bluuebunny/crossref_metadata_2025_split huggingface dataset:
The synthesis and characterization of polyesters based on 2,5‐pyridinedicarboxylic acid
Authors: East George C. , Gudiguntla Venu G. R. 
Published: April 2003

AbstractA series of novel polyesters based on 2,5‐pyridinedicarboxylic acid were synthesized using the reaction of the caesium salt of the acid with a variety of dibromo compounds in N‐methyl‐2‐pyrrolidone at 110°C. For the α,ω‐dibromoalkane Br(CH2)mBr series, the efficiency of the polymerization increases as the chain length increases, the highest weight‐average molecular weight of M̄w ≈ 47000 being obtained for the polymer with m = 10. All the polyesters were characterized by means of infrared and nuclear magnetic resonance spectroscopies, as well as elemental analysis. Solubility and thermal properties of these polyesters were determined and compared with their terephthalate analogues. The presence of the 2,5‐pyridinediyl unit improved the solubility behaviour and decreased the thermal stability. Compared to the analogous terephthalates, the polymers showed slightly higher glass transition temperature and lower melting temperature values.
Polymerization of 3,5,5‐trimethyl‐1‐hexene with Ziegler‐Natta catalysts
Authors: Endo Kiyoshi , Fujii Kazuyoshi , Otsu Takayuki 
Published: April 2003

AbstractPolymerization of 3,5,5‐trimethyl‐1‐hexene (TM1H) with TiCI3 and alkylaluminium catalysts was studied. TM1H can be polymerized, but the polymerization rate is quite low due to the bulky substituent of the side chain. During the polymerization of TM1H, the isomerization of TM1H to internal olefins was observed. The overall activation energy for polymerization of TM1H was estimated to be approx. 37 kJ/mol. By adding optically active L‐menthol to the TiCI3‐(i‐C4H9)3AI catalyst, a stereoelective polymerization was induced. Monomer‐isomerization copolymerization of TM1H and trans‐2‐butene took place, giving copolymers consisting of the corresponding 1‐olefin units.
Surface characterizations of copolymer films with pendant monosaccharides
Authors: Nakamae Katsuhiko , Miyata Takashi , Ootsuki Norihito , Okumura Masakazu , Kinomura Keisake 
Published: April 2003

AbstractWe copolymerized a monomer with a pendant glucose unit (GEMA) with methyl methacrylate (MMA) and prepared copolymer films with pendant monosaccharides by casting the copolymer solution on glass plates. The surfaces of the copolymer films were characterized by contact angle measurements, X‐ray photoelectron spectroscopy (XPS) and protein adsorption measurements, and compared with the surface of 2‐hydroxyethyl methacrylate (HEMA)‐MMA copolymer films. The surface free energy of the GEMA‐MMA and HEMA‐MMA copolymer was calculated from the contact angle of methylene diiodide and glycerol on the copolymer films. The surface free energy of the films increased gradually with increasing GEMA or HEMA content. The surface free energy of GEMA‐MMA copolymers was larger than that of HEMA‐MMA copolymers in the whole range of composition. The results of XPS measurements suggest that the fraction of GEMA at the copolymer surface increases as the content of GEMA in the copolymer increases. This indicates that introduction of GEMA makes the copolymer surface more hydrophilic. Further more, the higher the GEMA content is, the smaller amounts of fibrinogen and γ‐globulin are adsorbed at the copolymer surface. The copolymer with a GEMA content of 20 mol‐% hardly adsorbs fibrinogen and γ‐globulin at all.
Study of the miscibility of poly(N‐vinyl‐2‐pyrrolidone) with poly[styrene‐co‐(4‐hydroxystyrene)]
Authors: Zhu K. J. , Liqun Wang , Ji Wang , Shilin Yang 
Published: April 2003

