bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and permeation behavior of membranes from segmented multiblock copolymers containing poly(ethylene oxide) and poly(β‐benzyl L‐aspartate) blocks
Authors: Yokoyama Masayuki , Anazawa Hayato , Takahashi Akeo , Inoue Shohei , Kataoka Kazunori , Yui Nobuhiko , Sakurai Yasuhisa 
Published: April 2003

AbstractNovel segmented multiblock copolymers (7) were synthesized by linking poly(ethylene oxide) (PEO) blocks with poly(β‐benzyl L‐aspartate)(PBLA) blocks via urethane and urea bonds, which were formed by the reaction of 4,4′‐methylenediphenyl isocyanate (5) with the terminal hydroxyl groups of α‐hydro‐ω‐hydroxypoly(oxyethylene) (4) and the terminal amino groups of poly(β‐benzyl L‐aspartate)‐block‐iminohexamethyleneimino‐block‐poly(β‐benzyl L‐aspartate) (3) [prepared from 1,6‐hexanediamine (1) and β‐benzyl L‐aspartate N‐carboxy anhydride (2)], respectively. Membranes with various water contents were obtained from these copolymers by changing the lengths of the PEO and PBLA segments. The study of the permeation of 1‐phenyl‐1,2‐ethanediol, vitamin B12 and myoglobin through the membranes showed a high dependency of the permeability on the molecular weight of the solutes.
Electrochemical copolymerization of 3‐dodecylthiophene and 3‐methylthiophene
Authors: Sato Masa‐aki , Shimizu Toshimi , Yamauchi Aizo 
Published: April 2003

Abstract3‐Dodecylthiophene (1a) and 3‐methylthiophene (1b) were copolymerized electrochemically. The visible and IR spectra of the neutral copolymers prove the copolymers to be of random structure, which can be denoted as that of poly(3‐alkyl‐2,5‐thienylene)s. 1b polymerizes with preference over 1a. With increasing fraction of monomeric units of 1b in the copolymers, the conductivity increases and the solubility of the neutral copolymers decreases. The copolymer containing 58 mol‐% monomeric units of 1b has a high conductivity of 220 S/cm and a good solubility of 75 wt.‐% in chloroform. 1H NMR spectra of poly(3‐dodecylthienylene) and copolymers show two chemical shifts for the α(1)‐methylene protons of the monomeric units of 1a as well as of the methyl protons of the monomeric units of 1b. This fact may be explained by the presence of head‐to‐head and other constitutions.
Kinetic studies on the Menschutkin reaction of dimethylamino‐terminated poly(oxytetramethylene) with halides
Authors: Kohjiya Shinzo , Ohtsuki Tohru , Yamashita Shinzo 
Published: April 2003

AbstractThe kinetics of the Menschutkin reaction between dimethylamino‐terminated poly(oxytetramethylene) [AT‐PT (1), molecular weight 1160] and dihalides was followed by means of 1H NMR spectroscopy of NCH3 protons. For comparison, low‐molecular‐weight monoamines were subjected to similar experiments. No difference was found between the second‐order rate constants of AT‐PT and those of monoamines. But the rate constants depend on the kind of halide, i.e., the bromides [1,4‐bis(bromomethyl)benzene, 1,4‐dibromo‐2‐butene, benzyl bromide, allyl bromide] are much more reactive than the corresponding chlorides. Different from the usual nucleophilic reactions, the rate in a polar solvent (methanol) is smaller than that in the non‐polar chloroform. According to the activation parameters, this anomaly is due to hydrogen bonding, which has to be broken for the reaction to occur in a polar protic solvent.
Conformational properties and complex formation ability of poly(methacrylic acid)‐block‐poly(1‐methyl‐4‐vinylpyridinium chloride) in aqueous solution
Authors: Bekturov Esen A. , Frolova Vera A. , Kudaibergenov Sarkyt E. , Schulz Rolf C. , Zöller Joachim 
Published: April 2003

