bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interpenetrating polymer networks of poly(dimethylsiloxane) with polystyrene, polybutadiene and poly(glycerylpropoxytriacrylate)
Authors: Hamurcu E. Elif , Baysal Bahattin M. 
Published: April 2003

AbstractThe synthesis of full and semi interpenetrating networks (IPNs) based on poly(dimethy1‐siloxane) (PDMS)/polystyrene, PDMS/polybutadiene and PDMS/poly(glycerylpropoxytriacry‐late)1Glycerylpropoxytriacrylate (GFTA):
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is described. PDMS was used as host polymer in most cases. PDMS networks were prepared with two prepolymers having different number‐average molecular weights between junctions, M̄c = 15 · l03 and M̄c = 75 · l03. Physical properties of IPN samples such as stress‐strain behaviour, swelling and glass transition temperature (Tg) were examined. IPNs of both PDMS/polystyrene and PDMS/poly(glycerylpropoxytriacrylate) exhibit superior mechanical and elastomeric properties with respect to pure PDMS network. Most of the IPN systems studied in this work display two Tgs and indicate phase separation.
Photophysical behaviour of poly(p‐phenylene‐arylvinylene)s determined by polarized fluorescence spectroscopy
Authors: Damerau Thomas , Hennecke Manfred , Hörhold Hans Heinrich 
Published: April 2003

AbstractStationary polarized fluorescence spectra of poly(1,4‐phenylene‐1‐phenylvinylene), poly(1,4‐phenylene‐1,2‐diphenylvinylene) and poly(1,4‐phenylene‐1,2‐bis(4‐phenoxyphenyl)vinylene) in tetrahydrofuran solution and in polystyrene films were recorded at room temperature. In these matrices, different behaviour is found concerning the Stokes shift, the degree of polarization and the quantum yield; it is interpreted as a viscosity induced effect. The commonly accepted model of a conjugated polymer chain to consist of independent segments of various length should not be applied to the poly(phenylene‐arylvinylene)s studied in this work.
Anionic polymerization of carbazolyl‐substituted oxiranes initiated by potassium alkalide, potassium tert‐butoxide and potassium hydride
Authors: Buika Gintaras , Gražulevičius Juozas V. , Stolarzewicz Andrzej , Grobelny Zbigniew 
Published: April 2003

AbstractThe influence of the kind of initiating system and the addition of a crown ether on the anionic polymerization of oxiranes with a carbazoyl substituent is described. Potassium alkalide, potassium tert‐butoxide and potassium hydride were used as initiators. Selecting a suitable initiator and crown ether concentration, carbazolyl‐containing polymers with polymerization degrees from 4 to 60 can be produced. Using a suspension of potassium hydride in tetrahydrofuran, polymers with relatively high molar masses were obtained.
Viscosity and light scattering measurements of poly(2‐fluoro‐p‐phenylene‐2‐fluoroterephthalamide)
Authors: Grob Markus C. , Schurtenberger Peter , Suter Ulrich W. 
Published: April 2003

AbstractWe report on the characterization of the conformational properties of the fully aromatic polyamides poly(2‐fluoro‐p‐phenylene‐2‐fluoroterephthalamide) (FPFT) in methanesulfonic acid using dynamic and static light scattering and viscosity measurements. The results are in quantitative agreement with a model of polydisperse wormlike chains for the solution conformation of FPFT. A comparison with the results obtained for the unsubstituted polymer poly(p‐phenylenterephthalamide) (PPTA) under the same experimental conditions indicates that the introduction of halogen substituents on the aromatic rings has only a weak influence on the chain flexibility.
Photocontrol of orientation of photochromic dichroic dyes in cholesteric polymer films
Authors: Narisawa Hiroaki , Kishi Ryoichi , Sisido Masahiko 
Published: April 2003

