bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermostable block copolymers, 1. Thermotropic poly(ester‐imide) block copolymers
Authors: Eck Thomas , Gruber Heinrich F. 
Published: April 2003

AbstractNew poly(ester‐imide) block copolymers were prepared by polycondensation of aminoterminated poly(ester‐imide) blocks with molecular weights from 700 to 6 000 with terephthaloyl dichloride, isophthaloyl dichloride, 2,6‐naphthalenedicarbonyl dichloride, adipoly dichloride, dichlorodimethylsilane or dichlorotetramethylsiloxane as low‐molecular‐weight difunctional coupling reagents. The poly(ester‐imide) blocks were synthesized from readily accessible monomers. Dependent on block composition, molecular weight of the block (block length) and kind of spacer liquid‐crystalline polymers were obtained with high thermal stability and solubility in polar solvents, yielding tough films with good mechanical properties. The formation of thermotropic mesophases required the proper balance between the rigid blocks and the flexible, kinked or “crankshaft” spacers.
Protein adsorption on a copolymer having pendant monosaccharide groups. Relationship between surface free energy and protein adsorption
Authors: Miyata Takashi , Ootsuki Norihito , Nakamae Katsuhiko , Okumura Masakazu , Kinomura Keisuke 
Published: April 2003

AbstractProtein adsorption on copolymer films having pendant monosaccharide groups was investigated from the viewpoint of surface chemistry. The copolymers were synthesized by the copolymerization of a monomer having a pendant monosaccharide (GEMA) and methyl methacrylate (MMA). The contact angles of methylene iodide and air bubble on the GEMA‐MMA copolymer films were measured in water, and the surface free energy of the copolymer films in water was calculated from the contact angles. With increasing GEMA content, the amount of protein adsorbed on the GEMA‐MMA copolymer films decreased gradually. The relationship between protein adsorption and the surface free energy of the copolymer films in water is discussed. The differences between surface free energy before and after protein adsorption on the copolymer surface is closely related to the amount of adsorbed protein.
Effect of solvent evaporation rate on microphase‐separated structure of segmented poly(urethane‐urea) prepared by solution casting
Authors: Ikeda Yuko , Tabuchi Masato , Sekiguchi Yasuhiro , Miyake Yoshikazu , Kohjiya Shinzo 
Published: April 2003

AbstractA useful instrument for polymer film preparation by solution casting was employed in this study. It enabled us to control the solvent evaporation rate of the polymer solution. By using this instrument, the aggregation of hard segments in segmented poly(urethane‐urea) (SPUU) was investigated. SPUU was prepared from poly(tetramethy1ene oxide), 4,4′‐diphenylmethane diisocyanate and ethylenediamine. The effect of solvent evaporation rate on the microphase‐separated structure of SPUU was elucidated by dynamic mechanical analysis, tensile test, differential scanning calorimetry analysis, small‐angle X‐ray scattering measurement, IR and IR dichroism analyses. The aggregation of hard segments in SPUU was observed to be affected considerably by the solvent evaporation rate of the cast film during the preparation. It was found that the slower the solvent evaporation rate, the higher the aggregation of hard segments to form rigid hard segment domains in SPUU. Nine months after casting, this casting effect still remained on the aggregation state of hard segments of SPUU films, although the interdomain spacing was not influenced by its rate.
Semiflexible main‐chain liquid crystal polymers — the influence of the chemical structure on liquid crystalline properties
Authors: Pörschke Ralf , Höcker Hartwig 
Published: April 2003

AbstractTwo new homologous series of semiflexible main‐chain polyesters on the basis of 4‐hydroxy‐and 4‐carboxycinnamic acid in conjugation with 2‐tert‐butylhydroquinone and alkylene spacers with 3 to 8 methylene groups were prepared by low‐temperature solution condensation. The thermotropic properties were investigated by means of differential scanning calorimetry, polarising microscopy and X‐ray diffraction analysis. The differences in enantiotropic behaviour and thermal stability of the mesophases influenced by the two different linkage groups between alkylene spacer and rigid moiety are discussed in comparison to related systems known from the literature.
Ring‐opening‐closing alternating copolymerization of 2‐methyl‐2‐oxazoline with N‐methyldiacrylamide
Authors: Kadokawa Jun‐ichi , Matsumura Yoshitaka , Kobayashi Shiro 
Published: April 2003