AbstractPoly(N‐vinyl‐2‐pyrrolidone) (PVP) was blended with poly[styrene‐co‐(4‐hydroxytyrene)] (PSH) which was obtained from the random copolymer poly[styrene‐co‐(4‐acetoxystyrene)] (PSA). The miscibility of PVP/PSH blends in a composition 1 : 1 by weight was evaluated by differential scanning calorimetry (DSC), non‐radiative energy transfer (NET) and Fourier transform infrared (FTIR) spectroscopy. It was found that the blends become miscible when the hydroxystyrene units (HS) in PSH exceed 11 mol‐%. The driving force of miscibility may be attributed to hydrogen bonding between OH in PSH and in PVP. The experimental results of miscibility were compared with that estimated from a “miscibility parameter” (MP) concept, and we found that the general trend of MP values is in agreement with the experimental results.
Poly(phthalidylidenearylene)s. Effect of pressure on the conductivity of poly(3,3‐phthalidylidene‐4,4′‐biphenylylene)
Authors: Zolotukhin Mikhail G. , Lachinov Alexey N. 
Published: April 2003

AbstractPoly(3,3‐phthalidylidene‐4,4′‐biphenylylene) (PPB) was considered to be a polymer containing pressure‐sensitive moieties as repeating units in the main chain. The effect of pressure on the properties of PPB was studied. Thin films of the undoped polymer were found to become conductive under slight pressure. The conductivity increases from 10−14 up to 10−3 Ω−1 · cm−1 under a pressure of about 3 · 105 Pa (0,3 kg/cm2). An effective method is used to visualize the pattern of conducting sites. These may be represented by channels (or domains) in the polymer film.
Modifications in the mesogenic unit of poly(oxytetramethyleneoxycarbonyl‐3‐chloro‐1,4‐phenyleneoxyterephthaloyloxy‐2‐chloro‐1,4‐phenylenecarbonyl)
Authors: del Pino Javier , Gómez Marian A. , Ellis Gary , Marco Carlos , Fatou José G. 
Published: April 2003

AbstractThe effect of asymmetrical chlorine substitution in the mesogenic unit of poly(oxytetramethyleneoxycarbonyl‐3‐chloro‐1,4‐phenyleneoxyterephthaloyloxy‐2‐chloro‐1,4‐phenylenecarbonyl) (1) has been studied by means of differential scanning calorimetry, optical microscopy and X‐ray diffraction. The polymer presents three‐dimensional ordering, in spite of the substitution, and shows a transition to a nematic mesophase at 274°C and to the isotropic melt at 319°C. As for the unsubstituted polymer poly(oxytetramethyleneoxycarbonyl‐1,4‐phenyleneoxyterephthaloyloxy‐1,4‐phenylenecarbonyl), two different crystalline forms have been observed and some information about their structure has been obtained by Fourier‐Transform Raman spectroscopy and 13C solid‐state nuclear magnetic resonance. First results indicate that the most important structural differences between both polymorphs occur in the mesogenic unit.
Thermal degradation of polymers of captodative substituted olefins
Authors: Tanaka Hitoshi , Hall Henry K. 
Published: April 2003

AbstractThermal degradations of the polymers of some captodative substituted olefins were studied by means of thermal gravimetry, infrared and electron paramagnetic resonance (EPR) spectroscopy, and evolved gas analysis. It was found that the initial degradation temperature of the homopolymers varies from 166 to 291°C and is correlated to the magnitude of the EPR coupling constant of the β‐hydrogen of the radicals derived from the corresponding captodative olefins. It was also found that poly(methyl α‐methoxyacrylate) depolymerizes to the monomer, while poly(α‐cycanovinyl acetate) eliminates mainly acetic acid to give a polyene.
Synthesis and structural study of an ABA block copolymer consisting of poly(ε‐benzyloxycarbonyl‐L‐lysine) as the a block and poly(ethylene oxide) as the B block
Authors: Cho Chong‐Su , Jo Byung‐Wook , Kwon Joong‐Kuen , Komoto Tadashi 
Published: April 2003

AbstractABA‐type block copolymers composed of poly(ε‐benzyloxycarbonyl‐L‐lysine) (PCLL) as the A component and poly(ethylene oxide) as the B component were synthesized by polymerization of ε‐benzyloxycarbonyl‐L‐lysine N‐carboxyanhydride initiated by primary amino groups located at both ends of the PEO chain. From circular dichroism measurements in solution, as well as from infrared spectra measurements in the solid state, it was found that the polypeptide block exists in the α‐helical conformation, as in PCLL homopolymer. The intensity of wide‐angle X‐ray diffraction patterns of the block copolymers depends on the PEO content and shows basically similar reflections as the PCLL homopolymer. The morphology examined by transmission electron microscopy and differential scanning calorimetry revealed microphase‐separated structure.
Polylactones, 29. Preferentially syndiotactic poly(β‐(R,S)‐butyrolactone) obtained by ring‐opening polymerization with triphenyltin methoxide or diphenyltin dimethoxide
Authors: Kricheldorf Hans R. , Lee Soo‐Ran 
Published: April 2003

