bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of water‐soluble polysaccharides and their antitumor activity, 2. Branched polysaccharides from curdlan and curdlan acetate
Authors: Matsuzaki Kei , Yamamoto Iwao , Sato Takaya , Oshima Ryuichi 
Published: April 2003

AbstractPolysaccharides having β‐glycosidically linked D‐glucose branches were synthesized by condensation of 3,4,6‐tri‐O‐acetyl‐(1,2‐O‐ethylorthoacetyl)‐α‐D‐glucopyranose with activated curdlan (β‐(1→3)‐glucan) and its acetyl derivatives in boiling chlorobenzene in the presence of catalytic amounts of 2,6‐dimethylpyridinium perchlorate. The branched polysaccharides were converted into water‐soluble polysaccharides by saponification and then tested for their antitumor activity. Branched polysaccharides synthesized from unsubstituted curdlan with 60% or more branching and those from curdlan acetate with 30% or more branching are completely soluble in water. The structure of branched polysaccharides obtained from curdlan was determined from methylation analysis, and it was found that branching occurs preferentially at the C‐6 positions by β‐glycosidic linkages. Some of the synthesized branched polysaccharides with high molecular weight show high antitumor activity.
Synthesis of water‐soluble branched polysaccharides and their antitumor activity, 3. Branched polysaccharides from ivorynut mannan, ivorynut mannan acetate and konjak glucomannan
Authors: Matsuzaki Kei , Yamamoto Iwao , Sato Takaya , Oshima Ryuichi 
Published: April 2003

AbstractBranched polysaccharides of ivorynut mannan (β‐(1→4)‐D‐mannopyranan) and konjak glucomannan (β‐(1→4)‐linked copolymer of D‐mannopyranose and D‐glucopyranose with side chains) having β‐glycosidically linked D‐glucose branches were synthesized by condensation of 3,4,6‐tri‐O‐acetyl‐(1,2‐O‐ethylorthoacetyl)‐β‐D‐glucopyranose with activated ivorynut mannan, ivorynut mannan acetate and konjak glucomannan. When ivorynut mannan was used as main chain polymer, a branched polysaccharide with 11% degree of branching was obtained and found to be 50% soluble in water. Branched polysaccharides from ivorynut mannan did not lead to completely water‐soluble products, even if the condensation reaction was repeated or the acetyl derivative was used as a starting polymer. A branched polysaccharide with 5−10% degree of branching obtained from konjak glucomannan was completely soluble in water with out starting from the acetylated polymer. The structure of these branched polysaccharides was determined by methylation analysis, and it was found that branching of both water‐soluble polysaccharides obtained from ivorynut mannan and konjak glucomannan occurred preferentially at the C‐6 positions. The antitumor activity of these polymers was low as compared to that of branched polysaccharides obtained from cellulose and curdlan.
Biologically active polycations, 6. Polymeric pyridinium salts with well‐defined main chain structure
Authors: Ikeda Tomiki , Hirayama Hiroki , Suzuki Kazuhiro , Yamaguchi Hideki , Tazuke Shigeo 
Published: April 2003

AbstractPolyesters and polyamides with pendant N‐alkylpyridinio‐4‐ylmethyl groups and definite spacer length between the pyridinio groups were prepared. It was found that the polyesters generally exhibit higher antibacterial activity than the corresponding monomers. Furthermore, the longer the alkyl chain length attached to the nitrogen of the pyridine ring, the higher is the antimicrobial activity. Polyamides with various spacer length were fractionated by gel filtration chromatography to obtain samples with comparable average molecular weights. Antimicrobial assessment of the fractionated polyamide samples demonstrated the existence of an optimum spacer length for lethal action.
Synthèse et étude des propriétés rhéologiques de polyesters stéréoréguliers à base d'acide maléique et d'acide fumarique
Authors: Lacoudre Nelly , Leborgne Alain , Sepulchre Maurice , Spassky Nicolas , Djonlagic Jasna , Jacovic Mihailo S. 
Published: April 2003

