bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface acidic sites on supported titanium‐magnesium catalyst for propylene polymerization: ESR study via adsorption of stable nitroxyl radicals
Authors: Potapov Alexandr G. , Zakharov Vladimir A. , Mikenas Tatijana B. , Sergeev Sergeyi A. , Volodin Alexandr M.
Published: April 2003

ESR was used for studying the interaction between the stable nitroxyl radical TEMPO (2,2,6,6‐tetramethylpyperidin‐1‐oxyl) and the titanium‐magnesium catalysts TiCl4/MgCl2 and TiCl4/MgCl2 · nD (D is either diisobutyl phthalate or 2,2‐diisobutyl‐1,3‐dimethoxypropane), as well as TiCl4/MgCl2 · nD treated with triethylaluminium. In all cases, only part of the surface titanium complexes (18–53 mol‐%) exhibit Lewis acid properties and can interact with TEMPO. The portion of titanium complexes with acidic properties depends on the composition and preparation of the catalysts, and it decreases upon treatment with triethylaluminium.
Liquid crystalline networks from 1,4‐benzenedicarboxylic acid bis(4‐cyanatomethylphenyl) ester
Authors: Shiota Atsushi , Körner Hilmar , Ober Christopher K.
Published: April 2003

The phase behaviour and curing reaction of 1,4‐benzenedicarboxylic acid bis(4‐cyanatomethylphenyl) ester (LC dicyanate) as well as the mechanical properties of the LC network were examined. The overall reaction kinetics were found to be first order with an activation energy of 67.5 kJ/mol similar to many conventional dicyanate monomers. Gelation was detected by viscoelastic measurements and occurred at a conversion of ≈0.5. These results suggest that the topology of the network formed in the LC dicyanate system was the same as non‐LC dicyanates such as 2,2‐bis(cyanatophenyl)propane. The onset of the mesophase was found to start at a conversion of ≈0.06 and end at a conversion of ≈0.20, independent of the curing temperature (180–280°C). This observation indicates that small clusters comprising a small oligomer (mainly trimer) surrounded by 6–7 monomers dominate formation of the mesophase which possesses a clearing temperature above at least 280°C. Competition between liquid crystalline order and high crosslink density resulted in a large free volume in the glassy state. This large free volume strongly affects mechanical behavior as well as the glass transition temperature of the LC network.
UV/VIS and NMR spectroscopic studies on the structure of cationically polymerized cyclopentadiene on the surface of silica particles
Authors: Spange Stefan , Langhammer Elke
Published: April 2003

The cationic polymerization of cyclopentadiene (CPD) in the presence of silica gel particles is initiated by triphenylmethyl chloride, triphenylmethyl bromide, and methyl triflate in 1,2‐dichloroethane. The suspension polymerization yields soluble colourless polycyclopentadiene (PCPD) and intensively blue coloured silica particles (PCPD+ silica). The formation of the polymer structure on the silica surface in suspension is followed by transmission UV/VIS spectroscopy and solution (1H and 13C) NMR spectroscopy. The structure of the novel solid materials (PCPD modified silica particles) is additionally investigated by DRIFT spectroscopy, solid‐state 13C CP/MAS NMR spectroscopy and scanning electron microscopy (SEM).

The blue colour of the PCPD+ silica particles is caused by polyenylium sequences with five or six conjugated double bonds along the isomerized PCPD chains. The PCPD+ structures are compared with similar ionic model compounds derived from retinol and retinal, respectively. The remaining of the PCPD layer including the conjugated sequences on the surface is attributed to the formation of covalent SiOC bonds. Model reactions of the cationically active PCPD+ silica particles with benzyltriethylammonium chloride and hexachloroantimonate, as well as charge transfer complex formation of the PCPD polymer layer with carbenium salts, (C6H5)3C+AsF and C7HBF, are also investigated. A possible mechanism for the formation of crosslinked PCPD layers on the silica surface is suggested.
Cyclopolymerization, 24. Cyclopolymerizability of an unconjugated triene with functional groups with no homopolymerization tendency: Radical polymerizations of N,N‐diallyl‐2‐(methoxy‐carbonyl)allylamine
Authors: Kodaira Toshiyuki , Liu Qing‐Qing , Urushisaki Michio
Published: April 2003

N,N‐Diallyl‐2‐(methoxycarbonyl)allylamine (1a), a trifunctional compound with functional groups of low homopolymerizability, was synthesized and its radical cyclopolymerizability was investigated. Monomer 1a was polymerized to yield high molecular weight polymers with a considerably high polymerization rate; the degree of cyclization (DC) of poly(1a) was about 55%, irrespective of the polymerization conditions, while bifunctional compounds with functional groups of low homopolymerizability have been known to yield highly cyclized polymers. Pendant unsaturations detected in poly(1a) were found to consist almost exclusively of allyl groups. The acryloyl groups and one of the allyl groups of 1a can be regarded as one functional group in a pair with high polymerizability, since N‐allyl‐N‐propyl‐2‐(methoxycarbonyl)allylamine which has the structure of 1a with one of its allyl groups saturated has been known to yield linear polymers with a DC of 100%. This consideration indicates that 1a has similar cyclopolymerizability to unsymmetrical bifunctional monomers the functional groups of which have high and low homopolymerizability. This is the reason why 1a has low cyclopolymerizability, since such unsymmetrical bifunctional monomers have generally low cyclopolymerizability. The high polymerization tendency of 1a is attributed to the high conjugative nature of the acryloyl group as proven by 13C NMR.
Synthesis of molecularly uniform model oligomers for 1,5‐naphthalene diisocyanate and 1,4‐butanediol based polyurethanes by using the 3,5‐di‐tert‐butylbenzyloxy‐carbonyl protective group
Authors: Festel Gunter , Fischer Karl , Eisenbach Claus D.
Published: April 2003

