bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyanhydrides, 5. Thermotropic poly(ester anhydrides) derived from monoalkylthioterephthalic acids, hydroquinone and 4‐hydroxybenzoic acid
Authors: Kricheldorf Hans R. , Domschke Angelika 
Published: April 2003

AbstractMonoalkylthioterephthalic acids and their acyl chlorides were prepared via nucleophilic substitution of diethylbromo‐ or diethyl chloroterephthalate with thiols. Various poly(ester anhydrides) were synthesized by polycondensation of alkylthioterephthaloyl chloride with silylated 4‐hydroxybenzoic acid and silylated hydroquinone. The resulting poly(ester anhydrides) were characterized by elemental analyses, inherent viscosities, IR spectroscopy, differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS) measurements, optical microscopy and 13C NMR cross polarization/magic angle spinning (CP/MAS) spectroscopy. For the chain packing of these monosubstituted poly(ester anhydrides) a sanidic type of layer structure with a “back‐to‐back array” of the main chains is proposed. The alkyl side chains form ordered domains with predominantly all‐trans conformations. In most cases, three endotherms are observable in the DSC heating traces corresponding to the melting of the side chains and to reversible transitions into two different liquid‐crystalline phases.
Photodegradation of poly[ethylene‐co‐propene‐co‐(5‐ethylidene‐2‐norbornene)] rubbers, 2. Physical and dynamic‐mechanical behaviour under accelerated conditions
Authors: Scoponi Marco , Pradella Fiorella , Carassiti Vittorio , Tartari Davide 
Published: April 2003

AbstractThe physical and dynamic‐mechanical behaviour during the photo‐oxidation under accelerated conditons of three poly(ethylene‐co‐propene‐co‐5‐ethylidene‐2‐norbornene) (EPDM) rubbers with different contents of 5‐ethylidene‐2‐norborneneSystem. name: 5‐ethylidenebicyclo[2.2.1]hept‐2‐ene.
(ENB) are reported. These results show the dependence of the glass transition temperature both on the ENB content and on the photo‐oxidation time in accordance with network formation in the rubber matrix under accelerated conditions. The tensile experiments also show an increase of the elastic modulus as function both of ENB content and of photo‐oxidation time. The Murayama and Mooney‐Rivlin equations are applied to estimate the average molecular weight between two crosslinking nodes occurring in the rubber matrix during photo‐oxidation with tensile and dynamic‐mechanical experiments, respectively. Some correlations of physical and dynamic‐mechanical changes with the proposed mechanism of photo‐oxidation, due to the formation and reactivity of unsaturated groups, show that the crosslinking processes prevail over chain scissions.
Synthesis and magnetic properties of mesogenic side‐chain polymers containing stable radicals
Authors: Allgaier Jürgen , Finkelmann Heino 
Published: April 2003

AbstractAn amorphous and a liquid‐crystalline side‐chain polymer containing stable nitroxyl radicals are synthesized, the free radical being located either in a piperidine N‐oxyl or a 1,3‐oxazolidine N‐oxyl moiety. These polymers are available by reaction of precursor polymer having a formyl group in every repeating unit with low‐molecular‐weight nitroxyl free radicals functionalized with an amino group. The conversion of the polymer‐analogous reaction is nearly quantitative. Both the amorphous and the liquid‐crystalline polymer show paramagnetic behaviour in the temperature range from 6 to 300 K.
The system poly(4‐hydroxystyrene)/poly(vinyl acetate)/acetone: An experimental and theoretical study
Authors: Luengo Gustavo , Rubio Ramon G. , Sanchez Isaac C. , Panayiotou Constantinos G. 
Published: April 2003