AbstractPure poly(butylene maleate) and poly(butylene fumarate) of high molecular weights were synthesized by reaction of the corresponding caesium and potassium dicarboxylates with 1,4‐dibromobutane in 1‐methyl‐2‐pyrrolidone at 110°C. During the reaction a substantial amount of oligomeric products, consisting mainly of cyclic compounds, is formed. From the study of the rheological properties at high temperatures (175 to 240°C) it was concluded that some crosslinking occurs rather than isomerization.
Synthesis of spacer‐modified polymer supports with the aid of etherification and phase‐transfer catalytic activity of phosphonium salts derived from the polymer supports
Authors: Tomoi Masao , Shiiki Satoshi , Kakiuchi Hiroshi 
Published: April 2003

AbstractSpacer‐modified polystyrene supports containing ether linkages were prepared by using chloromethylated polystyrene and 10‐undecen‐1‐ol or p‐hydroxylated polystyrene and 11‐bromo‐1‐undecene as starting materials. The polymerization of p‐(6‐bromohexyloxy)styrene gave also spacer‐modified supports. Phosphonium salts derived from the spacer‐modified polymer supports showed phase‐transfer catalytic activities comparable to those of immobilized phosphonium salts linked to polystyrene by a heptamethylene spacer.
Synthesis of poly(2‐hydroxyethyl methacrylate)‐poly(tetramethylene glycol) ABA type block copolymers and their blood compatibility
Authors: Li Xue‐fen , Chen Chuan‐fu , Li Zhi‐fen , Gu Han‐qing , Lu Mo‐zhu , Han Yu‐zhi , Liu Xiao‐bing 
Published: April 2003

Abstract2‐Hydroxyethyl methacrylate was polymerized in presence of 2‐mercaptoethylamine to an amino‐semitelechelic poly(2‐hydroxyethyl methacrylate). Poly(tetramethylene glycol) was reacted with 4,4′‐methylenediphenyl diisocyanate to form a diisocyanato‐telechelic poly(tetramethylene glycol). Both prepolymers were linked together by coupling reaction between NH2 and NCO groups in DMF at 0°C, resulting in an ABA type block copolymer. The structure of the product was examined by IR, NMR and SEM. It was found that the block copolymer possesses a microphase separated structure. Animal experiments showed that this ABA type block copolymer has good blood compatibility and excellent permeability for uric poisonous substances.
Etude morphologique de bloc‐copoly(éther‐amide)s
Authors: Xie Ming , Camberlin Yves 
Published: April 2003

AbstractA series of ether‐amide block copolymers was studied by means of differential scanning calorimetry, mechanical analysis, and transmission electron microscopy. All of these techniques indicated a two‐phase structure. However, the degree of phase segregation was relatively low as measured by calorimetry, and in the same range as for conventional segmented linear polyurethanes. The existence of an important interphase can explain the appearance of plastic behaviour in hard domains at temperatures well below the polyamide melting points. The low ordering was confirmed by transmission electron microscopy. Only the ether‐amide copolymer with a composition in the phase inversion range exhibited a spherulitic, well‐defined polyamide structure.
Kinetics of polyamidation in solution, 2. reaction of diphenyl terephthalate and trimethylhexamethylenediamine in dimethyl sulfoxide
Authors: WeißKopf Klaus , Meyerhoff Günther 
Published: April 2003