AbstractIt is shown that the block‐like structure of the polyampholyte poly(methacrylic acid)‐block‐poly(1‐methyl‐4‐vinylpyridinium chloride) considerably influences its conformational behaviour. This specific behaviour is explained by the formation of intra‐macromolecular polyelectrolyte complexes stabilized by cooperative ionic contacts between acidic and basic units near the isoelectric point (i. e. p.). The structure of the block‐polyampholyte at the i. e. p. is suggested to be close to the structure of non‐stoichiometric polyelectrolyte complexes. The complex formation ability of the block‐polyampholyte with respect to anionic, cationic, and nonionic polymers is also studied. By means of potentiometric, conductometric, and viscometric methods the composition of interpolymer complexes is determined and the degree of conversion in complex formation reactions is calculated. The water solubility (or insolubility) of interpolymer complexes is determined by the length of acid or basic blocks. It is proposed that a dissociation of interpolymer complexes into their individual components takes place at the i. e. p. of the block‐polyampholyte.
Synthetic and thermodynamic investigations in the polymerization of ethylene carbonate
Authors: Vogdanis Lazaros , Martens Barbara , Uchtmann Hermann , Hensel Friedrich , Heitz Walter 
Published: April 2003

AbstractThe polymerization of ethylene carbonate using different metal alkoxides results in poly(oxy‐ethylene‐alt‐ethylene carbonate). Polymers containing low amounts of CO2 or pure poly(oxy‐ethylene) are formed with anionic and cationic initiators. Poly(ethylene carbonate) is not accessible from ethylene carbonate by variation of temperatures and concentration. The reason is not the low ceiling temperature, but the positive enthalpy of polymerization. A ΔHp‐value of 125,6 kJ/mol was obtained from calorimetric investigations.
Stereo block copolymers of L‐ and D‐lactides
Authors: Yui Nobuhiko , Dijkstra Pieter J. , Feijen Jan 
Published: April 2003

AbstractSequential diblock copolymers composed of L‐ and D‐lactic acid residues were synthesized through a living ring‐opening polymerization of L‐ and D‐lactide initiated by aluminium tris(2‐propanolate). The composition of the block copolymers was varied by changing the reaction conditions and monomer over initiator ratio and confirmed by 1H NMR analysis, molecular weight determination and optical rotation measurements. Molecular weights ranged from 1,3 to 2,0 · 104 with 1,2 < M̄w/M̄n < 1,4. Stereocomplex formation in all block copolymers was determined using differential scanning calorimetry showing melting temperatures of about 205°C.
Effect of Pt(II) coordination on the thermotropic liquid‐crystalline behavior of poly(acrylic ester)s containing 4′‐cyano‐4‐biphenylyloxy mesogenic groups
Authors: Hanabusa Kenji , Suzuki Takashi , Koyama Toshiki , Shirai Hirofusa , Hojo Nobumasa , Kurose Akio 
Published: April 2003

AbstractPoly(acrylic ester)s 3a–f and 4a–g, containing 4′‐cyano‐4‐biphenylyloxy mesogenic groups coordinating to Pt(II) ions with various contents, were synthesized by ligand exchange reaction of poly(acrylic ester)s 1 and 2 with dichlorobis(benzonitrile)platinum (II). The effect of Pt(II) coordination of the mesogen on the thermotropic liquid‐crystalline behavior was examined by DSC, X‐ray diffraction, and polarizing microscopy. For polymers 1, 3a–c with a content x of 4′‐cyano‐4‐biphenylyloxy mesogen coordinating to the Pt(II) ion less than 24 mol‐%, a nematic mesophase was observed between Tg and Tc. For polymers 2, 4a–e with x < 20 mol‐%, a smectic mesophase was found between Tg and Tc. On the other hand, polymers 3d–f and 4 f and g with a high amount of mesogenic groups coordinating to the Pt(II) ion do not form mesophases due to the cross‐linked structure resulting from the coordination of the mesogen to the Pt(II) ion.
Macromolecular prodrugs of 5‐aminosalicylic acid, 1. Azo‐conjugates
Authors: Callant Dominique , Schacht Etienne 
Published: April 2003

