel Rainer 
Published: April 2003

AbstractPoly(epichlorohydrin) and poly(epichlorohydrin‐co‐ethylene oxide) were modified by reaction with potassium thiocyanate (KSCN), tetrabutylammonium p‐toluenesulfinate (NBu4SO2C7H7) and tetrabutylammonium benzenesulfinate (NBu4SO2C6H5). Though the substitution of chlorine in the polymers with these nucleophilic reagents in most cases is accompanied by side reactions, appropriate reaction conditions allow degrees of substitution higher than 90% to be obtained. The glass transition temperature (Tg) of the thiocyanate‐modified homo‐ and copolymer exhibits only a small increase with increasing degree of substitution. While the Tg of the original homo‐ and copolymer is observed at −20°C and −38°C, respectively, the glass transition of the highly substituted homopolymer occurs at −12°C and for the copolymer at −31°C. On the other hand, the thiocyanate‐modified polymers show a remarkably higher decomposition temperature of about 250°C as compared with that of the unmodified polymers (160–180°C). In addition, the solubility is markedly influenced by the substitution. While the original homo‐ and copolymers are soluble in, e.g., benzene and toluene, the highly modified products are only soluble in polar solvents such as THF, acetone, DMSO and diglyme. Introducing sulfonyl groups, the resulting polymers exhibit a glass transition temperature increased to a greater extent. For the homopolymer with the highest degree of substitution (98,3%), a Tg of 73°C is observed. Concerning the decomposition temperature, a drastical increase up to 370°C occurs. Finally the influence of phase transfer catalysts on the described reactions was investigated.
New macromonomeric initiators (macroinimers), 2 Gelation in bulk polymerization of styrene with macroinimers
Authors: Hazer Baki 
Published: April 2003

AbstractMacroinimers were obtained by the reaction of 4,4′‐dicyano‐4,4′‐azovaleryl chloride (1), poly(ethylene glycol) and methacryloyl chloride. They were thermally homopolymerized and copolymerized with styrene in bulk (40 wt.‐%). Crosslinking increases as polymerization time increases.
Cationic polymerization of 1,2‐epoxy‐3‐nitropropane in the presence of ethylene glycol, 2 Higher oligodiols: Discrepancies with the activated monomer mechanism
Authors: Lagarde Florence , Reibel Leonard , Franta Emile 
Published: April 2003

AbstractThe cationic polymerization of 1,2‐epoxy‐3‐nitropropane (ENP) in the presence of ethylene glycol and boron trifluoride etherate is studied. The reaction was performed by adding the monomer stepwise in the reaction medium, so that the instantaneous mole ratio [ENP]/[OH] was below one, in order to favor the Activated Monomer Mechanism (AMM). We have shown previously that polymerization proceeds via AMM during the first two steps of the reaction (M̄n < 350). In this paper, we present our results concerning the subsequent stages. In addition to the expected molecules containing one ethylene glycol unit per chain $ [{\rm H \rlap{--} ( O}&#x0F8FF;{\rm CHR}&#x0F8FF;{\rm CH}_{\rm 2} \rlap{--} )_p {\rm OCH}_{\rm 2} {\rm - CH}_{\rm 2} {\rm O \rlap{--} ( CH}_{\rm 2}&#x0F8FF;{\rm CHR}&#x0F8FF;{\rm O\rlap{--} )}_q {\rm H (R} = {\rm CH}_{\rm 2} {\rm NO}_{\rm 2} )] $ we find also some α,ω‐ENP oligodiols which do not contain any ethylene glycol unit $ [{\rm H \rlap{--} ( O}&#x0F8FF;{\rm CH}_{\rm 2}&#x0F8FF;{\rm CHR}\rlap{--} )_i {\rm OH} $, some mono‐ or diethoxylated oligomers $ {\rm [C}_{\rm 2} {\rm H}_{\rm 5} \rlap{--} ({\rm O}&#x0F8FF;{\rm CH}_{\rm 2}&#x0F8FF;{\rm CHR\rlap{--} )}_i {\rm OH} $ and $ {\rm C}_{\rm 2} {\rm H}_{\rm 5} \rlap{--} ({\rm O}&#x0F8FF;{\rm CH}_{\rm 2}&#x0F8FF;{\rm CHR\rlap{--} )}_i {\rm OC}_{\rm 2} {\rm H}_{\rm 5} ] $ and some cyclics. The experimental hydroxyl concentration exceeds that introduced through the ethylene glycol used. Primary OH groups are present and the average molecular weight is limited to 500. The viscosity of the reaction medium decreases significantly when the polymerization is terminated, or simply when the medium is put in contact with atmospheric water.
On the activity of monomers and polymers on the basis of vinyl ethers of glycols in radical reactions
Authors: Nurkeeva Zauresh S. , Mun Grigorii A. , Golubev Vladimir B. 
Published: April 2003