AbstractStrong LCICD (liquid‐crystalline induced circular dichroism) was observed when a photochromic dichroic dye, 1, was doped into a cholesteric film of poly[(γ‐benzyl L‐glutamate)‐co‐(γ‐dodecyl L‐glutamate)]. The ICD at the absorption band of anthraquinone changed its intensity reversibly when the azobenzene group was photoisomerized between cis and trans form. The phenomenon was interpreted in terms of an orientational change of anthraquinone group associated with the photoisomerization of the azobenzene group. The structure‐ICD relationship was investigated using several photochromic dichroic dyes with different anchoring groups on the azobenzene group and different spacers between the azobenzene and anthraquinone group.
Relaxation processes and molecular motion in a new semicrystalline polyimide
Authors: Cheng Stephen Z. D. , Chalmers Tammy M. , Gu Yi , Yoon Yeocheol , Harris Frank W. , Cheng Jinlong , Fone Matilda , Koenig Jack L. 
Published: April 2003

AbstractA new polymide was synthesized from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and 2,2‐dimethyl‐1,3‐(4‐aminophenoxy)propane (DMDA), and abbreviated to be BTDA‐DMDA. This polymer possesses three relaxation processes which have been observed through dynamic mechanical and dielectric analyses above–150°C. The α relaxation process has been assigned to be the glass transition and occurs at about 250°C with an apparent activation energy of 420kJ/mol. Two subglass relaxation processes are a β relaxation process at around 100–170°C in a frequency range from 0,1 Hz to 100 kHz with an activation energy of 182 kJ/mol and a γ relaxation process occurs at around −80°C with an activation energy of 44 kJ/mol. Carbon‐13 solid state nuclear magnetic resonance experiments were carried out for the study of molecular dynamics at different temperatures. The results indicate that the γ relaxation is responsible for an oscillation and π flipping motion of the two phenoxy rings in the DMDA portion. The β relaxation was shown to pertain to the kHz‐motion of the aromatic imide rings in the BTDA portion. The molecular motion of the DMDA and BTDA protions are largely decoupled from each other in the frequency region studied.
New amphiphilic copolymers of N‐phenylmaleimides and vinyl ethers: thermal properties, Langmuir and Langmuir‐Blodgett films, gas permeation
Authors: Tebbe Heiko , van Ackern Frank , Tieke Bernd 
Published: April 2003

AbstractAmphiphilic copolymers 1 a–1d were prepared by radical copolymerization of hydrophilic N‐phenylmaleimide derivatives and lipophilic vinyl ethers in dichloromethane. Though the starting concentrations of the two monomers were always equimolar, none of the copolymers had a strictly alternating structure. Molecular weights were between 104 and 9 · 104. The copolymers prepared from ethyl 4‐maleimidobenzoate (2a) and isobutyl vinyl ether (3a) (copolymer 1a), and 2a and isooctyl vinyl ether (3b) (copolymer 1b) were thermally stable up to 300°C and showed glass transitions at about 150°C, while the copolymers prepared from 2a and octadecyl vinyl ether (3c) (copolymer 1c), and 4‐maleimidobenzoic acid (2b) and 3c (copolymer 1 d) were considerably less stable. All copolymers formed stable, condensed monomolecular layers at the air‐water interface, which could be transferred onto hydrophobic supports by the Langmuir‐Blodgett (LB) technique. Up to the 20th dipping cycle, a Y‐type deposition was found, while further dipping predominantly led to Z‐type deposition. Nitrogen and oxygen permeabilities (p) were studied after depositing the LB films onto porous Celgard membranes. Permeability and selectivity were dependent on the nature of the alkyl substituent group of the polymer. Copolymer 1a with the isobutyl group showed higher permeabilities than copolymer 1c with the octadecyl group, but no selectivity. The copolymer with the small alkyl group showed no selectivity of oxygen over nitrogen (α = )PO2/PN2 while for the copolymer with the long alkyl chain the α‐value was 1,3.
Ring‐opening copolymerization of anhydroalditols with tetrahydrofuran
Authors: Thiem Joachim , Strietholt Wilhelm A. 
Published: April 2003

AbstractBy ring‐opening copolymerization of 1,4‐anhydro‐2,3‐di‐O‐ethyl‐D‐erythritol (cis‐3,4‐diethoxyoxolane, 1) or 1,4:2,5:3,6‐trianhydro‐D‐mannitol (3) with tetrahydrofuran carbohydratecontaining copolyether polyols were obtained. Using trifluoromethanesulfonic acid as catalyst the molecular weights were in a range from M̄w = 13 000 up to 25 000 with about 10% of carbohydrate constituent. The novel copolyethers were studied by polymer analytical procedures, their structures4 and 5 tentatively assigned and compared to the homopolymerization products of the monomers. The present procedure features an approach to novel partially functionalized high molecular weight copolymer polyols based on carbohydrate‐derived materials.
Characterization of molar mass and dilute solution properties of poly(ether sulfone) with high glass transition temperature
Authors: Maes Christian , Godard Pierre , Daoust Daniel , Legras Roger , Strazielle Claude 
Published: April 2003