A modified benzyloxycarbonyl (BOC) protective group, the 3,5‐di‐tert‐butyl substituted BOC (3,5‐tBBOC) group, was introduced to the stepwise synthesis of molecularly uniform oligourethanes based on 1,5‐naphthalene diisocyanate (NDI) and 1,4‐butanediol (BDO) for the protection of the amino functions of the starting material 1,5‐naphthalene‐diamine (NDA). The tert‐butyl substituents of the 3,5‐tBBOC group significantly improved the solubility of the intermediate products in the oligourethane synthesis. Thus, applying this modified protective group, reactions could be carried out, which were not possible with the conventional BOC group, due to the insolubility of the compounds in all suitable solvents. Furthermore, the substituted BOC protective group considerably improved the efficiency of the liquid chromatographical purification of key intermediates of the synthesis route.
LC‐polyimides, 32. Characterization of the Mitsui‐Toatsu LC‐polyimide and related polyimides
Authors: Schwarz Gert , Sun S.‐J. , Kricheldorf Hans R. , Ohta Masahiro , Oikawa Hideaki , Yamaguchi Akihiro
Published: April 2003

Two polyimides were prepared from 1,3‐bis[4′‐(4″‐aminophenoxy)cumyl]benzene and 1,2:4,5‐benzenetetracarboxylic dianhydride (PMDA) or 1,8:4,5‐naphthalenetetracarboxylic dianhydride. A poly(amide‐imide) was prepared from the same diamine and trimellitic anhydride. Furthermore, two polyimides were prepared from 1,4‐bis‐[4′‐(4″‐aminophenoxy)cumyl]benzene or a mixture of the 1,3‐ and 1,4‐diamines. Moreover, one polyimide was synthesized from PMDA and 1,3‐(4‐aminocumyl)benzene. All polyimides were characterized by elemental analyses, optical microscopy, DSC and various X‐ray measurements. Only the polyimide of PMDA and the 1,3‐amine proved to be thermotropic. SAXS and WAXS measurements between 25 and 350°C, along with a fiber pattern suggest that this LC‐polyimide forms a smectic‐A phase in the melt and a disordered smectic‐B phase in the solid state. Also most other polyimides formed a disordered smectic‐B or a smectic‐A glass in the solid state. However, the polyimide derived from 1,3‐(4‐aminocumyl)benzene crystallized in the form of a smectic‐H phase with tilted mesogens. All results together underline the high potential of polyimides of form layer structures.
Shape memory effect of dehydrochlorinated crosslinked poly(vinyl chloride)
Authors: Skákalová Viera , Lukeš Vladimír , Breza Martin
Published: April 2003

Crosslinked poly(vinyl chloride) (CPVC) samples with various extent of dehydrochlorination x, exhibiting a shape memory effect, were prepared. In order to determine the optimal structure for the shape memory effect, electron microscopy, dilatometry, differential thermal analysis (DTA), thermal conductivity and tensile strength measurements were performed. The extremum of all the measured physical properties was found for the sample with x = 12%, corresponding to the optimal structure. The characteristic parameters of the expansion process were calculated from the fits of the experimental data. The extremum was qualitatively predicted by simplified quantum chemical models of a double PVC chain using the semiempirical AMI method. The generalized zip mechanism of CPVC dehydrochlorination might explain the extremum due to mutual chain reorientation with increasing x.
Silver ion‐selective extraction and transport by polystyrene derivatives with pendant ethoxycyclotriphosphazene
Authors: Inoue Kenzo , Ooshita Yuji , Itaya Tomoyuki , Nakahara Hisanori
Published: April 2003

Styrene derivatives with pendant cyclotriphosphazenes carrying ethoxy (1) and ethylene glycol monomethyl ether groups (O(CH2CH2)nCH3:2,n= 1;3,n= 2;4,n= 3) and their (co)polymers were prepared, and the selective binding and transport toward silver picrate by these ligands were examined. The extractabilities toward alkali metal and Ag+picrates are significantly affected by the length of side arms on the phosphazene ring, and1extracted only Ag+ion with a moderate efficiency, forming a 1:11‐Ag+complex. Although all of the homopolymers prepared by radical polymerization extracted almost entirely Ag+ion from the aqueous to the dichloromethane phase, the ratio of extracted amount of Ag+ion to alkali metal ions was in the range of 2.5–30. A significant improvement of the extractability toward Ag+ion was observed for poly(1‐co‐MMA) with 38.4 mol‐% of1(copoly(7)), which extracted Ag+ion with a high efficiency (65%) but has negligibly low ability to extract alkali metal ions. Reflecting this, the competitive transport in the Ag+/Na+and Ag+/K+systems with copoly(7) through liquid membrane showed that the rate of Ag+ion was 60 and 85 times higher than those of Na+and K+ions, respectively. The role of cyclophosphazene units in the selective binding and transport of Ag+ion is discussed.
Lightly crosslinked liquid crystalline epoxy resins: The effect of rigid‐rod length and applied stress on the state of order of the cured thermoset
Authors: Giamberini Marta , Amendola Eugenio , Carfagna Cosimo
Published: April 2003

Lightly crosslinked liquid crystalline epoxy resins were synthesized by reacting rigid rod epoxy‐terminated molecules with decanedioic acid (SA). The obtained networks exhibited a smectic phase even in the case of 2,6‐bis(2,3‐epoxypropoxy)naphthalene, whose aspect ratio is very low. Upon application of uniaxial stress, a smectic phase was surprisingly obtained also for the system obtained by reacting p‐bis(2,3‐epoxypropoxy)‐benzene (QH), whose aspect ratio is practically equal to one, and SA. Stretching of the smectic samples above the glass transition temperature determines orientation of polymer chains, yielding considerably high values of the order parameter S. Thermomechanical analysis showed, for one of these systems, that stretching induces a shift of the isotropization temperature to higher values.
Geometrical structure of star polymers in solution
Authors: Ishizu Koji , Ono Tomohiro , Uchida Satoshi
Published: April 2003

