bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpenetrating polymer networks of poly(dimethylsiloxane) with polystyrene, polybutadiene and poly(glycerylpropoxytriacrylate)
Authors: Hamurcu E. Elif , Baysal Bahattin M.
Published: April 2003

The synthesis of full and semi interpenetrating networks (IPNs) based on poly(dimethy1‐siloxane) (PDMS)/polystyrene, PDMS/polybutadiene and PDMS/poly(glycerylpropoxytriacry‐late)1

Glycerylpropoxytriacrylate (GFTA):
magnified image

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

Stationary 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

The 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

We 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

Strong 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

A 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

Amphiphilic 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

By 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

Characterization 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

A 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

The 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

Poly[(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

Block 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

Polymerization 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

The 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

A 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

The 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

The 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

The 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

Well‐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

A 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.
1,3‐Oxazoline intermediates in reactive processing applications, 2.multiphase polymer blends via in‐situ cationic melt phase polymerization of 2‐phenyl‐1,3‐oxazoline
Authors: Müller Philipp , Wörner Christof , Mülhaupt Rolf
Published: April 2003

2‐Phenyl‐1,3‐oxazoline was injected into poly(ethene‐co‐methacrylic acid), containing 4,25 mol‐% methacrylic acid units, at 225°C. In the first stage, 2‐phenyl‐1,3‐oxazoline reacted with carboxylic acid groups to form esteramide side chains via grafting reaction. In the second stage, 2‐phenyl‐1,3‐oxazoline containing methyl 4‐nitrobenzensulfonate initiator was added to initiate in‐situ cationic polymerization, yielding poly(N‐benzoylethylenimine) as dispersed phase with 0,2–3,5 μm average diameter. Morphological, mechanical and thermal properties of poly‐(ethene‐co‐methacrylic acid) blends, prepared by grafting combined with in‐situ polymerization of 2‐phenyl‐1,3‐oxazoline, were investigated.
Anionic polymerization of fluorine‐containing vinyl monomers, 12. Anionic polymerization mechanism of hexafluoro‐1,3‐butadiene
Authors: Nishimura Shin , Takahashi Akio , Narita Tadashi , Hagiwara Tokio , Hamana Hiroshi
Published: April 2003

Initiation and propagation reaction mechanisms of the anionic polymerization of hexafluoro‐1,3‐butadiene (HEBD) were investigated. The initiation reaction with caesium tert‐butoxide was found to be completed within 5 min although the reactions were carried out at a much lower temperature than that of the polymerization reaction. The initiation reaction was, therefore, inferred to take place in an anionic fashion by adding the tert‐butoxide anion to HFBD. In order to clarify the propagation reaction mechanism of HFBD which yielded a polymer with a polyvinylene structure, the polymerization reactivity of HFBD and hexafluoro‐2‐butyne (HFBY), the isomerization of HFBD to HFBY, and the structural difference between poly(HFBD) and poly(HFBY) were discussed. In spite of the low yield of HFBY by the isomerization reaction under polymerization conditions, higher yields of poly(HFBD) were obtained. Judging from the X‐ray analysis which showed that poly(HFBD) was highly crystalline and poly(HFBY) was amorphous, poly(HFBD) might not be produced by polymerization of HFBY. An addition reaction of the propagating anion to the carbon‐2 of the HFBD monomer followed by isomerization at the propagating living end to yield poly[1,2‐bis(trifluoromethyl)vinylene] is proposed.
Cationic polymerization of glycidol. Polymer structure and polymerization mechanism
Authors: Dworak Andrzej , Walach Wojciech , Trzebicka Barbara
Published: April 2003

Glycidol (2‐epoxy‐1‐propanol) was polymerized under the action of Lewis acids (BF3OEt2,, SnCl4) and protonic acids (CF3COOH, CF3SO3H). Polymers with number‐average molecular weights (M̄n) varying from 2500 to 6000 g/mol were obtained. The structure of obtained polymers was characterized by 13C and 29Si NMR spectroscopy, and the amount of 1‐3 units, 1‐4 units and chain branches was determined. The structure of the polymers was related to the polymerization mechanism, especially to the contribution of activated monomer mechanism in chain growth.
Polymerization of methyl methacrylate with achiral 4B group metallocene compounds
Authors: Deng Hai , Shiono Takeshi , Soga Kazuo
Published: April 2003

