bluuebunny/crossref_metadata_2025 huggingface dataset:
Porosity determination of poly[(trimethylolpropane trimethacrylate)‐co‐(methyl methacrylate)] gels
Authors: Schmid Andrea , Flodin Per
Published: April 2003

In this paper we studied the influence of the copolymerization of trimethylolpropane trimethacrylate (TRIM) with methyl methacrylate (MMA) on the pore structure of the resulting gels. TRIM and MMA were suspension‐copolymerized with toluene as pore‐forming agent. All gels have bimodal pore‐size distributions. The size distribution of large pores (r > 50 Å) of the solvent‐free poly(TRIM‐co‐MMA) broadens when the TRIM/MMA ratio decreases. The size distribution of small pores (r < 50 Å) shows sharp maxima for pores with a radius of 20 Å. In the swollen state the separation range for the poly(TRIM‐co‐MMA) particles of polystyrene standards varies with the TRIM/MMA ratio. The results of the porosity measurements of the swollen gels show good agreement with the results obtained from the dry gels. The porosity of the dry gels was studied with scanning electron microscopy, nitrogen adsorption/desroption and mercury porosimetry. The pore‐size distributions of the swollen poly(TRIM‐co‐MMA) gel particles were calculated from the size‐exclusion chromatography (SEC) results.
Multifunctional initiation of lactide polymerization by stannous octoate/pentaerythritol
Authors: Kim Soo Hyun , Han Yang‐Kyoo , Kim Young Ha , Hong Sung Ill
Published: April 2003

L‐Lactide was polymerized with stannous 2‐ethylhexanoate (stannous octoate) in the presence of pentaerythritol to investigate multifunctional initiation. The prepared oligomers contain starshaped 4‐arm molecules when the mole ratio of [lactide]/[pentaerythritol] is above 32. The molecular weight of oligomers coincides with the [lactide]/[pentaerythritol] ratio, indicating that pentaerythritol in conjugation with stannous octoate is an initiator for the “living” polymerization of L‐lactide.
Standardized polymerizations of ethylene and propene with bridged and unbridged metallocene derivatives: A comparison
Authors: Kaminsky Walter , Engehausen Rüdiger , Zoumis Konstantin , Spaleck Walter , Rohrmann Jürgen
Published: April 2003

Ethylene and propene were homopolymerized with 11 different metallocene‐methylalumin‐oxane (MAO) catalysts 1–11 using a constant set of parameters. The catalytic activity of the two unbridged and 9 ansa‐metallocenes as well as the properties of the polymers, such as molecular weight, width of molecular weight distribution, melting point, and, with polypropene, chain microstructure, were investigated. It was found that structure variations of the catalysts cause rather different catalytic behaviour, which further diversifies the performances with the two different monomers. In some cases this comparison allows insight into the nature of the influencing factors.
Stereospecific polymerization of methylthiirane in homogeneous phase, 2. Mechanism of stereoregulation
Authors: Dumas Philippe , Sigwalt Pierre , Guérin Philippe
Published: April 2003

In the living polymerization of methylthiirane initiated with bis(isopropyl‐(S)‐cysteinato)‐cadmium, stereospecificity depends on temperature of propagation, on initiator concentration and also on the length of the growing polymer chain. The kinetics of stereospecific and non‐stereospecific processes are described. In both cases, the order with respect to monomer is equal to zero and that with respect to initiator is one‐half. The stereospecific propagation is proposed to involve cadmium thiolates associated as “dimeric species” and coordinated by both the monomer and by an oligomeric or polymeric chain.
Investigation on the spherulitic morphology of poly(ether‐ether‐ketone)
Authors: Zhang Zhiyi , Zeng Hanmin
Published: April 2003

The spherulitic morphology of poly(ether‐ether‐ketone)

Systematic name: poly(oxy‐1, 4‐phenyleneoxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene).

(PEEK) has been studied by using polarizing light microscopy, IR and differential scanning calorimetry. It has been found that in distinct cases the spherulites of PEEK show radiated or banded morphology, which can change from one to another upon thermal treatment. The process was found to be reversible and also affected by the film thickness.
The effect of comonomer composition on the emulsion copolymerization of N,N′‐methylenebis(acrylamide) and an unsaturated polyester
Authors: Capek Ignác
Published: April 2003

The aqueous emulsion copolymerization of N,N′‐methylenebis(acrylamide) (MBA) and an unsaturated polyester (UP) initiated with potassium peroxodisulfate was kinetically investigated at 50°C as a function of comonomer feed compositions. The reaction order with respect to the monomer concentration was found to be proportional to the UP monomer concentration at medium conversions and independent of the UP monomer concentration at low conversions. The high reaction order obtained from the dependence of the particle concentration on UP monomer concentration was attributed to the multifunctionality of UP monomer. At low conversions, an enrichment of the copolymer in UP structural units is observed. The polymerization was suggested to proceed in the aqueous phase, in the UP micelles and in the shell of the polymer particles.
Asymmetric induction arising from the chiral twist of 2,2′‐binaphthyl template in the cyclopolymerization of divinyl ethers
Authors: Yokota Kazuaki , Kakuchi Toyoji , Yamamoto Toshiya , Hasegawa Toshiyuki , Haba Osamu
Published: April 2003

Cationic cyclopolymerization of divinyl ethers, which were derived from (R)‐ or (S)‐1, 1′‐bi‐2‐naphthol with methyl, phenyl, and bromo groups in the 3,3′‐positions, yielded polymers with changing optical rotation according to the reaction conditions. Model compounds, therefore, corresponding to the three stereoisomeric forms of the constitutional units, i. e., two racemo (R,R‐and S,S‐) forms and one meso form, were synthesized to confirm the origin of changing optical rotation in the polymers. 1H NMR analysis showed that the polymers change their optical rotation due to the configuration, which has a tendency to be preferentially a racemo‐diisotactic structure at higher monomer concentrations and in less polar solvents. The chiral twist of the (R)‐or (S)‐binaphthyl template induces the main chain to form an asymmetric R,R‐ or S,S‐racemo sequence, respectively, in the cyclopolymerization.
The structural order of some novel ionic polymers, 2. Models of molecular packing
Authors: Tsukruk Vladimir , Mischenko Nikolay , Köberle Peter , Laschewsky André
Published: April 2003