AbstractCharacterization of high‐temperature poly(ether sulfone) (HTPES) molar mass was performed using light scattering, viscometry and size‐exclusion chromatography (SEC). In pure N‐methyl‐2‐pyrrolidone (NMP), a large increase of the reduced viscosity at low concentration was observed. By addition of a salt such LiBr, this effect was suppressed. Using the viscosity laws of HTPES and poly(methyl methacrylate) (PMMA) in NMP + LiBr the SEC method was standardized via the universal calibration established with PMMA standards. The Mark‐Houwink‐Sakurada (MHK) relationship for HTPES in NMP containing 0,1 mol/L LiBr at 25°C with the intrinsic viscosity [η] and molecular weight M afforded the MHK constants K = 33,8 · 10‐5 dL · mola · g1+a and a = 0,70. The weight‐average molar masses obtained from SEC were very close to those obtained from light scattering. A comparison of number‐average molar masses obtained from 1H NMR, potentiometric titration of chain‐ends, and from SEC has shown more discrepancy for high molar masses. The study of dilute solution properties of HTPES macromolecules has shown the marked decrease of anisotropy with the number of repeating units, the low values of the characteristic ratio and of the Kuhn segment. All these conformational properties are similar to those of freely rotating chains.
Curing reactions of a liquid crystalline epoxy resin based on the diglycidyl ether of 4,4′‐dihydroxy‐α‐methylstilbene
Authors: Amendola Eugenio , Carfagna Cosimo , Giamberini Marta , Pisaniello Giuseppina 
Published: April 2003

AbstractA glycidyl‐terminated liquid crytalline (LC) monomer is cured with aromatic amines. A nematic structure suddenly develops during the curing reaction and is related to the molecular weight increase of the developing network. An unusual exothermal double peak is observed in the isothermal curves obtained in a defined temperature range. The calorimetric analysis is used to evaluate the kinetic parameters and is related to the initial formation of a linear prepolymer and to the subsequent development of the tridimensional network.
Water‐soluble polymers bearing biologically active residues, 3. Hydrolysis of polyethers and poly(ether‐ester)s bearing 1‐naphthylacetyl groups
Authors: Ignatova Milena , Manolova Nevena , Rashkov Iliya , Sepulchre Maurice , Spassky Nicolas 
Published: April 2003

AbstractThe hydrolysis of esters of naphthylacetic acid (NAA) and poly(ethylene glycol)s (PEG‐NAAs) or poly[oxytartaroyloxypoly(oxyethylene)]s (PTEG‐NAAs) was studied at pHs 9.2, 7,1 and 4, 5. The hydrolysis of complexes of PEG‐NAA with poly(methacrylic acid) (PMA) was also studied. UV spectroscopy and GPC were used to follow the release of NAA and the changes in the molecular weight of the polymers. The hydrolysis of PEG‐NAAs follows a first‐order kinetics. The rate constants of hydrolysis of PEG3000‐NAA are higher than those of PEG4000‐NAA, and this is attributed to a shielding effect of the polymer chain. The hydrolysis of PTEG‐NAA proceeds with release of NAA from the end‐groups and the pendent groups as well as with scission of the main‐chain ester groups. It is proposed that the very slow hydrolysis of complexes of PEG‐NAA with PMA is due to the localization of naphthylacetyl groups in the hydrophobic domains of the polycomplexes.
Oxidative crosslinking polymerization of poly[(methyl methacrylate)‐co‐(2‐(n‐pyrrolyl)ethyl methacrylate)] with iron chloride in nitromethane
Authors: Stanke Dietmar , Hallensleben Manfred L. , Toppare Levent 
Published: April 2003