AbstractPolymeric prodrugs of 5‐aminosalicylic acid, a drug used for the treatment of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease, were synthesized and characterized. The active drug 5‐aminosalicylic acid was first coupled to a spacer group via an azo bond. All spacer‐pharmacon systems prepared have a terminal primary amino function, which by nucleophilic reaction was coupled under mild conditions to poly(methyl vinyl ether‐co‐maleic anhydride) (5) and poly(1‐vinyl‐2‐pyrrolidon‐co‐maleic anhydride) (6), without crosslinking. The polymeric prodrugs were characterized by UV and NMR. All polymer derivatives are insoluble in water at acidic pH‐range, but dissolve slowly in neutral or slight alkaline medium.
Haloaldehyde polymers, 40. Stereostructure of chloral oligomers prepared with lithium tert‐butoxide: Helical conformation of the linear isotactic oligomers in crystal and in solution
Authors: Ute Koichi , Nishimura Tohru , Hatada Koichi , Xi Fu , Vass Frantisek , Vogl Otto 
Published: April 2003

AbstractThe stereostructures of linear chloral oligomers were determined by X‐ray single crystal analysis. The chloral oligomers from dimer to pentamer were isolated by distillation and by GPC fractionation from the oligomer mixture prepared with t‐BuOLi initiation and acetate endcapping. The dimer fraction was a diastereomeric mixture of the racemo (1) and meso (2) isomers, while the trimer, tetramer and pentamer fractions each contained a single diastereomer (3, 4 and 5). The single crystals of 2, 3, 4 and 5 grown from methanol solutions belong to the space groups P1−, P21/n, P21/a and Pca21, respectively. X‐ray analyses showed that the acetal backbones of 2, 3 and 4 consist exclusively of meso dyads. The backbone arrangements of 2, 3 and 4, are essentially identical and approximate the repeat gauche(+)‐skew(−) sequences from the t‐BuO group to the acetyl terminal group (for S‐configurations). The conformation of (S,S,S,S)‐4 is very similar to a unit sequence of a 4/1‐helical structure of isotactic polychloral with left‐handed helicity. The axis of the helix is parallel to the c‐axis of the crystal, and the repeat distance is 4,81 Å. The conformations of the acetal backbones of 4 and 5 in solution were also investigated by NMR spectroscopy, on the basis of dihedral angle dependence of 3JCOCH coupling constants.
13C NMR spectroscopic studies on polyanion‐polycation complexes and their component polyelectrolytes
Authors: Kötz Joachim , Ebert Andreas , Kunze Jürgen , Philipp Burkart , Lindberg Johan , Soljamo Kari 
Published: April 2003

AbstractPosition and intensities of the 13C NMR signals and relaxation times T1 of several anionic and cationic polyelectrolytes in the solid state were compared with those of the appropriate polyanion‐polycation complexes. At a high charge density of the components, the most significant changes of the parameters in question due to complex formation are observed for the C atoms adjacent to the charge centers, indicating a strong Coulombic interaction. At lower charge density, conformational changes of the polymer chains have also to be taken into consideration.
Large scale fractionation of polyethylene by means of the continuous polymer fractionation (CPF) method
Authors: Geerißen Heinz , Schützeichel Peter , Wolf B. A. 
Published: April 2003

AbstractThe countercurrent extraction method recently developed for the continuous polymer fractionation (CPF) was applied to linear polyethylene (M̄w = 55 kg/mol; M̄n = 16,7 kg/mol). At temperatures higher than 130°C, moderately concentrated solution of polyethylene were extracted to remove the low‐molecular‐weight components. Discontinuous fractionation experiments served to detect the best suited solvents. Diphenyl ether was chosen to demonstrate that the present extraction can be performed even with the same single solvent used to prepare the feed. For very high‐molecular‐weight polymers, mixed solvents are, however, normally better than single ones, since they allow an easier tailoring of thermodynamic conditions, and yield much less viscous solutions. Mixtures of tetralin and triethylene glycol turned out to be best suited for polyethylene. By means of four successive CPF runs with the single solvent, polyethylene fractions with non‐uniformities U = (M̄w/M̄n) − 1 of approx. 0,3 to 0,4 were obtained on a 100 g scale. The rule of thumb that U can be halved in each CPF step without extensive optimization of the method was corroborated.
High‐molecular‐weight poly(alkylene phosphonate)s by condensation of dialkylphosphonates with diols
Authors: Pretula Julia , Penczek Stanislaw 
Published: April 2003