The molecular packing and spatial correlations of two isomeric zwitterionic polymethacrylates and one polyacrylate analog are studied by means of X‐ray analysis and conformational calculations. The analysis of the correlation functions and density distribution profiles suggest a double‐layered molecular packing which is discussed for the three polymers investigated, with respect to their different chemical structures. Whereas the zwitterionic polymethacrylates studied exhibit liquid‐like short‐range order, the polyacrylate analog exhibits an ordered double‐layered superstructure.
Doped non‐conjugated polymers with enhanced electrical conductivity
Authors: Schopov Ivan , Sinigerski Vesselin
Published: April 2003

In order to elucidate the dependence of electrical conductivity on conjugation length, polyketones built up of short conjugated aromatic blocks and methylene chains of different length were studied. As obtained, the polymer exhibit very low electrical conductivities of about 10−15 S/cm. Upon doping with iodine the conductivity increases up to 10 orders of magnitude and samples become paramagnetic. The colour turns from yellow to black, and a new absorption maximum appears in UV spectrum at 365 nm characteristic of I3−. The monomers and a model compound do not absorb iodine. In the polymers we assume some ordering of the aromatic moieties, which enables enhanced π‐π interaction. The result could be considered as an extension of the conjugation, thus allowing partial oxidation (doping) and therefrom enhanced conductivity. We explain the doping and the conductivity of polydienes in a simillar way. The conclusion is that extended conjugation along the chain is not a prerequisite for higher conductivity.
Copolymerization of ε‐caprolactone and morpholine‐2,5‐dione derivatives
Authors: Veld Peter J. A. in't , Wei‐Ping Ye , Klap Richard , Dijkstra Pieter J. , Feijen Jan
Published: April 2003

Novel biodegradable poly(ester‐amide)s were prepared by ring‐opening copolymerization of ε‐caprolactone and 3‐ and/or 6‐alkyl‐substituted morpholine‐2,5‐dione derivatives. The copolymerizations were carried out in the bulk using stannous octoate as an initiator. Molecular weights of the copolymers ranged from 1,0 · 104 to 8,3 · 104 and decreased with increasing mole fractions of morpholine‐2,5‐dione derivatives in the feed. 13C NMR sequence analysis indicated that the copolymers had a random distribution of ε‐oxycaproyl and depsipeptide units, which resulted from the occurrence of transesterification reactions during copolymerization. The results of the DSC measurements and 13C NMR sequence analysis showed a close relationship between the crystallinity and average length of ε‐oxycaproyl blocks. Copolymers with a mole fraction of depsipeptide units smaller than 0,20 were semi‐crystalline, whereas incorporation of larger amounts of depsipeptide units resulted in amorphous copolymers. The melting point depression as a function of the molar composition of the semi‐crystalline copolymers was in good agreement with the melting point depression predicted by the Baur equation, which indicated the rejection of depsipeptide units from crystals consisting of ε‐oxycaproyl units.
Macromonomers via 1,3,6‐trioxocane polymerization
Authors: Krüger Hartmut , Pasch Harald , Much Helmut , Gancheva Valeria , Velichkova Rumiana
Published: April 2003

The ring‐opening polymerization of 1,3,6‐trioxocane (TO) in the presence of 2‐hydroxyethyl methacrylate (HEMA) leading to macromonomers is described. According to the activated monomer mechanism the oligo(1,3,6‐trioxocane)s are terminated with HEMA‐groups. The obtained macromonomers are non‐uniform in end functionality. With high‐performance liquid chromatography (HPLC) at the critical point of adsorption and supercritical fluid chromatography (SFC) it is possible to characterize the molar mass and functionality distribution of the macromonomers. Using these chromatographic methods functionality uniform fractions are available.
Changes in liquid‐crystalline phase behaviour of some poly[p‐(methacryloyloxyalkyleneoxy)benzoate]s with bromination at the m‐position in the mesogens
Authors: Ferg Ernst , Kühnpast Kurt , Cackovic Hinko , Springer Jürgen , Rodekirch Gerhard , Wolff Dietmar , Rübner Joachim
Published: April 2003

The structural properties of side‐group liquid‐crystalline polymers with large electronegative space‐filling substituents at the mesogenic groups were investigated. The synthesis and characterization of some poly[m‐bromo‐p‐(methacryloyloxyalkyleneoxy)benzoate]s are reported. Their liquid‐crystalline properties were investigated using differential scanning calorimetry and X‐ray diffraction techniques and were compared to some unsubstituted compounds found in the literature. A general decrease in the phase transition temperatures and in the order of the liquid‐crystalline phases for the Br‐substituted compounds was observed. It can be concluded that the liquid‐crystalline properties of polymers with large side‐group substituents at the mesogens can be maintained if long flexible or large electron‐rich end groups are introduced.
Cationic copolymerization of norbornadiene with styrene by AlEtCl2/tert‐butyl chloride catalyst system, 2. Effect of polymerization conditions on “crosslinking” and “polymer linking” reactions
Authors: Sagane Toshihiro , Minami Shuuji
Published: April 2003

The cationic copolymerization of norbornadiene (NBD) and styrene (St) was carried out with the AlEtCl2/tert‐butyl chloride catalyst system under various conditions. Detailed analyses were focused on the effect of reaction conditions on the two types of intermolecular reactions, that is, the “crosslinking” reaction to form an insoluble polymer and the “polymer linking” reaction to form a soluble polymer with a molecular weight higher than that of the non‐crosslinked polymer. The two types of crosslinking processes can explain the unique dependency of the polymer solubility on the NBD/St feed ratio. The “polymer linking” reaction is initiated after complete consumption of the monomers and is strongly affected by the polymerization conditions. For example, longer polymerization time, lower temperature, an initial monomer concentration [M]0 around 1,0–1,5 mol/L, a [t‐BuCl]0/[AlEtCl2]0 ratio around 0,75–1,0 and increasing [AlEtCl2]0 are the factors that facilitate the “polymer linking”.
Synthesis and rheological study of some maleic acid and fumaric acid stereoregular polyesters, 7. Rheological study of copolymerization reaction of configurationally pure unsaturated copolyesters and styrene
Authors: Jaćović Mihailo S. , Djonlagić Jasna , Sepulchre Maurice , Sepulchre Marie‐Odile , Spassky Nicolas
Published: April 2003

