bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyelectrolyte complexes from poly(N‐ethyl‐4‐vinylpyridinium bromide) and poly(sodium methacrylate). A stopped‐flow/light scattering investigation
Authors: Trinh Cam Khon , Schnabel Wolfram
Published: April 2003

Time‐resolved light scattering measurements performed in conjunction with the stopped‐flow method revealed information on the formation of polyelectrolyte complexes (PECs) of the weak polyelectrolyte (PE) couple poly(N‐ethyl‐4‐vinylpyridinium bromide) and poly(sodium methacrylate). The stability of the PECs depends, apart from other parameters, on the total ionic strength of the solution [I], the PE concentration and the concentration ratio (Φ) = [PVPE]/[PMA]. On the basis of Φ‐[I] diagrams, obtained for three PE combinations differing in average molar mass, the stability of PECs is characterized by the regimes A, B and C referring to conditions, where PECs are quite stable and water‐insoluble (A), PECs are not very stable and water‐soluble (B) and PECs are instable (not formed). The course of the curves separating regime A from regime B reflects the action of two competing effects regarding the stability of PECs, namely the increase in charge density and the increase in ion condensation with growing total ionic strength: Kinetic measurements revealed that, at low ionic strength right upon mixing, supramolecular complexes and later large aggregates are formed. The aggregates undergo rearrangements leading eventually to smaller complexes. At high ionic strength aggregates are formed rather slowly after mixing. This behavior is related to ion condensation. PECs can form only after the small ions occupying the charged sites at the PE chains are removed. Detachment of small ions from PE chains is a relatively slow process and is the rate‐determining step in PEC formation at moderately high ionic strength of the solution.
Studies of lyotropic liquid crystalline mesophases of some novel regioselective substituted cellulose derivatives, 1. Synthesis and characterization
Authors: Aust Nicolai , Derleth Christina , Zugenmaier Peter
Published: April 2003

Novel regioselective substituted cellulose derivatives, suitable for investigations of their liquid crystalline phase behaviour, were synthesized. The derivatives, tricarbanilates with varying substituents at the phenolic residue, were characterized according to their molecular weight and molecular weight distribution by means of size exclusion chromatography coupled with low angle laser light scattering (SEC/LALLS). A simple new method is presented, which allows the calculation of the constants K and a of the Staudinger‐Mark‐Houwink (SMH) equation, the viscosity‐average molecular weight Mη as well as the intrinsic viscosity [η] from the light scattering calibration curve of an SEC experiment. The calculated values of the intrinsic viscosity are in good agreement with those derived from measurements with a low‐shear viscometer. A plot [η] vs. weight‐average molecular weight Mw shows, that a substitution at the C‐2 and C‐3 position of the glucosic unit with 3‐chlorocarbanilate leads to a well pronounced enlargement of the polymer dimensions which is mirrored by larger values of [η] at the same Mw as compared with other cellulose derivatives.
A study on the effect of Cu2+ ions on the stability of triple helix poly[(riboadenylic acid):2 poly(riboinosinic acid)]
Authors: Yang Pin , Hua Erbing , Yang Binsheng
Published: April 2003

The effect of Cu2+ on the stability of the triple‐stranded helical structure of poly[(riboadenylic acid): 2 poly(riboinosinic acid)] poly(A : 21) was studied by means of circular dichroism spectroscopy and ultraviolet spectroscopy. The experimental results show that Cu2+ induces the hyperchromicity of poly(A : 2I) and causes the melting temperature Tm of poly(A : 2I) to decrease with increasing Cu2+ concentration. At the ratio of the concentration of Cu2+ to that of phosphate in poly(A : 2I), rt = 0, poly(A : 2I) is stable, is stable, at rt = 0.27, poly(A : 2I) decays in poly(A) and 2 poly(I), and at rt = 1.6, there is a racemate.
Polyhalide derivatives of poly[N‐(2‐aminoethyl)‐acrylamido]triethylammonium resins as iodinating reagents
Authors: Mitra Sudha Sumi , Sreekumar Krishnapillai
Published: April 2003

Poly[N‐(2‐aminoethyl)acrylamido]triethylammonium dichloroiodate, tetrachloroiodate and dibromoiodate resins have been developed as a new class of heterogeneous reagents. The use of the polyhalide derivatives for the selective iodination of aromatic amines and phenols is described. The influence of the various reaction parameters including nature of the solvent, effective molar concentration of the reagent and temperature were investigated to find out the optimum reaction conditions for achiveing selectivity for monoiodination.
Kinetic studies of the injection of comonomers during polymerization of ethene and propene with MgCl2‐supported Ziegler‐Natta catalysts
Authors: Wester Thale Sofie , Ystenes Martin
Published: April 2003

The effects of injecting ethene, propene, 1‐hexene, 2‐methylpropene, 3,3‐dimethyl‐1‐butene, cis‐2‐butene, trans‐2‐butene, 2,3‐dimethyl‐2‐butene, cyclopentene, styrene, 1,3‐butadiene and 1,4‐pentadiene during polymerizations of ethene and propene have been investigated. Catalysts used were a supported MgCl2/EB/TiCl4 ballmilled catalyst and precipitated MgCl2/2‐EH/TiCl4/DIBP catalysts activated with triethylaluminium in presence of EB. (EB = ethyl benzoate, 2‐EH = 2‐ethylhexanol, DIBP = diisobutyl phthalate). The polymerizations were performed at 50°C, in a heptane slurry at 1 atm (1.00 · 105 Pa) total pressure.