Methyl methacrylate (MMA) was polymerized with Cp2ZrCl2/ methylalyminoxane or Cp2M(CH3)2 (M: Zr, Hf; Cp = cyclopentadienyl) combined with B(C6F5)3 (1) or Ph3CB(C6F5)4 (2), (Ph = phenyl). in the presence of a Lewis acid like Zn(C2H5)2 with slow inititation, which gave syndiotactic‐rich poly(methyl methacrylate) (PMMA) with high molecular weight. The polymer yield increases with polymerization time, which indicates that the propagation rate is zero order in concentration of monomer. The polymer yield increases also with concentration of Cp2Zr(CH3)2.2, which indicates the zirconocene to be the real catalyst. The polymer yield and the initiation efficiency (N/[Zr]) increase with the concentration of Zn(C2H5)2, which indicates Zn(C2H5)2, to be involved in the initiation. It is also shown that the propagation reaction is independent of the concentration of Zn(C2H5)2.
Synthesis and properties of segmented poly(ether‐urethanes) with specially designed and symmetrically chain‐folding poly(N‐alkylurethane) hard segments
Authors: Eisenbach Claus D. , Stadler Edmund
Published: April 2003

The study of a series of segmented poly(ether‐urethanes) with highly flexible poly(oxytetra‐methylene) soft segments and especially designed, molecularly uniform poly(N‐alkylurethane) hard segments based on piperazine and 1,4‐butanediol bischloroformate has shown that size, shape and perfection of the hard domains can be varied by both the primary structure of the urethane chain and the sample history. Depending on the conformation or the stereogeometry of the built‐in central constitutive hard segment unit, chain‐extended or chain‐folded hard segment crystallization, i. e., the formation of cylindrical or lamellar shaped hard domains can be achieved. These thermoplastic elastomers exhibit distinctly different properties which correlate systematically with the supermolecular structure and the corresponding hard segment architecture, respectively.
Process analysis: properties of poly(ethylene terephthalate) measured by near infrared spectroscopy, 1. At‐line analysis of poly(ethylene terephthalate) chips
Authors: Van Uum Marinus P. B. , Lammers Hans , De Kleijn Jaap P.
Published: April 2003

Near infrared (NIR) reflectance spectra recorded from poly(ethylene terephthalate) (PET) chips contain a sufficient amount of information to estimate the number of carboxylic end groups and the relative viscosity. To obtain reliable results, careful attention has to be paid to the calibration procedure.
Process analysis: properties of poly(ethylene terephthalate) measured by near infrared spectroscopy, 2. In‐line analysis of poly(ethylene terephthalate) melt
Authors: Lammers Hans , Van Uum Marinus P. B. , De Kleijn Jaap P.
Published: April 2003

Near infrared (NIR) transmission spectra recorded from poly(ethylene trerephthalate) (PET) melt contain a sufficient amount of information to estimate the number of carboxylic end groups and the relative viscosity. In‐line monitoring of these quality parameters is feasible.
Columnar mesophase behaviour of poly(dibutylsiloxane) and related copolymers containing polar substituents
Authors: Out Gerardus J. J. , Schlössels Frank , Turetskii Alexei A. , Möller Martin
Published: April 2003

The columnar mesophase formation of poly(dibutylsiloxane) (PDBS) was studied with respect to the influence of molecular weight. Additionally, the synthesis of random copolymers containing dibutylsiloxane and butyl(3‐cyanopropyl)siloxane units was performed in order to examine the influence of side group polarity on the columnar mesophase behaviour without disturbing the overall molecular geometry. Introduction of 6% 3‐cyanopropyl groups appeared to hinder crystallization while copolymers containing 17% 3‐cyanopropyl groups did not show crystallization at all. All copolymers formed a columnar mesophase which seemed to gain stability from the presence of the polar substituents.
Polymeric photosensitizers, 1. Synthesis and photochemical properties of poly[(sodium p‐styrenesulfonate)‐co‐(4‐vinylbenzyl chloride)] containing rose bengal chromophores
Authors: Nowakowska Maria , Kepczyński Mariusz , Szczubialka Krzysztof
Published: April 2003