AbstractIn an effort to assess the intermolecular interactions between poly(4‐hydroxystyrene)IUPAC name: poly(4‐vinylphenol).
(P4HS) and poly(vinyl acetate) (PVAc), two types of experimental measurements were conducted: volumetric properties and vapor pressures of solutions in a common solvent (probe). The PVT measurements for a 50:50 (w/w) binary polymer mixtures were conducted over a pressure range from 0 to 100 MPa and a temperature range from 350 to 470 K. The vapor pressures of acetone over a series of ternary systems acetone/P4HS/PVAc, and for four intermediate weight ratios PVAc/P4HS, were measured at 298,15 K, 308,15 K and 318,15 K. PVAc and P4HS interact primarily through hydrogen bonding. The probe molecule (acetone) on the other hand interacts also through hydrogen bonding with P4HS. A recent equation‐of‐state theory of hydrogen bonding has been used to correlate these measurements. Application of the theory was requiring the knowledge of the volumetric behavior of pure P4HS. Extensive PVT measurements for this polymer have also been conducted. The PVT measurements for the polymer mixture were used in order to estimate the hydrogen bonding parameters for the hydroxyl‐ester pair. The vapor pressures of the system acetone/P4HS were used in order to estimate the hydrogen bonding parameters of the hydroxyl‐carbonyl pair. On the basis of this information the theory was used to predict the vapour pressures of the ternary system. The theoretical predictions are in quantitative agreement with the experiments.
Copolyesteramides, 8. A comparison of substantially alternating 12‐oxydodecanoyl/ω‐iminoalkanoyl polyesteramides with equivalent random copolymers
Authors: Goodman Isaac , Rodríguez Maria Teresa 
Published: April 2003

AbstractThe polycondensation of methyl N‐(12‐hydroxydodecanoyl)‐ω‐aminoalkanoates (HO(CH2)11CONH(CH2)xCOOCH3) has been studied as a source of the alternating polyesteramides [O(CH2)11CONH(CH2)xCO]n, and the properties of the products compared with those of equivalent random copolymers of similar co‐unit ratio. Polymerization of the esters with x = 10 and 11 occurred straight‐forwardly, giving crystalline products with were distinguishable from the random counterparts by DSC but not by 67 MHz 13C NMR. For x = 5 the reaction was complicated by progressive partial elimination of the amide moiety as 6‐hexanolactam and by transamidation leading, for the polymer of highest amide content obtained, to an imperfect structure with ca. 76% of the sub‐units in alternating arrangement, the remainder being composed of oligoester and diamide units. This deviation from ideality has been elucidated by a study of the 13C NMR spectra of a wide range of model compounds which has yielded criteria for the recognition of oligomeric iminohexanoyl units, and by the NMR and MS examination of the products of aminolytic degradation. The results explain the multiple signals found in the 13C NMR spectra of the imperfectly alternating polymer (x = 5) and of its random analogues.
Anthracene derivatives as novel initiators for anionic and cationic polymerizations
Authors: Bartz Thomas , Klapper Markus , Müllen Klaus 
Published: April 2003

AbstractAnionic polymerizations with an anthracene‐derived initiator are described as giving rise to polymers containing only one chromophore on each chain. The approach taken herein involves the deprotonation of dihydroanthracene (1) and the initiation of methyl methacrylate, vinylpyridine and styrene polymerization by the corresponding monohydromonoanion 2. Polymer‐analogous aromatization of the initiator generates a polymer end‐capped with an anthracene chromophore. Anthracene‐containing initiators are used also in the ring‐opening cationic polymerization of 2‐phenyl‐2‐oxazoline (3). The anthracene‐labelled polymers poly(methyl methacrylate) (4a), polyvinylpyridine (5a), polystyrene (6a) and polyphenyloxazoline (7) are examined by gelpermeation chromatography (GPC), ultraviolet (UV) and NMR measurements. The coupling of two anthracene‐labelled polymers via the [4π + 4π] cycloaddition between the terminal anthracene moieties is described.
Studies on helix‐sense‐selective copolymerization based on triphenylmethyl methacrylate
Authors: Chen Chuanfu , Ren Changyu , Zhang Janjiang , Xi Fu 
Published: April 2003