Polyisoprene (PI) stars were prepared by copolymerizing PI‐lithium with divinyl‐benzene (DVB) in heptane. The dilute‐solution properties of these stars (arm numbers f = 43–237) were characterized by static and dynamic light scattering (SLS and QELS), and viscometric measurements. From the results of QELS, it could be concluded that the non‐uniformity of the number of arms in PI starts is relatively narrow due to the organized copolymerization of ω‐functional PI‐lithium with DVB in uniform micelles. The ratio of the radius of gyration over the Stokes radius (RG/RH) in cyclohexane decreases gradually and approaches unity as f becomes large. Even PI stars with multiarms behave not as neat hard spheres but as soft spheres which in good solvents were penetratable near the edges.
Preparation of gradient refractive index rods using methyl methacrylate and benzyl salicylate
Authors: Liu Jui‐Hsiang , Liu Hung‐Tsai
Published: April 2003

A new method for preparing gradient refractive index (GRIN) rods by using the swollen‐gel polymerization technique was elaborated. The polymerization of MMA (methyl methacrylate) with BSA (benzyl salicylate) was carried out in the presence of BPO (benzoyl peroxide) in a PMMA (poly(methyl methacrylate)) tube. The three‐dimensional refractive index profile of plastic rods was estimated. The dependence of optical properties of the GRIN rod on swelling time, swelling temperature, polymerization temperature and MMA/BSA feed ratio were investigated. Image transmission without distortion is observed through the GRIN rods fabricated in this investigation.
Lamellar diblock copolymers under large amplitude oscillatory shear flow: Order and dynamics
Authors: Wiesner Ulrich
Published: April 2003

A survey is given on the effects of large amplitude oscillatory shear (LAOS) flow on the orientation behavior of lamellar polystyrene‐block‐polyisoprene (PS‐b‐PI) diblock copolymers with emphasis on the identification of key parameters that govern the observed behavior. For LAOS at temperatures close to the order‐disorder transition temperature, TODT, three orientation regimes related to the dynamic shear viscosity of the polymers are observed: parallel orientation at high frequencies, perpendicular orientation at intermediate frequencies, and parallel orientation again at very low shear frequencies. In annealing experiments it is found that the low frequency orientation behavior depends strongly on the thermal history of the samples. In conceptually new “dual frequency” experiments the effect of the superposition of two deformation components with frequencies in two different orientation regimes is described. From further studies identifying strain as the control parameter in these nonequilibrium experiments an orientation diagram for the long time orientation behavior of lamellar PS‐b‐PI diblock copolymers is constructed as a function of strain and frequency. For intermediate time scales in the experiments it is shown that the third orthogonal orientation component, the transverse orientation, can be obtained as a transient state. For all orientation components possible orientation mechanisms are discussed.
Anionic homo‐ and block copolymerization of vinylferrocene
Authors: Nuyken Oskar , Burkhardt Volker , Hübsch Christian
Published: April 2003

Vinylferrocene was polymerized by means of anionic initiators such as n‐BuLi, s‐BuLi and distyryl disodium in tetrahydrofuran as solvent. In all cases the polymerization shows the characteristics of a living polymerization. Depending on the sequence of the monomer addition, either block copolymers of the ABA or the AB type were synthesized.
Functionality type analysis of carboxy‐terminated oligostyrenes by gradient high performance liquid chromatography
Authors: Braun Dietrich , Henze Inka , Pasch Harald
Published: April 2003

Carboxy‐terminated oligostyrenes, prepared by radical polymerization using a dicarboxy‐functional initiator, can efficiently be separated by gradient high performance liquid chromatography (HPLC). On a normal phase chromatographic system, comprising a silica gel stationary phase and a tetrahydrofuran‐hexane eluent, elution occurs in the order of increasing polarity of the oligomers and separation into non‐, mono‐, and dicarboxy oligomer fractions is obtained. The chemical structure of the different functionality fractions is determined by matrix assisted laser desorption/ionization mass spectrometry (MALDI‐MS). The results indicate that further functionality fractions in addition to the carboxy oligomers are formed, due to contamination of the initiator or side reactions during the polymerization process.
Anionic ring‐opening polymerization of cyclodisilazanes, 3. Influence of the silicon substituent on the kinetics of polymerization
Authors: Cazalis Chrystelle , Mingotaud Anne‐Françoise , Soum Alain
Published: April 2003

The kinetics of the anionic ring‐opening polymerization of several cyclodisilazanes substituted with different groups on silicon atoms has been investigated in toluene/tetrahydrofuran (THF) using benzyllithium as initiator. Two different behaviours were observed: for hindered substituents (phenyl or allyl), the polymerization is not living; for less hindered groups, the polymerization is living but the rate constants differ markedly from one cyclodisilazane to another. They vary from 9 × 10−4 L · mol−1 · s−1 for DNMeEtDNMe 3 to 0,1 L · mol−1 · s−1 for DDNMe (8). These variations show that the presence of vinyl groups on the monomers tremendously increases the rate of polymerization. In order to discriminate the monomer reactivity from the active center reactivity, a model reaction between lithium silylamides and triethylchlorosilane has been kinetically studied (each lithium silylamide was chosen to modelize one particular active center). Contrary to the corresponding monomers, the less hindered is the silylamide, the faster is the reaction. Thus, the difference of reactivity between the monomers and the reactive center models is so high that the polymerization of cyclodisilazanes can be considered as principally controlled by the reactivity of the monomers.
Propagation rate coefficients in free‐radical homopolymerizations of butyl methacrylate and dodecyl methacrylate
Authors: Buback Michael , Geers Ute , Kurz Caroline H. , Heyne Joachim
Published: April 2003

