bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of chain length and size of alkyl group in radical polymerization of dialkyl fumarates as studied by electron paramagnetic resonance spectroscopy
Authors: Yamada Bunichiro , Fujita Mitsuo , Otsu Takayuki
Published: April 2003

Propagating radicals of diethyl and diisopropyl fumarates are detectable by electron paramagnetic resonance (ESR) spectroscopy in homogeneous systems at room temperature or above. Resolution of the spectra was found to be much improved by raising the temperature to 120°C, and the spectra are shown to correspond to three components according to chain length. Composition of the spectra was dependent on the polymerization conditions. The hyperfine splitting constants were determined by computer simulation of the spectra. The coupling constant for the α‐hydrogen is noted to be as small as 3 to 4 G, and those for the β‐hydrogen are ca. 4, 14 and 30 G.
Copolymerization of propene with 1‐alkenes using a MgCl2/TiCl4 catalyst
Authors: Xu Zhikang , Feng Lingxiang , Wang Dongli , Yang Shiling
Published: April 2003

Copolymerization of propylene

System name: propene.

and 1‐alkenes (1‐octene, 1‐decene, 1‐dodecene, 1‐tetradecene, 1‐hexadecene) were studied with the catalyst system MgCl2/TiCl4‐Al(i‐Bu)3. It was found that the polymerization productivity and the consumption rate of propylene are improved significantly in the presence of the comonomer. The total productivity of propylene/1‐alkene copolymerizations decreases as follows: 1‐octene > 1‐decene > 1‐dodecene > 1‐hexadecene > 1‐tetradecene. The reactivity ratios were estimated from the copolymerization results.
Synthesis and structural studies of new copolyimides 2. Influence of pyromellitimide rings on copolymer structure
Authors: Orzeszko Andrzej , Mirowski Krzysztof
Published: April 2003

The reaction of pyromellitic dianhydride (1,2 : 4,5‐benzenetetracarboxylic dianhydride) (1) with L‐ and D‐alanine (2L) and (2D) leads to new monomers which were used to synthesize new copolymers. These copolymers were obtained as a product of the condensation of optical isomers of bis[N‐(1‐chloroformylethyl)]pyromellitimides (CFEP) with poly(ethylene glycol) PEG‐2000 (5). The effect of monomer structure on the structure and thermal properties of the polymers was studied using X‐ray diffraction, differential scanning calorimetry and thermogravimetry. The copolymers were compared with similar copolyimides obtained previously from bis(N‐chloroformylmethyl)pyromellitimide and poly(ethylene glycol), PEG 2000. The dominating effect of poly(ethylene glycol) comonomer on the crystallinity, structure and thermal stability of these new copolymers is proven.
Liquid crystal polymers containing macroheterocyclic ligands, 7. Synthesis and characterization of 4‐[(4‐methacryloyloxy)‐undecyloxy‐2‐methylphenylethynyl]phenyl (benzo‐15‐crown‐5)‐4′‐carboxylate
Authors: Rodenhouse Randall , Percec Virgil
Published: April 2003

The synthesis and thermal characterization of 4‐[(4‐methacryloyloxy)undecyloxy‐2‐methyl‐phenylethynyl]phenyl (benzo‐15‐crown‐5)‐4′‐carboxylate (8) and of poly(8) are described. 8 exhibits monotropic nematic and smectic mesophases, while poly(8) shows enantiotropic nematic and smectic mesophases. In spite of its very long flexible spacer, poly(8) does not display sidechain crystallization.
Synthesis of polymer latex containing SH groups on the surface, 2. Emulsion polymerization of styrene in the presence of a polymerizable isothiuronium salt as a comonomer and the subsequent hydrolysis
Authors: Watanabe Shinji , Nakahama Seiichi , Yamaguchi Kazuo
Published: April 2003

Emulsion polymerization of styrene using various isothiuronium salts as comonomers and the subsequent alkaline hydrolysis of the product gave latices containing mercapto (SH) groups. Four styrene derivatives of isothiuronium salts and a methacrylate counterpart were employed as comonomers. The yield, size distribution, and sulfur content of the latices are affected by initiators and isothiuronium salts employed. With a cationic initiator (2,2′‐azobis[(2‐imidazolin‐2‐yl)propane] dihydrochloride) and any isothiuronium salt, latices of narrow size distributions were obtained in high yield. The sulfur content of the latices is comparable to that calculated from the feed ratio of the salt to styrene monomer. In case of an anionic initiator (K2S2O8), only 2‐[4‐vinylphenylmethyl]‐and 2‐[3‐(methacryloyloxy)propyl]‐isothiuronium chloride gave latices with narrow size distribution in high yield, whereas the sulfur content was lower than the calculated one. The isothiuronium salts on the latices were converted into mercapto groups by hydrolysis in aqueous alkaline solution. Thus, we obtained latices containing mercapto groups on the surface with narrow size distributions.
Effects of large ring‐substituents on radical polymerization behaviour of 2,6‐diisopropylphenyl methacrylate
Authors: Yamada Bunichiro , Matsumoto Akikazu , Otsu Takayuki
Published: April 2003

2,6‐Diisopropylphenyl methacrylate (DIPPMA) noted as a monomer bearing the largest ring substituents among polymerizable o‐substituted phenyl methacrylates was homo‐ and copolymerized. Steric hindrance caused by the substituents significantly reduced the overall rate of polymerization and reactivities in copolymerization. Suppression of termination by the steric effect seems to be of minor importance. The ceiling temperature was determined to be 49°C at a concentration of 1 mol · dm−3 in benzene. The overall rate and the degree of polymerization were confirmed to decrease with increasing temperature under the influence of the ceiling temperature. Triad tacticity of poly(methyl methacrylate) derived from poly(DIPPMA) was determined to be rr = 29%, rm = 53%, and mm = 18% at 40°C, indicating that the steric effect of the large substituents on propagation rendered almost random addition.
Determination of the molecular mobility and the free volume of thin polymeric films with fluorescence probes
Authors: Anwand Dirk , Müller F. Werner , Strehmel Bernd , Schiller Kurt
Published: April 2003