AbstractThe conditions of polycondensation of dimethyl phosphonate (1) with different diols were elaborated, leading to polymers with molecular weights up to 3,3 · 104. The novelty of the method is based on a two stage process. In the first stage an excess of 1 was used and short chains with methyl ester end groups were produced. These further react with elimination of 1 from the chain ends. In this way the coupling of macromolecules provides high‐molecular‐weight material and side reactions, due to the presence of the diols in the system (e.g. dehydration), are virtually suppressed.
Synthesis and structural studies of new copolyimides
Authors: Orzeszko Andrzej , Mirowski Krzysztof 
Published: April 2003

AbstractA series of copolyimides, deriving from pyromellitic anhydride, was synthesized. Copolymers were prepared by condensation of N,N‐bis(chloroformylmethyl)pyromellitimide (1) with polydiols 2. The resulting copolymers show good solubility and thermoplastic properties. The effect of molecular weight of the polyglycol units on crystallinity and melting point of the copolyimides was studied by X‐ray diffractometry and differential scanning calorimetry. The increase of the number‐average molecular weight of the polyglycol units (M̄n) causes an increase of the crystallinity of the copolyimides. The differences between the degree of the crystallinity and the weight fraction of the polyglycol units in the copolyimides prove that only some part of polyglycol in the copolyimides can be retained within the crystalline structure.
Polymerization in inverse microemulsions, 1. Homopolymerizations of water‐ and oil‐soluble monomers in inverse microemulsions
Authors: Vašková Viera , Juraničová Viera , Bartoň Jaroslav 
Published: April 2003

AbstractHomopolymerization of acrylamide (AAM) as well as of methyl methacrylate (MMA) in inverse microemulsions was studied and compared with the homopolymerization of these monomers in homogeneous systems. Initiators with various solubilities in water were used. Homopolymerization of AAM in inverse microemulsion was found to be an extremely fast reaction independent of the type of the initiator used. It is assumed that polymerization takes place predominantly in the interlayer between the aqueous phase and the oil phase. In the case of MMA the homopolymerization in inverse emulsion is a relatively slow process. It is assumed that polymerization of MMA in the systems studied takes place in the oil macrophase.
Thermo‐oxidative degradation of polyamide 6 and polyamide 6,6. Structure of UV/VIS‐active chromophores
Authors: Karstens Ties , Rossbach Volker 
Published: April 2003

AbstractIn heat‐treated polyamide 6 and polyamide 6,6 fibres UV/VIS‐active chromophores are found, which originate from two different sources: one type of chromophore (structured UV spectrum) arises during polycondensation and the spinning of the fibres (molten phase), the other (nonstructured UV spectrum) occurs as a result of a thermo‐oxidation is based on conjugated oligoenimies , as is shown by a combination of UV/VIS spectroscopy and fluorescence excitation and emission spectroscopy with chemical analysis. The concentration of the various oligoenimine species depends upon the temperature and duration of the thermooxidation. For a temperature of 160°C and a duration of 2 hours, for example, the following oligoenimine concentrations were found (UV spectroscopy with computer‐aided evaluation): for i = 0: 44; i = 1: 13; i = 2: 4; i = 3: 1; i = 4: 0,3 (values expressed in mmol/kg).
Unvernetzte epoxide‐amin‐additionspolymere, 32. Hochmolekulare polykationen vom michler‐hydrolblau‐typ und ihre dielektrische charakterisierung
Authors: Klee Joachim , Hörhold Hans‐Heinrich , Kremer Friedrich 
Published: April 2003