Propagation rate coefficients (kp) for the homopolymerizations of butyl methacrylate (BMA) and dodecyl methacrylate (DMA) were determined by the pulsed laser polymerization (PLP)/size‐exclusion chromatography (SEC) technique. At amibient pressure, the polymerizations of BMA and DMA were studied between −20 and 50°C and between 9 and 60 °C, respectively. For DMA the pressure dependence of propagation rate has been measured up to 1500 bar. The propagation rate coefficients of three major methacrylates (MMA, BMA, DMA) are available over an extended pressure and temperature range. The kp data at identical pressure p and temperature T are close to each other and exhibit a very pronounced family‐type behaviour with respect to both pressure and temperature dependence. The uncertainty of experimental data is estimated to be ± 10 per cent. The imperfect knowledge of the Mark‐Houwink coefficients may give rise to an increased error for the BMA and DMA data which should, however, stay below ± 20 per cent.
Synthesis and controlled release behaviour of dextran bioactive esters by direct reaction of dextran with the potassium salts of bioactive carboxylic acids
Authors: Macias Antonio , Sánchez‐Chaves Manuel , Rodríguez José Luis , Arranz Félix
Published: April 2003

This work deals with the coupling of model bioactive carboxylic acids (1‐naphthylacetic acid, 2‐(6‐methoxy‐2‐naphthyl)propionic acid (naproxen) and nicotinic acid) to dextran by direct reaction with their potassium salts using pyridine/sulfonyl chloride as activating agent. The structure of the resulting polymeric derivatives was determined by means of 1H and 13C NMR spectroscopy. The influence of the pyridine concentration, the type of sulfonyl chloride and the temperature on the reaction of dextran with potassium 1‐naphthyl acetate was evaluated. The activation energy was found to be 65,7 kJ/mol. 13C NMR spectra at 75,4 MHz of partially modified dextran with 1‐naphthyl acetate groups were studied in order to evaluate the selectivity of the reaction between dextran and potassium 1‐naphthyl acetate. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of the individual hydroxyl groups decreases in the order C2 > C4 > C3. The hydrolysis in the heterogeneous phase of some dextran polymers partially modified with 1‐naphthyl acetate groups shows that the release of the bioactive compound is dependent on the hydrophilic character of the polymer as well as the pH value of the medium.
EXAFS study of supported TiCl4/MgCl2 catalyst
Authors: Potapov Alexandr G. , Kriventsov Vladimir V. , Kochubey Dmitrii I. , Bukatov Gennadii D. , Zakharov Vladimir A.
Published: April 2003

Extended X‐ray absorption fine structure analysis (EXAFS) has been used to study supported TiCl4/MgCl2 catalysts containing 1.8 wt.‐% Ti. Adsorbed TiCl4 was found to exist on the MgCl2 surface as a dimeric complex. The possible structures of dimeric TiCl4 complexes on the (100) face of MgCl2 are discussed.
Laser light scattering studies of soluble high performance fluorine‐containing polyimides, 1. Polyimide synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)‐hexafluoropropane dianhydride and 2,2′‐(trifluoromethyl)‐4,4′‐biphenyldiamine
Authors: Kwan Simon Chi Man , Wu Chi , Li Fuming , Savitski Edward P. , Harris Frank W. , Cheng Stephen Z. D.
Published: April 2003

Five fractions of a polyimide synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′‐(trifluoromethyl)‐4,4′‐biphenyldiamine (PFMB) (6FDA/PFMB) in tetrahydrofuran (THF) at 30°C were investigated by a combination of static and dynamic laser light scattering (LLS). The relations of 〈Rh〉 (nm) = 2.38 x 10−2 Mw0.560 and A2 (mol · cm−3 · g−2) = 2.1 × 10−1 Mw−0.43 were established, where Mw, 〈Rh〉 and A2 are weight‐average molecular weight, average hydrodynamic radius and second virial coefficient, respectively. A combination of Mw and the translational diffusion coefficient distribution G(D) leads to a relation of D(cm2/s) = 2.41 × 10−4 M0.564. With this relation, we successfully convert each G(D) into a corresponding molecular weight distribution (MWD). On the basis of the Benoit‐Doty theory, we found that the persistence length and the Flory characteristic ratio C∞ of the 6FDA‐PFMB chain are ∼3.3 nm and ∼40, respectively, indicating that the 6FDA‐PFMB chain is more extended than typical random‐coil chains. On the other hand, the ratio of the radius of gyration to the hydrodynamic radius, i.e., 〈Rg〉/〈Rh〉 ∼ 1.8, together with the values of the exponents (∼0.56) indicate that the 6FDA‐PFMB chain has a coil chain conformation. Therefore, the 6FDA‐PFMB chain has an extended coil conformation in THF at 30°C.
High‐pressure free‐radical copolymerization of ethene and methyl acrylate
Authors: Buback Michael , Dröge Thomas
Published: April 2003

The free‐radical copolymerization of ethene (E) and methyl acrylate (MA) is studied between 220 and 290°C at 2000 bar. The reactions which have been induced thermally are carried out in a continuously operated device at total monomer conversions mostly below 1%. Monomer concentrations are obtained from measured mass fluxes. Copolymer composition is determined via elemental analysis. Reactivity ratio data, rE and rMA, are derived from non‐linear least squares fitting of the monomer mixture and copolymer compositions. rE and rMA, e.g., at 220°C and 2000 bar, are found to be 0,045 ± 0,002 and 5,3 ± 0,2, respectively. The rE and rMA values slightly, but significantly, differ from corresponding data for ethene‐butyl acrylate (BA) and ethene‐2‐ethylhexyl acrylate (EHA) copolymerizations. Toward higher temperature rE increases and the acrylate (MA, BA, EHA) reactivity ratio rA decreases. The temperature dependences of rE and rA can not be distinguished for the three ethene‐acrylate systems. From an experiment at two levels of polymerization pressure, 1500 and 2000 bar, the pressure dependence of rE has been estimated. The available data for rE and rA allow to model monomer concentration vs. polymer composition behavior of free‐radical ethene‐acrylate copolymerizations at technically relevant temperatures and pressures.
Miscibility behavior of syndiotactic and atactic polystyrene
Authors: Ermer Hubert , Thomann Ralf , Kressler Jörg , Brenn Rüdiger , Wünsch Josef
Published: April 2003