AbstractHelix‐sense‐selective copolymerizations based on triphenylmethyl methacrylate (TrMA) with methyl methacrylate (MMA), benzyl methacrylate (BzMA) and diphenylmethyl methacrylate (DPMMA) in the presence of the chiral anionic complex initiator (−)‐sparteine/9‐fluorenyl‐lithium (1) were investigated. The studies concentrated on the stereoregularity of the copolymers, the relative reactivity of the monomers, the specific rotation of the copolymers and the influence of the solvent on the copolymerization. The results show that the match of TrMA with MMA of smaller size would favour the form of the copolymer with isotactic one‐handed helix having higher specific rotation as compared with BzMA ad DPMMA in toluene, but the TrMA/MMA copolymer obtained in tetrahydrofuran possessed a very low specific rotation because of the action of the polar tetrahydrofuran on the anion complex.
Double‐tailed perfluoroalkyl telomeric surfactants derived from tris(hydroxymethyl)acrylamidomethane for medical applications
Authors: Myrtil Evelyne , Zarif Leila , Greiner Jacques , Riess Jean G. , Pucci Bernard , Pavia André A. 
Published: April 2003

AbstractA new family of perfluoroalkyl double‐tailed amphiphiles was synthesized in order to develop a new drug carrying and delivery system. They were obtained by telomerization of tris(hydroxymethyl)acrylamidomethane (THAM) in the presence of various double‐tailed primary and secondary thiols as chain‐transfer agents, and with AIBN as the initiator. With secondary thiols, telomerization occurred in low yields (25–35% with respect to the thiol), because of the competitive formation of a disulfide by‐product, but proceeded in higher yields (45–90%, depending on the stoichiometry of the reagents) with primary thiols, thus allowing the preparation of a new family of perfluoroalkyl telomeric THAM double‐tailed amphiphiles. Preliminary biological tests showed no detectable hemolytic activity on human red blood cells at concentrations up to 20 mmol/L (50–65 g/L), whereas the hydrocarbon analogs proved to be hemolytic at 0,002 mmol/L. The LD50 was found to be higher than 2500 mg/kg of animal.
Direct visualization of synthetic cellulose formation via enzymatic polymerization using transmission electron microscopy
Authors: Kobayashi Shiro , Shoda Shin‐ichiro , Lee Jong , Okuda Kazuo , Brown R. Malcolm , Kuga Shigenori 
Published: April 2003

AbstractThe process of synthetic cellulose formation in an acetonitrile‐buffer solvent system by enzymatic polymerization of β‐cellobiosyl fluoride monomer using cellulase as a catalyst was visualized by transmission electron microscopy. Synthetic cellulose could be observed as soon as 30 s after initiation of the polymerization. A micellar phase separation occurred at the initial stage of the reaction. Irregular aggregates of cellulose were formed at the boundary of the micellar particles, suggesting that the interface is the site of polymerization. The cellulose product after treatment with hot surfactant solution was strongly labeled with cellobiohydrolase I‐gold complexes, indicating that the produced polymer is cellulose. The electron diffraction pattern of the product showed the typical pattern of crystal structure of cellulose II.
Polymerization of 1,3‐dienes with methylaluminoxanetriacetylacetonatovanadium
Authors: Ricci Giovanni , Italia Salvatore , Porri Lido 
Published: April 2003

AbstractVarious 1,3‐dienes (1,3‐butadiene, isoprene, 2‐ethyl‐1,3‐butadiene, (E)‐ and (Z)‐1,3‐pentadiene, (E)‐2‐methyl‐1,3‐pentadiene) were polymerized with the soluble catalyst system methylaluminoxane/V (acac)3 (acac: acetylacetonato). Butadiene and (Z)‐1,3‐pentadiene gave trans‐1,4 polymers, at low and room temperature. Isoprene, 2‐ethyl‐1,3‐butadiene and (E)‐2‐methyl‐1,3‐pentadiene gave trans‐1,4‐polymers at low temperature (< −20°C), but polymers of mixed cis/trans structure at room temperature. (E)‐1,3‐pentadiene gave polymers of mixed 1,2/trans‐1,4 structure either at low or room temperature. An interpretation of the results is reported.
Polyimides by Diels‐Alder polyaddition of α‐pyrones
Authors: Alhakimi Gamil , Görls Helmar , Klemm Elisabeth 
Published: April 2003