AbstractThis paper describes a new ring‐opening‐closing alternating copolymerization (ROCAC) of 2‐methyl‐2‐oxazoline (five‐membered cyclic imino ether, 1) with N‐methyldiacrylamide (2). The reaction of a 1 : 1 monomer feed ratio proceeded without any added catalyst to give an alternating copolymer 3 having two structural units formed by ring‐opening and ring‐closing (cyclization). The structure of copolymer 3 was determined by 1H, 13C NMR, and IR spectroscopies. The extent of cyclization was at most 65%. The copolymerization was reasonably explained by a mechanism of propagation via zwitterion intermediates.
Biosynthesis of polyesters from some unusual amino acids having linear carbon skeleton by Alcaligenes eutrophus
Authors: Inoue Yoshio , Fujita Masayuku , Ohta Osamu , Nakamura Kazuhiro , Kuroki Hiroko , Yoshie Naoko 
Published: April 2003

AbstractThe biosynthesis of polyesters by Alcaligenes eutrophus from some unusual amino acids having a linear carbon skeleton was investigated. Poly(3‐hydroxybutyrate) (P(3 HB)) or poly(3‐hydroxy‐butyrate‐co‐3‐hydroxyvalerate) (P(3HB‐co‐3HV)) was found to be accumulated in the cells when a‐amino acids with a linear carbon skeleton were used as the sole carbon source. The 3HV mole fractions in copolyesters ranged up to 70%. The following pathway is proposed; the a‐amino acid with a linear carbon skeleton is at first metabolized to form the a‐keto acid by oxidative deamination with transaminase. Then the resulted a‐keto acid is converted into acyl‐CoA by oxidative decarboxylation, and the acyl‐CoA is further metabolized to the 3HB or 3HV unit through the same pathway as the fatty acids. P(3HB) was found to be produced from a‐amino acids having a linear skeleton with odd carbon number, whereas P(3HB‐co‐3HV) arises from a‐amino acids having a linear skeleton with even carbon number. This regularity is inverse to that of fatty acids, because amino acids are decarboxylated, with a reduction of one carbon atom, and then enter into the same synthetic pathway as fatty acids to form polyesters. On the other hand, when ω‐amino acids with a linear carbon skeleton were used as the sole carbon source, accumulation of polyesters was scarcely detected.
Langmuir‐blodgett films of photochromic polyglutamates, 7. The photomechanical effect in monolayers of polyglutamates with azobenzene moieties in the side chains
Authors: Menzel Henning 
Published: April 2003

AbstractMonolayers of the photochromic hairy‐rod type polymers poly(5‐[2‐[4‐(4‐hexylphenylazo)‐phenoxy]ethyl]‐L‐glutamate) (1) and poly(5‐(2‐[4‐(4‐decyloxyphenylazo)phenoxy]ethyl)‐L‐glutamate) (2) were investigated at the air/water interface. At constant surface pressure the monolayers of the polymers exhibit a reversible expansion upon irradiation with ultraviolet (UV)‐light, due to the photoinduced E‐Z‐isomerization of the azobenzene chromophore and a concomitant restructuring of the monolayer. The area increase is lower than expected from the isotherms of monolayers spread from irradiated and non‐irradiated solutions. This can be attributed to a hindrance of photoisomerization, as proved by UV/Vis spectroscopic investigations. The hindrance of photoisomerization, and the photomechanical effect depend on temperature, surface pressure and the nature of the polymer, which all influence the flexibility of the monolayer. From a comparison of the isomerization rate and the rate of the photomechanical effect a two‐step mechanism for the monolayer restructuring is deduced.
In situ poling and polymerization of multifunctional monomers for second harmonic generation
Authors: Kasic James F. , Kannurpatti Anandkumar R. , Bowman Christopher N. 
Published: April 2003