The instantaneous polymerization rate was observed by continuous monitoring of the monomer consumption, the time resolution of the measurements being less than one second. Two different kinetic effects can be observed after injection of the comonomer. First there is an immediate rate change, usually a rate reduction. Then a secondary effect may follow, which is a slow, and sometimes significant and persistent, activation. The two effects obviously have different causes, and for none of these we found single causes that can explain all the observations. The strongest immediate effect was observed after addition of dienes and indicates a direct association of the comonomer to the active center. A marked nonlinearity in the response may hint to inhomogeneity in the structural environment of the active centers. Addition of α‐olefins during ethene polymerization gave the strongest secondary effect. In general the immediate effects were stronger during propene polymerization than during the polymerization of ethene. A significant difference in the effects of cis‐2‐butene and trans‐2‐butene in the polymerization of propene indicates that steric effects may be important.
Monomolecular and bimolecular termination in the polymerization of di(meth)acrylates
Authors: Andrzejewska Ewa , Bogacki Mariusz B.
Published: April 2003

The termination mechanism in the polymerization of a series of analogous di(meth)‐acrylates differing only by the type of the heteroatom (S or O) in the ester group was investigated. The experimental method was based on differential scanning calorimetry measurements of photochemically initiated polymerization. The ratio of the bimolecular termination and propagation rate constants k/kp and/or the monomolecular termination rate constant k were determined according to three termination models (monomolecular, bimolecular, and mixed). Statistical techniques were used for choosing between the models to find out by which mechanism (monomolecular, bimolecular or mixed) the termination occurs. The results obtained prove than monomolecular reaction is an important termination way in the polymerization of multifunctional monomers and must be taken into account when kinetic constants are determined, even at low degree of conversion. The sulfur‐containing monomers are characterized by much lower k values than the analogous sulfur‐free monomers.
Thermal cis‐trans isomerization and temperature‐dependent phase behaviour of polyisoprene‐polyacetylene solutions
Authors: Dai Liming
Published: April 2003

Polyacetylene can be solubilized by making copolymers with polyisoprene via anionic polymerization of isoprene using BuLi as the initiator, followed by Ziegler‐Natta copolymerization of acetylene onto the polyisoprenyllithium chains using either Ti(OBu)4 or CoCl2. In the present study, the effects of temperature on cis‐trans isomerization of the polyacetylene blocks and the phase behaviour of the PI‐PA copolymers in solution were investigated. We found that isomerization of the cis‐polyacetylene blocks in a solution of the PI‐PA copolymer is retarded by some intramolecular barriers, making the cis‐isomer rather stable. Reducing the temperature below about 12°C was found to cause a phase transformation from the worm‐like structure to spherical micelles in solution.
Acrylonitrile‐sodium methallylsulfonate copolymer in dimethyl sulfoxide. NMR approach to the phase diagram
Authors: Viallat Annie , Margulies Monique Marie , Addad Jean‐Pierre Cohen , Thomas Michel
Published: April 2003

The temperature and concentration dependences of the physical state of solutions of an acrylonitrile‐sodium methallylsulfonate copolymer in dimethyl sulfoxide (DMSO) are investigated from calorimetric and NMR measurements within the temperature range where the solvent crystallization and/or polymer ordering in solution can occur. (i) For solutions of global monomeric molar fraction higher than 0.45, ordering of a fraction (<0.15) of the polymer can occur. Temperatures of polymer melting and polymer ordering are reported. The composition of the liquid phase coexisting with ordered polymer is found to depend on the global concentration of the solution. At low temperatures, i.e., at temperatures for which DMSO crystallizes, three phases are found to coexist: ordered polymer, crystalline DMSO and disordered solution. (ii) For solutions of global monomeric molar fractions smaller than 0.45, the polymer is disordered at all temperatures. Crystallization of pure DMSO is observed and the melting/crystallization curve of DMSO is determined by NMR and described with simple thermodynamic considerations.
Rheo‐optical fourier transform infrared spectroscopy of polyurethanes and their blends with polyolefins
Authors: Fischer Wolfgang B. , Pötschke Petra , Pompe Giesela , Eichhorn Klaus‐Jochen , Siesler Heinz W.
Published: April 2003

Rheo‐optical Fourier transform infrared spectroscopy was used to analyze the orientational behavior of hard and soft segments of thermoplastic poly(ether urethane)s (TPU‐Et) and poly(ester urethane)s (TPU‐Es) and their blends with a 20 mass‐% contribution of either polyethylene (PE) or polypropylene with an amorphous rubber phase (PP). The blends show a reduced stress level, lower elongation‐to‐break and a lower degree of orientation of the segments — especially for the TPU‐Es blends — compared to those of pure TPU's when uniaxially elongated. Blends of TPU‐Et with PP show reduced stress but increased strain compared to pure films of TPU‐Et. This is caused by an improved adhesion of the rubber phase in the polypropylene and the polyether phase of TPU‐Et. Optical micrographs visualize deformed polyolefin particles in elongated films of TPU‐Et/PP blends. In the TPU‐Et/PP blend we could achieve equivalent orientation for the polyolefin phase and the segments of TPU‐Et caused by this higher phase adhesion compared to the other blends. Orientation functions (OF's) of absorption bands which specifically represent hard or soft polyurethane segments or which are characteristic of the polyolefin phase have been calculated to monitor the molecular alignment due to the mechanical treatment.
Photoreactive diimide models of benzhydroltetracarboxylic dianhydride: Synthesis, characterization and photopolymerization
Authors: Rames‐Langlade Géraldine , Monjol Pierre , Sekiguchi Hikaru , Mercier Régis , Sillion Bernard
Published: April 2003

