bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal behavior, morphology and the determination of the polymer‐polymer interaction parameter of polycarbonate‐poly(butylene terephthalate) blends
Authors: Kim Woo Nyon , Burns Charles M.
Published: April 2003

Blends of bisphenol‐A polycarbonate (PC, poly(oxycarbonyloxy‐1,4‐phenylene‐2‐isopropylidene‐1,4‐phenylene)) and poly(butylene terephthalate) (PBT, poly(oxytetramethyleneoxy‐terephthaloyl)) have been investigated by differential scanning calorimetry and scanning electron microscopy. Blends were prepared by screw extrusion and solution casting with mass fractions of PC in the blends varying from 0,90 to 0,10. From the measured glass transition temperature (Tg) and apparent mass fractions of PC and PBT dissolved in each phase, it appears that the PBT dissolves more in the PC‐rich phase than does the PC in the PBT‐rich phase. Also, compatibility is greater in the case of extruded blends than in the case of solutioncast blends. The values of the Flory‐Huggins polymer‐polymer interaction parameter (χ12) were determined and found to range from 0,042 to 0,033 for extruded blends at 250°C and from 0,054 to 0,039 for solution casting at 25°C. The χ12 decreases with increase of PBT content throughout the investigated composition range. From the Tg's, the microscopy study and the extrudate swell ratios, it is concluded that compatibility is achieved in the blends having mass fractions 0,90, 0,20 and 0,10 of PC, but that these blends are not microscopically homogeneous.
Terpolymerization of sulfur dioxide and methyl acrylate with electron donor monomers
Authors: Florjańczyk Zbigniew , Floriańczyk Tadeusz , Zygadło Ewa
Published: April 2003

The radical terpolymerization of sulfur dioxide and methyl acrylate with 1,3‐butadiene, 2‐methylpropene, propene, 1‐hexene, 1‐octene and vinyl chloride was studied by comparing the composition of terpolymers obtained under different reaction conditions and by analysis of 13C NMR spectra of selected terpolymers and copolymers. In the majority of systems studied, products are formed in which the ratio of SO2 monomeric units to vinyl monomeric units is near to unity. The content of methyl acrylate monomeric units can change over a very wide range and depends mainly on the electron‐donor properties of the vinyl monomer used, feed composition and conversion. An increase of the methyl acrylate content is also observed in many systems with a rise of the reaction temperature. The results obtained are interpreted in terms of a mechanisms involving the addition of individual monomers and reversibility of steps in which carbon‐sulfur bonds are formed.
Radical ring‐opening polymerization behavior of ethyl 1‐substituted 2‐vinylcyclopropanecarboxylate
Authors: Endo Takeshi , Watanabe Makoto , Suga Katsufumi , Yokozawa Tsutomu
Published: April 2003

Ethyl 1‐substituted 2‐vinylcyclopropanecarboxylate derivatives (VCPs) were prepared from butadiene and the corresponding substituted diazoacetate in the presence of rhodium diacetate as a catalyst. The polymerization behavior of the obtained monomers was investigated revealing that VCPs undergo radical ring‐opening polymerization to form poly(1‐alkyl‐1‐ethoxycarbonyl‐3‐pentenylene)s and that there is a marked influence of the 1‐substituent of VCPs on the polymerization rate. The reaction of VCPs with thiophenol was also carried out as a model reaction of their polymerization.
Synthesis of poly(vinyl alcohol)‐graft‐poly(tetrahydrofuran)
Authors: Tezuka Yasuyuki , Okabayashi Atsushi , Imai Kiyokazu
Published: April 2003

The reaction of a living poly(tetrahydrofuran) (poly(THF)), prepared with methyl trifluoromethanesulfonate as an initiator, with 3‐sodiopropoxydimethylvinylsilane was carried out to produce a uniform poly(THF) macromonomer with a vinylsilane end‐group. Poly(vinyl acetate)‐graft‐poly(THF) of controlled graft segment length was then synthesized through radical copolymerization of this poly(THF) macromonomer with vinyl acetate. The subsequent saponification with NaOH in methanol provided poly(vinyl alcohol)‐graft‐poly(THF).
Morphology of cycloparaffins crystallized epitaxially on NaCl
Authors: Ihn Kyo Jin , Tsuji Masaki , Isoda Seiji , Kawaguchi Akiyoshi , Katayama Ken‐ichi , Tanaka Yasuyuki , Sato Hisaya
Published: April 2003

The cycloparaffins (CH2)36 and (CH2)60 were crystallized epitaxially from solutions on the (001) face of the NaCl crystal at various temperatures. Two types of crystals, so‐called edge‐on and flat‐on crystals, were separately obtained depending on crystallization temperature. The temperature for obtaining edge‐on crystals was higher by ca. 10°C than that for flat‐on crystals. In both flat‐on and edge‐on crystals, the long side (b‐axis) is aligned to the 〈110〉 direction of NaCl. The (001) plane in the flat‐on crystal and (202) in the edge‐on crystal are parallel to the substrate surface. The direction of the vector c′ defined as −a + c is parallel to the molecular axis in monoclinic cycloparaffin crystals. The angle β′ between c′ and the a‐axis is almost constant at about 119°, while c′ changes linearly with the number of carbon atoms in a molecule. The space group changes from Aa to Ia in the new unit cell with the dimensions a, b, c′ and β′.
Preparation of monomers functioning as initiators and use of their polymers for graft copolymerization
Authors: Yamada Bunichiro , Otsu Takayuki
Published: April 2003