AbstractThe kinetics of polyamidation was investigated for the reaction of diphenyl terephthalate as activated diester with trimethylhexamethylenediamine (1 : 1 mixture of 2,2,4‐ and 2,4,4‐trimethyl isomers) in dimethyl sulfoxide. The good solubility of the resulting polyamide (Trogamid®(poly(iminoterephthaloylimino‐x,y,z‐trimethylhexamethylene))) assured a reaction in which all reactants, especially the polyamide, were soluble. The conversion was followed by analysis of the phenol set free and by measuring the number‐average degree of polymerization P̄n of the polyamide. The reaction obeyed an overall second order with the principle of equal reactivity of functional groups fulfilled for P̄n ≿ 16. Deviations of this order of reaction were observed at the beginning of the reaction due to the enhanced reactivity of monomers and oligomers. The Arrhenius activation parameters were determined for the temperature range between 70 and 110°C.
Graph theory of configurational and viscoelastic properties of polymers, 2. Linear polymer chains containing small copolymer blocks
Authors: Yang Yuliang , Yu Tongyin 
Published: April 2003

AbstractThe graph theory of configurational and viscoelastic properties of polymers is extended to treat block copolymer chains. The analytical expressions for zero‐shear‐rate viscosity, η0, and steady‐state recoverable compliance, Je0, two important linear viscoelastic properties of polymers, are obtained for BmA2Bm, ABmA and BlABm type block copolymer chains. When the structure of a linear polymer is altered locally by incorporating a small amount of another monomer, the variation of the viscoelasticity cannot be ignored, their variation being strongly dependent on the block structure. Thus, the results obtained may prove useful for understanding and interpreting rheological data of block copolymers.
Funktionalisierung des perlcopolymerisationsprodukts aus methylacrylat und 1,4‐bis(vinyloxy)butan
Authors: Schott Herbert , Bretzger Waltraud 
Published: April 2003

AbstractThe ester groups of copolymer beads, prepared from methyl acrylate and 1,4‐bis(vinyloxy)‐butane, were substituted by aminolysis with hexamethylenediamine or aminoalcohols. The resulting gel carrying amino groups was transferred into an anion exchanger by alkylation with 2‐chloroethanol or into a cation exchanger by reaction with succinic anhydride. Hydrazinolysis of the starting copolymer beads resulted in gels with hydrazide groups which subsequently can be derivatized. Gels with hydroxyl groups linked to the matrix by means of spacers were obtained by reaction of the succinylated gels with 2‐aminoethanol. Phosphorylation of these hydroxyl groups afforded strongly acidic cation exchangers. The yields of the derivatized products are higher and the preparations are easier than those of the known methods. The 11 gel derivatives synthesized from the starting gel are mechanically stable, resistent to hydrolysis in the pH range between 1 and 14, chemically stable at temperatures up to 130°C and obtainable with a variety of pore sizes. The derivatized, cross‐linked polymer beads, applicable in aqueous systems as well as in organic solvents, should find application in chromatography, in solid‐phase synthesis and as basic gels in biotechnical processes.
Polymethacrylate‐supported linear polyethers as solid‐liquid phase transfer catalysts
Authors: Wakui Tadahiro , Xu Wen Ying , Chen Chi‐Sung , Smid Johannes 
Published: April 2003

AbstractOligo(oxyethylene)s immobilized as pendant groups on a polymethacrylate‐based resin were used as phase transfer catalysts in the reaction of solid alkali phenoxides with octyl halides in toluene and in the synthesis of benzyl acetate from benzyl bromide and solid alkali acetates in chloroform. The resins are cross‐linked homopolymers or copolymers of methyl ethers of oligo(ethylene glycol) methacrylates of the general formula H2CC(CH3)COO(CH2CH2O)n CH3 with n = 4 (MG4), 8 (MG8) or 22 (MG22), the comonomers being styrene, methyl methacrylate (MMA), acrylonitrile or 4‐vinylpyridine. The conversion of the organic halides into the respective products were found to be all pseudo first order reactions and the observed rate constants are proportional to the amount of added catalyst and decrease with increasing crosslinking density of the catalyst. Catalysts with longer oligo(oxyethylene) chains have considerably higher activity. Incorporation of more than 50 mol‐% MMA comonomer decreases the catalytic activity at least for the benzyl bromide reaction, but the structure of the comonomer has no significant effect. The catalysts are easily synthesized in large quantities from commercially available monomers.
Cationic polymerization of tetrahydrofuran initiated by multifunctional initiators
Authors: Cai Gang‐feng , Yan De‐yue 
Published: April 2003