AbstractA novel method for the synthesis of second harmonic generating (SHG) materials is proposed and tested in which liquid, multifunctional monomers with dissolved dopants are poled and polymerized simultaneously. Instead of requiring multiple steps and hours or days to synthesize SHG materials, this technique is able to produce doped guest/host systems in a single step process which takes two minutes or less. In addition, the polymer that is produced is highly crosslinked and provides good thermal and temporal stability of the SHG. To increase the stability of the SHG signal the dopant can be attached to the crosslinked network further decreasing the mobility. Advantages of this process include its simplicity, speed, stability, and the ability to make SHG materials of any thickness by successively polymerizing layers. This work presents a detailed description of the new procedure as well as results for the effect of dopant concentration, the magnitude of the SHG, and the structure of the crosslinked polymer that serves as the dopant host. Also, a method of synthesizing functionalized Disperse Red 1 that can be incorporated as a side chain is presented. Results are presented for the order parameter and SHG stability at room temperature and 100°C.
Poly(vinyl alcohol) functionalized by chloroacetate groups. Coupling of bioactive carboxylic acids
Authors: Arranz Felix , Bejarano Eva María , Sanchez‐Chaves Manuel 
Published: April 2003

AbstractPoly(vinyl alcohol) (PVAL) functionalized with chloroacetate groups was obtained by reaction of PVAL with chloroacetyl chloride using pyridine as catalyst and N‐methyl‐2‐pyrrolidone as solvent. The structure of the modified polymers was determined by means of IR, 1H and 13C NMR spectroscopies. The coupling of model bioactive carboxylic acids (1‐naphthylacetic acid and 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen)) to PVAL functionalized with chloroacetate groups was carried out by reaction with their potassium salts or directly in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). High degrees of modification were obtained in the reaction with the potassium salts. However, the esterification reaction is somewhat more efficient in the case of the potassium salt of 1‐naphthylacetic acid. The kinetic results were consistent with a second‐order reaction, and the activation energy in the reaction with the potassium salt of 1‐naphthylacetic acid was found to be 73,2 kJ/mol. The reaction of PVAL with 1‐naphthylacetic acid and naproxen in the presence of DBU showed deviation from second‐order kinetics, which may be a consequence of some steric effects. The hydrolysis in the heterogeneous phase of PVAL‐1‐naphthylacetic acid and PVAL‐naproxen adducts showed that the release of the bioactive compound from tablets is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.
Synthesis of side‐chain liquid‐crystalline polysalts with a poly(methylsiloxane) backbone
Authors: Ikker Andreas , Frère Yves , Masson Patrick , Gramain Philippe 
Published: April 2003

AbstractThe synthesis and thermal properties of side‐chain liquid‐crystalline polysiloxanes, incorporating quaternized pyridyl groups, are described. The polymers are obtained by hydrosilylation of poly(hydrogenmethylsiloxane) with a protected alcohol. Reaction of the deprotected polysiloxanes with 4‐(hydroxymethyl)pyridine and subsequent reaction with mesogenic alkyl bromides of different structure yielded the desired poly[(6‐{N‐[ω‐(4′‐alkoxy‐4‐biphenylyloxy)alkyl]‐4‐pyridiniomethoxy}hexyl)methylsiloxane bromide]. Four different types of polymers are prepared with either octyl or dodecyl alkyl chain, and with either methoxy or S‐2‐methyl‐1‐butoxy as an alkoxy group. Degrees of quaternization up to 80% are obtained. First results of their liquid‐crystalline behaviour investigated by optical polarizing microscopy and differential scanning calorimetry are reported.
Solvent‐induced ion selective transport properties of a crosslinked poly(L‐glutamic acid) membrane
Authors: Huh Yang‐Il , Kai Shojiro , Satoh Mitsuru , Komiyama Jiro 
Published: April 2003