New types of esters of methacrylic acid functioning as radical initiators, α,α′‐azobis(α‐methylbenzyl) dimethacrylate (1) and 1,1′‐azobis(1‐methylethyl) dimethacrylate (2), were synthesized by reaction of the corresponding chlorides with salts of methacrylic acid. These monomers1and2were utilized to produce copolymers containing the respective azoinitiator units. Decomposition of the initiator units in the presence of a second monomer resulted in graft copolymers. Polystyrene and poly(methyl methacrylate) were grafted onto the polymers bearing α‐azo‐α‐methylbenzyl units. Poly(styrene‐graft‐diisopropyl fumarate) was prepared by decomposition of polystyrene containing 1‐azo‐1‐methylethyl units in the presence of monomeric fumarate at 150 and 180°C. The number of the grafting sites along the main chain was estimated on the basis of the molecular weight of the polymer, the content of the initiator unit, and the decomposition rate.
Iodine‐poly(vinyl alcohol) interactions, 4. Stoichiometry of iodine/iodide in the polyiodide ion bound in the cage of poly(vinyl alcohol)
Authors: Yokota Toshio , Kimura Yoshiharu
Published: April 2003

Aqueous poly(vinyl alcohol) (PVA)‐iodine‐boric acid solution was treated with anion exchange resin and the system involving only the cage complex was isolated. The system was then extracted with carbon tetrachloride, and I2 and I−, which were released from the complex, were separated and pooled in the carbon tetrachloride and the aqueous layers, respectively. From the absorption spectra of the layers the amounts of I2 and I− were determined. The ratio I2/I− was found to be approximately 2,0, which corresponds to the I2/I− stoichiometry in the complex. This result suggested that the major species bound in the PVA cage are pentaiodide ions, i.e., I with linear configuration and/or I2· I with distorted chain structure. Judging from the resonance Raman spectrum of the PVA‐iodine solution that had been revealed before, it was concluded that the two absorption bands of the complex at λmax = 650 and 355 nm are ascribed to the I and I2 · I ions, respectively.
Solvent effect in radical copolymerization of styrene with p‐aminostyrene
Authors: Masuda Seizo , Tanaka Masami , Ota Tadatoshi
Published: April 2003

p‐Aminostyrene (1, M1) and styrene (M2) were radically copolymerized at 60°C in various solvents. There is a significant solvent effect on monomer reactivity ratios, especially on r1, suggesting a specific interaction between the solvent and the polymer radical with the p‐aminostyrene moiety at the terminal position. In order to clarify the solvent factor influencing the relative reactivity, the hydrogen‐bond‐accepting basicity of the solvent (β) was determined from enhanced UV shifts for 1 relative to N,N‐dimethyl‐p‐aminostyrene. Regression analysis of r1 with the solvatochromic parameters revealed that β is the major factor responsible for r1‐variations.
Sulfur‐containing azoinitiators and their properties
Authors: Nuyken Oskar , Knepper Thomas , Voit Brigitte
Published: April 2003

The thermolysis and photolysis of arylazosulfonates (1–3) and of arylazo phenyl sulfones (4–6) was studied. Compounds 1 to 3 are soluble in water. They are thermally stable up to 200°C; however, if they are irradiated with the light of a mercury‐xenon high‐pressure lamp, they decompose at room temperature. Their photolysis was studied either in water or in ethanol as solvent. For the photolysis in water an ionic mechanism of decomposition is suggested, while the results of the photolysis in ethanol can be explained on the basis of a competition of a radical with an ionic mechanism. Compounds 4 to 6 are thermally and photochemically instable. The thermal decomposition of 5 was studied in detail and found to be comparable to that of AIBN. Its decomposition follows first‐order kinetics. The photolysis of 4–6 was carried out in ethanol or chloroform. The mechanism of photolysis depends on the solvent polarity. 5 was successfully used as initiator for the polymerization of methyl methacrylate.
The use of low‐molecular‐weight model compounds in an investigation of polyelectrolytes, 1. Potentiometric properties of poly(methacrylic acid) and its 2‐dimethylaminoethyl ester
Authors: Přádný Martin , Holata Jan , Ševčík Stanislav
Published: April 2003

The potentiometric behaviour of poly(methacrylic acid) (PMA), poly(2‐dimethylaminoethyl methacrylate) (PDAEM), and low‐molecular‐weight compounds modelling the structural diad of these polymers, 2,2,4,4‐tetramethylglutaric acid (TMGA) and its 2‐dimethylaminoethyl ester (ETMG), is reported. The dissociation constants of these compounds to the 1st and 2nd degree were measured and compared with the values for polymers. It appears that TMGA adequately models the behaviour of PMA up to the conformational transition compact coil (stage “a”) — random coil (stage “b”) at higher ionic strength values of the titrated solution. On the contrary, ETMG behaves as a typical low‐molecular‐weight compound with properties differing from those of PDAEM.
Stress‐optical and thermomechanical measurements on liquid crystalline elastomers
Authors: Hammerschmidt Kathrin , Finkelmann Heino
Published: April 2003

For liquid crystalline polysiloxane‐elastomers, the orientation of the mesogenic side groups is determined under uniaxial compression and without load in the isotropic state in the vicinity of the isotropic to nematic phase transformation. The experimental results clearly indicate the following fundamental properties of liquid crystalline elastomers:

Depending on the chemical constitution of the flexible spacer a mechanical force causes a macroscopic orientation of the mesogenic side groups parallel or perpendicular to the direction of the force.

Strain causes a parallel (perpendicular), while compression causes a perpendicular (parallel) orientation of the side groups with respect to the direction of the mechanical force.