The crosslinking copolymerization of styrene and configurationally pure unsaturated copolyesters, containing phthalic acid and maleic or fumaric acid residues, was carried out in a dynamic shear field at a frequency of 6,28 rad · s−1 and ambient temperature. It was found that a clear distinction can be made between gelation and postgelation crosslinking. The former takes place between the onset at G′ ≈︁ G″ (G′, G″: storage and loss shear moduli) and the practical end point at (δG′/δt)max = k0, while the latter represents a first‐order process which is characterized by its rate constant, k1, and the corresponding crosslinking half‐time. The relationship between k0 and k1 was established. It appears that the reaction of the fumarate residues with styrene is much faster than that of the maleate residues. At the same degree of unsaturation of 50 mol‐%, k0 was about seven times higher for the reaction of fumarate copolyester than for the reaction of the maleates.
Viscoelastic properties of poly(dibutyl itaconate) melts
Authors: Hrabar Jova P. , Jaćović Mihailo S. , Velic̆ković Jovan S.
Published: April 2003

Complex dynamic viscosities η* of poly(dibutyl itaconate) melts were determined for nonuniform polymers with viscosity‐average molecular weights varying from 8000 to 327000 in the temperature range from 323 to 463 K and the frequency range from 0,1 to 100 rad/s. By applying the time and temperature superposition principle, master curves for the selected reference temperature T0 = 383 K were obtained, permitting the estimation of the Newtonian viscosity in terms of molecular weights. The temperature dependence of viscous flow was analysed by verification of the linearity of the aT shift factor, interpreted via the Williams‐Landel‐Ferry equation. Deviations from linearity were observed only for very low molecular weights M and at the highest temperatures. The activation energy of viscous flow was calculated by applying the concept of absolute reaction rates and the concept of free volume. Good agreement was observed. The linearized η* vs. M dependence changes slope at a critical molar mass Mc = 69000 with exponents of M α = 1,05 below and β = 2,92 above the Mc value in the function η* = f(M). The rheological properties of poly(dibutyl itaconate) are discussed in terms of substituent size and compared to those of other related vinyl polymers.
Synthesis and properties of liquid‐crystalline side‐chain polymers containing β‐diketonato transition metal complexes
Authors: Hanabusa Kenji , Suzuki Takashi , Koyama Toshiki , Shirai Hirofusa
Published: April 2003

Polymers (5‐7) containing β‐diketonato metal complexes of Cu2+, Ni2+ and Co3+ were synthesized from new thermotropic liquid‐crystalline poly(acrylate ester)s (4) with a mesogenic bidentate β‐diketone in the side chain, and the liquid‐crystalline properties were examined by differential scanning calorimetry (DSC), X‐ray diffraction and polarizing microscopy. The mesophase of 4 is an enantiotropic smectic A phase showing a batônnet and focal conic fan texture in polarizing microscopy. Polymers 5a‐c containing a bis(β‐diketonato) copper(II) complex also exhibit an enantiotropic smectic A phase, and polymer 5d prepared from the vinyl monomer 8 shows a nematic phase. Concerning the complexes of polymers 6 and 7 with nickel(II) and cobalt(III), only 6a and 7a containing a small amount of metal‐chelating β‐diketonate units exhibit liquid‐crystalline behavior like the parent polymer 4. It was found that the fourcoordinated square planar bis(β‐diketonate)copper(II) acts as the mesogen; both nickel(II) and cobalt(III) complexes do not work as mesogens and rather hinder the liquid crystallinity of 4. The electron spin resonance (ESR) spectra of 5a and 5b change markedly along with the transition from the smectic A phase to the isotropic one. The broadening and simplification of the spectra for the isotropic phase indicates increased interaction between neighboring bis(β‐diketonato)copper(II) complexes and substantial electron spin‐spin interaction. The ESR spectra of 5c and 5d also imply this increased interaction between neighbouring complexes and spin‐spin interaction regardless of the phase transition.
Synthesis and characterization of some acrylic monomer/sulfur dioxide copolymers
Authors: Tsonis Christos P. , Ali Sk. Asrof , Wazeer Mohammed I. M. , Abdennabi Abdul M.
Published: April 2003

The copolymerization of acrylic monomers (M) [acrolein (AL), methyl acrylate (MA), acrylamide (AM) and acrylonitrile (AN)] with liquid sulfur dioxide (S) at low temperature and high dilution in the presence of tert‐butyl hydroperoxide gives high SO2 incorporation into the resulting copolymers. Analysis of the composition of these polysulfones, by elemental analyses and 13C NMR, shows that they consist mostly of the MMM, SMM, MMS and MSM triad monomer sequences. Thermal (TG) analyses of selected samples demonstrate that their thermal stability, up to 30% weight loss, increases for different acrylic comonomers as follows: AL < AM < MA < AN. Preliminary flammability tests revealed that flame retardancy increases with increasing SO2 content in the copolymer.
Controlled synthesis of α,β‐difunctional poly(hexafluoropropylene oxide)
Authors: Ding Ji‐Feng , Proudmore Martin , Mobbs Richard H. , Khan A. Rashid , Price Colin , Booth Colin
Published: April 2003