The synthesis, characterization and photopolymerization of bisimide compounds carrying a photoreactive methacryloyl group were investigated. Those photoreactive diimide models, derived from benzhydroltetracarboxylic dianhydride (1), were prepared in N‐methyl‐2‐pyrrolinone (NMP), either by a thermal or by a chemical imidization. In the thermal method, the bisimide carrying benzhydrol group was first synthesized by condensation of 1 with 4‐tert‐butylaniline at 180°C. The hydroxyl group was then chemically modified by an excess of methacryloyl isocyanate (6) in NMP. In the chemical method, a photosensitive dianhydride, derived from the reaction between 1 and 6, was prepared and then condensed with aniline at 25°C by means of propionic anhydride with triethylamine, which leads to the formation of the corresponding imide. By means of IR, the photopolymerization of the methacrylic double bond that takes place in the presence of a photoinitiator under irradiation at 365 nm was then investigated. It was found that the most effective photoinitiator for these photoreactive model compounds is the Michler's ketone/triethanolamine system. The further aim of the present investigation is to prepare novel negative‐type photosensitive polyimides.
Determination of the polydispersity of poly(tetramethylene ether) glycol by means of high‐performance liquid chromatography and curve fitting
Authors: Graf Hermann , Schulz Günter , Plitzko Klaus‐Dieter
Published: April 2003

A modified high‐performance liquid chromatographic method for the analysis of the molecular weight distribution of poly(tetramethylene ether) glycol (PTMEG) is described. The weight percentage of the polymer homologues, up to a degree of polymerization X of 79, can be determined. This covers about 93 wt.‐% of the material with number‐average molecular weight M̄n = 1000, but only 65 wt.‐% of that with M̄n = 2000. Direct calculation of the means M̄n, M̄w, and M̄z from these percentages leads to erroneous results because of the neglect of the summands with X > 79. Therefore, a curve fit is performed and M̄n, M̄w, and M̄z are calculated from the fitting parameters. From the known molecular weight distribution functions, Wesslau's and Kubin's function yielded the best fit. The results of this method are compared with those of gel permeation chromatography, viscosimetric measurements, supercritical fluid chromatography, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and evaporative light scattering detector methods. The scope and the limitations of this method are discussed.
Liquid crystalline siloxane macromolecules with steroidal mesogens
Authors: McHugh Colin M. , Tomlin David W. , Bunning Timothy J.
Published: April 2003

Several new vinyl and allyloxybenzoate steroidal‐based mesogens were synthesized and attached to cyclic tetramethylhydrosiloxane rings using standard hydrosilation chemistry. The steroids examined, all derivatives of cholesterol, 3β‐hydroxy‐24α‐ethylcholest‐5,22‐diene, 3α‐hydroxyandrostan‐17‐one, 3β‐hydroxyandrostan‐17‐one, and 3β‐hydroxypreg‐5‐en‐20‐one were chosen because structural variations in the 17‐β aliphatic chain of the tetracyclic core were present. The synthesis and phase behavior of these mesogenic compounds are discussed with respect to previous systematic investigations linking structural features to mesomorphic behavior. Macromolecular cyclic siloxanes derivatized with these steroidal mesogens were characterized for liquid crystallinity using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X‐ray diffraction. Compounds with 17‐β ketone substituents possessing vinylbenzoate spacer groups do not exhibit liquid crystallinity, whereas similar compounds with allyloxybenzoate spacer units exhibit broad smectic mesophases. The ability to from partially or fully interdigitated layered mesophases with respect to the 17‐β substituent is examined using X‐ray diffraction. The results indicate the length and flexibility of the 17‐β group must be considered along with the nature of the spacer group in determining phase behavior.
Infrared spectra and compositional analysis of styrene/2‐ethylhexyl acrylate copolymers
Authors: Chatzi Eleni G. , Kammona Olga , Kentepozidou Anastasia , Kiparissides Costa
Published: April 2003

Compositional analysis of a series of free‐radical emulsion polymerized styrene/2‐ethylhexyl acrylate copolymers following close to random polymerization statistics was accomplished by elemental analysis, UV and IR. A satisfactory agreement was obtained between the three independent techniques. IR calibration curves were constructed based on sequence‐independent infrared absorption bands determined by plotting peak intensities against the number fraction of each of the possible monad, dyad and triad structures in the copolymers. The intensities of the skeletal ring breathing vibration of styrene units at 1 602 cm−1 as well as the CO stretching vibration of the saturated ester group of 2‐ethylhexyl acrylate units at 1158 cm−1 were shown to be representative of the copolymer composition, whereas the position and shape of the carbonyl stretching band at 1730 cm−1 were shown to depend on both the composition and the monomer sequence distribution. A calibration curve not requiring the use of an internal thickness band was obtained by plotting the ratio of absorbances of the 1 602 cm−1 and the 1 158 cm−1 peaks as a function of the mole ratio of the corresponding monomers in the copolymer.
Synthesis of block copolysaccharides by ring‐opening polymerization of anhydro sugar derivatives
Authors: Choi Yoon Soung , Uryu Toshiyuki , Yoshida Takashi
Published: April 2003

Ring‐opening polymerization of anhtydro sugar derivatives was carried out with Lewis acid catalysts to produce block copolysaccharides. Polymerization of 1,4‐anhydro‐2,3‐diO‐tert‐butyldimethylsilyl‐α‐D‐ribopyranose (ADSR) with boron trifluoride etherate proceeded linearly and rapidly within 1 h to give silylated 1,5‐α‐D‐ribofuranan in almost quantitative yield. Although the molecular weight distribution of the polymers was not narrow (M̄w/M̄n = 1.61 ∼ 1.73), the relationship between monomer conversion and number‐average molecular weight was linear, indicating livingness of the ring‐opening polymerization. Thus, an AB block copolysaccharide composed of two different polysaccharide chains was synthesized for the first time in the two‐stage polymerization of ADSR and 1,4‐anhydro‐2,3‐di‐O‐benzyl‐α‐D‐ribopyranose (ADBR) at −40°C. Block copolysaccharides having different stereoregular monomeric units (i.e., ribopyranosidic and ribofuranosidic units) were obtained by block copolymerization of 1,4‐anhydro‐2,3‐O‐benzylidene‐α‐D‐ribopyranose (ABRP) and ADBR. In addition, a block heteropolysaccharide consisting of (1 → 5)‐α‐D‐xylofuranan and (1 → 5)‐α‐D‐ribofuranan was prepared from 1,4‐anhydro‐2,3‐di‐O‐tert‐butyldimethylsilyl‐α‐D‐xylopyranose (ADSX) and ADBR by making use of this polymerization technique. The GPC curves of block copolymers shifted toward the higher molecular weight region, maintaining the molecular weight distributions of the corresponding homopolymers in the first stage of polymerization. The number‐average degree of polymerization of the polyADSR‐block‐polyADBR was estimated to be 113 for ADSR and 221 for ADBR unit. The 13C NMR spectra of the resulting block copolymers were different from those of the random copolymers.
Polyanhydrides 10. Aliphatic polyesters and poly(ester‐anhydride)s by polycondensation of silylated aliphatic diols
Authors: Kricheldorf Hans R. , Gomourachvili Zaza
Published: April 2003