Triphenylmethane (TPM) dyes were used as fluorescence probes for the characterization of thin polymeric layers. Glass transition temperature, mobility and free volume can be determined by this method. A correlation was found between the dye fluorescence and the free volume of the polymer. Above the glass transition temperature of the polymer the activation energies for the rotation of the dye phenyl groups were found at ca. 25–35 kJ/mol, at temperatures below the glass point these energies are in the range of 5–12 kJ/mol. Nearly all probes describe the free volume equally well. A relation was found between the dye mobility and gas diffusion constants (ammonia and oxygen).
Polymerization of lactones, 12. Polymerization of L‐dilactide and L,D‐dilactide in the presence of potassium methoxide
Authors: Jedliński Zbigniew , Wałach Wojciech , Kurcok Piotr , Adamus Graz̀yna
Published: April 2003

The anionic polymerization of L‐ and L,D‐dilactide initiated with potassium methoxide in solution of tetrahydrofuran at a temperature of 20°C is investigated. It is found that this process leads with high yield to the corresponding polyesters. The optical rotation measurements and the microstructure of the polymers obtained indicate that side reactions, i. e. racemization and transesterification, are strongly limited.
Physical ageing of amorphous polymers. Theoretical analysis and experiments on poly(methyl methacrylate)
Authors: Pérez Joseph , Cavaille Jean Yves , Calleja Ricardo Díaz , Ribelles José Luis Gómez , Pradas Manuel Monleón , Greus Amparo Ribes
Published: April 2003

Structural relaxation of glassy poly(methyl methacrylate) (PMMA) was studied with several techniques: differential scanning calorimetry (DSC), volumetry by thermomechanical analysis (TMA) and mechanical spectroscopy. A theory is proposed in order to interpret the data in a unique theoretical framework. This theory is developed on the basis of two main physical assumptions: (i) the existence in amorphous polymers of quasipunctual defects whose concentration decreases during structural relaxation, and (ii) the occurrence of hierarchical correlation effects conditioning molecular mobility. As a first approximation a self‐consistent semiquantitative description of the results is obtained, i. e., the experimental results obtained for the different quantities on PMMA can be accounted for employing always the same set of model parameters. However, it seems that a significant difference exists between the relaxation times associated with the different experimental techniques.
Particle formation in emulsion polymerization, 1. Oligomers in emulsion polymerization of vinyl acetate
Authors: Hergeth Wolf‐Dieter , Lebek Werner , Kakuschke Rolf , Schmutzler Klaus
Published: April 2003

The oligomers formed in the beginning of the emulsion polymerization of vinyl acetate were characterized by surface tension measurements, analysis of molecular weight distribution and light scattering. The results indicate that primary particle formation in the emulsion polymerization of vinyl acetate is due to an oligomeric micellization. Additionally, these oligomers are strongly adsorbed onto highly dispersed silica particles in the aqueous phase. This effect leads to a disaggregation of the filler particles during the beginning of the emulsion polymerization.
Living cationic polymerization of vinyl ethers with a bifunctional initiator
Authors: Yoshida Tatsuhiro , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

A new bifunctional initiator, CF3COOCH(CH3)OCH2CH2OC6H4C(CH3)2C6H4OCH2CH2OCH(CH3)OCOCF3 (2), was prepared from the corresponding divinyl ether and trifluoroacetic acid in carbon tetrachloride at 0°C. The 2/ethylaluminium dichloride (EtAlCl2) initiating system induced well‐defined living cationic polymerizations of isobutyl vinyl ether (IBVE; in hexane CH3(CH2)4CH3) and 2‐acetoxyethyl vinyl ether (2‐vinyloxyethyl acetate, AcOVE; in toluene) at temperatures up to +40°C in the presence of an excess amount of 1,4‐dioxane (an added base for cation stabilization). The number‐average molecular weights (M̄n) of the polymers increased in direct proportion to monomer conversion, continued to increase on addition of fresh monomer, and were close to the calculated values assuming that each molecule of 2 produces one living polymer chain. The bifunctionality of the living polymers was confirmed by comparing the polymerizations with 2 and its monofunctional analog C6H5OCH2CH2OCH (CH3)OCOCF3 (3), and further shown by quenching the living ends with the sodiomalonic ester Na⊕ ⊖CH(COOC2H5)2 to form telechelic polymers with malonate groups. The diester terminals could be transformed into the corresponding carboxylic acids by hydrolysis followed by decarboxylation. Sequential living polymerization of IBVE and AcOVE with the 2/EtAlCl2 initiating system in the presence of 1,4‐dioxane and subsequent hydrolysis of the pendant ester groups led to ABA‐type amphiphilic triblock copolymers where the hydrophilic poly(2‐hydroxyethyl vinyl ether) segment could be either center or outer blocks.
Preparation and permeability properties of chitosan membranes having hydrophobic groups
Authors: Seo Toshihiro , Ohtake Hitoshi , Kanbara Takaki , Yonetake Koichiro , Iijima Toshiro
Published: April 2003

Membranes consisting of N‐acylated chitosan and carrying hydrophobic groups were prepared and the states of water in these membranes were examined by differential scanning calorimetry (DSC). The contents of freezable and non‐freezable water were found to be closely related with the structure and properties of the membranes. On the other hand, their permeability properties for sodium salts are found to be affected considerably by modifying the membrane structure as well as the cationically charged groups. With respect to D,L‐amino acids, the selective permeation of the L‐isomer was enhanced in the hydrophobic chitosan membrane, suggesting the possibility to separate optical isomers by membrane transport.
[1.1.1]Propellanes. From a hydrocarbon curiosity to a versatile monomer for the synthesis of structurally new polymers
Authors: Schlüter Arnulf‐Dieter , Bothe Harald , Gosau Jan‐Michael
Published: April 2003