Due to a macroscopic orientation of the mesogenic side groups in the liquid crystalline state, the physical properties of the elastomers become anisotropic, which is directly reflected in the thermomechanical properties.
Dynamic‐mechanical losses in elastin networks swollen with glycols of various lengths
Authors: Andrady Anthony L. , Mark James E.
Published: April 2003

A Rheovibron DDV‐II‐C viscoelastometer was used to carry out loss tangent measurements on purified, swollen elastin networks. The diluents employed were HO(CH2CH2O)mH with m = 0–4, i.e. water, ethylene glycol, diethylene glycol (2,2′‐oxydiethanol), triethylene glycol (3,6‐dioxa‐1,8‐octanediol) and tetraethylene glycol (3,6,9‐trioxa‐1,11‐undecanediol) and the temperature range was −120 to 40°C. The results, in particular the effects of the various diluents on the α‐ and β‐transitions, are in support of the random‐network model rather than the twophase liquid‐drop model, for elastin in the rubberlike state.
Synthesis and gel‐permeation chromatography of oligo(oxyethylene) n‐alkyl ethers
Authors: Craven John R. , Mobbs Richard H. , Booth C. , Goodwin Elizabeth J. , Jackson David
Published: April 2003

Uniform samples of oligo(oxyethylene)s were synthesized: either H(OCH2CH2)mO(CH2)nH or CH3(OCH2CH2)mO(CH2)nH, with m in the range 4 to 16 and n = 9 or 15. The samples were eluted through a low‐porosity gel‐permeation chromatography column with either dichloromethane (DCM), tetrahydrofuran (THF) or N,N‐dimethylacetamide (DMA) as eluent. The elution volumes in the good solvents (DCM, THF) were insensitive to composition, while those in DMA depended on both chain length and composition.
Phosphorus functional telomers of vinyl polymers through functional thermal iniferter
Authors: Nair Chethrappilly P. Reghunadhan , Clouet Gilbert
Published: April 2003

The phosphorus‐functional iniferter, N,N′‐dimethyl‐N,N′‐bis[2‐(N‐diethoxyphosphinoyl‐N‐methylamino)ethyl]thiuram disulfide (2), was synthesized and characterized. Thermal polymerization of methyl methacrylate (MMA) and styrene in presence of this compound led to the formation of α, ω‐phosphorylated PMMA and polystyrene. The kinetics of polymerizations of MMA and styrene using this iniferter was studied at 70°C and the different parameters, related to initiation, chain transfer, and primary radical termination reactions, were evaluated. In the case of styrene the extent of primary radical termination was considerably less and mutual termination reactions were found to be absent. The telomers were analysed for their functionality.
Asymmetric induction in the cyclopolymerization of divinyl ethers derived from (R)‐ or (S)‐3,3′‐dimethyl‐1,1′‐bi‐2‐naphthol
Authors: Yokota Kazuaki , Kakuchi Toyoji , Sasaki Hiroshi , Ohmori Hiroshi
Published: April 2003

Optically active divinyl ethers, (−)‐(R)‐ and (+)‐(S)‐2,2′‐bis[2‐(2‐vinyloxyethoxy)ethoxy]‐3,3′‐dimethyl‐1,1′‐binaphthyl [(R)‐1b and (S)‐1b] were polymerized to produce chiral poly(crown ether)s. Their optical rotation was found to be profoundly influenced by the polymerization conditions. When increasing the monomer concentration from 0,1 to 0,3 mol · 1−1, after polymerization with SnCl4 in CH2Cl2 at 0°C, the optical rotation of the resulting polymers is drastically changed from +44,5° to −17,3° for (R)‐1b and from −35,6° to +20,9° for (S)‐1b. The analysis of 1H NMR showed that the polymers have changed their optical rotation due to a configuration which has a tendency to be preferentially racemic diad at higher monomer concentrations in a nonpolar solvent. There are indications that the twist of 2,2′‐binaphtyl moieties, the methyl groups in 3‐, and 3′‐positions as steric barrier, and the intramolecular solvation of the growing carbo‐cation cooperatively control the propagation to induce the asymmetry in the main chain.
New polymer syntheses, 36. Functionalized aromatic polyethers derived from 4′‐substituted 2,6‐difluorobenzophenones
Authors: Kricheldorf Hans R. , Delius Ulrich
Published: April 2003

Toluene, anisol, thioanisol, 4‐phenoxyacetophenone and N,N‐diacetyl‐4‐phenoxyaniline were subjected to a Friedel‐Crafts acylation with 2,6‐difluorobenzoyl chloride. The resulting 4′‐substituted 2,6‐difluorobenzophenones 1a–e were condensed with trimethyl silylated Bis‐phenol‐A (2) to yield homopolyethers with pendant functional groups. A series of copolyethers was analogously prepared by concondensation of 4′‐substituted 2,6‐difluorobenzophenones with a diphenol and 4,4′‐difluorobenzophenone (4a) or bis(4‐fluorophenyl) sulfone (4b), and another series by cocondensation of 2 with mixtures of 4′‐substituted 2,6‐difluorobenzophenones and 2,6‐difluorobenzonitrile (8) or 2,6‐difluoropyridine (9). All polyethers were characterized by inherent viscosities, elemental analyses and DSC‐measurements. In individual cases GPC‐measurements, thermomechanical and thermogravimetric analyses were conducted. The quantitative polymer‐analogous oxidation of methylthio groups into methylsulfinyl and finally into methylsulfonyl groups is demonstrated.
Water‐soluble and photosensitive copolymers from methyl methacrylate and sodium 3‐vinylphenylazosulfonate
Authors: Nuyken Oskar , Voit Brigitte
Published: April 2003

The synthesis of sodium 3‐vinylphenylazosulfonate (4) and its copolymerization with acrylamide and methyl methacrylate (MMA) is described. Copolymers of 4/MMA containing more than 15 mol‐% of 4 are water‐soluble. The trans‐azosulfonate is perfectly stable up to 200°C. However, it decomposes at room temperature after transformation into the cis‐isomer by UV light. This irradiation reaction was used to convert completely water‐soluble copolymers from 4/MMA into water‐insoluble products.
A calorimetric investigation of interactions in aqueous solutions of poly(oxyethylene), 2. Determination of excess heat capacities and application of association theory
Authors: Živný Antonín , Biroš Ján , Pouchlý Julius
Published: April 2003