AbstractIon‐selective transport of alkali metal chlorides (LiCl, NaCl, KCl and CsCl) is reported for a crosslinked poly(L‐glutamic acid) membrane immersed in aqueous alcohols CH3OH, C2H5OH and 2‐propanol ((CH3)2CHOH). In aqueous CH3OH and C2H5OH, an appreciable ionselectivity was observed for the permeability coefficient, i.e., Li+ < Na+ < Cs+ ≤ K+, in a higher alcohol composition region. This counterion sequence results from a significant increase in the salt solubility coefficient of KCl and CsCl and a substantial decrease in the diffusion coefficient of LiCl and NaCl in the relevant alcohol composition region. Membrane conductivity measurements, which were performed concomitantly for the aq. C2H5OH system, suggest the same ion specificity for the counterion mobility as for permeability. It has been suggested that the specific counterion binding to polymer charges is an essential factor for ion specificity.
Polymerizable mesoionic 4,6‐dioxo‐1,3‐diazines, 1. Synthesis and photochemical behavior of polystyrenes with mesoionic 4,6‐dioxo‐1,3‐diazines as pendant groups
Authors: Ritter Helmut , Sperber Rolf , Weisshuhn Carl Michael 
Published: April 2003

AbstractMesoionic 5‐alkyl‐4,6‐dioxo‐1,3‐diphenyl‐2‐(3‐vinylbenzylthio)‐1,3‐diazine (6) was prepared by condensation of alkylmalonic acid (5) with 1,3‐diphenyl‐2‐(3‐vinylbenzyl)isothiourea (4) by use of dicyclohexylcarbodiimide (DCC). Homopolymerization of 6 led to new polystyrene derivatives (7) with mesoionic 4,6‐dioxo‐1,3‐diazines as pendant groups. UV irradiation of 7 yielded polystyrene derivatives with bis(β‐lactam) moieties as pendant groups (8). The change of some physical properties during the irradiation is discussed. 5‐Heptyl‐4,6‐dioxo‐1,3‐diphenyl‐2‐(3‐methylbenzylthio)‐1,3‐diazine (11) and 4‐heptyl‐1‐(3‐methylbenzylthio)‐3,5‐dioxo‐2,6‐diphenyl‐2,6‐diazabicyclo[2.2.0]hexane (12) as low‐molecular‐weight model compounds were synthesized for structural analysis.
Oxidation of 2,6‐di‐tert‐butylphenol by molecular oxygen catalyzed by tetrasodium phthalocyaninatocobalt(II)tetrasulfonate bound to a polymer colloid
Authors: Hassanein Mahmoud , Selim Adel , El‐Hamshary Hany 
Published: April 2003

AbstractCrosslinked cationic latexes based on polystyrene, poly[styrene‐co‐(methyl methacrylate)] and poly(methyl methacrylate) were prepared by an emulsion polymerization process using 2 mol‐% of a quaternary ammonium surfactant monomer. Phthalocyaninatocobalt(II)tetrasulfonate (CoPcTs) bound to these latexes were found to enhance the rate of autoxidation of 2,6‐di‐tert‐butylphenol in water. All CoPcTs‐latex catalysts were more active than the water soluble CoPcTsNa4. The styrene latex bound with CoPcTs was the most active catalyst. The reaction products were identified as the oxidative coupling products 3,3′,5,55′‐tetra‐tert‐butyl‐4,4′‐dioxo‐1,1′‐bicyclohexadienylidene (DPQ) and 2,6‐di‐tert‐butyl‐1,4‐benzoquinone (BQ). The ratio DPQ/BQ was found to be affected by the nature of microenvironment. The rate of autoxidation catalyzed by CoPcTs bound to the styrene latex was found to be zero order with respect to the phenol concentration. The reaction rates increase with pH in the range 7–9. The rate of autoxidation increases with increasing concentration of CoPcTs from 1,0 · 10−6 to 2,5 · 10−5 mol/L and then it levels off. At constant concentration of CoPcTs in the reaction mixture, the rate as a function of the weight of latex shows a maximum. The rate shows a linear dependence on partial pressure of dioxygen. Recycling of the latex catalyst results in a reduced activity after successive runs.
Amino acids attached to poly(alkylene phosphate)s, 1. Synthesis
Authors: Kaluzynski Krzysztof , Penczek Stanislaw 
Published: April 2003