The new polymeric photosensitizer poly[(sodium p‐styrenesulfonate)‐co‐(4‐vinylbenzyl chloride/rose bengal)] for singlet oxygen production in aqueous solutions was synthesized and studied. The polymer contains rose bengal (4,5,6,7‐tetrachloro‐2′,4′,5′,7′‐tetraiodofluorescein) chromophores covalently attached to the polymer chain. The quantum yield of singlet oxygen formation by the polymer‐bound chromophore was found tobe close to that determined for free rose bengal. The polymer has been shown to photosensitize oxidation reactions in aqueous media.
Anionic polymerization of alkyl methacrylates in the presence of diethylzinc
Authors: Ozaki Hiroyuki , Hirao Akira , Nakahama Seiichi
Published: April 2003

The anionic polymerizations of methyl methacrylate (MMA), isopropyl methacrylate (IPMA), and tert‐butyl methacrylate (TBMA) in THF in the presence of diethylzinc were investigated. The addition of diethylzinc to the reaction mixture remarkably lowers the polymerization rates of the methacrylates initiated with potassium diphenylmethanide to afford polymers with the predicted molecular weights and very narrow molecular weight distributions, while PMMA and poly(IPMA) produced with potassium diphenylmethanide in the absence of diethylzinc have rather broad molecular weight distributions. The stereospecificities of PMMA, poly(IPMA) and poly(TBMA) are not affected by diethylzinc. From the result of the block copolymerization of MMA with TBMA, it was found that the presistency of the anionic propagating end of PMMA is significantly enhanced by the addition of diethylzinc. The retardation of the polymerization rates and the enhancement of the persistency of the propagating end in the presence of diethylzinc may be caused by the weak coordination of diethylzinc toward the enolate anions at the propagating end groups.
Structural characterisation of a new heparinisable material based on ethylene/vinyl alcohol/vinyl acetate terpolymer and a poly(amido‐amine)
Authors: Lamponi Stefania , Tempesti Federica , Magnani Agnese , Benvenuti Manuela , Barbucci Rolando , Ranucci Elisabetta , Cimmino Sossio , Martuscelli Ezio , Baszkin Adam , Boissonnade Marie‐Martine
Published: April 2003

Partially hydrolyzed ethylene/vinyl acetate copolymers (EVALVA) were modified by covalent binding of a heparin‐complexing poly(amido‐amine) (N2LL). The physicochemical characterisation of the starting and modified materials was carried out through thermal analysis, dynamic mechanical thermal analysis, mechanical tensile test, contact angle, potentiometric measurements, water uptake and FT‐IR spectroscopic measurements. The behaviour of this material in both the dry and the wet state was stressed, evidencing the different orientation of the chemical groups, which are buried or exposed according to whether its nature is hydrophilic or hydrophobic. The material was heparinised, and the presence of heparin was revealed by energy dispersive X‐ray analysis (EDAX) and FT‐IR.
Preparation of a triphenylcarbinol moiety‐containing cellulose derivative and its properties
Authors: Arai Kenichiro , Kawabata Yumi
Published: April 2003