[1.1.1]Propellanes are introduced to polymer chemistry as a new class of highly reactive monomers which polymerize regiospecifically with breaking of the central CC σ‐bond. These rather unique hydrocarbon monomers undergo ring‐opening polymerizations with formation of both homo‐ and copolymers and, in addition, can be used as starting materials for classical poly‐condensation chemistry. A wide variety of new polymers is presented all of which contain the bicyclo[1.1.1]pentane fragment, a linearly connecting, rigid unit. This article focusses on questions related to synthesis and structure elucidation.
Interpolymer association between poly(acrylic acid) and vinyl alcohol‐vinyl acetate copolymers in dilute aqueous solutions
Authors: Staikos Georges , Bokias Georges
Published: April 2003

Interpolymer association and complexation between poly(acrylic acid) and vinyl alcohol‐vinyl acetate copolymers (PVAL‐AC) in dilute aqueous solutions were investigated by means of reduced viscosity and pH measurements. The influence of the degree of saponification of PVAL‐AC and of the molecular weight of both polymers on complexation were examined. The viscosity measurements show the formation of gel‐like or compact complexes and that association is strongly increased by the presence of acetate units in the PVAL‐AC copolymer. The degree of complexation was calculated from the results of pH measurements. Some special aspects of the two different experimental approaches are discussed.
Modelling and kinetic study on radical polymerization of methyl methacrylate in bulk, 1. Propagation and termination rate coefficients and initiation efficiency
Authors: Shen Jiacong , Tian Yuan , Wang Guobin , Yang Meilin
Published: April 2003

In this work the exact data of the rate coefficients of propagation kp and termination kt, and initiator efficiency f as well as their variations with conversion during the whole processes of the polymerization of methyl methacrylate in bulk have been measured using electron paramagnetic resonance (ESR) without any assumptions and approximations. kp was calculated directly from the synchronously measured data of the concentration of radicals and polymerization rate. kt was determined under nonsteady‐state conditions by using the after‐effect technique in the ESR measurement. f for the initiation with dimethyl 2,2′‐azoisobutyrate was evaluated from the initiation and termination rates. The ESR spectra show that the polymerization system is in a micro‐heterogeneous state and there exist inactive radicals. A model of a diffusion‐controlled reaction is proposed.
Liquid‐crystalline polymer gels, 4. Photocontrol of dye orientation in a polymer gel having a cholesteric liquid‐crystalline order
Authors: Kishi Ryoichi , Sisido Masahiko
Published: April 2003

A dichroic dye, 1,4‐diaminoanthraquinone, was covalently linked to an azobenzene derivative carrying a long alkyl group. The photochromic dye showed a trans‐to‐cis photoisomerism with somewhat reduced quantum yield, probably due to an energy transfer from the azobenzene unit to the dye unit. The cis‐to‐trans reverse photoisomerization was induced not only by irradiating the absorption band of the cis‐azobenzene unit, but also by irradiating the red‐edge of the absorption band of the dye unit. The photochromic dye was doped in a polymer gel having a cholesteric liquid‐crystalline order (CLC gel). Circular dichroism was induced at the absorption bands of both the azobenzene and the dye unit. The induced circular dichroism (ICD) of the dye absorption band was reversibly changed when the azobenzene unit was photoisomerized reversibly, indicating that the orientation of the dye group is affected by the structural change of the azobenzene unit.
Thermodynamics of copolymerization of 1,3‐dioxolane with 1,3‐dioxepane and 1,3‐dioxane
Authors: Szymanski Ryszard
Published: April 2003

The equilibrium copolymerization of 1,3‐dioxolane with 1,3‐dioxepane in CH2Cl2 solution and with 1,3‐dioxane without solvent is analyzed, and the equilibrium constants of homo‐ and cross‐propagations are estimated and discussed. The corresponding thermodynamic parameters are calculated. The reported thermodynamic parameters of homopolymerization of 1,3‐dioxane (ΔHss = −3,1 kJ · mol−1, ΔSss = −35,5 J · mol−1 · K−1), were determined on the basis of the copolymerization data. Predictions of comonomer concentrations and microstructure of copolymers in the equilibrium copolymerization system are presented for any initial composition, on the basis of the determined equilibrium constants.
Equilibrium between 1,3‐dioxane and its cyclooligomers
Authors: Szymanski Ryszard
Published: April 2003

The equilibrium between 1,3‐dioxane and its cyclooligomers in bulk has been studied. The equilibrium constants of cyclooligomerization at three temperatures (273, 294 and 313 K) and the corresponding thermodynamic parameters were estimated. The only relatively stable cyclooligomer is the dimer. The thermodynamic parameters of its polymerization were found to be ΔHss

The subscript “ss” indicates that as the initial state for the dimer and as the final state for the polymer solutions were chosen of the corresponding compounds in the equilibrium reaction mixture.