AbstractThe synthesis of poly(alkylene phosphate)s with attached amino acids was elaborated. Two methods of coupling through P—NH bond were used. They were based on the direct reaction of amino acid esters or N,O‐bis(trimethylsilyl) substituted amino acids with poly(alkylene chlorophosphate)s. The assumed microstructure of the resulting polymers was confirmed by analysis of the 1H, 13C and 31P NMR spectra. Preliminary data on the hydrolytic stability of amino acids modified poly(alkylene phosphate)s are also given.
Preparation of chiral stationary phases based on anionically polymerised (4S,5S)‐4‐methyl‐5‐phenyl‐2‐(4‐vinylphenyl)‐2‐oxazoline
Authors: Terfloth Gerald , Blaschke Gottfried 
Published: April 2003

Abstract(4S,5S)‐4‐methyl‐5‐phenyl‐2‐(4‐vinylphenyl)‐2‐oxazoline(1) was prepared. The anionic polymerisation of 1 was initiated in toluene with butyllithium (BuLi) at −78°C to afford poly(1) of narrow molecular weight distribution. The resulting poly(1) was immobilised on modified silica gel to give chiral stationary phases for the separation of racemic compounds.
Influence of morphology on the microhardness of poly(ethylene naphthalene‐2,6‐dicarboxylate)
Authors: Rueda Daniel R. , Viksne Armanda , Malers Laimonis , Calleja Francisco J. Baltá , Zachmann Hans G. 
Published: April 2003

AbstractThe microhardness (H) of poly(ethylene naphthalene‐2,6‐dicarboxylate) (PEN) with a wide range of crystallinities, spherulitic morphologies and different lamellar periodicities has been determined. The influence of the temperature and time of crystallization from the glassy state upon the microhardness values has been examined. For structures where primary crystallization is incomplete, it is shown that H increases linearly with the volume fraction of spherulites. For materials where primary crystallization is completed, H depends on the crystallization temperature and appears to be a function of both the crystallinity and the crystal size. The results are discussed in the light of theoretical predictions of hardness.
Preparation and characterization of photoresponsive poly(methyl methacrylate) microspheres bearing phosphorylcholine‐analogous and spirooxazine moieties
Authors: Sugiyama Kazuo , Nakano Hisashi , Ohga Koji 
Published: April 2003

AbstractThe photoresponsive copolymer microspheres [poly(MAIP‐co‐MMA)] were prepared from the emulsifier‐free emulsion copolymerization of 2‐[2‐(methacryloyloxy) ethyldimethylammonio]‐ethyl indolinonaphthooxazine phosphate (MAIP) and methyl methacrylate (MMA). From the kinetics of the copolymerization of MAIP and MMA, it was found that the initial rate of polymerization of MMA increased by the addition of a small amount of MAIP. From the X‐ray photoelectron spectroscopy (XPS) measurements MAIP moiety was found to be located on the surface of a particle. The introduction of a MAIP moiety into poly(MMA) microspheres results in a decrease in the amount of bovine serum albumin (BSA) adsorbed. A photoresponsive adsorption of BSA on poly(MAIP‐co‐MMA) microspheres was observed with spirooxazine‐merocyanine photoisomerization caused by UV irradiation.
Rheological study of the kinetics of photoinitiated free radical polymerizations with the quartz microbalance
Authors: Ottersbach Peter , Lennarz Klaus , Bargon Joachim 
Published: April 2003