AbstractA high‐molecular‐weight poly(leuco base) (Mn = 11000–18000) was obtained by addition polymerization of N,N′‐dibenzyl‐4,4′‐methylenedianiline (2) and 2,2‐bis[4‐(2,3‐epoxypropoxy)‐phenyl]propane (diglycidyl ether of Bisphenol A) (1).The oxidation of this addition polymer with chloroanil, iodine, bromine, chlorine or antimony pentachloride results in polymeric dyes (absorption at λ = 620 nm) containing units of the “Michler Hydrolblau” type. The dielectric behavior in the frequency range 102 Hz up to 107 Hz shows a dependence of the conductivity on the temperature. Polymer 4c exhibits a conductivity of σ = 6 · 10−6 S/cm at 134,3°C and 106 Hz.
Synthesis and mesomorphic properties of a semiflexible polyester based on 4,4′‐sebacoyldioxydibenzoyl chloride and methylhydroquinone
Authors: Costa Giovanna , Trefiletti Vincenzo , Valenti Barbara , Gallot Bernard 
Published: April 2003

AbstractMany samples of a semiflexible thermotropic polyester were synthesized by low‐temperature solution polycondensation of 2‐methylhydroquinone (5) and 4,4′‐sebacoyldioxydibenzoyl chloride (4) and characterized by polarizing microscopy, differential scanning calorimetry and X‐ray diffraction. The influence of some experimental parameters, such as polymerization temperature, tertiary amine and monomer concentration, on polymer yields and molecular weights was studied. Thermal behaviour, in terms of thermal stability of the polyesters and range of mesophase stability, was investigated as a function of the molecular weight of the samples. Thermal treatments and X‐ray diffraction at different temperatures were performed to achieve a better understanding of the transitions characteristic of this polyester. All the samples give a nematic phase; on as‐polymerized specimens a solid‐solid transition was also detected.
Crosslinking reactions of polyphenylene type polymers containing acetyl end‐groups with o‐carboranylmethoxy‐containing organosilazanes
Authors: Teplyakov Mikhail M. , Khotina Irina A. , Dmitrenko Alla V. , Korshak Vasili V. , Ismailov Boris A. , Myakushev Victor D. 
Published: April 2003

AbstractCarborane‐containing oligoorganosilazanes (COS) (20 to 60 wt.‐%) prepared by coammonolysis of (o‐carboranylmethoxy)dichloro(phenyl)silane and trichloro(phenyl)silane (COS 1), or 1‐chloro‐1‐phenyl‐1‐sila‐2,7‐dioxa‐4,5‐(1,2‐carborano)cycloheptane and dichloro(dimethyl)‐silane (COS 2), were used to crosslink polyphenylene type prepolymers on the basis of 4,4′‐oxydiacetophenone and acetophenone (FPP‐1). This allowed the reduction of the crosslinking temperature of FPP‐1 by 100–150°C, retaining a high heat resistance of the final crosslinked polymer. Octamethylcyclotetrasilazane (15 wt.‐%) was used to crosslink the carborane‐containing prepolymers on the basis of 1,2‐bis[4‐(4‐acetylphenoxy)phenyl]‐o‐carborane and acetophenone (FPP‐2) and 1,2‐bis(4‐acetylbenzyl)‐o‐carborane and acetophenone (FPP‐3). At 350°C a polymer was formed with a gel fraction amounting to 94%.
Liquid‐crystalline poly(4‐hydroxybenzoate)s with phenethyl side chains
Authors: Vogel Wilfried , Heitz Walter 
Published: April 2003

AbstractAn important means to decrease the melting point of LC‐polymers is the statistical arrangement of substitutents along the chain. Thermotropic liquid‐crystalline poly(4‐hydroxybenzoate)s bearing one phenethyl substituent in different positions of the monomer were synthesized via melt polycondensation. The relation between the arrangement of the substituent along the polymer backbone and the properties of the polyesters was investigated. The two homopolyesters with the substitutent either in 2‐ or 3‐position reveal highly crystalline and poorly soluble products. In contrast to this, the random copolyester is an amorphous and well soluble polymer.
Targetable photoactivatable drugs, 2. Synthesis of N‐(2‐hydroxypropyl)methacrylamide copolymeranti‐thy 1.2 antibody‐chlorin e6 conjugates and a preliminary study of their photodynamic effect on mouse splenocytes in vitro
Authors: Krinick Nancy L. , R̆íhová Blanka , Ulbrich Karel , Strohalm Jir̆í , Kopec̆ek Jindr̆ich 
Published: April 2003