AbstractPoly[(methyl methacrylate)‐co‐(2‐(N‐pyrrolyl)ethyl methacrylate)] (PMMA‐co‐PEMA, 1) containing 0,7 to 7 mol‐% pyrrolylethyl methacrylate (PEMA) units was crosslinked via oxidative polymerization with FeCl3 in inert atmosphere. The properties of the products 2 depended on the amount of electroactive side groups and on the molecular weight of the precursor copolymers 1 as well as on the reaction conditions. Crosslinking between pendant pyrrole groups and an increase in the glass transition temperature in the oxidative coupling could be avoided using precursor copolymers 1 with low PEMA content (<1 mol‐%).
Morphology of (methoxyethoxy/trifluoroethoxy)phosphazene copolymers
Authors: Kojima Morio , Magill Joseph H. , White Michael L. , Matyjaszewski Krzysztof 
Published: April 2003

AbstractBlock copolymers were synthesized by the anionically initiated copolymerization of (CH3OCH2CH2O)(CF3CH2O)2PNSi(CH3)3, followed by the addition of (CF3CH2O)3PNSi(CH3)3. Random copolymers were made by simultaneous polymerization of these monomers. These copolymers exhibit a linear dependency on the mole fraction “m” of the repeating units bearing a methoxyethoxy pendant side group as well as on molecular weights. The thermal and morphological characteristics of the block copolymers are different from those of the random copolymers of analogous “m” and molecular weight. All copolymers undergo a mesophase T(1) transition for a range of temperatures depending upon “m” and molecular weights of the copolymers. Morphological and structural features essentially resemble those of the low molecular weight (trifluoroethoxy)phosphazene homopolymer. Upon heating and cooling the solution cast copolymer specimens through T(1), most of them transform into an orthorhombic form with the unit cell dimensions a = 2,060 nm, b = 0,940 nm and c = 0,486 nm from their initial monoclinic form with a = 1,003 nm, b = 0,937 nm, c = 0,486 nm and γ γ 91°. These unit cell dimensions agree completely with those of the low molecular weight PBFP. Complicated morphologies comprised of square and globular shapes that depend upon the copolymer composition were obtained from dilute tetrahydrofuran/p‐xylene copolymer solutions. Electron microscopy directly reveals that chain extension occurs for the meltcrystallized copolymer specimen. The non‐crystallizable minor component in the block copolymers is rejected from the crystal lattice. In the random copolymers, the methoxyethoxy pendant side group enters into the crystal lattice and influences their morphological and structural features.
Number of active centers and propagation rate constants in the propene polymerization on supported Ti–Mg catalysts in the presence of hydrogen
Authors: Bukatov Gennadii D. , Goncharov Valerii S. , Zakharov Vladimir A. 
Published: April 2003

AbstractPolymerization inhibition with radioactive carbon monoxide was used to determine the number of active centers (Cp) and the propagation rate constant (Kp) in the isospecific polymerization of propene with the catalytic system TiCl4/diisobutyl phthalate/MgCl2—AlEt3—PhSi(OEt)3. The presence of hydrogen was found to decrease Cp (by a factor of ≈ 2) and to increase kp (by a factor of ≈ 4). In the absence of hydrogen a considerable part of the active centers (titanium‐polymer bonds) reacting with 14CO seems to be inactive in the propene polymerization for steric reasons. Hydrogen is able to transform such centers into an active state. Thus, kp ≈ 2,5 · 103 L/(mol · s) at 70°C obtained in propene polymerization in the presence of the hydrogen seems to be correct, since the portion of centers in the active state is maximum. The influence of polymerization time, external and internal donors on Cp and kp was studied.
Side‐chain polyrotaxanes, 3. Synthesis, characterization and enzymatically catalyzed degradation of non‐covalently anchored cyclodextrines in the side chains of poly(ether‐ether‐ketone)s
Authors: Born Markus , Koch Thomas , Ritter Helmut 
Published: April 2003

AbstractThe synthesis of a new side‐chain polyrotaxane containing dimethyl‐β‐cyclodextrin is described. The rotaxane side groups are attached via amide functions at a poly(ether‐ether‐ketone). Some characteristics of the polyrotaxane are compared with those of a corresponding guest model compound. It was found that the glass transition temperature, the solubility in methanol and some 1H NMR shifts are significantly influenced by the non‐covalently anchored cylodextrin. Additionally, it was observed that the non‐covalently anchored cyclodextrins could be completely degraded by enzymatic reaction.
Electrical properties of an acrylic elastomer‐LiClO4 complex as a polymeric solid electrolyte
Authors: Seki Miharu , Sato Kojiro , Haga Yutaka , Kobayashi Takayuki , Yosomiya Ryutoku 
Published: April 2003