A triphenylcarbinol (TPC) moiety‐containing cellulose derivative (TPC‐Cell) was prepared by a two‐step reaction. First, microcrystalline cellulose was dissolved in SO2‐diethyl‐amine‐dimethyl sulfoxide and homogeneously reacted with p‐bromobenzyl bromide to obtain tri‐O‐(p‐bromobenzyl)cellulose (BB‐Cell). Second, the BB‐Cell was reacted with butyllithium and then with Michler's ketone. The degree of substitution (DS) of the obtained ethanol‐soluble TPC‐Cell was up to 0,56. The leuco form of TPC moiety in TPC‐Cell showed a small extent of ionic dissociation in ethanol under irradiation with UV light of λ > 290 nm, accompanied by a large extent of decomposition of the structure. With additions of acid and then of alkali, the TPC structure was reversibly isomerized from the leuco form to the colored from and then from the colored from to the leuco form. However, repeated cycles of the additions of acid and alkali resulted in considerable fatigue with the number of cycles.
Synthesis of a polyethylene‐graft‐polystyrene copolymer and its compatibilization for linear low density polyethylene/poly(phenylene oxide) blends
Authors: Chen Hui , Wang Jianguo , Zhang Xuequan , Tang Tao , Huang Baotong
Published: April 2003

Based on unsteady diffusionkinetics, polyethylene(PE)‐graft‐polystyrene (PS) copolymers were designed and synthesized with a heterogeneous high yield titanium‐based catalyst by copolymerization of ethylene with a PS‐macromonomer using 1‐hexene as a short main agent to promote the incorporation of the PS‐macromonomer. The presence of 1‐hexene facilitated the diffusion of the PS‐macromonomer, giving rise to the significantly increased incorporation of the PS‐macromonomer. Compatibilization of blends of linear low density polyethylene (LLDPE)/poly(phenylene oxide) (PPO) with the PE‐g‐PS copolymer were investigated using scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA).
Degradability of hydrogels containing azoaromatic crosslinks
Authors: Yeh Ping‐Yang , Kopečkova Pavla , Kopeček Jindřich
Published: April 2003

A novel type of biodegradable, pH‐sensitive hydrogels was synthesized by crosslinking of N,N‐dimethylacrylamide copolymer precursors. These hydrogels contained azoaromatic crosslinks which may be degraded by the azoreductase activities in the colon. Hydrogel degradation experiments were performed both in vitro and in vivo, using rat cecum contents and implantation into the rat cecum, respectively. In order to evaluate the influence of the detailed network structure on the degradation properties, the degradability of hydrogels synthesized by two different methods, i.e., crosslinking of polymeric precursors and crosslinking copolymerization, were compared. Two different patterns of the degradation of hydrogels were observed, i. e., a surface erosion process and a bulk‐degradation‐like process. The azo bond cleavage rate of hydrogels prepared by crosslinking of polymeric precursors was faster than that of hydrogels prepared by crosslinking copolymerization. The differences in the gel degradation pattern and the cleavage rate of azo bonds were attributed to the differences in the structure of the hydrogel network, i. e., the molecular weight of primary chains and the formation of chain entanglements. Under the experimental conditions used, the degradation rate in vivo was 3 to 5 times faster than that in vitro. It appears that these hydrogels have a potential for colon‐specific drug delivery.
Télomérisation en milieu aqueux, 1. Télomérisation de l'acide acrylique avec l'acide thioglycolique
Authors: Boutevin Bernard , Rigal Gérard , El Asri Mohammed , Lakhlifi Tahar
Published: April 2003

The telomerization of acrylic acid with thioglycolic acid (mercaptoacetic acid) in aqueous medium, with various initiators (H2O2,Na2S2O8,K8 thermal initiation and 2,2′‐azobis (2‐amidiniopropane) dihydrochloride) has been achieved. Thus, we were able to point out the limitation of the chain length due to the transfer agent, which is characteristic of a telomerization reaction. Mono‐, di‐and tri‐adducts were isolated and characterized after esterification of the reaction medium with ethanol, then hydrolized. These various adducts were used as standards for size‐exclusion chromatography, and the influence of the reaction parameters (initiator, temperature, quality of solvent, amount of telogen was investigated). We also determined the transfer constant of thioglycolic acid (CT = 0,47). It is worth to note that knowing this value, it is possible to control precisely the number ‐average degree of polymerization of this type of reaction. This allowed us to prepare telomers with a 50% final weight concentration in the dry extract, as it was recommended for their use in paper industry.
Composition‐dependent Flory‐Huggins parameters: molecular weight influences at high concentrations
Authors: Petri Hans‐Michael , Wolf B. A.
Published: April 2003