A new class of biodegradable copolyesters was prepared by polycondensation of sebacoyl chloride with mixtures of silylated isosorbide and silylated O,O′‐bis(2‐hydroxyethyl)hydroquinone in bulk. A class of poly(ester‐anhydride)s was synthesized from sebacoyl chloride and mixtures of silylated O,O′‐bis(2‐hydroxyethyl)hydroquinone and silylated 4‐hydroxybenzoic acid. A second class of poly(ester‐anhydride)s was obtained by polycondensation of sebacoyl chloride with mixtures of silylated isosorbide and silylated 4‐hydroxybenzoic acid. The molar ratio of anhydride and ester groups was varied via the proportion of 4‐hydroxybenzoic acid in the feed. All polyesters were characterized by inherent viscosities, elemental analyses, 1H NMR and IR spectra, WAXS and DSC measurements. All polyesters proved to be semicrystalline materials.
Molecular characterization and chain flexibility of linear polyacetals containing poly‐perfluoro(oxymethylene‐ran‐oxyethylene) macromers
Authors: Turri Stefano , Sanguineti Aldo , Levi Marinella
Published: April 2003

Proper samples of polyacetals containing poly‐perfluoro(oxymethylene‐ran‐oxye‐thylene) macromers were synthesized by polycondensation of a fluorinated macrodiol (Fomblin ®ZDOL) and formaldehyde and fractionated by solvent/non‐solvent separation. Of eight selected fractions, whose compositional homogeneity was checked by 19F and 13C NMR spectroscopy, the following measurements were performed: Mw by static light scattering; retention volume Vr at GPC; [η] by conventional capillary viscometry; glass transition temperature by DSC. 1,1,2‐Trichlorotrifluoroethane was used for solution measurements, from which the second virial coefficient A2, the linear Mw−Vr equation of GPC calibration, and the [η]‐Mw Mark‐Houwink‐Sakurada constants K and a were determined. From [η] and Mw data, the Kθ value (unperturbed state) was estimated by the Stock‐mayer‐Fixman‐Burchard extrapolation procedure, and the characteristic ratio C∞ of polyacetals containing poly‐perfluoro(oxyethylene‐ran‐oxymethylene) macromers was calculated through the Fox‐Flory equation. Factors related to chain flexibility were finally discussed and compared with those of corresponding fully perfluorinated copolyethers.
Etude de la dégradation thermique de deux copolymères réalisés entre l'acrylonitrile ou le méthacrylonitrile et l'α‐acétoxyacrylate de méthyle. Analyse thermogravimétrique et chromatographique en phase gazeuse couplée à la spectrométrie de masse
Authors: Ouillon Isabelle , Raihane Mustapha , Zerroukhi Amar , Bionon Bernard
Published: April 2003

The thermal degradation behaviour of two copolymers poly(acrylonitrile‐co‐methyl α‐acetoxyacrylate) and poly(methacrylonitrile‐co‐methyl α‐acetoxyacrylate) was studied by means of dynamic and isothermal thermogravimetry in the range 246–302°C and gas chromatography/mass spectrometry analysis. The main volatil products are acetic acid and methyl acetate and methanol in minor amounts. There is no monomer from the first copolymer. The global reaction order is zero over a wide range of conversion (α = 0,1 – 0,6), then it is one for α > 0,7, with activation energies of 160,5 and 142,9 kJ ˙ mol−1, respectively. Some amount of comonomers was found in addition in the case of the second copolymer. The kinetic law may be written as:

where A and C are constants for every temperature. The global activation energy was found to be 127,0 kJ ˙ mol−1. A kinetic model of a one order reaction with a partial auto catalytic character allows a very good fit of the experimental data with the theoretical curves over a wide range of conversion (α = 0,1–0,8).
Liquid crystal properties of poly(2‐vinylpyridine) fully quaternized with a mesogenic group
Authors: Bravo‐Grimaldo Elda , Navarro‐Rodriguez Dámaso , Guillon Daniel
Published: April 2003

Two poly(2‐vinylpyridine)s fully quaternized with a ω‐(4′‐methoxy‐4‐biphenylyloxy)‐alkyl group (alkyl chain of 9 and 11 carbon atoms) have been synthesized by the well known spontaneous polymerization of vinylpyridinium salts. When heated, these polymers (P2VPC9 and P2VPC11) show thermotropic liquid crystal properties. According to the X‐ray diffraction data, the observed smectic mesophase in both polymers is of the type A (SA). Results are discussed in comparison with other molecular and polymeric pyridinium salts previously described. A molecular arrangement model for the P2VP derivatives is proposed.
Methylaluminoxane: NMR analysis, cryoscopic measurements and cocatalytic ability in ethylene polymerization
Authors: Tritto Incoronata , Méalares Christel , Sacchi Maria Carmela , Locatelli Paolo
Published: April 2003

Methylaluminoxane (MAO) solutions containing known amounts of AlMe3 and solutions of different MAO samples were characterized by several methods: (a) low temperature 13C NMR analysis; (b) determination of the molecular weight of the MAO samples by cryoscopy in benzene; (c) titration of AlMe3 using 31P NMR analysis of the AlMe3 · PPh3 complex (PPh3 = triphenylphosphine) formed after addition of defined amounts of PPh3 to the MAO solutions. The results confirm the disproportionation reaction caused by AlMe3 addition. The MAO molecular weights are shown to decrease after the AlMe3 addition according to a linear relationship.