AbstractA series of multifunctional cationic initiators was synthesized from 1,5,9‐cyclododecatriene and from methylbenzenes by the Wohl‐Ziegler reaction with N‐bromosuccinimid. The initiators were treated with silver perchlorate to prepare star‐shaped polytetrahydrofurans with three to six arms.
Kinetic studies on the dehydrochlorination of poly(vinyl chloride) in the presence of a phase transfer catalyst
Authors: Howang Kyu Tak , Iwamoto Kazutoshi , Senō Manabu , Kise Hideo 
Published: April 2003

AbstractThe reaction rate of the dehydrochlorination of poly(vinyl chloride) in the presence of a phase transfer catalyst was studied. It was found that the order of reaction for NaOH and for the catalyst is 1,1 and 0,43, respectively. A mechanism like a radical‐chain transfer reaction of the zipper‐type may well account for the experimental data.
Excluded volume effect on polymer chains: Internal parts vs. free chain expansion
Authors: Ganazzoli Fabio 
Published: April 2003

AbstractA self‐consistent Fourier configurational approach is used to describe the swelling of a polymer chain and of its inner parts in a good solvent. Minimization of the free energy yields the full spectrum of the expansion coefficients for the interatomic mean‐square distances assumed to have a Gaussian distribution with the actually perturbed second moment. Due to the repulsive effect of the outer segments, the internal parts are more expanded than a free chain with the same molecular weight under identical conditions, in good agreement with recent experimental findings, but contrary to what is predicted by mean‐field theories and by the blob model.
Functional metal‐porphyrazine derivatives and their polymers, 15. Synthesis and properties of poly(γ‐benzyl‐l‐glutamate)s containing covalently bound metalphthalocyanine moieties in the side chains
Authors: Hanabusa Kenji , Kobayashi Chihiro , Koyama Toshiki , Masuda Etsuko , Shirai Hirofusa , Kondo Yoshiyuki , Takemoto Kiichi , Iizuka Eisaku , Hojo Nobumasa 
Published: April 2003

AbstractMetal‐2,9,16,23‐tetracarboxyphthalocyanines (1a — d) (Mt = Fe(III), Co(II), Ni(II) and Cu(II)) were transformed into their acid chlorides 2a — d which, by Friedel‐Crafts reaction with the benzyl groups of poly(γ‐benzyl‐L‐glutamate) (3), gave the polymers 4a — d. The resulting substituted poly(γ‐benzyl‐L‐glutamate)s were found to contain about 0,2 to 2,8 mol‐% of phthalocyanine rings covalently bound to the polymer main chain. Polymers 4a — d are soluble in chloroform, 1,4‐dioxane, dichloroacetic acid, DMF etc. The coordination spheres around the metalphthalocyanine rings were characterized by electronic and ESR spectra. The polymers could be shown to have α‐helical conformation, green or blue colored lyotropic mesophases being formed in concentrated solutions.
Conformation and gas permeability of poly(α‐amino acid) membranes
Authors: Kawai Tohru , Narita Hiroki , Lai Juin‐yih , Ebert Gotthold 
Published: April 2003