AbstractA polymeric solid electrolyte having a low glass transition temperature, obtained by complexing LuCIO4 with an acrylic elastomer (AR) containing ester groups in the side chains, shows a conductivity of 2,0 · 10−4 S/cm (LiCIO4: 2,1 mmol/g AR, film thickness: ca. 100–300 μm) at 80°C. From the relationship between ionic conductivity and LiCIO4 concentration, we conclude that LiCI4 dissociates in the acrylic elastomer to produce carrier ions. We also suggest, in regard to temperature characteristics of ionic conductivity and reciprocal dielectric relaxation time, that the driff of ions is related to the motion of acrylic elastomer chains. The carrier mobility in the acrylic elastomer‐LiCIO4 complex was measured by using the voltage polarity reversing method. The carrier mobility increased with increasing LiCIO4 concentration and temperature.
Synthesis of novel sulfonyl‐containing liquid‐crystalline side‐chain poly(vinyl ethers)
Authors: Trollsås Mikael , Hult Anders , Percec Virgil 
Published: April 2003

AbstractThe synthesis of some new liquid‐crystalline polymers with sulfonyl‐containing mesogenic groups is described. 4‐[(S)‐(‐)‐2‐MethylbutyIsulfonyl]‐4′‐[(11‐vinyloxy)undecyloxy]biphenyl (10‐11), 4‐[(S)‐(‐)‐2‐methylbutylsulfonyl]‐4′‐[8‐(vinyloxy)octyloxy]biphenyl (10‐8), 4‐[(S)‐(‐)‐2‐ methylbutylsulfonyl]biphenyl 4‐[11‐(vinyloxy)undecyloxy]benzoate (12‐11), 4‐[(S)‐(‐)‐2‐methylbutylsulfonyl]biphenyl 4‐[8‐(vinyloxy)octyloxy]benzoate (12‐8), 4‐[(S)‐(‐)‐2‐methylbutyloxy]‐4′‐ [11‐(vinyloxy)undecylsulfonyl]biphenyl (18‐11) and 2‐[11‐(vinyloxy)undecyloxy]‐6‐{4‐[(S)‐(‐)‐2‐ methylbutylsulfonyl]phenyl}naphthalene (23‐11) were all synthesized, and polymerized with the initiating system CF3SO3H/S(CH3)2 in CH3Cl3 at 0°C. Monomers 10‐11, 10‐8, 18‐11 and 23‐11 are crystalline, while both 12‐11 and 12‐8 show an enantiotropic smectic A phase. All polymers exhibit the same thermotropic behaviour as their corresponding monomers, except poly(23‐11) which exhibits an enantiotropic smectic A (sA) and a monotropic chiral smectic C phase (S*C).
New polymer syntheses, 79. Hyperbranched poly(ester‐amide)s based on 3‐hydroxybenzoic acid and 3,5‐diaminobenzoic acid
Authors: Kricheldorf Hans R. , Löhden Gerd 
Published: April 2003

AbstractThe reaction of 3‐acetoxybenzoyl chloride (4) with N,N′,O‐tris(trimethylsilyl)‐3,5‐diaminobenzoic acid (5) proceeds by highly selective and almost quantitative acylation of both amino groups. The resulting 3,5‐bis(3‐acetoxybenzamido)benzoic acid (6a), or its silylated derivative (6b), was polycondensed in bulk. The silylated monomer yielded the higher molecular weights. The condensation of 3,5‐diacetoxybenzoyl chlorides with diamines containing aliphatic protons yielded acetylated tetraphenols which served as “star centers” for polycondensation. The polycondensation of silylated 3,5‐bis(3‐acetoxybenzamido)‐benzoic acid (6b), with these “star centers” yieled in turn hyperbranched star polymers. The feed ratio of monomers and “star centers” allows the control of the molecular weight. 1H NMR spectroscopy of these hyperbranched star polymers was used to determine the average degree of polymerization (DP) and the average degree of branching (DB). 1H and 13C NMR spectroscopy also revealed that all polycondensations involve a significant extent of ester‐amide interchange reactions.
Synthèse et polymérisation de monomères acryliques fluorés substitués en position α, 4. Applications à l'α‐acétoxyacrylate et à l'α‐propionyloxyacrylate de 2‐perfluorooctyléthyle
Authors: Guyot Bernard , Améduri Bruno , Boutevin Bernard , Sidéris André 
Published: April 2003