The cocatalytic ability of these characterized MAOs was tested in ethylene polymerization catalyzed by rac‐Et(ind)2ZrCl2 (ind = indenyl) and the influence of the AlMe3 content, the “type” and the “aging” of MAO is correlated to the cocatalytic performance.
Synthesis and characterization of poly(arylene ether sulfone amide)s
Authors: Hsiao Sheng‐Huei , Huang Perng‐Chih
Published: April 2003

Methyl‐substituted or unsubstituted aromatic dicarboxylic acids and diamines containing ether and sulfone linkages between phenylene units were used alone or in combination with p‐phenylenediamine, m‐phenylenediamine, terephthalic acid, and isophthalic acid to prepare flexible or semirigid aromatic polyamides by direct polycondensation activated by triphenyl phosphite and pyridine. The inherent viscosities of the obtained polymers ranged from 0.40 to 1.01 dL/g. The wholly flexible polyamides are amorphous, are readily soluble in N,N‐dimethylacetamide, dimethyl sulfoxide, and m‐cresol, and can afford transparent, flexible, and tough films by solution‐casting. The polyamides prepared from p‐phenylenediamine or terephthalic acid are partially crystalline and melt around 410°C. Differential scanning calorimetry shows glass transition temperature in the 202–255°C range for the wholly flexible polyamides. All the polyamides are thermally stable in excess of 400°C. The methyl‐substituted polyamides had higher glass transition temperatures, but lower initial decomposition temperatures, than the corresponding unsubstituted polyamides.
Preparation of hydrolyzed pH responsive ion track membrane
Authors: Tamada Masao , Asano Masaharu , Spohr Reimar , Vetter Johann , Trautmann Christine , Yoshida Masaru , Katakai Ryouichi , Omichi Hideki
Published: April 2003

The porous copolymer films of N‐methacryloyl‐L‐alanine methyl ester and diethyleneglycol‐bis‐allylcarbonate (diallyl oxydiethylene dicarbonate) were hydrolyzed with 1 M NaOH solution for 40 min at 25°C. The pores of the films showed pH response in diameter. The pore diameter of 3,7 μm in the buffer solution of pH 3 was closed completely at pH 5.
Transcrystallinity of thin films of isotactic poly(propylene)
Authors: Setz Stefan , Schnell Rupert , Thomann Ralf , Kressler Jörg , Mülhaupt Rolf
Published: April 2003

The isothermal crystallization behavior of thin films of isotactic poly(propylene) between plates coated with chromium, Teflon® or gold is studied by polarized light microscopy. At all contact surfaces between poly(propylene) and the other materials, transcrystallinity can be observed and competes with the growth of entities which originate in the bulk phase. The shape of these entities can be described by two intersecting paraboloids.
Synthesis of soluble, all‐trans poly(2,5‐diheptyl‐p‐phenylenevinylene) via metathesis polycondensation
Authors: Thorn‐Csányi Emma , Kraxner Peter
Published: April 2003

The synthesis of substituted poly(p‐phenylenenvinylene) (PPV) was carried out via metathesis polycondensation of 2,5‐diheptyl‐1,4‐divinylbenzene (DHepDVB). A stable molybdenumcarbene complex served as catalyst. The preparation of the educt employed (DHepDPV, 3a) is described. The obtained poly(2,5‐diheptyl‐1,4‐phenylenevinylene) (DHepPPV, 5), an intensely yellow product, has an all‐trans‐configuration and, with a degree of polymerization of ≈ 10 is soluble in conventional organic solvents.
Spectroscopic investigation of diacetylene cross‐linking in polyamide matrices of different configurations
Authors: Gerasimov Genrikh N. , Popova Elena L. , Phomin Sergey M. , Kiryanova Tatyana V. , Teleshov Eduard N.
Published: April 2003

We compared the cross‐polymerization of diacetylene units, incorporated in different ways into polyamide (PA) matrices: as fragments of the PA main chains (PA1) and as pendant groups of the PA main chains (PA2). At room temperature the reaction proceeds only in PA1 via 1,4‐addition (cross‐links I). However at high temperature besides of cross‐links I another type of cross‐links (cross‐links II) is formed, presumably via 1,2‐addition reaction. In PA2 only cross‐links of type II are formed at high temperatures.
A phase polymorphism NSAdI in liquid‐crystalline polymethacrylates with 4′‐trifluoromethoxyazobenzene mesogenic side groups
Authors: Ruhmann Ralf , Thiele Thomas , Prescher Dietrich , Wolff Dietmar
Published: April 2003

The mesophase behaviour of liquid‐crystalline polymethacrylates with 4′‐trifluoromethoxyazobenzene mesogens and alkylene spacers \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {\rlap{--} ({\rm CH}_{\rm 2} \rlap{--} )_n ,n = 2 - 6} \right) $\end{document} in the side chains was investigated and compared with that of the corresponding non‐fluorinated polymers. The fluorinated polymers with spacer lengths n = 5 and 6 are the first side‐group liquid‐crystalline polymethacrylates showing a nematic phase below a smectic A phase.
Self‐oscillating swelling and deswelling of polymer gels
Authors: Yoshida Ryo , Ichijo Hisao , Hakuta Toshikatsu , Yamaguchi Tomohiko
Published: April 2003

Novel gel systems demonstrating rhythmically pulsatile mechanical motion similar to that of a heartbeat were developed. Self‐oscillations of swelling and deswelling for the polymer hydrogels were realized by coupling pH and temperature sensitive hydrogels with a non‐linear chemical reaction in the external solution media. The novel gel dynamics exhibiting cyclic and rhythmical oscillations may establish a new concept for functional materials that work under dynamic oscillating states.
Amphiphilic liquid‐crystalline networks — phase behavior and alignment by mechanical fields
Authors: Fischer Peter , Schmidt Claudia , Finkelmann Heino
Published: April 2003