AbstractThe permeability of some poly(ϵ‐amino acid) (PAA) membranes like such of poly(N,δ‐carbobenzoxy‐L‐lysine) (PCBL), poly(N,δ‐carbobenzoxy‐L‐ornithine) (PCBO) as well as of copolymers of L‐lysine and carbobenzoxy‐L‐lysine to oxygen and carbon dioxide were determined at different water content especially with regard to their use for artificial lungs. The conformations of these polymer membranes were studied by means of IR‐spectra and X‐ray diffraction. The results on the diffusion coefficient obtained for PCBL and PCBO were analysed in terms of Eyring's theory. They suggest that the microvoids in the interstices between the α‐helices, assumed on the basis of X‐ray analyses, play an important role, especially below the glass transition temperature Tg of the side‐chains. This seems also to contribute partly to the diffusion of gas through the membrane even above Tg and results in an abnormally high “apparent activation energy” of diffusion in the wet state below Tg. It was found that the permeability of the membrane of partially decarbobenzoxylated PCBL for oxygen in a certain temperature range is higher than that for carbon dioxide. This has never been observed for any other synthetic polymer, because usually carbon dioxide has a higher solubility in these materials than oxygen. In the case of the partially decarbobenzoxylated PCBL membranes, however, the diffusion coefficient of carbon dioxide, and therefore the permeation of this gas, decreases much more than that of oxygen with increasing decarbobenzoxylation accompanied by the formation of β‐structure and concomitantly the formation of intermolecular hydrogen bonds. Obviously, this phenomenon may be responsible for the permselectivity of these membranes for oxygen compared with carbon dioxide.
ESCA study of new antithrombogenic materials: Surface composition of poly(propylene oxide)‐segmented nylon 610 and its blood compatibility
Authors: Yui Nobuhiko , Kataoka Kazunori , Sakurai Yasuhisa , Sanui Kohei , Ogata Naoya , Takahara Atsushi , Kajiyama Tisato 
Published: April 2003

AbstractSurface composition and blood compatibility of a series of segmented polymers based on poly(propylene oxide) (PPO) and nylon 610 were investigated. Electron spectroscopy for chemical analysis (ESCA) measurements revealed that the chemical composition of PPO‐segmented nylon 610 surface is regulated by nylon 610 crystallization, and the PPO enrichment effect on the air‐facing surface was correlated with both the degree of crystallinity of nylon 610 and the nylon 610 crystallite thickness. Platelet adhesion was minimized for the copolymer having a long period of approximately 12 nm and a crystallite thickness of 6,5 nm. This copolymer surface had the same chemical composition as the bulk, indicating that the particular surface microstructure composed of crystalline and amorphous phases could be a determining factor for suppressing platelet adhesion.
Unified study of the mechanical and optical properties of polyoxymethylene applying the composite model for the temperature range from −60 to 120°C
Authors: Biswas Prabir K. , Sengupta Shyamal , Basu Asok N. 
Published: April 2003

AbstractA unified study of the optical and mechanical properties of polyoxymethylene (POM) is attempted in the framework of the composite model for a wide range of temperature (−60 to 120°C) which covers a region well below and above the γ‐relaxation temperature. It was found that the existing two phase models for semicrystalline polymers are not adequate for interpreting the mechanical properties of POM over a wide temperature and drawing ratio range. The composite model takes into consideration the effects due to the change in crystallinity and orientation on drawing. The elastic moduli of the composite units are also calculated in terms of those of its constituents. The orientational changes on drawing were directly computed from the birefringence data. It was observed that the general agreement of the calculated and experimental values of the elastic moduli over the entire temperature and drawing ratio range is quite satisfactory.
Reusable heterogeneous catalysts of α‐amino acid racemization, 1. Immobilization of 4‐hydroxy‐3‐formylbenzenesulfonic acid (5‐sulfosalicylaldehyde) on strongly basic anion exchangers
Authors: Belokon' Yuri N. , Tararov Vitali I. , Savel'eva Tatiana F. , Saporovskaya Marina B. , Belikov Vasili M. 
Published: April 2003