= 3,7 kJ · mol−1, ΔSss = 22,6 J · mol−1 · K−1.
Crystal structure of fibers from a novel rigid‐rod aromatic polyamide containing a pyrimidine moiety
Authors: Rutledge Gregory C. , Oertli Alfred G.
Published: April 2003

Fibers of a novel rigid‐rod polyamide containing a 1:1 ratio of phenylene:pyrimidine moieties have been produced and evaluated. The lyotropic liquid‐crystalline behavior of the polymer and the spinnability of the nematic dope were established. The as‐spun fibers exhibit low degrees of orientation and crystallinity. Heat treatment of the dry fibers resulted in crystallinities as high as 45% in coexistence with an amorphous phase component. Evaluation of the crystal structure by wide‐angle X‐ray diffraction suggests a pseudo‐orthorhombic crystal cell with lattice dimensions (a; b; c) of (7,3 Å; 5,1 Å; 12,8 Å) and containing two repeating units per unit cell.
2H NMR study of molecular motions in polydimethylsiloxane and its mixtures with aerosils
Authors: Litvinov Victor M. , Spiess Hans Wolfgang
Published: April 2003

2H NMR was used to investigate the effect of fillers on the molecular motions in mixtures of polydimethylsiloxane (PDMS) with different fillers. For active fillers with hydrophilic surface OH groups the molecular mobility at the polymer‐filler interface is strongly different from that outside the adsorption layer. The influence of concentration and type of filler on molecular motions was determined. In particular an adsorption layer differing in mobility from bulk PDMS could be detected just above the glass transition temperature in systems filled with hydrophobic Aerosil. The role of molecular dynamics at the polymer‐filler interface for the reinforcement of silicon rubbers is discussed.
Stationary‐state kinetics in the polymerization of ethyl α‐cyanoacrylate by phenazines
Authors: Pepper David Charles
Published: April 2003

Amines 1–5 of a family of phenazines have been examined as initiators for the anionic polymerization of ethyl α‐cyanoacrylate in tetrahydrofuran at 20°C. 1 and 2 are inactive; 3 initiates a polymerization of the slow‐initiation‐no‐termination (SINT) type. 4 and 5 induce different kinetic patterns of which that from 5 (Chlofazimine) has been studied in detail. Coloured polymers are produced, whose absorbance gives an (inverse) measure of the chain length. Stationary‐state kinetics are established and values of all rate constants evaluated or estimated. The mechanism is interpreted as a zwitterionic polymerization initiated at the secondary NH group, thus making the initial group of the chain a tertiary ammonium ion, whose potentially acidic proton can then act as terminator to the carbanionic propagating ends.
Polymerization of furfuryl alcohol with trifluoroacetic acid: the influence of experimental conditions
Authors: González Regino , Martínez Ricardo , Ortiz Pedro
Published: April 2003

Furfuryl alcohol was polymerized by trifluoroacetic acid in methylene chloride to give a colored polymer. This polymer possesses two main sequences in which the furan rings are connected by methylene groups (sequence 1) or by dimethylene ether groups (sequence 2). The polymer is not linear but highly branched, as detected by 1H and 13C NMR spectroscopy. Variations of the experimental conditions, such as the presence of air, the trifluoroacetic acid concentration, the reaction temperature and the solvent, do not allow a significant increase in the linear structure of the polymer. However, an increase in the acid concentration or an increase in temperature produce a decrease in the ether‐bridged structure (sequences 2).
Viscosity‐temperature relationships of a polycarbonate melt: Williams‐Landel‐Ferry versus Arrhenius behaviour
Authors: Lomellini Paolo
Published: April 2003

The melt viscosity of polycarbonate from bisphenol‐A

System name: 4,4′‐isopropylidenediphenol.

was measured in a wide range of temperatures, from Tg + 55°C up to about Tg + 185°C. The experimental results are discussed in terms of the classical WLF (Williams‐Landel‐Ferry) and Arrhenius models. There are clear indications that the WLF approach holds over the entire temperature range investigated. This is rather unusual as the Arrhenius behaviour is reported to be the correct one for temperatures above approximately Tg + 100°C. The most critical factor in our case seems to be the restricted number of bonds with rotational degree of freedom in the polycarbonate unit. The reduced number of virtual bonds with respect to real ones is discussed to be a possible reason for the large temperature range in which the free volume is the rate‐limiting factor for the flow process.
Energy spectra of poly(arylenevinylene)s containing different aromatic units
Authors: Ohlemacher Angela , Schenk Rainer , Weitzel Hans Peter , Tyutyulkov Nikolai , Tasseva Maria , Müllen Klaus
Published: April 2003

The energy gaps of poly(p‐arylenevinylene)s with phenylene, naphthylene and anthrylene subunits are determined by extrapolating the UV/VIS spectroscopic data of the oligomers. The band structure of the three polymers was theoretically investigated. The topology‐, geometry‐ and correlation‐factors were determined upon which the energy spectra of this class of one‐dimensional π‐electron systems depend.
Partitioned polymerization, 4. Seeded emulsion polymerization of methyl methacrylate
Authors: Barton̆ Jaroslav , Hloušková Zuzana , Juraničová Viera
Published: April 2003

The shape of the conversion curves and the rates of the emulsion polymerization in batch of methyl methacrylate (MMA) in the presence of seed particles of poly(butyl acrylate) (PBA) depend on the mass ratio of methyl methacrylate/poly(butyl acrylate) MMA/PBA and on the presence or absence of 2,2,6,6‐tetramethyl‐4‐octadecanoyloxypiperidinyl‐1‐oxyl (STMPO). Irrespective of the presence and/or absence of STMPO in the reaction system, the diameter of a polumer particle experimentally found and calculated on the assumption that no new crop of polymer particles is formed, agrees well for systems with “low” (0,632) mass ratio of MMA/PBA. For systems with “high” (3,160) mass ratio of MMA/PBA, the calculated diameter is higher than that experimentally measured. This indicates that for “low” values of MMA/PBA, all poly(methyl methacrylate) formed was only used for building up shells of poly(butyl acrylate) particles. For “high” values of MMA/PBA, about 37 mass‐% (in the absence of STMPO) or 57 mass‐% (in the presence of STMPO) of poly(methyl methacrylate) formed was used for generating a crop of poly(methyl methacrylate) particles. Retardation of the polymerization rate in the presence of STMPO is more pronounced for systems characterized by a “low” value of the mass ratio MMA/PBA. Only short inhibition periods (up to five minutes) were observed for both “low” and “high” MMA/PBA ratios. It is shown that for the “low” mass ratio of MMA/PBA the “inner” monomer transport (from PBA particles swollen with MMA) to the locus of propagation is decisive. For systems with a “hugh” mass ratio MMA/PBA, the “outer” monomer transport from monomer droplets and micelles swollen by monomer to the locus of propagation is of primary importance. To explain the experimental results a reaction mechanism for the seeded emulsion polymerization is proposed.
Radical bulk functionalization of polyethylenes with ester groups
Authors: Aglietto Mauro , Bertani Roberto , Ruggeri Giacomo , Ciardelli Francesco
Published: April 2003