AbstractThe synthesis of the two monomers 2‐perfluorooctylethyl α‐acetoxyacrylate (1) and 2‐perfluorooctylethyl α‐propionyloxyacrylate (2) was performed in two steps starting from ethyl pyruvate and 2‐perfluorooctylethanol with overall yields of about 56% and 50%, respectively. Transesterification of ethyl pyruvate with the adequate fluorinated alcohol followed by enol acylation gave 1 and 2, respectively. The kinetic study of polymerization of monomers 1 and 2, led to the determination of the values of the ratio of the square of the rate constant of propagation over the rate constant of termination k2p/kte equal to 9,2 · 10−3 and 9,1 · 10−3 L · mol−1 ·s−1, respectively, and were compared to those of commercially available fluorinated acrylates and methacrylates.
Functional poly[(ethylene oxide)‐co‐(β‐benzyl‐L‐aspartate)] polymeric micelles: block copolymer synthesis and micelles formation
Authors: Cammas Sandrine , Kataoka Kazunori 
Published: April 2003

AbstractWell‐defined α‐methoxy‐ω‐amino and α‐hydroxy‐ω‐amino poly(ethylene oxides) (PEOs), obtained by chemical modifications of α‐hydroxy‐ω‐amino PEO, were studied for block copolymerization with β‐benzyl‐L‐aspartate‐N‐carboxy anhydride (BLA‐NCA); the block copolymers were obtained via polymerization of BLA‐NCA with the primary amino end‐groups of the PEOs as initiator in the mixture CHCl3/N,N‐dimethylformamide (DMF) (vol. ratio10/1). Gel‐permeation chromatography (GPC) of both block copolymers showed the presence of BLA oligomers. α‐Methoxy PEO/PBLA and α‐hydroxy PEO/PBLA block copolymers were submitted to selective precipitation in 2‐propanol; this method allowed total elimination of oligomers as shown by GPC of the purified block copolymers. Moreover, for each block copolymer, the number of BLA units determined by 1H NMR spectroscopy (in CDCl3) was in good agreement with the number calculated from the ratio BLA‐NCA/amino end‐groups of PEO. The polymeric micelles having hydroxy functions or methoxy groups on the outer‐shell were prepared by dialysis against water of the corresponding solution of the pure block copolymers. These polymeric micelles were characterized by dynamic light scattering (diameter) and by fluorescence spectroscopy (critical micellar concentration, cmc) using pyrene as a fluorescence probe. Both polymeric micelles have a small diameter (<50nm) and a very low cmc (<20 mg/L in water).
Emulsion copolymerization of 2‐(acryloyloxy)ethylphosphoryl‐choline with vinyl monomers and protein adsorption at resultant copolymer microspheres
Authors: Sugiyama Kazuo , Ohga Koji , Aoki Hitoshi 
Published: April 2003

AbstractA series of copolymer microspheres of 2‐(acryloyloxy)ethylphosphorylcholine (APC) with comonomers (M) such as methyl (MMA), ethyl (EMA), butyl (BMA), hexyl methacrylate (HMA), and styrene (St), i. e. poly(APC‐co‐M) microspheres, were prepared by emulsifier‐free emulsion copolymerization. From the kinetics of the copolymerization, it was found that the initial rate of polymerization of St increases in the presence of small amounts of APC. The diameters of poly‐(APC‐co‐M) microspheres were much smaller than those of the corresponding homopolymer, poly(M). It was confirmed by X‐ray photoelectron spectroscopy measurements that the APC moiety is concentrated on the surface of the particles. A series of poly(APC‐co‐M) microspheres was found to adsorb both bovine serum albumin (Alb) and human serum γ‐globulin (Glo) less that the corresponding poly(M) microspheres as a control.