Blends of atactic and syndiotactic polystyrene have a single composition dependent glass transition temperature. This does not confirm the miscibility of both polymers, however, unambiguously because there is only a small difference of 10°C in the glass transition temperatures of both neat polymers. Diffusion measurements of syndiotactic polystyrene and deuterated atactic polystyrene using the nuclear reaction D(3He,α)p confirm at least partial miscibility of both components. The average diffusion coefficient at 190°C is 2.3 ± 0.2 × 10−15 cm2/s.
Synthesis and characterization of polymers containing 4‐cyanobiphenyl‐based side groups for nonlinear optical applications, 4. Poly[(4,4‐dimethyl‐2‐vinyl‐5‐oxazolone)‐co‐(methyl methacrylate)]s
Authors: Guichard Bertrand , Noël Claudine , Reyx Danièle , Chevalier Samy , Senet Jean‐Pierre , Kajzar François
Published: April 2003

This paper describes the synthesis, characterization and nonlinear optical properties of a series of side chain copolymers prepared by chemical modification of poly[(4,4‐dimethyl‐2‐vinyl‐5‐oxazolone)‐co‐(methyl methacrylate)]s (P(VDM‐co‐MMA)s) with 4,4′‐disubstituted biphenyl. First, a poly(4,4‐dimethyl‐2‐vinyl‐5‐oxazolone) (PVDM) and four P(VDM‐co‐MMA)s were prepared by free‐radical polymerization. Chemical transformation reactions were then performed on these polymer backbones with 4‐cyano‐4′‐(β‐aminoethoxy)biphenyl. This amine was synthesized according to a novel procedure. The functionalized polymers are isotropic and show glass transition temperatures up to 132°C. They can easily be processed by spin‐coating into thin films of optical quality. These films were oriented by a corona discharge process, and ultraviolet spectroscopic measurements were performed to study the axial ordering kinetics as a function of poling conditions. Second‐order nonlinear optical coefficients (d33 and d31) were measured at a fundamental wavelength of 1064 nm. The ratio d33/d31 was found to be close to 3, as expected for amorphous isotropic polymers. No significant relaxation was observed at ambient conditions in 2 months. Hydrogen bonding between CO‐NH groups of neighboring side chains are felt to contribute to the stability of the second‐order nonlinear optical properties in these PVDM systems.
Rigid maleimide‐alt‐vinylpyridine copolymers with pendant chromophores. Synthesis, characterization and monolayer formation
Authors: Noordegraaf Marina A. , Kuiper Gert Jan , Marcelis Antonius T. M. , Sudhölter Ernst J. R.
Published: April 2003

A new series of rigid polymers was synthesized via radical copolymerization of N‐phenylmaleimides, bearing pendant chromophores, with 4‐vinylpyridine or styrene. Structural characterization was achieved by 1H NMR and 13C NMR spectroscopy, gel permeation chromatography (GPC), elemental analysis and differential scanning calorimetry (DSC). The thermal properties as well as the morphology of the investigated polymers at the air‐water interface appear to be related to their rigidity. In spite of the presence of excellent mesogenic units, the polymers do not exhibit liquid crystalline behaviour. The 4‐vinylpyridine copolymers form stable monolayers at the air‐water interface. The attached chromophores electronically behave as monomers, as shown with in situ UVVIS absorption spectroscopy. Brewster angle microscopy shows a spontaneous aggregation of these polymers into domains on a neutral subphase, whereas on an acidic subphase a more homogeneous monolayer is formed. The monolayers give Z‐type transfer onto hydrophilic quartz. However, the chromophores seem to be oriented randomly at the substrate surface. The styrene copolymers do not form stable monolayers as a result of crystallization at the air‐water interface.
Syntheses and radical polymerizations of methacrylamides derived from optically active amino alcohols
Authors: Koyama Emiko , Sanda Fumio , Endo Takeshi
Published: April 2003

Syntheses and radical polymerizations of methacrylamides derived from optically active amino alcohols were carried out. The monomers were prepared by condensation of optically active amino alcohols and methacrylic acid using 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride (EDC · HCl). Radical polymerizations of the monomers were carried out in the presence of 2,2‐azoisobutyronitrile (AIBN) (3 mol‐%) in methanol and N,N‐dimethylformamide (DMF) as solvents, resulting with good yields in polymers with Mn's in the range 17 800–81 000. The monomer reactivity ratios of N‐(1‐hydroxy‐4‐methyl‐2‐pentyl)methacrylamide (MA‐Lol) and methyl methacrylate (MMA) in the copolymerization were estimated to be 0.50 and 2.38, respectively. The lower reactivity of MA‐Lol in comparison with MMA is similar to common methacrylamide derivatives. The hydrophilicity of the polymers was evaluated by the heat of fusion of water using differential scanning calorimetry (DSC). The determined order poly(MA‐Aol) > poly(MA‐Lol) > poly(MA‐Fol) reflects the bulkiness of the side chains.
Triblock copolymer based thermoplastic elastomeric gels of a large service temperature range: preparation and characterization
Authors: Yu Jian M. , Jérôme Robert , Overbergh Noel , Hammond Phil
Published: April 2003

Poly(methyl methacrylate)‐block‐polybutadiene‐block‐poly(methyl methacrylate) (MBM) triblock copolymers and their hydrogenated counterparts with poly(ethylene‐co‐1,2‐butylene) midblock (MEBM) were swollen by an aliphatic oil of high boiling point which is a selective solvent for the central block. Thermoreversible gels are accordingly formed by both MBM and MEBM copolymers above a critical polymer content (Cr), which depends on the nature of the midblock and not on the copolymer molecular weight, at least in the investigated range. Cr has been found to be 5 wt.‐% for an MBM block copolymer and 2 wt.‐% for MEBM copolymers of various molecular weights. Gels of MEBM triblock copolymers exhibit interesting mechanical properties, such as high elongation at break (up to 870%) and high tensile strength (32 kPa). The most interesting feature of the MEBM gels is an upper service temperature as high as 170°C, thus more than 100°C higher than the value (47°C) reported for gels of an SEBS copolymer (S = polystyrene) of comparable molecular weight (100000) and composition (ca. 30 wt.‐% hard block). The morphology of MEBM gels was studied by scanning electron microscopy (SEM) and found to be cocontinuous in case of a gel containing 20 wt.‐% copolymer.
Multinuclear NMR investigation of methylaluminoxane
Authors: Babushkin Dmitrii E. , Semikolenova Nina V. , Panchenko Valentina N. , Sobolev Anatolii P. , Zakharov Vladimir A. , Talsi Evgenii P.
Published: April 2003