AbstractThe absolute values of reaction constants of various radicals with vinyl ethers of glycols and aminoalcohols and with N‐vinyl‐2‐pyrrolidone have been determined by the spin‐trapping method. It was shown that the radicals are associated with the β‐carbon atoms of the vinyl groups. The kinetics of the process is considerably determined by the polarity of the monomers. It was established that the rate of elimination of H atoms from methylene groups in the side groups is considerably higher than that from methylene groups in the main chain of the macromolecules. The over‐all activity of poly(ethylene glycol monovinyl ether) is about 3 times higher than that of poly(diethylene glycola monovinyl ether).
Synthesis and reaction of polymethacrylate bearing cyclic carbonate moieties in the side chain
Authors: Kihara Nobuhiro , Endo Takeshi 
Published: April 2003

Abstract(2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl methacrylate (6) was prepared by fixation of CO2 into glycidylSystematic name: 2,3‐epoxypropyl.
methacrylate (2). Pure 6 polymerized spontaneously at room temperature. Radical polymerization of 6 (purity 94%) was carried out at 60°C using 2,2′‐azoisobutyronitrile as an initiator in dimethyl sulfoxide (DMSO) to give the corresponding homopolymer 1 (yield: 99%) which is soluble in DMSO and N,N‐dimethylformamide. 1 was reacted with butylamien at room temperature in DMSO for 24 h to the corresponding polymethacrylate 13 (yield: 100%) having a hydroxyurethaneThe systematic name for urethanes is carbamates.
group in the side chain. No reaction of the ester groups of 1 with butylamine was observed. This was also demonstrated by the model reaction of (2‐oxo‐1,3‐dioxolan‐4‐yl)methyl isobutyrate (9) with butylamine in which the corresponding hydroxyurethanes 10, 11 and 12 were isolated in 96% yield.
Liquid‐crystalline polysiloxanes containing fluorene mesogens, 2. A new class of liquid‐crystalline side‐chain polymers with terminal 2‐fluorenyl groups
Authors: Koßmehl Gerhard , Schulz Michael , Vieth Hans‐Martin 
Published: April 2003

AbstractThe synthesis, characterization and liquid‐crystalline (LC) properties of polysiloxanes containing side chains with terminal 2‐fluorenyl groups and various lengths of spacers is reported. The polymers which have no flexible tail segment exhibit two smectic mesophases (SA and SE), as confirmed by polarizing microscopy, differential scanning calorimetry (DSC) and X‐ray investigations; a nematic mesophase was not found. The clearing temperatures of the polymers (in the range between 120 and 170°C) are generally 70–80°C higher than the melting temperatures of the non‐liquid‐crystalline precursors with a terminal vinyl group. With increasing spacer length the less ordered SA phase is favoured and has been found in a temperature range of up to 100 K width. For polymers with an SE phase no glass transition was detectable with DSC. The synthesized polymers are examples of the strong potential of the fluorene core to form LC phases without further structural stabilization.
Stereoblock polypropene from the Ziegler‐Natta catalyst system TiCl4/octylsodium
Authors: Busico Vincenzo , Corradini Paolo , De Biasio Rosanna , Trifuoggi Marco 
Published: April 2003