AbstractUsing a quartz microbalance operating in solutions, a very sensitive determination of the increasing viscosity during the very early stages of polymerization reactions is possible in a continuous fashion. Kinetic data have been obtained for methyl methacrylate as the monomer and benzoin, its methyl ether, and 2,2‐dimethoxy‐2‐phenylacetophenone as photoinitiators using an excimer laser operating at 351 nm. This in situ method represents a very sensitive, convenient, and inexpensive technique for obtaining kinetic data under a variety of boundary conditions including photopolymerization, the example outlined here.
On the influence of temperature in the physical and mechanical characterization of polymer oxidation profiles
Authors: Dole Patrice , Chauchard Jacques 
Published: April 2003

AbstractThe diffusion‐limited thermodegradation of a poly[ethylene‐co‐(methyl acrylate)] rubber was studied using an original pinpoint dynamic mechanical analysis (PDMA). The importance of the temperature of the analysis in the physical and mechanical determination of oxidation profiles was clearly illustrated. The variations of the tan δ (δ: loss angle) at the glass transition temperature allows the determination of the apparent activation energy of the diffusion‐limited thermooxidation phenomena.
Thermodynamics of mixing of propylene oxide oligomers with different end groups and of statistical and block cooligomers of ethylene oxide and propylene oxide in tetrachloromethane
Authors: Killmann Erwin , Cordt Frank , Möller Friedrich , Zellner Helmut 
Published: April 2003

AbstractMixing enthalpies and Gibbs energies of liquid propylene oxide oligomers with hydroxyl and methoxy end groups and of block and statistical cooligomers of ethylene oxide and propylene oxide in tetrachloromethane are obtained by microcalorimetry and vapour pressure measurements. The thermodynamic excess quantities ΔH, ΔGE and ΔSE of mixing are influenced by induced dipol interactions of the ether segments with CCl4 and by the hydrogen bond interactions of the OH end groups. An expanded theoretical treatment using the Huggins approach of quasichemical equilibrium between the contacting segment surfaces is successfully applied on the experimental results.
Copolymérisation de la N‐acryloyl‐L‐valine et de la N‐acryloyl‐L‐phénylalanine avec l'acrylamide
Authors: Camail M. , Maesano J. C. , Margaillan A. , Vernet J. L. 
Published: April 2003

AbstractThe synthesis of N‐acryloyl‐L‐valine (NAVAL) and N‐acryloyl‐L‐phenylalanine (NAPHE) have been carried out from L‐valine and L‐phenylalanine. The chiral compounds have been characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and polarimetry. The copolymerization of NAVAL salt, (NAVAL Na, monomer A) or NAPHE salt (NAPHENa, monomer A′) with acrylamide (AM, monomer B) has been investigated using K2S2O8 as initiator, over a range of the feed compositions for NAVALNa (or NAPHENa) from 10 to 100 mol‐%. The compositions of copolymers have been systematically assessed through 13C NMR. The reactivity ratios for the couple A, B were determined as rA = 0,67, rB = 0,91 and for the couple A′, B they have been evaluated to be: rA′ = 0,40, rB = 0,91. The azeotropic composition is located at 21 mol‐% for the couple A, B and at 13 mol‐% for the couple A′, B. Drag reduction effects are obtained with these polymers.
Copolymers of N‐vinyl‐2‐pyrrolidone and 2‐(dimethylamino)ethyl methacrylate, 3. Viscosity of quaternized copolymers in aqueous solution
Authors: Deboudt Karine , Delporte Michèle , Loucheux Claude 
Published: April 2003

AbstractN‐Vinyl‐2‐pyrrolidone (VP) — 2‐(dimethylamino)ethyl methacrylate (DMAEM) copolymers were quaternized with octyl, dodecyl or hexadecyl bromide. The behaviour of the modified copolymers in aqueous solutions was studied by viscosimetry. As typical of classical polyelectrolytes, by increasing the ionic strength of the solutions, their viscosity decreases. Since the DMAEM mole fraction in the modified copolymers is low, the pH of the solutions does not have a great influence on the extension of the macromolecules. The influence of the size of the alkyl chains and of the mole fraction of quaternized units were studied: the formation of hydrophobic microdomains is easier for copolymers which have a low fraction of long quaternized units than for copolymers with a high mole fraction of short quaternized units.