The radical functionalization of different types of polyethylene, such as high‐density (HDPE) and linear low‐density (LLDPE) polyethylene, with diethyl maleate (DEM) as a polar functional monomer and dicumyl peroxide (DCP) as radical initiator was investigated, and conditions for obtaining a controlled degree of functionalization and a low amount of degradation products without crosslinking were determined. Attention was paid to achieve a moderate functionalization of the polymer, in order to limit the modification of the mechanical and physical properties of the polyolefins. The molecular weight distribution of some of these polyethylenes was only moderately affected by the functionalization reaction. A critical discussion of the results outlines the fundamental role of process parameters such as stirring rate and heat exchange.
Radical‐initiated copolymers of styrene and p‐formylstyrene, 1. Solution copolymerization and characterization
Authors: Charleux Bernadette , Pichot Christian , Llauro Marie‐France
Published: April 2003

Kinetics of solution homopolymerization of p‐formylstyrene

System name: 4‐vinylbenzaldehyde.

(A) and copolymerization with styrene (S) have been examined at 60°C in N,N‐dimethylformamide with 2,2′‐azoisobutyronitrile as initiator. For p‐formylstyrene, kp/k = 0,135 L1/2 · mol−1/2 · s−1/2 was estimated from the plot of monomer consumption versus time, i.e. a value greater than that for styrene (Kp and Kt are the rate constants of propagation and termination and termination, respectively). Reactivity ratios have been determined to be rA = 3,0 and rS = 0.2, indicating the reactivity of p‐formylstyrene to be higher than that of styrene. Moreover, from initial copolymerization rates, the cross termination factor was calculated and found to depend upon the copolymer composition. Some solution properties of the homo‐ and copolymers have been analysed: solubility of (co)polymers, their molecular weight and its distribution (by gel permeation chromatography), and their composition and monomer sequence distribution (using 1H and 13C NMR spectroscopy).
Gel permeation chromatography using porous glass beads modified with temperature‐responsive polymers
Authors: Gewehr Markus , Nakamura Katsunori , Ise Norio , Kitano Hiromi
Published: April 2003

Poly(N‐isopropylacrylamide) (PIPA) with a carboxyl group at its end was coupled with amino group‐carrying porous glass beads by the active‐ester method. Gel permeation chromatography of dextran was carried out by using a column packed with the PIPA‐carrying glass beads. The chromatograms of dextrans with various molecular weights are strongly affected by temperature: the elution time of dextran is largely changed between 25 and 32°C due to a change in the effective pore size by the transition of the PIPA chains from coils to globules on the surface of the pores of the glass beads. These results suggest the usability of PIPA‐carrying glass beads as devices for thermo‐controllable chromatography.
Modification au deuxième degrá de polymères époxydés, 4. Fixation de i'acide naphtylacétique sur polyisoprène‐1,4 de synthèse et caoutchouc naturel liquide époxydés
Authors: Brosse Jean‐Claude , Klinpituksa Pairote , Soutif Jean‐Claude
Published: April 2003

The reaction of naphthylacetic acid (a plant growth stimulator) on epoxidized 1,4‐polyisoprene has been studied. The increase of the rate of addition of the acid on the oxirane rings, catalyzed by the tetramethylammonium salt of the acid, with temperature, time and concentration of the reagents, is fairly well represented by a second‐order kinetic law.
Enzymes in polymer chemistry, 6. Lipase‐catalyzed acylation of comb‐like methacrylic polymers containing OH groups in the side chains
Authors: Pavel Konstantin , Ritter Helmut
Published: April 2003

The enzymatically catalyzed acylation of poly[N‐(2‐hydroxypropyl)‐11‐methacryloylaminoundecanamide‐co‐styrene] and the corresponding monomer was performed in the presence of a lipase, with vinyl acetate, phenyl acetate, 4‐fluorophenyl acetate and phenyl stearate as acylating agents. The kinetics of the enzymatically catalyzed reaction was followed by 1H NMR spectroscopy and correlated with sterical and chemical effects. The reactivity of monomer towards acylation is higher than that of the copolymer, and that of the copolymer depends on copolymer composition, pointing at steric and hydrophobic effects.
Morphological and structural properties of poly[bis(p‐phenylphenoxy)phosphazene]
Authors: Kojima Morio , Magill Joseph H.
Published: April 2003

Poly[bis(p‐phenylphenoxy)phosphazene] (PB(4‐Ph)PP) has been investigated employing X‐ray diffraction technique and electron microscopy. Its unit cell dimensions were determined to be a = 4,18 nm, b = 1,83 nm and c = 0,957 nm with space group Pca21. At 21 5–220°C , PB(4‐Ph)PP transforms into an anisotropic liquid‐like phase corresponding to a new molecular ordering array. The thicker films are composed of the linked globules approximately 100 nm in diameter. Upon drawing, the globules transform into a rod‐like morphology 15–40 nm in width and exhibit a highly oriented X‐ray diffraction pattern. These unusual morphological features have been compared with features found in poly[bis(phenoxy)phosphazene] and poly[bis(halophenoxy)phosphazene] polymers. X‐ray diffraction and crystallization results support a smectic‐like side chain morphology.
Dielectric properties of poly(dibenzyloxyphosphazene)s
Authors: Moriya Keiichi , Tomii Koji , Yano Shinichi , Kajiwara Meisetsu
Published: April 2003