Flory‐Huggins interaction parameters χ were determined by means of equilibrium vapor pressures (measured via a combination of a head‐space sampler with a gas chromatograph) and light scattering as a function of composition and temperature for the systems cyclohexanone/polystyrene [CHO/PS] and cyclohexanone/poly(butyl methacrylate) [CHO/PBMA]. The investigation of molecular weight influences on χ with the system CHO/PBMA demonstrates that they persist almost up to the pure polymer. In order to rationalize this result, it is postulated (in accord with experimental findings and theoretical predictions) that the dimensions of polymer chains may vary upon the addition of solvent even in highly concentrated solutions. From the information concerning χ(T) the inter action parameters were split into their enthalpy and entropy part. In the case of CHO/PS these quantities vary considerably with composition and turn out to be linearly interrelated.
New chain transfer agents for radical polymerization based on the addition‐fragmentation mechanism
Authors: Jiang Shuiping , Viehe Heinz G. , Oger Nicole , Charmot Dominique
Published: April 2003

This study describes 15 compounds with allylic or pentadienic structure carrying either captodative (cd) carbon‐ or heteroatom substituents as potential radical leaving groups in an addition‐fragmentation reaction. Their experimental evaluation as chain‐transfer agents (CTA) was achieved in radical polymerization of styrene and methyl methacrylate. The α‐(cd‐substituted methyl)acrylates 9 and 11 were more efficient than the t‐thioether 10 in lowering molecular weight of polystyrene. The dienes are particularly effective and provide macromonomers with terminal diene functions which are very useful for further copolymerization with a variety of vinyl monomers.
Cyclopolymerization. Chirality induction for the synthesis of chiroselective corand/ionophore ligands
Authors: Yokota Kazuaki , Haba Osamu , Satoh Toshifumi , Kakuchi Toyoji
Published: April 2003

This article presents several methods to prepare polymeric chiral crown ethers by cyclopolymerization. Chiral templates such as 1,1′‐bi‐2‐napthol, D‐mannitol, L‐threitol, and pyranosidic sugars are very useful for synthesizing the polymers by cyclopolymerization of divinyl ethers, polymers which posses the ability of chiral recognition towards α‐amino acids. The chiral twist of the (R)‐ or (S)‐binaphthyl template induces the main chain to form a chiral, R,R‐ or S,S‐racemo sequence, respectively. Other templates with chiral axis can be also used as a tool for chirality induction in cyclopolymerization and cyclocopolymerization. The initiating system consisting of chiral alkylsulfonic acid and Lewis acid induces the enantioselective cyclopolymerization of a divinyl acetal (37). Chiral diepoxides polymerize regio‐ and stereospecifically with Lewis acid and KOH, and especially the diepoxide originating from D‐mannitol forms a polymer having the character as a new macromolecular ionophore.
Rare earth metal initiated polymerizations of polar and nonpolar monomers to give high molecular weight polymers with extremely narrow molecular weight distribution
Authors: Yasuda Hajime , Ihara Eiji
Published: April 2003

Organolanthanide (III) initiated polymerizations of alkyl methacrylates and alkyl acrylates proceed in a living fashion and yield high molecular weight polymers with extremely narrow molecular weight distribution at high conversion. Random and block copolymerizations of alkyl acrylates are carried out successfully to give almost “monodisperse” polymers. Rare earth metal initiated polymerizations of lactones such as ε‐caprolactone and δ‐valerolactone produce again high molecular weight polymers with narrow molecular weight distribution. Bulky divalent and trivalent rare earth metal complexes catalyze the living polymerization of ethylene and α‐olefins and the Sm (OR)3/AIR3H2O initiator system catalyzes the polymerization of propylene oxide to give polymers with narrow molecular weight distribution.
Kinetics of free radical solution polymerization of methyl methacrylate over an extended conversion range
Authors: Beuermann Sabine , Buback Michael , Russell Gregory T.
Published: April 2003