AbstractTriphenyltin methoxide (Ph3SnOMe) and diphenyltin dimethoxide (Ph2Sn(OMe)2)‐initiated polymerizations of β‐(R,S)‐butyrolactone were conducted in bulk at 50 and 75°C. The low catalytic reactivity of the initiator prevented lower temperatures. The stereosequences of the isolated poly(β‐(R,S)‐butyrolactones) were analyzed by 13C NMR spectroscopy and characterized by the ratio of isotactic and syndiotactic diads (i/s‐ratios down to 0,4/1,0 were found). With Ph3SnOMe relatively high molecular weights (ηinh = 0,3 dL/g, M̄w ≈ 25 000−30000) were obtained but the stereoselectivity of the polymers obtained with both Ph3SnOMe and Ph2Sn(OMe)2 is not higher than that with Bu3SnOMe (published previously). Selected poly(β‐(R,S)‐butyrolactone) samples were characterized by IR spectra, WAXS powder patterns and DSC measurements.
Copolymers with soft and hard segments based on 2,2‐dimethyltrimethylene carbonate and ε‐caprolactone
Authors: Gerhard‐Abozari Eva , Keul Helmut , Höcker Hartwig 
Published: April 2003

AbstractThermoplastic elastomers with ABA‐block structure, A representing the hard segment and B the soft segment, were prepared by ring‐opening polymerization from 2,2‐dimethyltrimethylene carbonate (DTC, 1) and ε‐caprolactone (ECL, 2) as monomers. Typical anionic initiators, viz. the dilithium salt of hydroxytelechelic poly(ethylene oxide) 200 (4) and of polytetrahydrofuran 1000 (5) and as an insertion initiator the bis(diethylaluminium) salt of triethylene glycol were used. The soft block is formed by a sequence of random (or tapered) structure comprising equimolar amounts of the two monomers and obtained by simultaneous polymerization of DTC and ECL. The hard blocks consist of highly crystalline poly(2,2‐dimethyltrimethylene carbonate) sequences. The thermal properties of the polymers depend on the sequence length, the content of heterodiads in the soft block and the thermal history of the samples. Copolymer films with short end blocks and high content of heterodiads show rubber‐elastic properties at normal conditions.
Soluble polystyrene derivatives of metal bis(3,4‐dicarboxybenzoyl)phthalocyaninates: Synthesis, thermal analysis, and sensitivity towards toxic gases
Authors: Zhou Rongnong , Tang Ligong , Geckeler Kurt E. , Göpel Wolfgang 
Published: April 2003