A cross‐linked polysiloxane carrying non‐ionic amphiphilic side‐groups attached with their hydrophobic end to the polymer backbone is synthesized. The amphiphilic groups are selectively deuterated at the α‐position of the hydrophobic alkyl chains. The phase behavior with water is studied by deuterium nuclear magnetic resonance spectroscopy. A lamellar phase (La) is observed on the low‐water‐concentration side of the liquid‐crystalline regime. The domains of the La‐phase can be aligned macroscopically by uniaxial compression of the sample.
Transition metal catalyzed ring‐opening polymerization of silicon‐bridged [1]ferrocenophanes at ambient temperature
Authors: Ni Yizeng , Rulkens Ron , Pudelski John K. , Manners Ian
Published: April 2003

A new route to poly(ferrocenylsilanes) under mild conditions via the ring‐opening polymerization of silicon‐bridged [1]ferrocenophanes is presented. Catalytic amounts of the transition metal complexes [Rh(cyclooctene)2(μ‐Cl)]2, Pd(1,5‐cyclooctadiene)Cl2, PdCl2 and PtCl2 in C6D6 at room temperature afforded high molecular weight poly(ferrocenylsilanes) (2). In some cases a symmetrical dimer (3) was obtained as a byproduct.
Soft and wet touch‐sensing system made of hydrogel
Authors: Sawahata Kiyoshi , Gong Jian Ping , Osada Yoshihito
Published: April 2003

Mechanical deformation of water‐swollen polyelectrolyte gels with carboxylic groups induces a spontaneous ionization, which in turn produces an electrical potential as large as a few millivolts. On the base of this phenomenon, a tactile sensor capable of lighting a photo diode array according to the amplitude of deformation has been made. This system may offer a soft and wet touch‐sensor due to its soft tissue‐like rheological characteristics.
Copolymerization of styrene and isoprene with Ni(acac)2‐methylalumoxane catalyst
Authors: Endo Kiyoshi , Masaki Koji
Published: April 2003

Copolymerization of styrene (St) and isoprene (IP) with nickel(II) acetylacetonate [Ni(acac)2] and methylalumoxane (MAO) catalyst was investigated. It was found that the Ni(acac)2‐MAO catalyst is effective for the copolymerization of St and IP. From the copolymerization of St (M1) and IP (M2) and IP (M2) with the Ni(acac)2‐methylalumoxane catalyst, the monomer‐reactivity ratios were determined to be r1 = 1,18 and r2 = 0,88, i.e., ideal copolymerization was found to proceed to give perfectly random copolymers without formation of any homopolymer. The microstructure of IP units in the copolymers exhibits high cis‐1,4 contents.
Viscometric study of the coil‐globule transition of poly(N‐isopropylacrylamide) in solutions of surfactant
Authors: Staikos Georges
Published: April 2003

The coil‐globule transition of poly(N‐isopropylacrylamide) (systematic name: poly‐[1‐(isopropylaminocarbonyl)ethylene]) has been viscometrically investigated in low‐concentration aqueous sodium dodecyl sulfate solution. In this environment, even if the macromolecular coils collapse as the temperature increases above the lower critical solution temperature of the polymer, 34°C, the polymer does not precipitate. It seems that the hydrophobically collapsed macromolecular coils do not aggregate, but remain in solution with the aid of surface charges supplied by surfactant ions adsorbed through hydrophobic interactions.
Investigation on the surface orientation of cylindrical microdomains in styrene‐butadiene‐styrene triblock copolymers by scanning force microscopy/transmission electron microscopy
Authors: Gattiglia Ercole , Turturro Antonio , Ricci Davide , Bonfiglio Annalisa
Published: April 2003

The orientation of the microdomains at the free surface of solvent‐cast films of a polystyrene‐block‐polybutadiene‐block‐polystyrene triblock copolymer with cyclindrical morphology was studied by coupling transmission electron and scanning force microscopies (SFM‐TEM). It was found that the cylinders of polystyrene, which are assembled in grains randomly oriented in the bulk, tend to reorient with the main axis perpendicular to the surface. SFM investigation indicates that the hexagonal symmetry of the cylinders is also maintained at the free surface which is characterized by protrusions and corrugation with size and characteristic distances closely related to the cylindrical morphology visible in the bulk. Good quantitative agreement between TEM and SFM measurements is observed.
Poly(silamine)s as new electron‐beam resist materials
Authors: Nagasaki Yukio , Yamazaki Noriyuki , Deguchi Ken‐Ichiro , Kato Masao
Published: April 2003

Several types of poly(silamine)s were prepared and their structure‐characteristics relationships were investigated. When a phenyl ring in the organosilyl unit and/or a cyclic structure in the amino unit was introduced, the glass transition temperatures were increased significantly in order to increase film formability. From the thermogravimetric analysis of the poly(silamine)s, it was found that the thermal decomposition of poly(silamine)s starts at ca. 380–400°C. On electron‐beam irradiation of the poly(silamine) films, degradation of the polymer took place. On the basis of these results, poly(silamine)s can be one of the candidates for new positive‐type polymeric resists.
Study of ionomer blends based on a polyurethane cationomer and an acrylic anionomer
Authors: Mahesh Gopalasamudram Narayanan , Ramesh Subramanian , Radhakrishnan Ganga
Published: April 2003

Polyurethane and polyurethane cationomers were synthesized using 2,3‐dihydroxypyridine and 2,3‐dihydroxypyridine hydrochloride as chain extenders. Poly(butyl methacrylate‐co‐methacrylic acid) was synthesized by free radical solution polymerization and was converted into its sodium salt. The polyurethane cationomer and the acrylic anionomer were blended in different proportions in N,N‐dimethylformamide. Simple blends without ionic groups were also prepared. Miscibility enhancement in these systems was studied by means of differential scanning calorimetry and scanning electron microscopy.
Preparation of liquid crystalline polymers with monosubstituted ferrocenyl pendant groups and generation of unpaired electrons by complexation with tetracyanoethylene in the solid state
Authors: Tanaka Hitoshi , Hongo Takahiro , Hall H. K.
Published: April 2003