An improved method is described for the preparation of difunctional poly(hexafluoropropylene oxide) of moderate molecular weight (Mn ≈ 6000) in good yield (>80 wt.‐%). With the dependence of chain transfer constant on initiator concentration known, at least under controlled conditions, good molecular‐weight control can be achieved.
Synthesis and 1H NMR study of aromatic poly(amide‐thioether)s
Authors: Nykolyszak Tania , Fradet Alain , Maréchal Ernest
Published: April 2003

The synthesis of aromatic poly(amide‐thioether)s by reaction between 4,4′‐thiodianiline, 4,4′‐thiodibenzoic acid and 4‐(4‐aminophenylthio)benzoic acid is studied. Depending on the initial monomer ratio, polymers with head‐to‐head, head‐to‐tail or statistical distribution of amido groups along the polymer chains were obtained. Corresponding triads effects were observed in the 1H NMR spectra and assigned. The synthesis of the same aromatic poly(amidethioether)s by reaction between dichlorobenzanilides and Na2S is also studied. Only the Cl substituents in para position to a carbonyl groups are reactive and a head‐to‐head poly(amidethioether) was obtained by reaction of N,N′‐thiobis(1,4‐phenylene)‐di‐4‐chlorobenzamide (2f) with Na2S.
Sequencing analysis and study of substituent effects in aromatic poly(amide‐thioether)s by 13C NMR spectroscopy
Authors: Nykolyszak Tania , Fradet Alain , Maréchal Ernest
Published: April 2003

Poly(amide‐thioether)s with different microstructures are studied by 13C NMR spectroscopy. Alternating copolymers with head‐to‐head or tail‐to‐head arrangement of amido groups in the chain give quite different NMR spectra which are assigned. The spectra of statistical copolymers exhibit resonances which are not present in the spectra of alternating copolymers due to the existence of new triads. The study of chemical shift differences between the alternating copolymers and copolymers with 4‐iminobenzoyl, terephthaloyl or 1,4‐diiminophenylene units show that these sequencing effects are transmitted through S links but not through CONH links. This was explained by the participation of the sulfur atom in the mesomeric system of the two neighbouring 1,4‐phenylene groups.
Radical polymerization and copolymerization of bis{3‐[tris(trimethylsiloxy)silyl]propyl} fumarate
Authors: Otsu Takayuki , Yoshioka Masahiro
Published: April 2003

Radical polymerization and copolymerization of bis{3‐[tris(trimethylsiloxy)silyl]propyl} fumarate (BSPF (1)) were investigated. The reactivity of BSPF in homopolymerization was found to be very low, and only low‐molecular‐weight poly(BSPF) was obtained in low yields. On the other hand, copolymerizations of BSPF with diisopropyl fumarate (DiPF) and di‐tert‐butyl fumarate (DtBF) proceed with moderate rates to give high‐molecular‐weight copolymers. The monomer reactivity ratios were determined to be as follows; r1 = 0,07, r2 = 0,87 for BSPF (M1) and DiPF (M2); r1 = 0,21, r2 = 0,67 for BSPF (M1) and DtBF (M2). The resulting copolymers are soluble in many common organic solvents. Tough and brittle films were obtained by solution casting of the copolymers of BSPF and DtBF. The copolymers exhibit excellent oxygen permeability.
Swellable polymeric networks with star‐like branching points from styrene, acrylonitrile and multifunctional cyclosiloxanes
Authors: Koβmehl Gerhard , Fluthwedel Andrea , Schäfer Horst
Published: April 2003

Cyclosiloxanes with four and six vinyl groups, 2,4,6,8‐tetramethyl‐2,4,6,8‐tetravinylcyclotetra‐siloxane (2a) and 2,2,4,4,6,6‐hexavinylcyclotrisiloxane (2b), were copolymerized with styrene and acrylonitrile, both in bulk and under special preparation conditions, to yield macroporous polymers. The reproducible sorption properties of the obtained materials in several organic solvents (with swelling degrees up to 1828% for toluene and 98% for phenol) were compared with networks from styrene and acrylonitrile cross‐linked with p‐divinylbenzene (DVB) (with swelling degrees up to 637% for toluene and 80% for phenol). Macroporous polymer networks cross‐linked with DVB exhibit considerably smaller pore diameters than those cross‐linked with 2a or 2b.
Size control of poly(methyl methacrylate) particles by dispersion polymerization in polar media
Authors: Kobayashi Shiro , Uyama Hiroshi , Matsumoto Yasuhiro , Yamamoto Ikuo
Published: April 2003

Dispersion polymerization of methyl methacrylate (MMA) in aqueous methanol solution was carried out using poly[(propionylimno)ethylene] (PPIE) as a steric stabilizer. The dispersion polymerization in the aqueous methanol solution (methanol: water = 70:30 wt.‐%) gave monodisperse particles in the micrometer range. The diameter of the particles decreased as the molecular weight and the concentration of PPIE increased. Effects of other polymerization parameters, such as monomer and initiator concentrations, solvent composition, and addition of methyl 2‐methylpropionate, on the size and size distribution of the particles were examined.
Multiblock poly(ether‐ester‐amide)s based on polyamide‐6 and poly(ethylene glycol), 1. Effect of polyether segment length on the properties of poly(ether‐ester‐amide)s with various polyamide/polyether ratios
Authors: Fakirov Stoyko , Goranov Konstantin , Bosvelieva Eliana , Du Chesne Alexander
Published: April 2003

A series of multiblock poly(ether‐ester‐amide)s (PEEA) based on polyamide‐6 (PA6) and poly(ethylene glycol) (PEG) is synthesized in a two‐step process. The first step represents the hydrolytic polymerization of ε‐caprolactam (CL) in the presence of adipic acid (AA) to carboxyl‐terminated PA6 oligomers of different chain lengths and the second is their polycondensation with PEG of molecular weights 420 (PEG 400) and 1150 (PEG 1000) in the presence of catalyst and thermostabilizer. The formation of the new ester bond between PA6 and PEG is proved by infrared spectroscopy. The content of the hard (PA6) and the soft (PEG) segments in the copolymer is determined by 1H NMR and elemental analysis. The shift in glass transition temperature Tg above that of pure PEG and the depression of the melting temperature Tm assigned to PA6 are characteristic for phase‐separated block copolymers. The degree of crystallinity of the PA6 component does not seem to be affected by the actual weight composition but depends on the different segment lengths. For the copolymers containing PEG‐1000 it is close to that of the respective homopolymer PA6. The tensile parameters of the copolymers studied are similar to those of available PEEA products.
New comb‐like polymers with prospective nonlinear optical properties
Authors: Combellas Catherine , Petit Michel A. , Thiébault André , Froyer Gérard , Bosc Dominique
Published: April 2003