The low and intermediate conversion solution polymerization kinetics of methyl methacrylate in toluene and in 2‐butanone are investigated. For this purpose, repetitively applied laser pulses are employed to stimulate initiation, and quantitative near infrared spectroscopy is used to determine methyl methacrylate concentrations. The monomer concentration change per pulse is measured; it is shown how this information may be converted into coupled values of the rate coefficient for propagation kp, the rate coefficient for termination kt, and the total efficiency of (photo)initiation. In the present case kp is already known from independent investigations, which enables our pseudostationary state methods to yield kt directly. The major thrust of this paper, therefore, concerns the effect of solvent on kt: it is found that at both low and intermediate conversions, kt increases as the solvent concentration increases; possible causes of this are discussed. The effect of initial solvent fraction on the variation of kt with conversion is also reported. Although all our experimental measurements are carried out at an elevated pressure (1000 bar) and a single temperature (30°C), there is no reason for suspecting that our findings regarding solution polymerization termination should not be representative for polymerizations of methyl methacrylate (and other methacrylate monomers) in general.
Concurrent crystallization and interdiffusion in microlayers of polycarbonate and a copolyester
Authors: Nazarenko Sergey , Haderski Denise , Hiltner Anne , Baer Eric
Published: April 2003

Concurrent crystallization and interdiffusion of two miscible polymers, polycarbonate (PC) and a copolyester (KODAR), was studied in microlayers with 657 alternating layers. Minimal mixing of the two components during processing was indicated by separate glass transitions of the PC and KODAR layers. Changes in the glass transitions after the microlayers were annealed above the glass transition of PC were determined by DSC and DMTA. When the annealing temperature was 200°C or higher, interdiffusion was much faster than crystallization and the glass transitions gradually shifted closer together until they merged into a single transition. An analysis based on Fick's law of diffusion described the relationship between the glass transition temperatures and the annealing time. At 195°C, the rates of interdiffusion and crystallization were comparable. Annealing at this temperature resulted in more complex changes in the glass transitions, including the persistence of two transitions after long annealing times. This behavior was understood by considering an interlamellar amorphous phase that was trapped in the spherulites and not available for interdiffusion. Models were developed from the spherulite morphology observed in the optical microscope. Two cases were considered: a continuous layer of impinged spherulites in the PC/KODAR 20/80 (w/w) composition, and isolated spherulites aligned with the center of the KODAR layer in PC/KODAR 40/60 and 60/40. These models satisfactorily reproduced the principal features of concurrent crystallization and interdiffusion.
Synthesis and catalytic activity of adenine containing polyamines
Authors: Décout Jean‐Luc , Vergne Jacques , Maurel Marie‐Christine
Published: April 2003

N6‐Ribosyladenine has been obtained as a major product in the condensation of adenine and ribose under presumably prebiotic conditions. This abnormal nucleoside exhibits a pronounced catalytic activity as compared to histidine, in the hydrolysis of p‐nitrophenyl acetate. The N6‐substituted adenine ring could be considered as a substitute for the imidazole moiety, which could have played a catalytic role in primitive enzymes. To study in more details the catalytic properties of such a group when placed in a favourable microenvironment, it was linked to poly(allylamine). The presence of one adenine ring in ten residues accelerated the p‐nitrophenyl butyrate hydrolysis at pH 8. The rate was increased two‐fold compared to the starting polymer and 100‐fold compared to free adenine. A remarkable, more than 400‐fold acceleration compared to free adenine was measured when long hydrophobic dodecyl side chains were attached as substrate binding sites on the polyamine containing adenine rings. Under mild basic conditions, the catalytic activity of the polymers in the hydrolysis of p‐nitrophenyl esters strongly increases with pH. A cooperative effect between the unprotonated aliphatic amino groups and adenine rings in proton transfers could explain these results. The imidazole ring of N6‐substituted adenine derivatives could act in catalysis with water as a proton‐relay system through a tautomeric equilibrium as the imidazole residue in actual enzymes.