AbstractStrongly basic anion‐exchange resins in OH− form, partially neutralized with 4‐hydroxy‐3‐formylbenzenesulfonic acid (5‐sulfosalicylaldehyde) (SSA) could be shown to catalyse the racemization of neutral and basic optically active α‐amino acids in the presence of copper (II) ions at moderate temperatures (25‐45 °C). Under these conditions (S)‐asparagine is racemized without hydrolysis of its amide groups. The heterogeneous racemization of (S)‐alanine is accelerated by a factor of 880 as compared to a homogeneous reaction. The efficiency of heterogeneous catalysis depends on (1) the extent of neutralization of anion exchanger with SSA, (2) the type of the resin used and (3) the quantity of Cu(II) ions in the reaction mixture. The experimental data are in accordance with the fact that heterogeneous racemization of amino acids proceeds via the formation of a reactive copper(II)‐Schiff's base complex. The heterogeneous catalysts can be recycled. The anion exchangers can be regenerated and, if necessary, re‐used.
Polymerizable tautomers, 1. Tautomerism and polymerization of ethyl 3‐oxo‐4‐pentenoate
Authors: Masuda Seizo , Tanaka Masami , Ota Tadatoshi 
Published: April 2003

AbstractSolvent effects on the tautomerism and polymerization of ethyl 3‐oxo‐pentenoate (1) were studied. Regression analysis of the tautomeric constant reveals that the equilibria depend on the polarity and hydrogen‐bond donor acidity of the solvents. The polymerization was investigated in benzene and acetonitrile. In both solvents, the kinetic results do not meet the conventional model of radical polymerization.
Phase transitions and defect structure in the lamellar surface of polyethylene and n‐alkane crystallites. Magic angle spinning 13C NMR studies
Authors: Möller Martin , Cantow Hans‐Joachim , Drotloff Hansotto , Emeis Detlef , Lee Kwang‐Sup , Wegner Gerhard 
Published: April 2003

AbstractVariable temperature magic angle spinning 13C NMR experiments on linear alkanes and low molecular weight polyethylene allowed the observation of up to six carbon atoms at the chain ends near the surface of the lamellar crystallites. Conformational order‐disorder and intermolecular packing effects are reflected by the spectra. The effects are discussed with regard to the peculiar phase behaviour of the n‐alkanes and the fringed micella model for low molecular weight polyethylene. The solid‐solid transitions of nonadecane and hexatriacontane appear to be correlated with the occurrence of specific non‐liquid‐like conformational disordering. Thus, conformational defects were observed for the “rotator phase” which depend on the chain length and which vary along the chain. Whilst the center part of the chain remains all‐trans ordered, significant gauche defects were observed for the bonds at the chain ends. For a polydisperse low molecular weight linear polyethylene as well as for monodisperse octahexacontahectane reversible liquid‐like conformational disordering of the terminal chain segments could be detected when the melting point was approached. Hence, in this case the NMR spectra indicate pre‐melting of the lamella surface, while in case of the shorter n‐alkanes the occurrence of end‐gauche defects is correlated with solid‐solid transitions.
Lattice expansion by water absorption and side‐chain interactions in synthetic polypeptides having a urethane group in the side chains
Authors: Sasaki Shintaro , Iwanami Yoshimu 
Published: April 2003

AbstractTwo polypeptides with a urethane group in the side chains, poly(δ‐N‐methoxycarbonyl‐L‐ornithine) (PMCO) and poly(ε‐N‐methoxycarbonyl‐L‐lysine) (PMCL), were synthesized. Their crystal structures were investigated from X‐ray diffraction. In both polymers, the molecules take the α‐helical conformation, and helices are packed in a (pseudo)hexagonal array. The lateral size of the unit cell changes reversibly with relative humidity (rh), while the axial dimension is constant irrespective of water absorption. The expansion of unit‐cell volume for rh = 100% with reference to rh = 0% was 5,8% for PMCO and 7,1% for PMCL at 20°C. In the dry state, side chains are partly associated via hydrogen bonds. The dielectric behavior of these films is discussed in terms of side‐chain interactions.
Odd‐even variations in the melting points of some ethylene polyesters
Authors: Bhaumik D. , Mark J. E. 
Published: April 2003

AbstractMolecular mechanics calculations on poly(ethylene adipate), poly(ethylene pimelate), and poly(ethylene suberate) indicate that the odd‐even variation in the melting points of the polyesters

n with the number y of methylene groups is due to differences in packing of the chains in the crystalline state.