Liquid crystalline (LC) polymers with monosubstituted ferrocenyl units in the side chain were prepared by radical polymerizations of the corresponding LC and non‐LC acrylates. It was demonstrated that polymerization is useful for the LC orientation and expands the LC temperature range. In addition, these mesogenic ferrocenes form a complex with tetracyanoethylene (TCNE) to give spin labeled molecules simply by mixing the ferrocenyl compounds with TCNE in the solid state at ambient temperature.
The role of the membrane‐assisted hydrophobic interaction between di‐, tri‐, or tetrapeptide catalysts and amino acid esters for the enhancement of stereoselective hydrolysis reactions
Authors: Ohkubo Katsutoshi , Urabe Kenji , Usui Satoshi , Sagawa Takashi
Published: April 2003

The peptide catalyst having the amino acid sequence (Z‐L‐Leu (or Phe)‐L‐His) was found to be the most stereoselective among the L‐histidyl group‐containing di‐, tri‐, or tetrapeptide catalysts in the hydrolysis of enantiomeric amino acid substrates in vesicular membranes. The role of the membrane‐assisted hydrophobic interaction between the peptide catalyst and enantiomeric substrates for the improvement of the hydrolysis stereoselectivity was demonstrated by means of direct measurements of nuclear Overhauser effect spectroscopy (NOESY) spectra of the interaction system and by the extremely high stereoselectivity itself obtained by intensifying the membrane‐promoted hydrophobic interaction between the catalyst and the substrates.
Structural study on poly(ether ether ketone ketone)‐poly(ether biphenyl ether ketone ketone) copolymers
Authors: Zhang Hongfang , Yang Baoquan , Mo Zhishen , Na Hui , Wu Zhongwen
Published: April 2003

Structures of poly(ether ether ketone ketone)‐poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X‐ray scattering and the one‐dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (nb). When nb = 0.35, invariant Q, long period L, average thickness of crystal lamellae d̄, electron density difference ηc − ηa and degree of crystallinity Wc, x assume minimum values.
Solvent induced structural transitions in a liquid crystalline polyester
Authors: Carotenuto Maurizio , Guadagno Liberata , Vittoria Vittoria , Galli Giancarlo , Chiellini Emo
Published: April 2003

Quenched nematic films of a liquid crystalline polyester were crystallized either thermally or by solvent induced crystallization, and their structural organization was analyzed. All techniques show that the thermal crystallization transforms part of the nematic phase into a crystalline one, the remaining part leaving unchanged. By contrast, the solvent induced crystallization does transform a part of the nematic phase into a crystalline phase, leaving the residual part in a much more disordered state resembling the amorphous state.
Protonation of polyaniline with lightly sulfonated polystyrene
Authors: Fu Yueping , Weiss R. A.
Published: April 2003

Protonation of polyaniline base with lightly sulfonated polystyrene in polar solvents such as dimethyl sulfoxide and N‐methyl‐2‐pyrrolidone was investigated by UV‐Vis absorption spectra. As the molar ratio of sulfonated polystyrene/polyaniline increases, the conversion from polyaniline base form to salt form is observed owing to increased protonation. The isosbestic point clearly shows that quinoid unit and semiquinoid unit are in equilibrium. They are functions of the sulfonic acid concentration and solvent media.
Enzymatic degradation of aliphatic polyesters copolymerized with various diamines
Authors: Nagata Minoru
Published: April 2003

Poly(hexamethylene adipate) copolymers with 10–40 mol‐% (in feed) of aliphatic diamines of various methylene chain lengths were prepared by melt polycondensation. In vitro degradation was performed in buffer solution at 37°C with a lipase and was evaluated by weight loss of the films. The weight loss increased greatly by the copolymerization and showed a maximum at 10 mol‐% of comonomer content. Degradation also increased in a zig‐zag fashion with decreasing number of methylene chains in the diamine comonomers. Both effects on the enzymatic degradation are discussed.
Copolymerization of ethylene and styrene to a nearly‐alternating crystalline copolymer
Authors: Oliva Leone , Izzo Lorella , Longo Pasquale
Published: April 2003

An almost alternating stereoregular copolymer can be obtained by copolymerizing ethylene and styrene with the catalyst ethylenebis(1‐indenyl)zirconium dichloride activated by methylaluminoxane at −25°C. The regular microstructure pointed out by the NMR spectrum allows the copolymer to crystallize as shown by calorimetric and X‐ray diffraction measurements.
Recruitment of enzyme activity in albumin by molecular imprinting
Authors: Ohya Yuichi , Miyaoka Junya , Ouchi Tatsuro
Published: April 2003

The catalytic activity of bovine serum albumin (BSA) modified physically by molecular imprinting using transition‐state analogue (TSA) as a template molecule was studied. The resultant imprinted serum albumin (Imp‐BSA) showed the rate acceleration of dehydrofluorination reaction from (4R,4S)‐4‐fluoro‐4‐(4‐nitrophenyl)butan‐2‐one (1) and followed the type of Michaelis‐Menten reaction in ethyl acetate solution. The enzymatic activity of Imp‐BSA was competitively inhibited by (4R,4S)‐4‐hydroxy‐4‐(4‐nitrophenyl)butan‐2‐one (4).
The crystal structure and drawing induced polymorphism in poly(aryl ether ketone)s, 3. Crystallization during hot‐drawing of poly(ether ether ketone ketone)
Authors: Wang Shanger , Liu Tianxi , Mo Zhishen , Wang Junzuo , Xu Feng , Wu Zhongwen
Published: April 2003