New methacrylic copolymers with prospective second‐order nonlinear optical effects are synthesized by radical copolymerization of methyl methacrylate with conjugated zwitterionic methacrylate monomers (2,6‐di‐tert‐butyl‐4‐[1‐(ω‐methacryloyloxyalkyl)‐4‐pyridino]phenolates,1a and 1b). These monomers are obtained via a multi‐step reaction. First, 4‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)pyridine (2) is electrosynthesized by an SRN1 reaction in liquid ammonia. Then, this pyridine derivative is N‐alkylated by an ω‐bromoalkyl methacrylate (5a or 5b) which, in its turn, is obtained by esterification of an ω‐bromoalcohol and methacryloyl chloride.
Transition kinetics of smectic liquid‐crystalline polyesters
Authors: Tsai Ruey‐Shi , Tsai Hong‐Bing , Hu Andrew Teh , Lee Yu‐Der
Published: April 2003

Two smectic main‐chain liquid‐crystalline polyesters containing biphenyl as mesogen and spacers with 8 and 18 methylene carbon atoms were prepared, and their transition kinetics were investigated by means of differential scanning calorimetry (DSC). The isothermal liquid‐crystallization was analyzed using the Avrami equation. The Avrami exponent n was found to be 2 to 4 indicating that the liquid‐crystallization of these two smectic polyesters would be a process of two‐to three‐dimensional growth rather than of one‐dimensional growth as for nematic liquid‐crystalline polymers. The nonisothermal liquid‐crystallization and crystallization were also analyzed by means of DSC. The crystallization from the smectic phase was found to be a very fast process and the supercooling of crystallization was small. Thus, the smectic phase might nucleate crystallization. The transition kinetics of these two smectic polyesters are considerably different from those of nematic liquid‐crystalline polymers due to the different orders of the liquid‐crystalline phases.
New perfluoroalkyl telomeric non‐ionic surfactants: synthesis, physicochemical and biological properties
Authors: Pavia André A. , Pucci Bernard , Riess Jean G. , Zarif Leila
Published: April 2003

Both the experimental conditions and the kinetic parameters governing the telomerization of hydroxy‐functional acryloyl derivatives in the presence of perfluoroalkanethiols were determined with the purpose of synthesizing new amphiphilic telomers with high surface activity for the preparation of stable perfluoro emulsions capable of carrying oxygen in vivo. Several perfluoro‐alkylated non‐ionic telomeric surfactants (FmTACn) were obtained in one step with an average yield of 80%, by free‐radical telomerization of tris(hydroxymethyl)acrylamidomethane in the presence of various perfluoroalkanethiols as chain‐transfer reagents. Surface activity, critical micelle concentration and emulsifying capability established the superiority of the FmTACn surfactants over Pluronic® F68, the major surfactant used presently in the FDA‐approved injectable fluorocarbon emulsion: Fluosol®.
Influence of intermolecular interactions on phase behaviour and miscibility of para‐linked aromatic polyesters with polycarbonate and mechanical properties of the blends
Authors: Land Horst‐Tore , Heitz Walter , Karbach Alexander , Pielartzik Harald
Published: April 2003

The synthesis of aromatic liquid‐crystalline polyesters soluble in common organic solvents is described. The polyesters carry methyl, tert‐butyl, phenyl and 4‐biphenyl substituents. The polyesters with biphenyl substituents have an isotropization temperature below 300°C. Blends of these polyesters with polycarbonate show one glass transition temperature in differential scanning calorimetry whereas transmission electron microscopy indicates a homogeneous dispersion of the polyester in the polycarbonate, but not on a molecular level. The moduli of the components of the blends are additive.
Bis(dialkylamino)‐substituted isopropenyltriazines: effect of the length of the alkyl chains on the polymerization as well as on the properties of the resulting comb‐like polymers
Authors: Kunisada Hideo , Yuki Yasuo , Kondo Shuji , Goto Ken‐ichi
Published: April 2003

New isopropenyltriazines, e.g., 2‐diethylamino‐4‐dimethylamino‐6‐isopropenyl‐1,3,5‐triazine (2a) and 2‐dimethylamino‐4‐dioctadecylamino‐6‐isopropenyl‐1,3,5‐triazine (2b) were prepared by the alkylation reaction of 2‐amino‐4‐dimethylamino‐6‐isopropyl‐1,3,5‐triazine (1) with corresponding alkyl halides in the presence of sodium hydride. In the free‐radical homopolymerization of these monomers, the polymerization yield of 2b was lower than that of 2a due to a lower ceiling temperature. Copolymerizations of these monomers with styrene and methyl methacrylate were carried out, and monomer reactivity ratios (r1 and r2) were determined. The monomer reactivity decreases by the introduction of two octadecyl groups into the monomer. Exothermic crystallization and endothermic melting peaks based on the octadecyl side chains were observed in differential scanning calorimetry of the resulting comb‐like polymers. The thermal stability of the polymers is not affected by the long alkyl groups.
Synthesis and characterization of homo‐ and co‐oligomers of tetracyclo[4.4.0.12,5.17,10]dodecene‐3 by cationic polymerization
Authors: Sagane Toshihiro , Mizuno Akira , Takata Toshimasa
Published: April 2003