AbstractPolystyrene‐bound metal [2,9 or 2,10 (or 2,16 or 2,17) bis(3,4‐dicarboxybenzoyl)]phthalocyaninates were synthesized by Friedel‐Crafts reaction of polystyrene with the corresponding metal phthalocyaninates. Co(II) and Cu(II) [2,9 or 2,10 (or 2,16 or 2,17) bis(3,4‐dicarboxybenzoyl)]‐phthalocyaninate (PS‐CodaPc and PS‐CudaPc) contained 0,13 mmol · g−1 (12,4 wt.‐%) and 0,13 mmol · g−1 (12,8 wt.‐%) of CodaPc and CudaPc, respectively. They were soluble in N,N'‐dimethylformamide, but only partially soluble in chloroform, tetrahydrofuran (THF), dimethyl sulfoxide, N‐methyl‐2‐pyrrolidone, and pyridine. The THF extracts contained 0,12 mmol · g−1 (11,4 wt.‐%) and 0,18 mmol − g−1 (17,2 wt.‐%) of PS‐CodaPc and PS‐CudaPc, respectively. The thermal stability of the polymers was studied using thermogravimetric and differential thermal analysis in nitrogen and synthetic air atmosphere. The contents of MdaPc(M: metal) in THF‐extracted polymers calculated from the data of residue in thermogravimetric analysis are 0,12 mmol · g−1 for PS‐CodaPc and 0,19 mmol · g−1 for PS‐CudaPc. In addition, the sensitive properties of the polymers towards toxic gases were also investigated by quartz microbalance transducers. The results show that the quartz microbalance sensors coated with both polymers were sensitive to NO2 and chlorinated hydrocarbons, i.e. chloroform and perchloroethylene. The sensitivity to NO2 was 6,53 · 10−7 m3 · mL−1 · s−1 for PS‐CodaPc and 1,90 · 10−6 m3 · mL−1 · s−1 for PS‐CudaPc, and that to chloroform and perchloroethylene was 2,33 · 10−8 and 4,60 · 10−8 m3 · mL−1 · s−1, respectively, for PS‐CodaPc and 4,79 · 10−8 and 9,51 · 10−7 m3 · mL−1 · s−1 for PS‐CudaPc.
Monomer sequence distributions in the copolymerization of ethylene and 1‐decene
Authors: Peña Begoña , Delgado Juan A. , Pérez Ernesto , Bello Antonio 
Published: April 2003

AbstractFour ethylene‐1‐decene copolymers, covering a wide range of compositions, were analyzed in solution by means of 13C NMR spectroscopy. A detailed assignment of the signals to the different triad sequences was carried out. The experimental triad distributions were compared with calculations assuming Bernouillian and first‐order Markov statistics, finding a better agreement for the latter model. The triad distributions were also used for the determination of the reactivity ratios of the two comonomers.
Miscibility of an oligo(p‐phenylenevinylene) with polystyrene studied by solid‐state nuclear magnetic resonance
Authors: Nouwen Johan , Adriaensens Peter , Gelan Jan , Verreyt Gunther , Yang Zhou , Geise Herman J. 
Published: April 2003

AbstractMolecular proximity of cis/trans mixtures of 2,5‐dimethoxy‐1,4‐bis[2‐(3,4,5‐trimethoxyphenyl)vinyl]benzene (MPV, 1) and polystyrene (PS) in mixtures of different MPV/PS weight ratios up to 60/40 is shown by 1H combined rotation and multiple pulse spectroscopy (CRAMPS) using 2D exchange experiments. The MPV/PS mixtures up to a weight ratio 60/40 are homogeneous, whereas the mixture with a weight ratio MPV/PS = 80/20 is heterogeneous. The comparison of the cross polarization/magic angle spinning (CP/MAS) 13C NMR spectra of pure MPV and of MPV mixed with PS shows significant linebroadening in case of intimate mixing, while the heterogeneous mixture shows some extra finestructure. The miscibility results were confirmed by proton spin‐locking relaxation time measurements (T1ρH) on the mixtures. On intimate mixing, T1ρH is averaged out and varies linearly as a function of the composition of the mixture. CRAMPS‐spectra and T1ρH measurements show that iodine‐doped MPV/PS mixtures (weight ratios 40/60 and 60/40) are heterogeneous. Furthermore, doping causes a slight proton chemical shift change and reduces the T1ρH‐values of those oligomer‐polymer systems.
TiCl4/MgH2‐supported Ziegler‐type catalyst system, 4. The influence of 14CO contact time and mole ratio Al(C2H5)3/Ti on concentration of active sites in ethylene homo‐ and copolymerization
Authors: Jaber Isam A. , Fink Gerhard 
Published: April 2003

AbstractThe effect of varying 14CO contact time upon the concentration of active centres C* in ethylene homopolymerization using the TiCl4/MgH2 · Al(C2H5)3 catalytic system shows that the polymer radioactivity, and hence C*, increase sharply in the first sixty minutes of 14CO contact with the polymerization centres. For contact times longer than one hour, the polymer radioactivity continues to increase, but very slowly. Studies on the effect of the mole ratio Al(C2H5)3/Ti on ethylene homopolymerization show that both the catalytic activity and C* increase sharply when increasing the mole ratio Al(C2H5)3/Ti in the range from 5 to 20. When increasing the mole ratio Al(C2H5)3/Ti above 50, C* tends to decrease very slightly. In ethylene/1‐hexene copolymerization a similar effect of the mole ratio Al(C2H5)3/Ti on the polymerization is observed. However, even though the catalytic activity in copolymerization is observed to be higher than in homopolymerization, at the same mole ratio Al(C2H5)3/Ti, yet C* in both cases is found to be more or less the same.
Copolymerization of styrene, maleic anhydride and acrylonitrile up to high conversion
Authors: Santos Regina De J. , Soares Bluma G. , Gomes Ailton S. 
Published: April 2003