By means of 27Al, 1H, 17O and 13C NMR spectroscopy the structure of the methylaluminoxane (MAO) cocatalyst of Kaminsky‐Sinn catalysts was investigated. We have found that the 27Al NMR resonance line of MAO is extremely broad at room temperature (δ ≈ 60, Δω1/2 50 ± 10 kHz). At elevated temperatures (40–120°C) MAO exhibits an 27Al resonance at δ 110 ± 10, Δω1/2 15–10 kHz, that is, within the range reported for the aluminoxane clusters [(t‐Bu)Al(μ3‐O)]6 and [(t‐Bu)Al(μ3‐O)]9 with cage structures. The 27Al resonance at δ 149–153, usually attributed to MAO, belongs to AlMe3 present in MAO samples. The 17O NMR resonance of MAO at 50°C (δ 67, Δω1/2 1.7 kHz) is within the range typical for three‐coordinate oxo ligands, but it can be attributed only to a minor part of MAO oligomers. It was shown that the intensity of 27Al and 17O NMR resonances of MAO increases with increasing temperature, whereas the width of both resonances is almost constant. The results obtained lead to the conclusion that at ambient conditions MAO forms oligomers (MeAlO)n with cage structure and MeAlO3 environment. Upon increasing the temperature these oligomers reversibly break into smaller MAO units. Based on the 27Al NMR data the average radius (R) of MAO oligomers is approximately 5.1 ± 0.3 Å at 120°C. This radius corresponds to (MeAlO)n species with 9 < n < 14. At ambient conditions the predominant part of MAO forms oligomers with R = 7 ± 0.5 Å and 20 < n < 30.
Polymer complexes of dimethylbenzylalkylammonium chlorides
Authors: Anufrieva Elizaveta V. , Panarin Eugenij F. , Pautov Vladimir D. , Kirpach Andrej B. , Krakovyak Mark G. , Luschik Vanda B. , Solovskij Michael V.
Published: April 2003

The interaction of cationic surfactants from the series of dimethylbenzylalkylammonium chlorides (DMBAAC, alk. = CnH2n+1 (n = 10, 12, 14)) with water‐soluble copolymers of N‐vinyl‐2‐pyrrolidones (VP) with methacrylic, acrylic, and crotonic acids in aqueous and aqueous‐salt solutions was investigated by polarized luminescence. It was established that the main factors determining the stability of water‐soluble DMBAAC complexes with carboxyl‐containing VP copolymers include the composition and structure of the copolymer, the length of the alkyl group of DMBAAC, the ratio of the interacting components, the pH, and the ionic strength of the solution. The equilibrium dissociation constants of these complexes in aqueous solution were determined. Potentiometric titration, turbidimetry, and viscometry showed that the complexation features manifested by the interaction of individual DMBAAC's with carboxyl‐containing VP copolymers are also characteristic of complexation processes occurring with participation of industrial DMBAAC, which is a mixture of individual DMBAAC's.
Synthesis and characterization of ABA‐triblock copolymers with polystyrene and main‐chain liquid crystalline polyester segments
Authors: Reichelt Norbert , Schulze Uwe , Schmidt Hans‐Werner
Published: April 2003

This paper reports on the synthesis and characterization of polystyrene‐block‐poly(2,2′‐dimethyl‐4,4′‐biphenylene phenylterephthalate)‐block‐polystyrene. The ABA‐triblock copolymers were synthesized by condensation reactions of telechelic poly(2,2′‐dimethyl‐4,4′‐biphenylene phenylterephthalate) with anionically prepared ω‐hydroxy polystyrenes. Three different lengths of the liquid‐crystalline polyester (M̄n = 2650, 5 500, 10 100 g/mol) were used as central block B. The number‐average molecular weight M̄n of the polystyrene segments was varied in the range of 690 to 10 000 g/mol. The liquid crystalline behavior and the transition temperatures are discussed with respect to the molecular weight of the polystyrene segments and the block copolymer composition. A comparison with the corresponding polymer blends is given and first results on the morphology of the block copolymers are presented.
Study of the long‐period changes in samples of isotactic poly(propylene) obtained by quenching from the melt and subsequent annealing at different temperatures
Authors: Gerardi Francesco , Piccarolo Stefano , Martorana Antonio , Sapoundjieva Diana
Published: April 2003

The structural modifications induced in samples of isotactic poly(propylene) obtained by quenching from the melt at 100°C/s and subsequently annealed at 40, 60 and 80°C for different annealing times have been studied using simultaneous wide‐angle and small‐angle X‐ray scattering at the synchrotron radiation source of DESY. The occurrance of two different long‐period values is demonstrated. These values are related to the mesomorphic phase, existing in the starting quenched material, and to the α‐monoclinic one, which settles during the annealing process, respectively.
Polymerization of acrylates by atom transfer radical polymerization. Homopolymerization of glycidyl acrylate
Authors: Matyjaszewski Krzysztof , Coca Simion , Jasieczek Christina B.
Published: April 2003