AbstractTwo N‐(2‐hydroxypropyl)methacrylamide (HPMA, 1) copolymer‐chlorin e6‐anti‐Thy 1.2 antibody conjugates were synthesized. They differ in the method of antibody binding. In conjugate 11, the polyclonal anti‐Thy 1.2 antibody was bound via Nϵ‐amino groups of lysine residues. Conjugate 14 contained anti‐Thy‐1.2 antibodies bound via oxidized carbohydrate groups present near the hinge region in the Fc part of the antibody molecule. The photodynamic activity of these conjugates towards mouse splenocytes in vitro was compared with the activity of a nontargetable HPMA copolymer‐chlorin e6 conjugate (15) and free chlorin e6. Whereas free chlorin e6 was cytotoxic both when kept in the dark and when splenocytes were irradiated, the binding of the drug to HPMA copolymers considerably decreased its cytotoxicity in the dark. Conjugates 11 and 14 containing targeting polyclonal anti‐Thy 1.2 antibodies were more biologically active compared to the nontargetable conjugate 15. Conjugate 14, which contained anti‐Thy 1.2 antibodies bound at a specific location was the most active both in its photodynamic effect on viability of splenocytes and/or suppression of the primary antibody response of mouse splenocytes towards sheep red blood cells in vitro. The results demonstrate the importance of the chemistry of antibody binding on the biological activity of targetable polymeric drugs.
Interaction between DNA and biometal ions. Variations of structural and macromolecular parameters
Authors: Kornilova Svetlana V. , Blagoi Yuri P. , Shkorbatov Alexander G. 
Published: April 2003

AbstractThe interaction of Mg2+, Ca2+, Mn2+, and Cu2+ ions with the DNA macromolecule is studied in a wide range of ionic strengths, 2 · 10−4 to 10−1 mol · 1−1. It is shown that the observed considerable changes in the intrinsic viscosity and the excluded volume parameter of DNA are due to the screening of the phosphate groups and nitrogen bases of DNA during the direct binding of the ions. The bivalent ion binding to DNA leads to suppression of the effects of the long‐range interactions in the macromolecules at concentrations two or three orders of magnitude lower than those for monovalent ions. The intrinsic viscosity and the excluded volume parameter are universally dependent on the ion binding degree.
Molecular structure of plasticizers and antiplasticization
Authors: Suvorova Anna I. , Hannanova Elvira G. 
Published: April 2003

AbstractPlasticization of the polycarbonate of bisphenol A (1) by dibutyl 4,4′‐ethylenedibenzoate (2) and dibutyl 4,4′‐stilbenedicarboxylate (3) was studied in order to establish the influence of the molecular rigidity on the antiplasticization phenomenon. UV spectroscopy, dielectric and mechanical properties proved that a rigid trans‐configuration of the “plasticizer” molecules and a strong interaction enhance antiplasticization.
Model reactions of pyridinecarboxylic acids with glycidyl phenyl ether
Authors: Hsu Ying Gev , Chen Keng Ming 
Published: April 2003

AbstractThe reactions of 3‐pyridinecarboxylic acid (nicotinic acid, NA) and 4‐pyridinecarboxylic acid (isonicotinic acid, ISNA) with 2,3‐epoxypropyl phenyl either (glycidyl phenyl ether, GPE) were studied by means of high performance liquid chromatography (HPLC). It is found that both reactions involve two‐step mechanisms and have induction periods. Two products, pyridinium salt and ester, are obtained in each study. The formation of pyridinium salt is the cause of the occurrence of the induction period. After the induction period, the kinetics of the reaction is second order. Pyridinium ions do not form complexes with carboxylate ions of pyridinecarboxylates but form activated complexes with the hydrogen‐bonded complexes of pyridinecarboxylic acids and GPE to activate the esterification reactions. The mechanisms of the reactions are discussed in detail.