AbstractTerpolymers of styrene, maleic anhydride and acrylonitrile were synthesized by variation of the molar ratios of the three monomers at total monomer conversion up to 90 mol‐%. Polymerizations were performed with total initial monomer concentrations of 0,25 g/mL in benzene at 60°C with AIBN as initiator. The composition of the terpolymers was determined by elemental analysis. Although this ternary system comparises only one electron‐donor monomer and two electron‐acceptor monomers, maleic anhydride is the most reactive monomer and is incorporated in higher proportions than the other monomers.
Thermal and mechanical properties of poly(ether urethane) modified by copolyamide segments
Authors: Ahn Tae Oan , Choi Il Seok , Lee Sang Won , Jeong Han Mo 
Published: April 2003

AbstractThermoplastic polyurethane elastomers (TPUs) from diol‐terminated poly(tetramethylene glycol) (PTMG), 1,4‐butanediol (BD), and 4,4′‐methylenediphenyl diisocyanate (MDI) were modified by copolymerizing diamine‐terminated nylon‐6/6,6 copolyamide oligomer. In TPUs modified by the copolyamide segment, the hard segment showed decreased crystallinity and melting point depression as the content of copolyamide segment was increased, which is probably due to mixing and strong interaction between copolyamide and hard segments. As some of the hard segments were replaced by copolyamide segments, the crystallinity of PTMG segments increased. This suggests that the copolyamide‐PTMG segment interaction is weaker than the interaction between hard and PTMG segments. Tensile properties of TPUs are discussed based on the thermal properties.
Forced surface diffusion of polyelectrolytes
Authors: Noolandi Jaan 
Published: April 2003

AbstractThe controlled diffusion of polyelectrolytes across a surface is of interest for preparing ordered surface structures, studying molecule‐surface interactions (molecular friction), obtaining information about surfaces using standard molecular probes, separating large DNA fragments, and also for basic studies of the different modes of motion of polyelectrolytes along the surface. We suggest a simple scheme for studying forced surface diffusion of charged macromolecules across a surface under a conducting fluid. Some of the possible modes of motion are discussed.
Water‐soluble polymers with styrenesulfonate and maleic acid units in the backbone
Authors: Bortel Edgar , Kochanowski Andrzej , Witek Ewa 
Published: April 2003

AbstractThe radical copolymerization of maleic acid (MAc) with sodium p‐styrenesulfonate (sodium 4‐vinylbenzenesulfonate) (NaSS) in aqueous solution yielded copolymers containing both: carboxylic and sulfonic groups attached to the backbone. By changing initiator concentrations and temperatures, the weight‐average molecular weights, M̄w, were tailored in the range between 83 · 103 and 265 · 103. The corresponding intrinsic viscosities extended from 0,270 to 810 cm3/g, giving rise to the Mark‐Houwink equation: [η] = 7,65 · 10−6 · M0,924 solvent aqueous 0,1 M NaCl; (25°C). The highest degree of conversion at the conditions employed amounted to 83%. Based on the sulfur content found analytically, an equal share of both monomeric units was established. The structure of the copolymer poly[(maleic acid)‐co‐(sodium p‐styrenesulfonate)] obtained was elucidated by means of 13C NMR, 1H NMR and IR spectroscopy. After converting the sulfonate groups to their H+ ‐form through ion exchange, the copolymer was submitted to potentiometric 0,1 M NaOH titration yielding a dE/dV vs. α curve (with E electromotive force, V volume of titrant and α degree of neutralization), which deviates in shape from theoretical expectations. This deviation was attributed to high ionic strength within the polymeric coils.
Binary copolymerizations of styrene and conjugated diolefins in the presence of cyclopentadienyltitanium trichloride‐methylaluminoxane
Authors: Zambelli Adolfo , Proto Antonio , Longo Pasquale , Oliva Patrizia 
Published: April 2003