Atom transfer radical polymerization (ATRP) was applied to the homopolymerization of glycidyl acrylate (GA). This functionalized monomer can be polymerized to high conversions and high molecular weights using halogenated initiators and CuBr/4,4′‐bis(5‐nonyl)‐2,2′‐bipyridine (dNbipy) as the catalyst. The polymerizations exhibit first order kinetics and molecular weights increase linearly with conversion. The M̄n of the products is controlled by the ratio Δ[M]0/[I]0. The polymers obtained showed narrow molecular weight distributions, M̄w/M̄n = 1.25.
Synthesis and characterization of metal containing polychloranilamides
Authors: Allmendinger Thomas
Published: April 2003

2,5‐Diamino‐3,6‐dichloro‐1,4‐benzoquinone (chloranilamide) condensates, under generation of HCl, above 300°C to form polychloranilamide. The reaction was studied by thermovolumetric measurements, especially in the presence of different metal salts (cobalt, iron and manganese). The composition of the brittle black polymers is as expected, and the IR spectra resemble to those of the corresponding model compounds based on 5,8‐dihydroxyquinoxaline. Their electrical conductivity is 10−8 – 10−5 S · cm−1. Metal contents of up to 25 wt.‐% were achieved corresponding to 80% of the theoretical value. The metal complexes are not stable against acids, and the compounds are not very resistant in a strongly alkaline milieu. Nevertheless, they could be promising, e.g., as ion exchangers, as precursors for organic materials with high metal contents such as catalysts, or as model compounds for similar polymers.
Catalytic behavior of a silica‐supported polystannazane‐copper complex for the oxidation of methanol to formaldehyde at mild reaction conditions
Authors: Tang Li‐Ming , He Qiang , Huang Mei‐Yu , Jiang Ying‐Yang
Published: April 2003

A very cheap catalyst, a silica‐supported polystannazane‐copper complex (abbreviated as SiO2SnNCu) was prepared by the reaction of the silica‐supported polystannazane ligand with CuCl2 in ethanol. The results showed that SiO2SnNCu can catalyze the oxidation of methanol to formaldehyde in high yield at mild conditions, i.e. at 40°C and 1 atm of oxygen. The catalyst could be recovered and could catalyze the reaction repeatedly.
Synthesis and properties of polyurethanes containing phosphatidylcholine analogues in the polymer backbone
Authors: Yamada Mitsuaki , Li Yujun , Nakaya Tadao
Published: April 2003

New polyurethanes (4a, 4b) and a segmented polyurethane (4c) bearing phosphatidylcholine moieties in the main chain were synthesized. They are thermally stable up to 300°C and show the viscosity behaviour of common polyelectrolytes. Preliminary studies suggest that these polyurethanes are interesting new biomaterials.
On the difference of reactivities of various aggregated forms of aluminium triisopropoxide in initiating ring‐opening polymerizations
Authors: Duda Andrzej , Penczek Stanislaw
Published: April 2003

The polymerization of ε‐caprolactone (εCL) initiated with aluminium triisopropoxide (Al(OiPr)3) trimer (A3) and/or tetramer (A4) was studied. The rate of A3 ⇔︁ A4 interconversions in the diluted (≤0,1 mol · L‐1) C6D6, C6D6/εCL, and THF/εCL solutions were found to be slow, when compared with the rate of propagation. Comparison of the 1H NMR spectra of the initiators with those of the polymerization mixtures revealed that A3 is much more reactive than A4 in their reactions with εCL. From the initiator reacted with εCL all threeOiPr groups from Al(OiPr)3 are transferred into the poly(εCL) as end groups. Kinetic studies of polymerization confirmed the large reactivity difference between A3 and A4.
Structural correlation between the columnar mesophase and the melt in poly(di‐n‐alkylsiloxane)s
Authors: Out Gerardus J. J. , Turetskii Alexei A. , Möller Martin
Published: April 2003

Phase transitions of poly(dialkylsiloxane)s substituted with propyl and butyl groups are reported based on X‐ray diffractometry. The structure in the mesophase and in the melt of polymers with 2 to 10 carbon atoms in each side chain is compared. Both phases display a linear dependence of the molecular cross‐section on the length of the alkyl group demonstrating their structural similarity. By means of differential scanning calorimetry it is shown that the temperature range of the mesophase remains practically unchanged in width as well as in absolute temperature for dibutyl up to dihexyl substituted polysiloxanes.
Copolymerization of ethylene and 1‐butene with highly active TI/MG bimetallic catalysts. Effect of partial activation by Alet2Cl
Authors: Kim Jae Ha , Han Taek Kyu , Choi Hong Ki , Kim Il , Woo Seong Ihl
Published: April 2003

Copolymerization of ethylene and 1‐butene were performed using the catalyst system TiCl3 · 1/3 AlCl3/MgCl2/THF with or without partial activation by AlEt2Cl. The catalyst and the copolymers were characterized by IR spectroscopy. The experimental results reveal that partial activation strongly affects the catalytic sensitivity toward 1‐butene and obviously leads to a two‐step polymerization rate profile.
Fourier‐transform infrared study of the switching process in a ferroelectric liquid crystalline polymer
Authors: Shilov Sergej V. , Okretic Stefano , Siesler Heinz W. , Zentel Rudolf , Öge Tanja
Published: April 2003

The implementation of the step‐scan technique on our FT‐IR spectrometer enabled us to follow the electric‐field induced reorientation dynamics of different molecular segments of a ferroelectric liquid crystalline polymer on a sub‐millisecond time scale. It was detected that not only the mesogen but also the spacer and at least part of the backbone take part in the reorientation process.
Selective salt transport through a crosslinked poly(L‐glutamic acid) membrane for KCl/LiCl mixed systems
Authors: Huh Yang‐Il , Satoh Mitsuru , Komiyama Jiro
Published: April 2003

Selective salt transport of KCl over LiCl has been studied for a crosslinked poly(L‐glutamic acid) membrane immersed in 80 vol.‐% ethanol. The permeabilities (Ps) and solubilities were measured for various mixing ratios of the salts. The highest permselectivity (Ps (KCl)/Ps (LiCl) = 4,3) has been obtained at a LiCl mole fraction of 0,2. It is similar to that obtained in single salt systems.
Semi‐rigid thermotropic liquid‐crystalline copolycarbonates comprising main‐chain hexafluoropentane segments
Authors: Sato Moriyuki , Tada Yuji , Goto Yusuke , Mukaida Ken‐ichi
Published: April 2003