AbstractPropene polymerization in the presence of the heterogeneous catalyst system TiCl4/Na‐octyl yielded polymers with unusually high molecular weights and relatively high amounts of prevailingly syndiotactic stereosequences. The characterization of such polymers proved that a fraction of the active species were able to invert their stereocontrol — from isospecific to prevailingly syndiospecific — during the growth of individual macromolecules. This suggests that, in principle, at least in conditions of limited occurrence of chain transfer reactions, the stereo‐chemical environment of the catalytically active metal in a heterogeneous Ziegler‐Natta system may not be invariant during the process of chain growth, even for the most stereospecific active species.
Sequence determination in vinyl acetate/alkyl methacrylate copolymers prepared by semicontinuous batch process by NMR spectroscopy
Authors: Kapur G. S. , Brar A. S. 
Published: April 2003

AbstractTwo series of copolymers, vinyl acetate/ethyl methacrylate (V/E) and vinyl acetate/butyl metha‐acrylate (V/B) copolymers, were prepared by free‐radical‐initiated emulsion copolymerization using a semicontinuous batch process. Copolymer compositions determined from 1H NMR spectroscopy were found to be in good agreement with those expected theoretically. The carbonyl and quaternary carbon resonances in 13{1H} NMR spectra were assigned to different alkyl methacrylate‐centered triad sequences by observing the changes in intensities of the resonances with copolymer composition and were used for calculating alkyl methacrylate‐centered triad fractions. The resonances giving information regarding the V‐centered triads were not properly resolved.
The structural order of some novel ionic polymers, 1. X‐ray scattering studies
Authors: Köberle Peter , Laschewsky André , Tsukruk Vladimir 
Published: April 2003

AbstractA set of novel zwitterionic side‐chain polyacrylates and polymethacrylates is studied by X‐ray scattering. The structural order both in the short‐range and long‐range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are analysed.
Transparent poly(vinyl alcohol) hydrogel with high water content and high strength
Authors: Cha Won‐Ill , Hyon Suong‐Hyu , Ikada Yoshito 
Published: April 2003

AbstractTo develop a transparent poly(vinyl alcohol) (PVA) hydrogel with high water content and high strength, we studied the physical gelation of PVA solutions and found that low temperature crystallization of PVA solutions in mixed solvents consisting of water and a water‐miscible organic solvent yields transparent gels. The strength and transparency of the PVA hydrogel is dependent on both the type of organic solvent and the mixing ratio of water/organic solvent. A mixed solvent from water/dimethyl sulfoxide resulted in the highest transparency and the highest tensile strength among the water/organic solvent combination studied. A plausible mechanism is proposed for the formation of transparent and strong hydrogels on the basis of the results obtained.
Studies on the polymerization of ethylene using a high‐yield MgCl2‐supported titanium catalyst, 2. Kinetic studies
Authors: Heller Detlef , Bilda Dieter , Fuhrmann Hans 
Published: April 2003

AbstractPolymerization of ethylene was carried out in a batch process under pressure with an optimized high‐yield Ti/Mg‐catalyst. It was shown through gas chromatography analysis as well as by educt/product mass balances that no side‐reactions take place, and therefore, the monomer is quantitatively converted to polyethylene. It is demonstrated that influences of diffusion are excluded under the described experimental condition. The dependence of the overall polymerization rate on time shows that the rate at constant pressure is constant from the beginning over a certain period of time. The rate of polymerization under isobaric as well as isochoric conditions was determined to be first order with respect to monomer concentration and catalyst concentration. The overall activation energy obtained for this catalytic system was determined to be 32 kJ · mol−1.