Excess heat capacities are given as functions of composition and temperature for non‐dilute aqueous solutions of poly(oxyethylene) and its oligomeric models, i. e. from the glycol monomer to tetramer and dimethyl ethers of these compounds. A theoretical model based on the concept of association equilibria was used to predict the excess heat capacities of aqueous mixtures of dimethyl ethers at 298K and 350K. Numerical values of parameters of the model were obtained by treatment of the heats of mixing reported in the first part of this study. It was sufficient to adjust two parameters of self‐association of water, and for each system also the parameter characterizing hydration of ether groups in oligomers. The agreement between theory and experiment was very good for both enthalpy and heat‐capacity data, with the exception of the concentration range rich in water, where the interaction scheme is probably more complicated.
Kinetics of polymer degradation in transient elongational flow
Authors: Nguyen Tuan Q. , Kausch Henning‐H.
Published: April 2003

An expression of the kinetics describing the rate of bond scission under stress is proposed and applied to the case of degradation of polymers in transient elongational flow. The new equation permits to take into account the existence of critical values, either for molecular weight or strainrate, below which no chain scission occurs. Compared with the other types of mechano‐chemical degradation, depolymerization in transient elongational flow is characterized by a short residence time and an inhomogeneous flow field in which the scission rate constants change drastically with the spatial coordinates. The evolution of molecular size distribution during the degradation process has been investigated using a general polymer fragmentation scheme. The set of differential equations was solved exactly with a matrix technique. Excellent concordance between calculations and experimental results from dilute polystyrene solutions was obtained, providing the spatial distribution of the strain‐rate was properly incorporated into the degradation kinetics.
Purification of thermotropic liquid‐crystalline siloxane oligomer with supercritical carbon dioxide
Authors: Krishnamurthy Sushil , Chen Shaw H.
Published: April 2003

The effects of the purification of thermotropic liquid‐crystalline siloxane oligomer with supercritical carbon dioxide were investigated. It was found that low‐molar‐mass contaminants, presumably the two alkene precursors, can be effectively removed at 80°C and carbon dioxide pressures up to 31,0 MPa. In support of this observation is the fact that glass transition temperature goes up as a result of purification. In addition, the selective reflection wavelength was found to increase at increasing purity level, as achieved by extraction at increasing carbon dioxide pressure.
Acid‐ and base‐functionalization of ethylene‐propene rubbers, 3. Mechanical and dynamic‐mechanical characterization of the elastomer networks
Authors: D'Amore Alberto , Greco Pietro , Immirzi Barbara , Laurienzo Paola , Malinconico Mario , Martuscelli Ezio
Published: April 2003

Influences of type and content of functional groups on the mechanical response of various functionalized (grafted) ethylene‐propene rubbers (EPRs) are reported. Grafted molecules include succinic anhydride (SA), monomethyl succinate (MMS) and 2‐(dimethylamino)ethylsuccinimide (DAESI). A semiquantitative correlation between the decrease of the mechanical properties at high grafting degree and degradation of the polyolefinic backbone is given. Also a study of the dynamic‐mechanical properties of the functionalized rubbers is reported. A rubbery plateau is found, the strength and temperature dependence of which is a function of the type and content of the grafted molecules.
A carbonyl‐olefin exchange reaction. New route to conjugated polymers, 4. Chain growth. Side reactions
Authors: Schopov Ivan , Mladenova Lyudmila
Published: April 2003

In order to prove that the carbonyl‐olefin exchange reaction (COER) is a step reaction, a shorttime experiment was carried out, from which only linear oligomers were obtained. The dimer was identified by comparison with an authentic sample. The polymer can also be obtained starting from the dimer. The polymer retains its reactivity. Treated with WCl6 alone or in the presence of the corresponding monomer it yields products of increased molecular weight. The reaction takes place even in the presence of its low‐molecular‐weight by‐product benzophenone. Treatment of the polymer with benzophenone and WCl6 leads to a molecular weight increase. These results prove that the COER proceeds as a non‐equilibrium polycondensation.
Carboxymethyl‐histaminocarbonylmethylamylose as a mimetic system of chymotrypsin in the catalytic hydrolysis of esters
Authors: Hui Yongzheng , Zou Wei
Published: April 2003

A new type of polysaccharide host, carboxymethyl‐histaminocarbonylmethylamylose (2b), containing carboxylic, imidazolyl and hydroxyl groups in the backbone, was used as a mimetic system for chymotrypsin in the catalytic hydrolysis of 3‐acetoxy‐N‐dodecylpyridinium iodide (1). The substrate is located in the hydrophobic cavity of the amylose helix. The apparent saturation, the entropy‐favored kinetics and the pronounced catalytic efficiency (9 times higher than that of a system consisting of the same concentration of carboxymethylamylose and histamine) show that 2b is a good enzyme model in which the definite binding site, active center and self‐organization characteristics are present. Most distinctly, the pH‐rate constant profile of the hydrolysis of 1 and 2b is of bell‐type and has an optimum at pH 7,98, which is very close to 7,90 for chymotrypsin. In conclusion, the charge relay mechanism is also involved in the catalytic effect of 2b.
Polymers with carbazolylalkyl groups and their charge transfer complexes with 2,5‐cyclohexadien‐1,4‐diylidenedimalononitrile (TCNQ)
Authors: Simionescu Cristofor I. , Grigoras Mircea , David Geta
Published: April 2003

Four novel acrylic and methacrylic monomers (8b, c and 9b, c) containing carbazolylalkyl groups, their corresponding polymers and low‐molecular‐weight model compounds (7b, c) were synthesized. The charge transfer complexes of the synthesized polymers with 2,5‐cyclohexadien‐1,4‐diylidenedimalononitrile were prepared and characterized by UV‐vis spectroscopy. The ionisation potentials and complexation constants were determined. It could be shown that increasing spacer length favours the interaction between donor and acceptor. Polymethacrylates with 3 methylene groups in the spacer show the highest complexation constants.
Direct copolymerization of L‐lactic acid with γ‐butyrolactone in the absence of catalysts
Authors: Fukuzaki Hironobu , Aiba Yoshikazu , Yoshida Masaru , Asano Masaharu , Kumakura Minoru
Published: April 2003