Poly(dibenzyloxyphosphazene) (PBP), poly[bis(4‐methylbenzyloxy)phosphazene] (PMBP) and poly[bis(4‐chlorobenzyloxy)phosphazene] (PCIBP) were synthesized by reaction of poly(dichlorophosphazene) (PDCIP) and the corresponding sodium benzyl alkoxide. PDCIP was prepared by a ring‐cleavage polymerization from hexachlorocyclotriphosphazene. The dielectric properties of the polymers were studied in the temperature range of 80 to 390 K at several frequencies between 0,1 and 100 kHz. Two relaxations, a relaxation above the glass transition temperature Tg and β relaxation below Tg, were observed in PBP and PMBP. The β relaxation was only observed in PCIBP. The a relaxations are related to a glass‐rubber transition and the β relaxations to the local molecular motion of the short segments.
Analysis of the linear methods of determining copolymerization reactivity ratios, 11. Copolymerization of styrene with methyl α‐cyanocinnamate and fumaroyldipyrrolidone
Authors: Braun Dietrich , Czerwinski Wojciech K. , Bednarski Ralf , Kelen Tibor , Tüdős Ferenc
Published: April 2003

The composition of copolymers was determined as a function of the monomer feed for two systems: styrene/methyl a‐cyanocinnamate in toluene and styrene/fumaroyldipyrrolidone in dimethyl sulfoxide both at 60°C with 2,2′‐azoisobutyronitrile (AIBN) as initiator. To ascertain the accuracy of reaction modelling in terms of the classical and the penultimate model, the extended linearized forms of both models were applied. The styrene/methyl a‐cyanocinnamate system was found to copolymerize non‐classically; the two‐parameter penultimate model described properly the experimental data yielding r'1/r1 ≈ 3–6. The styrene/fumaroyldipyrrolidone system showed only a slight penultimate effect. However, in this case, the terminal model gave a better fit of experimental data.
Cationic polymerization of bis(1‐alkylvinyl)benzenes and related monomers, 5. New thermostable polyindanes
Authors: Nuyken Oskar , Leitner Michael B. , Maier Gerhard
Published: April 2003

The cationic cyclopolymerization of six monomers of the type “1,4‐bis(alk‐2‐en‐2‐yl)benzene” is described. The length of the unsaturated chains of the monomers ranges from 3 (propenyl) to 8 (octenyl) carbon atoms. The polymerization yields polyindanes containing different isomeric indane structure elements, which have alkyl substituents ranging from methyl to hexyl groups. The number of carbon atoms in the alkyl side chains greatly influences the glass transition temperature Tg, which is depressed from 246°C (methyl‐substituted polyindane) to 26°C (hexyl‐substituted polyindane). Thermal stability is also affected, though far less than Tg: the temperature, at which the material has lost 2% of its original weight is lowered from 420°C to 340°C. The polyindanes are soluble in a number of organic solvents. Their degree of polymerization is limited by a side reaction which provides non‐reactive end groups. Thus, the number‐average molar masses obtained are between 2800 and 4300 g/mol.
End group identification and molecular weight determination of a diels‐alder ladder polymer
Authors: Godt Adelheid , Schlüter Arnulf‐Dieter
Published: April 2003

The end groups of the double‐stranded polymer 2 were identified using NMR spectroscopy and end‐capping reactions. The number‐average molecular weight of a representative sample of 2 was determined as P̄n = 45.
Polyacetylenes with cholesteryl side‐groups: synthesis, linear and non‐linear optical properties of soluble conjugated polymers
Authors: Moigne Jacques Le , Hilberer Alain , Kajzar François
Published: April 2003

New polyacetylenes with cholesteryl side‐groups with different spacer lengths are polymerized through classical metathesis reaction in solution with the transition metal halides WCl6, MoCl5, and TaCl5. The highest polymerization yield and the best average molecular weight are obtained with the cholesteryl 4‐pentynoate (CP5) with the 1 ,4‐dioxane/WCl6 couple and the measured values are, respectively, 87% and 15 · 104. All of the other esters, cholesteryl propynoate or cholesteryl 10‐undecynoate give low polymerization yields. Poly(CP5) is a red transparent solid; it can be dissolved in common organic solvents and can be cast from solution into films. The solid‐state film presents a transition to a thermotropic liquid‐crystalline phase at 189°C and a transition to the isotropic phase at 189°C. A progressive decoloration occurs in solution and in the liquid‐crystalline phase. The results are interpreted as conformational changes of the polyene planar chain in a less conjugated backbone. The third‐order susceptibility χ3 measured by third harmonic generation on the red polymer lies in the range of 10−21 V2·m−2 in accord with the low content of the active part in the molecule and to a moderate length of conjugation of this highly crowded polyacetylenic chain.
On the conformation and the crystalline structure of an ethylene‐chlorotrifluoroethylene alternating copolymer
Authors: Guerra Gaetano , Rosa Claudio De , Iuliano Mauro , Petraccone Vittorio , Corradini Paolo , Pucciariello Rachele , Villani Vincenzo , Ajroldi Giuseppe
Published: April 2003

The conformation and the packing of the chains of the alternating ethylene‐chlorotrifluoro‐ethylene copolymer (ECTFE), in the crystalline phase, are investigated by X‐ray diffraction analysis, by calculations of the conformational energy and by calculations of the Fourier‐transforms of models. These analyses suggest that the crystalline form of ECTFE is a mesomorphic form, with a pseudo‐hexagonal packing of the axes of nearly trans‐planar chains (interchain distances of 5,69 Å) and a nearly complete translational and rotational disorder along the chain axis.
Preparation and properties of macromolecular complexes consisting of chitosan derivatives and potassium metaphosphate
Authors: Kubota Naoji , Kikuchi Yasuo
Published: April 2003