Novel semi‐rigid fluorocarbon‐containing coplycarbonates composed of biphenyl moiety and rigid rod‐like hexafluoropentane chain were prepared by melt polycondensation of 6,6′‐(biphenyl‐4,4′‐diyldioxy)dihexanol (1) and 2,2,3,3,4,4‐hexafluoro‐1,5‐pentanediol (2) with alkylene diphenyl dicarbonates 3 of various aliphatic lengths (m = 6, 8, 10 and 12). The structures of the copolymers 4 were confirmed by FT‐IR, 1H and 13C NMR spectra and elemental analyses. The thermal and liquid‐crystalline (LC) properties were examined by differential scanning calorimetry (DSC), polarizing microscopy and temperature‐changeable X‐ray analyses. These measurements indicated that the copolymers show well‐defined thermotropic nematic textures and have block‐like sequences. It is suggested that the introduction of the hexafluoropentane chain into the main chain gives more stable LC phases.
Structure of chain‐ends in polybutadiene produced with the CoBr2(PPh3)2/MgCl2/SiPh2(OCH3)2‐Al(CH3)3 catalyst system
Authors: Takeuchi Masaki , Shiono Takeshi , Soga Kazuo
Published: April 2003

Polymerization of 1,3‐butadiene with the CoBr2(PPh3)2/MgCl2/SiPh2(OCH3)2‐Al(CH3)3 catalyst system was conducted in the presence of ethylene. It was found that addition of ethylene causes a marked decrease in the molecular weight of polybutadiene although ethylene is not incorporated at the chain‐end. The structure of chain‐ends was analyzed using very low molecular‐weight polybutadiene produced in the presence of ethylene, which led to the conclusion that 1,2 and 2,1 insertion reactions predominate at the initiation and propagation steps, respectively.
Anionic polymerization of β‐lactones initiated with potassium hydride. A convenient route to polyester macromonomers
Authors: Kurcok Piotr , Matuszowicz Andrzej , Jedliński Zbigniew
Published: April 2003

The anionic polymerization of 2‐oxetanone and 4‐methyl‐2‐oxetanone initiated with the potassium hydride/18‐crown‐6 complex was investigated. The α‐proton abstraction of the monomer was found to proceed at the initiation step of this polymerization. The salt of the unsaturated carboxylic acid formed initiates further propagation, leading to functionalized polyesters with unsaturated, dead end‐groups.
Comments on the paper “Living cationic polymerization of styrene monomers” by M.‐L. Yang, K. Li and H. D. H. Stöver
Authors: Matyjaszewski Krzysztof
Published: April 2003

The mechanism of cationic polymerization of styrene monomers leading to well defined polymers proposed by Yang, Li and Stöver is criticized. The growth does not occur on the “colorless nondissociated ion pair” represented as polarized covalent species but includes dynamic equilibration between covalent species and carbocations. In addition, ligand exchange between 1‐phenylethyl bromide and SnCl4 leads to the formation of Lewis acids with much more labile Sn‐halide bonds. The observed colors are due to the generation of side products, presumable indanyl cations, and not to the alleged propagating free ions.
Synthesis of polypropene‐block‐poly(ethylene‐co‐propene) by short‐period polymerization with MgCl2‐supported Ziegler catalyst
Authors: Mori Hideharu , Yamahiro Mikio , Tashino Kunihiko , Ohnishi Kouki , Nitta Koh‐hei , Terano Minoru
Published: April 2003

The short‐period polymerization method was successfully applied to the synthesis of a novel diblock copolymer, polypropene‐block‐poly(ethylene‐co‐propene). The polymerization was carried out for ca. 0,1 s with a MgCl2‐supported Ziegler catalyst. The copolymers obtained showed unimodal curves in gel‐permeation chromatography without any peak in the low‐molecular‐weight region. After extraction with heptane, the fraction of poly(ethylene‐co‐propene) remained unchanged in the copolymer but disappeared in a commercial so‐called block‐type copolymer. All the results the formation of polypropene‐block‐poly(ethylene‐co‐propene), in which poly(ethylene‐co‐propene) is chemically linked with polypropene.
Synthesis of a biodegradable polymeric supramolecular assembly for drug delivery
Authors: Ooya Tooru , Mori Hideharu , Terano Minoru , Yui Nobuhiko
Published: April 2003

A novel design of a biodegradable carrier for drug delivery was established by constructing a supramolecular assembly of drugs and polymer backbones without any covalent bonds. A biodegradable polyrotaxane was synthesized in which α‐cyclodextrins (α‐CDs) as drug carriers were threaded onto poly(ethylene glycol) chains which then were capped at each chain end by L‐phenylalanine via peptide linkages. The release of α‐CDs was observed only when the terminal peptide linkages were degraded.
Regiospecificity of 1‐butene polymerization catalyzed by C2‐symmetric group IV metallocenes
Authors: Busico Vincenzo , Cipullo Roberta , Borriello Anna
Published: April 2003

The regiospecificity of isotactic 1‐butene polymerization promoted by typical C2‐symmetric group IV metallocene catalysts was studied by means of 13C NMR spectroscopy. In particular, the formation of 1,4 monomer enchainments is discussed.
Synthesis of metal‐complexing latices via polymerization in microemulsion
Authors: Antonietti Markus , Lohmann Sabine , Eisenbach Claus D. , Schubert Ulrich S.
Published: April 2003

Microlatex dispersions with ca. 120 m2 bipyridine‐functionalized surface per g polymer were synthesized via copolymerization in microemulsion using two new comonomers containing bipyridine groups. The resulting polymer particles were used for binding diverse metal ions in water as well as in organic solvents. Binding of the ions usually occurs intramolecularly. The colloidal characteristics of the dispersions are preserved.