Cationic homopolymerization of tetracyclo[4.4.0.12,5.17,10]dodecene‐3 (TCD) and its copolymerization with styrene (St) were carried out with the catalyst system Al(C2H5)Cl2/tert‐butyl chloride, and the effects of temperature and TCD/St feed ratio, on polymer solubility, molecular weight and glass transition temperature (Tg) were investigated. A soluble oligomer with a molecular weight of 1000 was prepared by homopolymerization of TCD at +10°C or by copolymerization with St (>4 mol‐% in the feed) at −50°C. 13C NMR analysis of the TCD homo‐ and TCD/St copolymers revealed both 3,4‐ and 3,11‐additions for the repeating units from TCD. A polymerization mechanism including initiation, propagation, termination (deprotonation), and further crosslinking reactions is proposed. Moreover, it was demonstrated that a TCD/St copolymer with a controlled Tg in the range of 100 to 260°C can be prepared by selecting the TCD/St composition.
Preparation and co‐catalytic properties of amphiphilic diblock copolymers consisting of polystyrene and ionene
Authors: Schipper Eugène T. W. M. , van Hest Jan C. M. , Piet Pieter , German Anton L.
Published: April 2003

Well defined amphiphilic diblock copolymers, consisting of an oligomeric quaternary ammonium block, a so‐called ionene, and a polystyrene block, were synthesized. The route started with the preparation of monofunctionalized polystyrene by anionic polymerization, using 3‐(dimethyl‐amino)propyllithium as initiator. The polystyrene was obtained with relatively narrow molecular weight distributions (M̄w/M̄n = 1,2–1,4). This polystyrene was coupled stepwise with a number of different monodisperse oligomer units of 2,4‐ionene, having reactive end‐groups, resulting in a monodisperse 2,4‐ionene block. End‐group titration, size exclusion chromatography, thin‐layer chromatography and infrared spectroscopy were utilized to characterize the polymers. Additionally the block copolymer in combination with tetrasodium phthalocyaninatocobalt(II)tetrasulfonate (CoPc(NaSO3)4) was tested as co‐catalyst in the phase‐transfer‐catalyzed autoxidation of 1‐dodecanethiol. Very high catalytic activities (775 mol O2/(mol Co · s)) were achieved, 40 times higher as compared with the polymer‐free system, due to a combination of the formation of the most active species and hydrophobic interaction with the hydrophobic thiol. This hydrophobic interaction resulted in an enhancement of the autoxidation rate by a factor 2,5, compared with the analogous hydrophilic homopolymer 2,4‐ionene.
Sulfur‐containing optically active polymers, 1. Synthesis and chiroptical properties of poly(γ‐ketosulfide)s derived from (−) (2R, 3R)‐1,4‐dimercapto‐2,3‐butanediol
Authors: Angiolini Luigi , Carlini Carlo , Salatelli Elisabetta
Published: April 2003

The synthesis of optically active poly(γ‐ketosulfide)s from bis‐Mannich bases or α,β,α′,β′‐unsaturated ketones and (−) (2R, 3R)‐1, 4‐dimercapto‐2,3‐butanediol, is described. The corresponding low‐molecular‐weight analogs were also synthesized. The products were fully characterized and their stereochemical features investigated by NMR. The relations between chiroptical and conformational properties in solution were also studied by circular dichroism measurements. Although an appreciable local asymmetric induction on the chromophores belonging to the starting achiral co‐reagent is observed, the macromolecules do not display any occurrence of ordered secondary structures due to a low stereoregularity degree orginated by the presence of randomly distributed constitutional repeating units having different diastereomeric configurations.
Intrinsic viscosity versus molar mass relationship of poly(3‐hexylthiophene) in toluene
Authors: Bi Xiping , Ying Qicong , Qian Renyuan
Published: April 2003

The Mark‐Houwink‐Sakurada equation for poly(3‐hexylthiophene) (PHTh) in toluene has been determined from seven fractions of a chemically polymerized sample: [η] = 1,312 . 10−2 M0,77. The polymer chain turned out to be rather flexible, and a persistence length of 25 Å was obtained from a Bohdanecky treatment of the Yamakawa‐Fujii theory for a worm‐like cylinder. In order to reconcile the conjugation length of six monomeric units (23,4 Å along the backbone) and the statistical Kuhn length of 50 Å, a block copolymer model of rigid coplanar segments of six monomeric units and flexible segments, involving many successive rotating inter‐ring bonds, has been proposed for the PHTh chain in solution.
Metathesis polymerization behavior of 2‐cyanobicyclo[2.2.1]hept‐5‐ene
Authors: Asrar J. , Curran Sean A.
Published: April 2003

This paper describes the ring‐opening methathesis polymerization of homopolymers and copolymers of exo‐ and endo‐2‐cyanobicyclo[2.2.1]hept‐5‐ene (norbornenenitrile) in solution. Polymerization kinetics were followed via 1H NMR spectroscopy in real time while the final polymer microstructure was determined via 13C NMR. While pure endo monomer does not polymerize readily, it copolymerizes with exo monomer, rapidly and to high conversions. The structure of the copolymer appears to be quite similar to that of exo homopolymer. We conclude that exo monomer adds directly to either exo or endo, while endo‐endo addition is sterically hindered.
Synthesis of functional unsaturated polyesters using rare earth coordination catalysts, 3. Mechanistic aspects of maleic anhydride‐epichlorohydrin copolymerization with Nd[(RO)2 PO2]3/Al[CH2CH(CH3)2]3 as a catalyst
Authors: Chen Xianhai , Zhang Yifeng , Shen Zhiquan
Published: April 2003

Ring‐opening alternating copolymerization of maleic anhydride and epichlorohydrin was carried out at 70°C with rare earth coordination catalysts composed of Nd[(RO)2 PO2]3 (R = CH3(CH2)3CH(C2H5)CH2)and trialkylaluminium. Anlaysis of end‐groups showed that the copolymer chain contains one OH and one CHCHCOCH2CH(CH3)2 end‐group. IR, UV‐Vis, 1H NMR and GPC results imply that a catalyst‐maleic anhyride complex is formed in the initiation step that the ring‐opening copolymerization proceeds via coordinate insertion mechanism accompanied with chain‐transfer.
Sucrose‐based polymers, 1. Linear polymers with sucrose side‐chains
Authors: Jhurry Dhanjay , Deffieux Alain , Fontanille Michel , Betremieux Isabelle , Mentech Julio , Descotes Gérard
Published: April 2003