AbstractNew linear polyimides 11 were synthesized via Diels‐Alder addition polymerization of α‐pyrones 9 with bismaleimides 10. The number‐average molecular weights Mn range from 10 000 to 34 000 g. mol (gel‐permeation chromatography). The chemical structure of these polymers is supported by X‐ray crystallography, NMR spectra and model reactions. The Diels‐Alder addition occurred with high endo selectivity.
Pivalolactone, 3. Reactive blending of polypivalolactone with polycarbonate
Authors: Tijsma Edze Jan , van der Does Leen , Bantjes Adriaan , Vulić Ivan , Buning Gerard Hidde Werumeus 
Published: April 2003

AbstractThe occurrence of interchange reactions during heating of polypivalolactone (PPVL) with three polymers and their influence on the blend properties were studied. Physical blends of PPVL and bisphenol‐A polycarbonate (PC) were found to be immiscible. By heating of PPVL/PC blends in the melt at 280°C, in diphenyl ether at 260°C and in a twin‐screw extruder (TSE) at 280°C partial formation of copolymers was observed, provided that tetrabutyl orthotitanate (TnBT) was added. After heating of equimolar PPVL/PC blends in a TSE for 15 min, a PPVL‐PC block copolymer could be isolated containing 25 mol‐% pivalolactone (PVL) units. The results from thermal analyses indicated that PPVL/PC blends had become more miscible, due to the presence of copolymers formed by interchange reactions. After heating of equimolar mixtures of PPVL and a polyarylate (PAr) in a TSE for 15 min, PPVL‐PAr copolymers with 5 mol‐% PVL units could be isolated. Probably due to this low degree of interchange, no effect on the miscibility of the initially immiscible PPVL/PAr blends could be observed. PPVL/poly(butylene terephthalate) (PBT) blends, obtained after heating in a TSE, decomposed at a temperature between the melting temperatures of PPVL and PBT, indicating that interchange reactions may have occurred.
Thermotropic liquid‐crystalline aromatic‐aliphatic polyimides, 3. Poly(imide‐carbonate)s composed of 3,4:3′,4′‐biphenyldicarboximide
Authors: Hirata Tomohiro , Sato Moriyuki , Mukaida Ken‐ichi 
Published: April 2003

AbstractN,N′‐Bis(ω‐hydroxyalkyl)‐3,4:3′,4′‐biphenyldicarboximide (l = 3, 6) were prepared by a two‐step reaction (via intermediates) of 3,4:3′,4′‐biphenyltetracarboxylic dianhydride and ω‐amino‐alcohols. Polycondensation of dihydroxyalkyl derivatives of the 3,4:3′,4′‐biphenyldicarboximide (l = 3, 6) and/or biphenyl with alkylene bis(phenylcarbonate)s (m = 3, 6) afforded poly(imidecarbonate)s with high molecular weights in high yields, which were characterized by FT‐IR and NMR measurements and elemental analyses and showed good solubilities in organic solvents. The mesogenic properties of the polymers were evaluated by means of differential scanning calorimetry (DSC), observation in the polarizing microscope equipped with a hot stage and by means of powder X‐ray diffraction. The DSC curves of the imide unit rich polymers without annealing only display glass transition steps. The curves after annealing, however, show some endotherms. The polarizing microscope observation and X‐ray analyses indicated that the homo‐and copolymers from the 3,4:3′,4′‐biphenyldicarboximide derivative with longer methylene chains (l = 6) form nematic liquid‐crystalline mesophases.
Synthesis of crystallizable comb‐like oligomers by coupling of stearyl acrylate to butadiene oligomers via ene reaction and the influence of side‐chain order on the network formation by autoxidation
Authors: Luchtenberg Jürgen , Ritter Helmut 
Published: April 2003