The copolymerization of L‐lactic acid (LA) with γ‐butyrolactone (BL), performed without catalyst at 200°C under nitrogen in order to obtain a relatively low‐molecular‐weight copolymer, proceeds via direct condensation between linear LA and linear 4‐hydroxybutyric acid produced by hydrolysis of the cyclic BL. The copolymers were characterized with respect to the copolymerizability (13C NMR spectroscopy), composition (1H NMR spectroscopy), molecular weight (terminal group analysis and gel permeation chromatography), and crystallinity (differential scanning calorimetry). The copolymerizability of BL is low, e. g., the contents of BL units in the copolymers were found to be 12, 16, and 19 mol‐% for initial BL contents in the monomer feed of 30, 50, and 70 mol‐%, respectively, in which copoly(LA/BL) is composed of blocks of lactyl units separated by single γ‐oxybutyryl unit.
Reactivity of a polyamine macromonomer in radical copolymerization with 2‐hydroxyethyl methacrylate
Authors: Nabeshima Yoshikuni , Tsuruta Teiji
Published: April 2003

A series of copolymerization reactions of polyamine macromonomer 1 having controlled molecular weight with 2‐hydroxyethyl methacrylate (HEMA) were examined, in order to obtain a reliable estimation of the reactivity of the macromonomer in radical copolymerization. The monomer reactivity ratio r2 (HEMA as M2) was estimated to be 0,49 by a newly developed method which is expressed by Eqs. (4) and (5). This method, however, could basically be applied only to the estimation of the r2 value. On the other hand, a novel method for the evaluation of the copolymer composition from the conversion of each monomer using gas chromatography and ultraviolet fourth‐order derivative spectra enabled us to estimate r1 as well as r2. Numerical values obtained for the system macromonomer 1 (M1)/HEMA (M2) amounted to r1 = 0,16 and r2 = 0,48; r1 is much smaller than the reactivity ratio of a low‐molecular‐weight analogue of 1, a fact which indicates that the reactivity of the growing radical with a 1 terminal toward 1 should be remarkably smaller than in case of a low‐molecular‐weight analogue of 1. This may be explained by the presence of the kinetic excluded volume effect.
Mesomorphism — structure relationships in polyesters based on twin p‐oxybenzoate mesogens
Authors: Caretti Daniele , Angeloni Annino S. , Laus Michele , Chiellini Emo , Galli Giancarlo
Published: April 2003

Three homologous series of semiflexible polyesters constituted by twin spaced p‐oxybenzoyl diads were studied with respect to their mesomorphic behaviour as a function of the relative length of the two different spacers [oligo(oxyethylene) and polymethylene] connected in an alternating fashion in the repeating unit. Within each series the oligo(oxyethylene) segment was maintained constant (n = 2, 3, 4), whereas the polymethylene segment varied in steps of one methylene unit from pentamethylene to decamethylene (m = 5 to 10). Indications are gained of how the parity of both ether and hydrocarbon spacers may affect the phase diagrams of the samples. The parity of the oligo(oxyethylene) segments appears in particular very effective in maximizing the orientational correlation between the mesogenic p‐oxybenzoyl diads.
Synthesis and characterization of dextran carboxylates for the specific chemical modification of human hemoglobin
Authors: Sacco Daniel , Prouchayret Florence , Dellacherie Edith
Published: April 2003

The present study deals with the fixing of benzenehexacarboxylate (BHC) on dextran, with the aim of obtaining polyanionic polymers capable of decreasing the oxygen affinity of hemoglobin (Hb) by interacting with its phosphate binding site (allosteric site). The covalent coupling of these polymers onto oxyHb has been investigated for the synthesis of oxygen carriers with low oxygen affinity. This type of covalent conjugate could be of interest in intravascular use. Several steps were necessary to synthesize dextran with linked BHC (DEX‐BHC). In each step, the structure of the modified dextran was determined by means of gel permeation chromatography, 1H and 13C NMR spectroscopy, and low‐angle laser light scattering. The aim was to determine the conditions of the reaction which lead to a minimization of cross‐linking phenomena. The DEX‐BHC obtained (0,27 mmol BHC/g polymer) decreased the oxygen affinity of Hb in the same way as the natural effector, 2,3‐diphosphoglycerate (2,3‐DPG) i.e., by reacting specifically with the amines of the protein allosteric site. This decrease in oxygen affinity was more accentuated after covalent coupling onto oxyHb, which means that the fixing point was probably localized in the 2,3‐DPG binding site.
Enzyme‐analogue built polymers, 26. Enantioselective synthesis of amino acids using polymers possessing chiral cavities obtained by an imprinting procedure with template molecules
Authors: Wulff Günter , Vietmeier Jürgen
Published: April 2003

The asymmetric synthesis of a‐amino acids within chiral cavities of special crosslinked polymers was investigated. Chiral cavities prossessing definite shapes and specific arrangements of the functional groups were obtained by preparation of crosslinked polymers in the presence of suitable templates. Best results with an enantiomeric excess of 36% were obtained by using a polymer which was imprinted by L‐DOPA. The cavities contained a salicylaldehyde and a phenylboronic acid moiety each. L‐Threonine was prepared by reaction of the polymer bound anion of a salicylideneglycine nickel complex with acetaldehyde.
Ring‐opening polymerization of carbohydrate‐derived dialkoxyoxolanes. Approaches to functionalized poly(oxytetramethylene)s
Authors: Thiem Joachim , Strietholt Wilhelm A. , Häring Thomas
Published: April 2003

A series of various cis‐3,4‐diacyloxy‐ and dialkyloxy‐oxolanes (4 to 14) as well as the oxolanes 16 and 17 were prepared. Ring‐opening polymerizations of the dialkyloxy derivatives 4, 6, and 11 using the super‐acids FSO3H and CF3SO3H led to novel functionalized poly[oxy(2,3‐dialkyloxy‐tetramethylene)]s. The reaction parameters were thoroughly studied, and optimum conditions lead to a DPn up to 35. All polyethers were fully assigned by polymer analytical procedures such as GPC, osmometry, 1H NMR spectroscopy and end group determination. In the case of the mixed benzyloxy methyloxy polymer 22, by subsequent hydrogenolysis a component with hydroxy functions was obtained. This procedure features a novel change of functionality in selectively derivatized polyethers originally derived from regrowing carbohydrate material.
Solvent effects on chain structure and conformation of poly(amic acids) and their crystallosolvate formation
Authors: Chu Ning‐Jo , Huang Jiann‐Wen , Chang C. H. , Whang W. T.
Published: April 2003