Polymers and copolymers based on the monomethacryloyl ester and the vinylbenzyl ether of sucrose, bearing either blocked or free hydroxyl groups, were synthesized in the presence of free‐radical catalysts, and their structures and dimensions were characterized. A range of copolymers of styrene and O‐methacryloylsucrose was prepared. Reactivity ratios of the comonomers were calculated by the extended Kelen‐Tüdős method. The influence of the hydroxyl groups of the sucrose moiety on the thermomechanical properties was assessed by comparing the glass transition temperatures of both blocked and unblocked copolymers. Their solubility characteristics were also determined, and it was shown that the hydrophilic‐hydrophobic properties can be controlled by the amount of sucrose methacrylate in the copolymer.
Preparation of the precursors of new tannin‐like polymers with potential biological effects
Authors: Yuan Hui Liang , Fei Bi Hua , Párkányi Cyril , Caple Gerald , Eastman Michael P. , Loy Douglas A.
Published: April 2003

New acrylate based polymers, with the potential to be converted to polyphenolic polymers — poly[2‐(4‐benzyloxyphenyl)ethyl acrylate] (4) and poly[3‐(4‐benzyloxy‐3‐methoxyphenyl)propyl acrylate] (9) — were prepared from the corresponding monomers 3 and 8 by free‐radical polymeri‐ zation, initiated by 2,2′‐azoisobutyronitrile (AIBN). The acrylate monomers, 2‐(4‐benzyloxy‐ pheny1)ethyl acrylate (3) and 3‐(4‐benzyloxy‐3‐methoxyphenyl)propy1 acrylate (8), were synthes‐ ized from acryloyl chloride and the corresponding alcohols — 2‐(4‐benzyloxyphenyl)ethanol(2) and 3‐(4‐benzyloxy‐3‐methoxyphenyl)‐ 1 ‐propano1 (7), respectively. The monomer 7 was prepared from 3‐(4‐benzyloxy‐3‐methoxyphenyl)‐1‐propene (6) by hydroboration/oxidation and 6 was obtained from eugenol(4‐allyl‐2‐methoxyphenol) as the starting material. The compounds were characterized by1H NMR,13C NMR, FTIR, and elemental analyses. The molecular weight of the synthesized polymers was determined by gel‐permeation chromatography (GPC).
Synthesis of frequency doubling polymeric materials, 1. Second‐order nonlinear optical properties of poled chromophore‐functionalized polymethacrylates
Authors: Rondou Philippe , Beylen Marcel Van , Samyn Celest , S'Heeren Gert , Persoons Andre
Published: April 2003

The synthesis and second harmonic coeficients d33, d 31 and the susceptibilities χ(2) are reported of three series of (co)polymethacrylates that possess 4‐(2,2‐dicyanovinyl)‐ or 4‐(2‐cyano‐2‐methoxycarbonyl)vinyl‐N,N‐dialkylaniline (P1 and P2), 4‐(2,2‐dicyanovinyl)‐ or 4‐(2‐cyano‐2‐methoxycarbonyl)vinyl‐(‐piperidino)benzene (P5 and P6) and 4‐(2,2‐dicyano)‐ or 4‐(2‐cyano‐2‐methoxycarbonyl)vinyl‐1‐alkoxybenzene (P3 and P4) dyes

System. names of the monomers see Exptl. part.

. The second‐order nonlinear optical properties of corona‐poled aligned polymer films were evaluated by second harmonic generation measurements. The χ values for the P1 and P2 polymers vary from 58 to 318, respectively 32 to 106 · 10−9 esu, for P3 and P4 from 7,6 to 19, respectively 4,4 to 7,4 · 10 −9 esu and for P5 and P6 from 219 to 42,8 respectively 28,1 to 8,1 · 10−9 esu, depending on the dye chromophore concentration incorporated in the polymer structure.
The formation of oligomers in the inhibited thermal copolymerisation of styrene and acrylonitrile
Authors: Schellenberg Jürgen , Wigand Günter
Published: April 2003

The formation of oligomers up to molecular weights as high as about 800 was investigated in the iodine‐ and 4‐nitrosophenol‐inhibited thermally initiated copolymerisation of styrene and acrylonitrile by using column exclusion chromatography. In contrast to other possible approaches, such as the estimation of the rate of inhibition by analysing the inhibition period or trapping the initiating radicals through spin traps, this method offers the advantage of detecting the molecular species appearing during the inhibition reaction by directly estimating their molecular weights even in the higher ranges. A structural assignment of the discovered species is suggested and supported by the results of copolymerisation statistics. With iodine and 4‐nitrosophenol as inhibitors, the oligomers of the thermal reaction of copolymerisation initiation, the reaction products of inhibitors with initiating radicals, as well as components of a higher molecular weight were detected and classified, and the mechanisms of their formation are discussed.
Structural behaviour of thermotropic liquid crystals from poly(4‐vinylpyridine) fully and partially quaternized with a mesogenic group
Authors: Navarro‐Rodriguez Dámaso , Guillon Daniel , Skoulios Antoine , Frère Yves , Gramain Ph.
Published: April 2003

Liquid crystals were obtained from poly(4‐vinylpyridine) quaternized with 1‐bromooctane and 1‐bromododecane ω‐substituted with 4′‐methoxy‐4‐biphenyloxy mesogenic groups. Their thermotropic polymorphism was studied by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction. Three types of smectic mesophase, namely A, B, and E, were identified and described from a structural point of view. Their structure was found to be very similar to that previously reported for their monomer counterparts. The mesogenic pendant groups are arranged in single layers with the polymer backbones inserted in between. As a function of decreasing degree of quaternization, the smectic period increases slowly, reflecting the expansion of the sublayers containing the polymer backbones along with the free pyridine rings.
Kinetics of step polymerization of 3,6‐dibromo‐N‐ethylcarbazole catalyzed by a Ni(0)‐based complex
Authors: Aboulkassim Aïcha , Faïd Karim , Siove Alain
Published: April 2003