Glycol chitosan (GC) and methyl glycol chitosan (MGC) were, individually, reacted with potassium metaphosphate (MPK) to form a series of water‐insoluble macromolecular complexes (MC) in aqueous solution at different hydrogen ion concentrations (GC‐MPK and MGC‐MPK systems). GC was reacted with MPK in the presence of CaCl2 (GC‐MPK‐CaCl2 system) as well as in the absence of CaCl2. The properties of MC obtained were studied. On the basis of elemental analysis, solubilities, and thermogravimetry analysis, it is suggested that the molecular structure of each MC depends on the hydrogen ion concentration and whether Ca2+ ion is present or not. MC prepared at pH 1,0 are composed of a relatively loose network including a small quantity of MPK, whereas those MC prepared at neutral and higher pH are composed of a relatively tight network including a large quantity of MPK. As compared with MC in the GC‐MPK system, those in the GC‐MPK‐CaCl2 system are anticipated to have a rather tightly bound network structure due to the cross‐linkings through Ca2+ ions.
Polymerization in inverse microemulsions, 4 locus of initiation by ammonium peroxodisulfate and 2,2′‐azoisobutyronitrile
Authors: Vašková Viera , Hloušková Zuzana , Bartoň Jaroslav , Juraničová Viera
Published: April 2003

The locus of the initiation using the water‐soluble radical initiator ammonium peroxodisulfate (APS) and/or the partially water‐soluble radical initiator 2,2′‐azoisobutyronitrile (AIBN) in the inverse microemulsion system toluene/water (mass ratio 10:1) was studied. The homopolymerization and/or copolymerization of the water‐soluble monomer acrylamide (AAM) with the oilsoluble methyl methacrylate (MMA) was investigated. It was found that the locus of initiation by APS in the given system is the water micropool, and the locus of initiation by AIBN is the interlayer between the water micropool and the toluene macrophase.
Thermotropic polyesters, 8, comparison of two methods of synthesis of regular liquid‐crystalline multiblock copolymers
Authors: Piraner Olga N. , Tenkovtsev Andrey V. , Bilibin Alexander Yu.
Published: April 2003

Two methods of synthesis of regular liquid‐crystalline (LC) multiblock copolyesters are compared. A new method for the synthesis of polyesters with increased length of mesogenic units is given. This method is based on the preparation of intermediate oxalate‐groups‐containing polymers which are hydrolyzed in the next stage. The difference consists in the structure of the initial complex monomer. The new complex monomer makes it possible to obtain LC polyesters with seven 1,4‐phenylene fragments in the mesogenic unit by a simpler route.
Water‐soluble photoresins based on azosulfonates
Authors: Dauth Jochen , Nuyken Oskar , Strohriegl Peter , Voit Brigitte
Published: April 2003

Water‐soluble polymers with pendant azosulfonate groups were synthesized by radical copolymerization of 3‐vinylphenylazosulfonate with methyl methacrylate or styrene. The copolymerization parameters were determined for these systems. Furthermore, photoactive polymers were obtained by reaction of poly[(methacryloyl chloride)‐co‐(methyl methacrylate)] with azosulfonates containing phenolic or amino groups. Due to their solubility in water and their photocrosslinking behaviour, these polymers are attractive candidates for photoprinting and photoresist materials.
Synthesis of block copolymers from 1‐chloro‐1‐octyne and other acetylenes through their sequential living polymerization by MoOCl4n‐Bu4SnEtOH
Authors: Akiyoshi Kazunori , Masuda Toshio , Higashimura Toshinobu
Published: April 2003

Block copolymerizations of 1‐chloro‐1‐octyne (1‐ClO) with several substituted acetylenes were examined by means of living polymerization. o‐(Trifluoromethyl)phenylacetylene (o‐CF3PA), o‐(trimethylsilyl)phenylacetylene (o‐Me3SiPA), 1‐chloro‐2‐phenylacetylene (1‐ClPA), p‐butyl‐o,o,m,m‐tetrafluorophenylacetylene (p‐BuF4PA), and tert‐butylacetylene (t‐BuA) were used as comonomers, and the MoOCl4‐n‐Bu4Sn‐EtOH (mole ratio 1:1:1) catalyst, which is known to effect living polymerization of substituted acetylenes, was employed. When o‐CF3PA and 1‐CIPA were the comonomers in combination with 1‐CIO, block copolymers were exclusively obtained in both orders of monomer addition. In the cases of o‐Me3SiPA and p‐BuF4PA as comonomers, the copolymerizations initiated from 1‐CIO produced block copolymers selectively, whereas the homopolymers of o‐Me3SiPA and p‐BuF4PA also formed if the order of monomer addition was reversed. The pair of 1‐CIO and t‐BuA did not selectively yield block copolymers irrespective of the order of monomer addition. Thus, block copolymerization occurred between 1‐CIO and monomers that show high “livingness” and close reactivities.
Molecular characterization of water‐soluble, cationic polyelectrolytes
Authors: Griebel Thomas , Kulicke W.‐Michael
Published: April 2003