Poly(amic acids) (PAAs) were prepared from pyromellitic dianhydride (PMDA) and diamines such as 2,2′‐difluoro‐, 3,3′‐difluoro‐ and 2,2′‐dichloro‐4,4′‐methylenedianiline. These PAAs form liquid crystals in N‐methyl‐2‐pyrrolidone (NMP) solution, in addition to the PMDA/4,4′‐methylenedianiline (MDA) system reported previously. NMP was the only solvent in which liquid crystals were formed. The “liquid crystal” was shown to be a polymer crystallosolvate (PCS) of PAA and NMP. 1H NMR spectroscopy revealed that PAAs derived from PMDA contain isophthalamide and terephthalamide repeating units in nearly equal proportion, which varies slightly between samples prepared in NMP and dimethylacetamide (DMAc). WAXS showed that the PAA from PMDA/MDA is non‐crystalline but forms a liquid crystalline state in NMP solution. The rate of crystallization is, however, vastly different between samples prepared in different solvents. This was attributed to their difference in chain conformation, which has to be an extended one for PCS formation. The morphologies of PCS are given, and limitations in PCS formation are discussed in terms of PAA structure and solvent.
Thermal polymerization of bis(trihalophenoxo)copper(II) complexes in excess dimethylformamide and dimethyl sulfoxide as ligands
Authors: Kisakürek Duygu , Sanli Oya
Published: April 2003

Thermal decomposition of bis(trihalophenoxo)copper(II) complexes was achieved at 50°C in dimethylformamide or dimethyl sulfoxide. The resulting polymers, poly(oxydihalophenylene)s (2), were characterized by FTIR, 1H NMR and 13C NMR spectroscopy and by differential scanning calorimetry. The molecular weights were determined by the vapour pressure method. Tribrominated phenol derivatives prefer 1,4‐substitution, whereas with trichlorophenol derivatives 1,2‐and 1,4‐substitutions take place at equal rates in either solvent.
Reactivities of 4‐trimethylsilylmethylstyrene and 4‐bis(trimethylsilyl)methylstyrene
Authors: Nagasaki Yukio , Tsuruta Teiji , Hirano Tsuneo
Published: April 2003

4‐Trimethylsilylmethylstyrene (1), and 4‐bis(trimethylsilyl)methylstyrene (2) were synthesized and polymerized. The reactivities of 1 and 2 in free radical and nucleophilic reactions are discussed, referring to 1H NMR and UV spectral data. The absolute values of the negative e‐ values were found to be higher than those of styrene and other styrene derivatives such as 4‐methylstyrene. The reactivities of these monomers toward nucleophilic reagents are lower than those of other styrenes. From these investigations it was concluded that the trimethylsilylmethyl group, located at 4‐position of vinylbenzene, exhibits an electron donating effect. As anticipated, the effect of the bis(trimethylsilyl)methyl group is larger than that of the trimethylsilylmethyl group. AM1 calculations showed that the effect is attributable to the σ‐π‐hyperconjugation between the SiC σ‐bond and the π‐electron system of the phenyl ring. The larger effect of 2 as compared with 1 may be explained by additional σ‐π‐hyperconjugation between the second CSi bond in horizontal position and the phenyl π‐orbital in addition to the σ‐π‐hyperconjugation of the first CSi bond in vertical position.
Synthesis and oligomerization of a paramagnetic monomer
Authors: Seidemann Rolf
Published: April 2003

The synthesis of the paramagnetic amino acid ester 19, starting from 2,2,6,6‐tetramethyl‐4‐oxopiperidine (8) via eight reaction steps was optimized. Saponification, disilylation and phosgenation were performed to obtain the new radical monomer 3‐(2,5‐dioxo‐1,3‐oxazolidine‐4‐ylmethyl)‐2,2,5,5‐tetramethyl‐3‐pyrrolin‐1‐yloxyl (7), which was oligomerized without destroying the paramagnetic centre. These stable oligospins may have interesting magnetic properties.
Polymeric prodrugs, 6. Synthesis and examination of 6‐purinethiol bound to poly(1‐vinyl‐2‐pyrrolidone‐co‐maleic acid)
Authors: Móra Melinda , Pató János , Tüdős Ferenc
Published: April 2003

A low‐molecular‐weight disulfide derivative of the antileukemic agent 6‐purinethiol (2) was used for coupling with a macromolecular carrier, poly(1‐vinyl‐2‐pyrrolidone‐co‐maleic acid) via spacer groups. The in vitro hydrolytic stabilities of the polymeric prodrugs were examined at pH 7,2 and 8,8. An enhanced cleavage of the disulfide bridge yielding 6‐purinethiol was observed. Enzymatic hydrolysis of the prodrug containing an enzyme‐sensitive spacer was also done in the presence of elastase.
Synthesis and characterization of copolymers from acrylamide and methacrylamide carrying peptide side chains
Authors: Boulahia Jalel , Carrière François , Sekiguchi Hikaru
Published: April 2003

N‐Benzylacrylamide (1) and N‐(3‐aminopropyl)methacrylamide hydrochloride (2) were copolymerized to give poly[N‐benzylacrylamide‐co‐N‐(3‐aminopropyl)methacrylamide hydrochloride] (3). The reactivity ratios r1 and r2 were found to be r1 = 0,87 and r2 = 0,66 in which r1r2 < 1 indicate a statistical copolymer composition. Dehydrochlorination of the copolymer liberated primary amino groups to which peptide chains were grafted by reaction with L‐alanine‐NCA. The solubility of the resulting graft copolymers (6) in trifluoroacetic acid allowed the characterization of the products both by NMR and polarimetry. These methods and IR spectroscopy showed that the primary amino groups have only partially participated in initiating the NCA polymerization. The length of grafted peptide chains was found to be always higher than the one calculated from the ratio [NCA]/[NH2].
Preparation of ABCBA‐type block copolymers by use of macro‐initiators containing peroxy and azo groups
Authors: Hazer Baki , Ayas Alipaşa , Beşirli Necati , Saltek Necdet , Baysal Bahattin M.
Published: April 2003