The dehalogenative polycondensation of 3,6‐dibromo‐N‐ethylcarbazole was catalyzed by a Ni(0)‐based complex, generated in N,N‐dimethylacetamide by electroreduction of NiBr2/2,2′‐bipyridine. The process involves three different successive reaction steps: electrolysis of Ni(II) to Ni(0); insertion of the latter into a CBr bond of monomer leading to CNiBr* active species; dehalogenative coupling between active sites and monomer, yielding oligomers. From kinetics of electrogeneration of the catalytic system in the absence of monomer, a first‐order reaction was determined. Insertion and coupling reactions were found to be second order, and comparison of the values of the corresponding rate constants clearly showed that couplings is the rate‐determining step of the process.
Syndiospecific polymerization of styrene with the catalytic system [Ti2(OC2H5)8Cl]2Mg2(μ‐Cl)2/methylaluminoxane compared with MgCl2‐supported and unsupported Ti(OC2H5)4
Authors: Dall'Occo Tiziano , Sartori Franco , Vecellio Giancarlo , Zucchini Umberto , Maldotti Andrea
Published: April 2003

As a part of our interest in the performance of [Ti2(OC2H5)8Cl]2Mg2(μ‐Cl)2 as Ziegler‐Natta catalyst, the polymerization of styrene with a toluene solution of this compound and methyl‐aluminoxane as cocatalyst was performed. It was found that the present catalytic system promotes the syndiospecific polymerization of styrene with high stereoregularity and the results were compared with those obtained with MgCl2‐supported or unsupported Ti(OC2H5)4 catalysts. Determination of the titanium oxidation states and electron spin resonance (ESR) measurements both in the absence and in the presence of styrene were carried out for all the catalytic systems aimed at shedding some light on the nature of the active species.
Synthesis of poly(vinyl alcohol) having a thiol group at one end and new block copolymers containing poly(vinyl alchohol) as one constitent
Authors: Sato Toshiaki , Terada Kazutoshi , Yamauchi Junnosuke , Okaya Takuji
Published: April 2003

Poly(vinyl alcohol) (PVA) and poly(vinyl acetate) having a thiol group at one end were synthesized by free‐radical polymerization of vinyl acetate in presence of thioacetic acid as a chain transfer agent followed by treating with sodium hydroxide/methanol and ammonia, respectively. It was found that block copolymers containing the PVA sequence as one constituent were obtained by the redox‐initiated polymerization of some vinyl monomers, for example, acrylic acid (AA) and acrylamide (AAm), using PVA having a thiol end group as reductant and an oxidant such as potassium bromate and potassium persulfate.
Investigation of the mechanism of chain termination and transfer by 1,2‐butadiene in the butyllithium‐initiated polymerization of 1,3‐butadiene in non‐polar solvents
Authors: Puskas Judit E.
Published: April 2003

1,2‐Butadiene (BD‐1,2) was shown to be a chain terminating/transferring agent in the butyllithium (nBuLi)‐initiated polymerization of 1,3‐butadiene in hexane solvent by Adams et al. Based on model reactions and circumstantial evidence they proposed that BD‐1,2 terminates the polymerization by extracting Li from the living chain end. The lithiated BD‐1,2 formed may initiate new chains causing chain transfer or isomerize to lithiated ethylacetylene (system. name: 1‐butyne), a nonactive species. This paper proposes a modification of the mechanism suggested by Adams et al. Kinetic investigations of the model reaction between nBuLi and BD‐1,2 by infrared spectroscopy have shown that the first, and rate‐determining, step is the isomerization of BD‐1,2 to ethylacetylene, followed by lithiation. It is proposed that the lithiated ethylacetylene can initiate new chains, thereby causing chain transfer.
Synthesis and properties of thermotropic liquid‐crystalline polymers linked through bis(ß‐diketonato)copper(II) complex
Authors: Hanabusa Kenji , Isogai Tadashi , Koyama Toshiki , Shirai Hirofusa
Published: April 2003

Thermotropic liquid‐crystalline polymers (2a–2e, 3a–3c) linked via the bis(ß‐diketonato)‐copper(II) complex were prepared by mixing the bifunctional bidentate ligand (1a–1c) with copper(II) chloride. The homopolymers 2c–2e and the copolymers 2a–3c were ascertained to exhibit a stable mesophase by means of polarizing microscopic observation. The homopolymers show at least a smectic mesophase and the copolymer exhibit both smectic and nematic ones. Fibers were prepared by melt‐drawing of the molten polymers at the mesophase temperature into air at room temperature except for 2a and 2b. Electron spin resonance (ESR) spectra of the melt drawn fibers indicated that the plane of the square planar bis(ß‐diketonato)copper(II) complex in the fiber is oriented parallel to the fiber axis. X‐ray diffraction patterns from the melt‐drawn fibers are characterized by several sharp inner reflections at meridional position and a diffuse one at equatorial position, suggesting that the fibers possess an axial orientation with smectic A phase which is frozen in during melt‐drawn spinning.
Charge‐transfer complexation in mixtures of polysiloxanes containing carbazolyl electorn‐donor and dinitrobenzoyl electron‐acceptor moieties
Authors: Setz Stefan , Schneider Hans Adam
Published: April 2003

The study of the charge transfer (CT) complexation in mixtures containing carbazolyl electron donor (D) and dinitrobenzoyl electron‐acceptor (A) moieties show stronger association effects in mixtures of polysiloxanes than in mixtures of low‐molecular‐weight model compounds. The increasing CT‐association in polymer systems is explained by a “macromolecular cage effect”. Cooperativity effects are believed to cause a “zip‐like” matching of the complementary polymeric backbones. UV‐spectroscopy and viscometric data indicate the formation of both bimolecular D : A and trimolecular D:2A associates.