The evolution of crystallinity and polymorphism during hot‐drawing of amorphous poly(ether ether ketone ketone) (PEEKK) as a function of strain rate, draw ratio, and temperature was investigated. In modification I, the competition of chain extension and molecular alignment is responsible for the strain rate and temperature dependence. Modification II crystallization is basically controlled by chain extension during stretching. The former can be transformed into the latter via relaxation during stretching or annealing at elevated temperature.
Redox polymerization of acrylamide to high molecular weights: effect of the mineral clay montmorillonite
Authors: Bera P. , Saha S. K.
Published: April 2003

Polymerization of acrylamide with the redox couple Fe(III)/thiourea in the presence of the mineral clay montmorillonite has been investigated. Polyacrylamide is obtained in good yield having molecular weight (ca. 0.7–2.5 × 106) approximately one order of magnitude higher than without clay. Apparently, the locus of polymerization is the interlayer space of the clay.
Polymerization of N‐(2,3,4,5,6‐pentafluorophenyl)‐maleimide
Authors: Hagiwara Tokio , Kawashima Naoyuki , Hamana Hiroshi , Narita Tadashi
Published: April 2003

A novel fluorine‐containing polymer, poly[N‐(2,3,4,5,6‐pentafluorophenyl)maleimide], was prepared by the anionic polymerization of N‐(2,3,4,5,6‐pentafluorophenyl)maleimide (PFPMI). Anionic polymerization with alkali metal tert‐butoxides gave poly(PFPMI) in 14–32% yield. Phenyllithium and sec‐butyllithium also afforded poly(PFPMI). No polymer was obtained with a radical initiator such as 2,2′‐azoisobutyronitrile. The polymerization took place only via the vinylene group of PFPMI and no appreciable side‐reaction occurred. The obtained poly(PFPMI) shows unimodal molecular weight distribution and begins to decompose at 325°C.
Synthesis of an amphiphilic triarm star copolymer based on polystyrene, poly(ethylene oxide) and poly(ε‐caprolactone)
Authors: Lambert Olivier , Dumas Philippe , Hurtrez Guy , Riess Gérard
Published: April 2003

The synthesis of an amphiphilic triarm star copolymer based on polystyrene, poly(ethylene oxide) and poly(ε‐caprolactone) block has been achieved by a novel strategy which consists in the preparation of a diblock copolymer, polystyrene‐block‐poly(ethylene oxide), having a protected anionic initiator group at the junction of the two blocks. After deprotection, this function is activated by a coloured and weakly basic carbanion. The generated alcoholate initiates the ε‐caprolactone anionic polymerization.
Complex formation of poly(ε‐caprolactone) with cyclodextrin
Authors: Harada Akira , Kawaguchi Yoshinori , Nishiyama Toshiyuki , Kamachi Mikiharu
Published: April 2003

Poly(ε‐caprolactone) was found to form inclusion complexes with α‐cyclodextrin to give crystalline compounds. The complexes are stoichiometric one‐to‐one (cyclodextrin: monomer unit) compounds. The yields of the complexes decreased with increasing the molecular weight of the polymer. They were characterized by IR, 1H NMR, 13C CP/MAS NMR, and X‐ray diffraction. The inclusion modes are discussed.
Pd(II)‐catalyzed copolymerization of a norbornadiene derivative with substituted phenylacetylenes
Authors: Tamura Hiroshi , Kanamaru Hitoshi , Hirose Osamu , Yamamoto Seika
Published: April 2003

Copolymerizations of diethyl 7‐oxabicyclo[2.2.1]hepta‐2,5‐diene‐2,3‐dicarboxylate (DOHDD) with phenylacetylene (PA) or p‐methoxyphenylacetylene (MeOPA) were successfully performed in chloroform using PdBr2 as catalyst. The products of reactivity ratios r1 · r2 for poly(DOHDD‐co‐PA) and poly(DOHDD‐co‐MeOPA) are 0.026 and 0.0077, respectively. These values suggest a maximum degree of alternating sequences of 86 and 92% in the two systems, hence a high alternating tendency. It is interesting to note that the present copolymerizations occur by combination of different types of monomer, alkene and alkyne.
Oligo(ether‐sulfones), 2. Synthesis of a novel macrocyclic aromatic ether sulfone bearing two carboxylic groups and the corresponding polyamide via direct condensation of the macrocycle with 4,4′‐diaminodiphenylmethane
Authors: Rodewald Barbara , Ritter Helmut
Published: April 2003

A new macrocyclic arylene ether sulfone bearing two carboxylic groups, 4, was prepared by use of pseudo high dilution techniques. In a first step, 4,4‐bis[4‐(4‐(4‐chlorophenylsulfonyl)phenoxy)phenyl]pentanoic acid (3) was prepared from bis(4‐chlorophenyl)sulfone (1) and an excess of 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (2). Then, the purified trimer 3 was cyclocondensed with 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (2), yielding the bifunctionalized macrocycle 4. The existence of the ring‐shaped molecule was proved by use of MALDI‐TOF, NMR‐ and IR‐spectroscopy. The free carboxylic groups of 4 were used to build up polyamides that contain the macrocycle in the main chain and 4,4′‐diaminodiphenylmethane (5) as an aromatic diamine.
Stereospecific polymerization of styrene using a homogeneous lanthanide catalyst
Authors: Liu Li , Gong Zhi , Zheng Yulian , Jing Xiabin
Published: April 2003

Stereospecific polymerization of styrene was catalyzed by homogeneous neodymium phosphonate [Nd(P507)3]‐H2O‐Al(i‐Bu)3 catalytic system. The polymer was separated into isotactic polystyrene and atactic polystyrene by extracting the latter with boiling 2‐butanone. The conversion of styrene and the yield of isotactic polystyrene (IY) were influenced by the [H2O]/[Al(i‐Bu)3] mole ratio and the solvent polarity. The reaction is first order with respect to monomer at 70°C.