Some new macroinitiators (5) containing azo and peroxy groups were synthesized by transformation of esters of poly(ethylene glycol) (1) (PEG) of different molecular weight with hydroxyl end groups and an azo group in the middle into the corresponding polymers with tert‐butylperoxycarbonyl end groups by reaction with terephthaloyl chloride and subsequently with tert‐butyl hydroporoxide. Decomposition in the presence of styrene at 60°C or with 3,6,9‐triazaun‐decane‐1,11‐diamine in presence of methyl methacrylate gave the corresponding ABA block copolymer 6 and the ABBA block copolymer 7, respectively. Both block copolymers were used as polymeric initiators. The ABCBA block copolymer 8 was synthesized from 6 and methyl methacrylate or from 7 and styrene by thermally induced polymerization at 80°C. The resulting block copolymers were separated from the homopolymers by selective solvent extraction and characterized by spectroscopic and fractional precipitation methods.
Supported propene polymerization catalysts, 2. Supports derived from dialkylmagnesium/dibutyl butylphosphonate complexes
Authors: Karayannis Nicholas M. , Skryantz John S. , Johnson Bryce V. , Hoppin Charles R. , Khelghatian Habet M.
Published: April 2003

Following the earlier development of highly active supported propene polymerization catalysts prepared by activating supports derived from Mg dialkyl complexes with the rare and very expensive ethyl esters of 2,6‐dimethyl‐ (1) or 2,4,6‐trimethylbenzoic acid (2), research was undertaken to uncover low‐cost and commercially available substitutes for 1 and 2. Several phosphonate, phosphate, and phosphite alkyl esters, as well as ethers and amines, were investigated. Dibutyl butylphosphonate (5b) adducts with Mg dialkyl were found to produce catalysts with comparable activity, improved, narrower particle size distribution, and only slightly lower stereospecificity and polymer powder bulk density relative to catalysts made using MgR2 adducts with 1 or 2 as starting materials (R = n‐C4H9). Optimized catalysts based on MgR2 · 5b adducts, prepared by precipitating the support by reaction of a solution of the adduct with SiCl4 and subsequent activation by treatment of the support with TiCl4 and diisobutyl phthalate in chlorobenzene, realize yields of 16–17 kg polypropylene/g catalyst in 2‐h hexane slurry polymerizations at 70°C, 10,2 atm, with 1,2–1,5 wt.‐% boiling hexane extractables and 0,40–0,41 g/ml polymer powder bulk density. The cocatalyst‐external modifier package used consists of Al(C2H5)3‐dimethoxydiphenylsilane. The narrow particle size distribution of the polymer powder produced renders the new catalysts suitable for use in both slurry and solventless propene polymerization processes, while the low cost and ready availability of 5b make the catalyst preparation commercially feasible.
Polyimides based on poly(2,5‐furandiylmethylene), 1
Authors: Patel Hasmukh S. , Lad Babu D.
Published: April 2003

Polyimides were prepared by Diels‐Alder (DA) reaction of furfuryl alcohol (FA) resin [poly(2,5‐furandiylmethylene)] with the bis(maleimides) N,N′‐hexamethylenebis(maleimide) and N,N′‐1,4‐phenylenebis(maleimide), respectively. The DA reaction was carried out in tetrahydrofuran as solvent, as well as in bulk, followed by aromatization of tetrahydrophthalimide intermediates in the presence of acetic anhydride. All the polyimides were characterized by elemental analyses, IR spectral studies and thermogravimetry. The results show that polyimides based on FA resin exhibit moderate thermal stability. The results of preliminary tests for glass reinforcement of produced polyimides suggest that laminates with good mechanical strength can be obtained.
Analysis of composition data for copolymers of N‐phenylmaleimide with styrene in terms of various copolymerization models
Authors: Florjańczyk Zbigniew , Krawiec Włodzimierz
Published: April 2003

Composition data for the copolymerization of N‐phenylmaleimide (M) with styrene (S) in toluene at 60°C were obtained and analyzed according to terminal, penultimate and Lowry's model, using a non‐linear least squares optimization routine. Lowry's mechanism involving depropagation of a monomeric unit of M, if it is attached to another monomeric unit of M, was found to be the most adequate one to describe the system studied. According to this model the reactivity ratios of the monomers are equal to rS = 0,0066, rM = 0,1615 and the constant for the propagation‐depropagation equilibrium in homoaddition of M is equal to 0,9196 dm3 · mol−1.
Interaction between the amino and carbonyl groups in copoly(2‐dimethylaminoethyl methacrylate/N‐phenylmaleimide)
Authors: Přádný Martin , Lokaj Jan , Novotná Miroslava , Ševčík Stanislav
Published: April 2003

Interactions between the carbonyl and amino groups in copolymers of 2‐dimethylaminoethyl methacrylate with N‐phenylmaleimide are reported. The existence of interactions ensues from potentiometric measurements and UV‐VIS spectra. Interactions in these copolymers result in the formation of energetically very advantageous chromophores, reflected in an intense red colour of the substances obtained.
Solution polymerization of selected polyphosphazenes
Authors: Mujumdar Ashutosh N. , Young Scott G. , Merker Robert L. , Magill Joseph H.
Published: April 2003