AbstractBinary copolymerizations of styrene, isoprene, butadiene and 4‐methyl‐1,3‐pentadiene, in the presence of the catalyst cyclopentadienyltitanium trichloride‐methylaluminoxane (CpTiCl3‐MAO), are investigated. The reactivity ratios as well as the reactivities of the different monomers in homopolymerization are tentatively correlated to a possible polymerization mechanism. A qualitative explanation of the reactivity of different monomers in homo‐ and copolymerization is achieved by considering the nucleophilicity of the monomers and the electrophilicity of the active species. The latter is affected by the nature of the bond between the active Ti and the last unit of the growing chain end. The block copolymerization of ethylene with styrene is also tentatively explained by considering that the more the active species are electrophilic the less they should be selective toward monomers of different nucleophilicity.
Thermotropic elastomers with poly(oxy‐1,4‐butanediyl) units in the main chain
Authors: Pospiech Doris , Komber Hartmut , Voigt Dieter , Häußler Liane , Meyer Evelin , Schauer Gottfried , Jehnichen Dieter , Böhme Frank 
Published: April 2003

AbstractThe paper describes the synthesis of thermotropic elastomers from trimellitimide‐terminated poly(oxy‐1,4‐butanediyl) [synonyms: poly(tetramethylene ether glycol), PTMG; poly(tetrahydrofuran), poly(THF)] and acetoxy group‐terminated rigid blocks. Copolyester imides are formed by transesterification polycondensation in the melt. According to 13C NMR investigations, their chain sequence distribution is characterized by a block‐like structure in which the preformed rigid units are partially exchanged by transesterification reactions during the melt polycondensation. The degree of transesterification depends on the reaction time. The influence of the length of the flexible PTMG units and of the concentration of rigid units on the phase behaviour as well as on the thermal behaviour and the dynamic‐mechanical behaviour of the block copolymers is discussed with respect to aromatic model compounds.
Synthesis and properties of aromatic polyamides from 2,7‐triptycenediamine
Authors: Kasashima Yoshio , Kaneda Takuya , Saito Go , Akutsu Fumihiko , Naruchi Kiyoshi , Miura Masatoshi 
Published: April 2003

AbstractAromatic polyamides were synthesized by the low‐temperature solution polycondensation of 9,10‐dihydro‐9,10‐o‐benzeno‐1,5‐anthracenediamine (2,7‐triptycenediamine) with aromatic diacyl dichlorides. All the polycondensations proceeded in quantitative yields. The obained aromatic polyamides have high inherent viscosities (ca. 1,04–3,24 dL/g). They are soluble in various organic solvents such as 1‐methyl‐2‐pyrrolidone (NMP). The polyamides show high glass transition temperatures (Tg ≈ 337–370°C) and high decomposition temperatures (ca. 446–486°C at 5% weight loss). In particular, the polyamide prepared from the diamine and 4,4′‐sulfonyldibenzoyl dichloride not only was soluble in dimethyl sulfoxide, N,N‐dimethylformamide, hexamethylphosphoric triamide, NMP, N,N‐dimethylacetamide and pyridine, but also showed high Tg (370°C).
Polybutadiene‐poly(methyl methacrylate) core‐shell latexes studied by high‐resolution solid‐state 13C NMR and DSC: Influence of the surface coverage of the polybutadiene seed latex and the latex composition on the interphase formation
Authors: Nzudie Denis Tembou , Delmotte Luc , Riess Gérard 
Published: April 2003

AbstractHigh‐resolution solid‐state 13C NMR and differential scanning calorimetry (DSC) were used to examine the effect of the surface coverage of the polybutadiene seed latex by the surfactant and the latex composition on the interphase of PBut‐PMMA core‐shell latexes. On the basis of the determination of the relaxation time (T1ρ(H)), glass transition temperature (Tg) and transition zone (ΔTg), information on the interphase was obtained, such as the fraction of the PMMA in the interphase and the interphase thickness. An optimum surface coverage of the PBut seed latex particles was found to lead to the largest amount of interphase.