Poly{acrylamide‐co‐[2‐(acryloyloxy)ethyltrimethylammonium chloride]} (1), Poly{acrylamide‐co‐[2‐(methacryloyloxy)ethyltrimethylammonium chloride]} (2) and Poly{acrylamide‐co‐[3‐(acryloylamino)propyltrimethylammonium chloride]} (3) with cationic monomeric unit mole fractions of 8, 25, and 50 mol‐%, and the corresponding homopolymers were characterized with respect to their molecular dimensions in 1 M sodium chloride solution at 25°C in the molecular weight range from 200000 to 16000000, using light‐scattering and viscometric measurements. It was possible to establish correlations between molecular weight, intrinsic viscosity and radius of gyration. Whereas a steady increase in the exponents of the [η] vs. M‐ and 〈R2G〉0,5 vs. M‐relationships can be observed with increasing charge density, there is an initial decrease in the values of the exponents for 2 and 3, when 8 mol‐% of the cationic monomer is inserted into poly‐acrylamide. If the charge density is increased further, these values can also be seen to rise steadily. The findings are explained by the different structures in solution, which are formed by the copolymers and homopolymers investigated due to their chemical structure. The radii of gyration were calculated from the intrinsic viscosities with the aid of the Flory‐Fox equation. However, neither the results obtained with the Flory‐Fox constant Φ0= 3,69. 1024 mol−1, nor those with the value of Φ0= 2,10. 1024 mol−1 showed good agreement with the experimentally recorded data.
Cationic polymerization of 1,2‐epoxy‐3‐nitropropane in the presence of ethylene glycol, 1. Lower oligodiols obtained according to the activated monomer mechanism
Authors: Lagarde Florence , Reibel Léonard , Franta Emile
Published: April 2003

The early stage of cationic polymerization of 1,2‐epoxy‐3‐nitropropane in the presence of ethylene glycol and borontrifluoride etherate is examined. It is shown that the reaction proceeds according to the Activated Monomer Mechanism: initiation and propagation involve the nucleophilic attack of an hydroxyl end‐group moiety onto a protonated monomer molecule; this attack takes place on the carbon atom located in the β‐position with regard to the CH2NO2 group.
Polyarylenes and poly(arylenevinylene)s, 9 The oxidized states of a (1,4‐phenylene) ladder polymer
Authors: Scherf Ullrich , Bohnen Angelika , Müllen Klaus
Published: April 2003

The oxidized states of double‐stranded, planar (1,4‐phenylene)‐type ladder polymers are characterized by means of UV/VIS/NIR

NIR: Near infrared.

spectroscopy and cyclic voltammetry. The oxidation with antimony pentachloride or iron trichloride proceeds as a two‐step process; first, radical cationic (polaronic) species are generated, followed by the formation of dicationic (bipolaronic) ones. Especially the polymeric radical cations formed possess an outstanding chemical stability. The findings of cyclovoltammetric investigations are in full agreement with the chemical oxidation experiments.
Kinetics of polymerization of mixed diacetylene single crystals determined from dielectric measurements
Authors: Orczyk Maciej , Pater Ewa , Sworakowski Juliusz
Published: April 2003

Results of investigations on the kinetics of thermal polymerization of mixed single‐crystalline diacetylenes are reported. The polymerization was studied at 333 K on a series of mixed 1 (pTS)–3 (pFBS) crystals of various compositions. The polymer contents were determined from the measurements of electric permittivities of the samples during polymerization. A simple qualitative model was put forward to explain changes in the kinetics of polymerization as function of the composition of mixed crystals. At early stages of polymerization, the process of initiation of the growth of polymer chains seems to be dependent on the concentration of defects associated with a misfit between pTS and pFBS molecules.
Molecular mobility in the adsorption layer and chain orientation in strained poly(dimethylsiloxane) networks by 2H NMR
Authors: Litvinov Victor M. , Spiess Hans Wolfgang
Published: April 2003

The molecular mobility at the elastomer/active filler interface is studied in Aerosil‐filled poly(dimethylsiloxane) networks. It is shown that in unstrained samples two regions of different local chain mobility can be distinguished, namely chain units in the adsorption layer and outside of it. The fraction of chain units with relatively low mobility in the adsorption layer is estimated. In a uniaxially strained sample, immobilization of chain units near the filler surface is observed at temperatures up to 20 K above the melting temperature of an unstrained sample. The network structure of unfilled and filled networks is probed by analysis of the quadrupolar splitting in 2H solid‐echo spectra of uniaxially strained samples. The local chain order at a given elongation is larger by a factor of 1,5–2 in the filler system. This is interpreted in terms of an increased number of effective cross‐links and the differences between macroscopic and microscopic strains.
Steric effects in 3‐substituted polythiophenes: comparing band gap, nonlinear optical susceptibility and conductivity of poly(3‐cyclohexylthiophene) and poly(3‐hexylthiophene)
Authors: Goedel Werner A. , Somanathan Narayana Sastri , Enkelmann Volker , Wegner Gerhard
Published: April 2003

We present the synthesis, characterization (NMR, mass spectroscopy, IR) and polymerization of 3‐cyclohexylthiophene. Although anodic polymerization is ineffective, it was possible to polymerize 3‐cyclohexylthiophene with FeCI3 as the oxidizing reagent, the resulting poly(3‐cyclohexylthiophene) (PC6T) having a peak molar mass of 73 000 g · mol−1. NMR‐Investigations reveal that the coupling ocurred mainly via the 2,5‐positions, and the band gap, as determined from UV‐vis spectroscopy and cyclic voltammetry, was 2,3–2,4 eV. The nonlinear susceptibility χ(3)(−3ω; ω ω ω) of the neutral polymer and the electrical conductivity of the CIO4− and PF−6 salts were determined. The effect of the steric requirements of the cyclohexyl substituent was estimated by comparing the polymer to a poly(3‐hexylthiophene) (PN6T) of the same molar mass and with a comparable number of defects (mainly head‐to‐head and tail‐to‐tail coupling of the subunits). In the case of PC6T the band gap of the neutral polymer is larger by 0,3 to 0,4 eV, the nonlinear susceptibility has approximately half the value, and the electrical conductivity of the oxidized polymer is two orders of magnitude lower than the corresponding values of PN6T. These effects are explained by the increased sterical requirements of the cyclohexyl substituent, which forces the thiophene rings out of a coplanar conformation and thus reduces the conjugation length.