Several alkoxy/aryloxy‐substituted phosphazene polymers [P(OR)2  N]n, where R = C6H5, CH2CF3, C8H10, were prepared by the reaction of polydichlorophosphazene with their corresponding sodium salts. The polydichlorophosphazene was obtained by the solution polymerization of hexachlorocyclotriphosphazene in 1,2,4‐trichlorobenzene. Sulfamic acid and ammonium sulfamate were used as catalysts. Apparently, sulfamic acid functions as a catalyst through its acid group in some decomposed form. New catalysts, p‐toluenesulfonic acid and sulfobenzoic aicd, have been developed for this solution polymerization. The polymerization favors a cationic mechanism. A promoter, CaSO4·2H2O, was found to speed up the polymerization reaction. Effect of several parameters such as dilution, catalyst concentration, and promoter concentration on the properties of the final polymer were investigated. The polymers were characterized by differential scanning calorimetry, gel permeation chromatography, and 31P solution NMR spectroscopy.
Synthèse de composé photoréticulables, 9. Modification du polybutadiène carboxytéléchélique par des monomères acryliques
Authors: Boutevin Bernard , Fleury Etienne , Parisi Jean‐Pierre , Piétrasanta Yves
Published: April 2003

The addition of mercaptoacetic acid upon radical initiation onto carboxytelechelic polybutadienes (1) which have an average mass M̄n = 4400 gives polyacids having about twelve carboxylic groups. The reaction is followed by 13C NMR, 1H NMR and by GPC. The thiol disappears according to a first order law. Besides, the value of the modification rate obtained from acido‐basic titration confirms that obtained from NMR. In a second step, 2,3‐epoxypropyl methacrylate is added to the acid groups to obtain an insaturated and carboxylated polydienic oligomer 5. An application of these oligomers processed with a reactive diluter shows their high cross‐linking ability under UV irradiation and confirms the improvement of the flexibility properties compared to those of traditional insaturated oligomers.
Synthesis of a polydimethylsiloxane macromonomer and its copolymerization with ethylene
Authors: Li Weidong , Huang Baotong
Published: April 2003

An allyl‐terminated polydimethylsiloxane (PDMS) macromonomer was synthesized by anionic polymerization of hexamethylcyclotrisiloxane (D3) initiated by allyllithium. The molecular weight (MW) of the macromonomer was consistent with that calculated from the ratio of the monomer consumed to the amount of the initiator used, and the molecular weight distribution (MWD) of the macromonomer was narrow. Graft copolymers with polyethylene backbone and uniform PDMS grafts, PE‐g‐PDMS, were prepared by copolymerization of the macromonomer with ethylene using VOCl3/Et2AlCl as the catalyst. Under the copolymerization conditions, the scission of SiOSi bonds by the catalyst is negligible, so that MW and MWD of the PDMS grafts could be considered to be the same as those of the original PDMS macromonomer.
Synthesis of biodegradable poly(L‐lactic acid‐co‐D,L‐mandelic acid) with relatively low molecular weight
Authors: Fukuzaki Hironobu , Aiba Yoshikazu , Yoshida Masaru , Asano Masaharu , Kumakura Minoru
Published: April 2003

A homopolymer of L‐lactic acid (LA), which was synthesized by direct polycondensation in the absence of a catalyst at 200°C, is crystalline, in contrast to the homopolymer of D,L‐mandelic acid (MA) which is amorphous. Poly(LA‐co‐MA), obtained under the above conditions, is amorphous over a wide range of composition from 15 to 100 mol‐% of monomeric units of MA. The in vitro degradation mechanism of these homopolymers shows a parabola‐type degradation pattern for poly(LA) and no degradation throughout an experimental period of 15 weeks for poly(MA). In poly(LA‐co‐MA) the degradation mechanism leads to a typical S‐type degradation pattern, which may be divided into two processes, initial swelling at the surface of the matrix without degradation (induction period), followed by the erosion of oligomers produced by degradation of the main chain in the swollen state.
Membrane from a graft copolymer of butyl methacrylate with the macromonomer 2‐(N‐methyl‐N‐4‐vinylphenethylamino)‐ethylaminopoly[N5‐(ω‐hydroxyalkyl)‐L‐glutamine]. Effect of conformation of the polypeptide branch on the permeability of phenyl‐1,2‐ethanediol across the membrane
Authors: Ishiyama Naoko , Chung Dae‐won , Maeda Mizuo , Inoue Shohei
Published: April 2003

Graft copolymers composed of monomeric units of hydrophobic butyl methacrylate and those of the hydrophilic, non‐ionizable macromonomer 2‐(N‐methyl‐N‐4‐vinylphenethylamino)ethylaminopoly[N5‐(2‐hydroxyethyl) or (3‐hydroxypropyl)‐L‐glutamine] (4a or 4b) were synthesized. The permeability of phenyl‐1,2‐ethanediol across the membranes prepared from these copolymers was found to be affected by the conformation of the poly[N5‐(ω‐hydroxyalkyl)‐L‐glutamine] branch which depends on its chain length and the hydrophobicity of the solvent (water or water/methanol mixture).
Polymeric chiral crown ethers, 5. Synthesis of polymers by cyclopolymerization of divinyl ethers containing moieties deriving from L‐tartaric acid, and the chiral recognition toward amino acids
Authors: Kakuchi Toyoji , Takaoka Tohru , Yokota Kazuaki
Published: April 2003

The synthesis of polymers with chiral crown ether units containing moieties deriving from L‐tartaric acid via cyclopolymerization of divinyl ethers was studied. 1,4‐Di‐O‐benzyl‐ and 1,4‐di‐O‐trityl‐2,3‐bis{O‐[2‐(2‐vinyloxyethoxy)ethyl]}‐L‐threitol (1a and 1b) were polymerized with cationic catalysts to produce polymers (2a and 2b) consisting of only cyclic constitutional units. The trityl groups in polymer 2b were easily cleaved by hydrogen chloride to form a water‐soluble, chiral polymer. Polymer 2b was found to complex predominantly with the L‐enantiomer of ester salts of phenylglycine, phenylalanine, valine, and methionine in the same way as a chiral polymer incorporating 1,3:4,6‐di‐O‐benzylidene‐D‐mannitol moieties.