AbstractThe kinetics of the ene reaction of stearyl acrylate with polybutadiene oils in the temperature range of 180 to 220°C is described. The ene reaction was found to be of pseudo 1st order with respect to stearyl acrylate because of the excess of polybutadiene double bonds. The rate constants correlate with the reaction temperature according to the Arrhenius law. The products show typical side‐chain crystallization, which has a strong influence on the viscosity and the autoxidation kinetics of the unsaturated polymeric backbone. Just below the crystallization temperature of the side chains the network formation by autoxidation is much slower than above the melting point.
(Co)polymers of L‐lactide, 1. Synthesis, thermal properties and hydrolytic degradation
Authors: Grijpma Dirk W. , Pennings Albert J. 
Published: April 2003

AbstractCopolymers of L‐lactide with D‐lactideAccording to IUPAC the name dilactide is preferred to lactide.
, glycolideIUPAC name: diglycolide.
, ε‐caprolactone and trimethylene carbonate, and networks with spiro‐bis‐dimethylene‐carbonate (2,4,7,9‐tetraoxaspiro[5.5]undecane‐3,8‐dione) were prepared in bulk at standardized polymerization conditions. The properties of the nascent copolymers were evaluated with respect to the nature of the comonomer. Copolymerization with comonomers entailing low glass transition temperature simultaneously reduces the crystallinity. 300 MHz 1H nuclear magnetic resonance is shown to be a useful technique for the determination of the average monomer sequence lengths in ε‐caprolactone and trimethylene carbonate copolymers. The presence of crystallizable L‐lactide sequences, due to differences in monomer reactivity, has a large effect on the thermal properties of the copolymer as well as on the long‐term degradation characteristics.
Synthesis of graft polymers from an ozonised ethylene‐vinyl acetate copolymer, 2. Determination of the efficiency and of the decomposition rate of macroinitiators
Authors: Fargère Thierry , Abdennadher Mohamed , Delmas Michel , Boutevin Bernard 
Published: April 2003

AbstractPolymers can be treated with an ozone/oxygen mixture to create peroxide and hydroperoxide groups on the polymer chain. These heat‐sensitive functional groups can serve to initiate radical polymerization of vinyl monomers to form graft copolymers. The efficiency and the decomposition rate constant of an ozonized ethylene‐vinyl acetate copolymer (EVA) are determined using the polymerization rate of styrene. The thermal polymerization of styrene is studied in the presence of non‐ozonized EVA. The thermal polymerization has no effect on the polymerization of styrene at the beginning of the reaction. Transfer reactions between the growing polystyrene radical and the EVA chain are negligible. The activation energy of the decomposition rate of ozonized EVA is calculated and reaches 46 kJ/mol. The entropy variation of the decomposition reaction is also calculated. The result obtained shows an important decrease (−45 cal · mol−1 · K−1) of the entropy which is opposite to the common behaviour (−6 to +13 cal · mol−1 · K−1) expected. The efficiency observed for the ozonized polymers is low and reaches only 20% at 100°C, this can be explained by the lack of mobility of the created radicals.
Functionalized polysulfones from 4,4‐bis(4‐hydroxyphenyl)pentanoic acid, 2,2‐isopropylidenediphenol and bis(4‐chlorophenyl) sulfone: synthesis, behaviour and polymer analogous amidation of the carboxylic groups
Authors: Koch Thomas , Ritter Helmut 
Published: April 2003

AbstractTwo reactive polysulfones with carboxylic side groups were synthesized by polycondensation of different amounts of 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (1) and 2,2′‐isopropylidenediphenol (bisphenol‐A,2) with bis(4‐chlorophenyl) sulfone (3). The amorphous polycondensate 4a was cast from solution in N,N‐dimethylformamide (DMF) to produce a homogeneous membrane which is clear and colourless. With ethanol/water as permeate, preferred permeability of water occurs. Additionally, the carboxylic groups of 4a were condensed with several alkylamines via the acyl chlorides. The obtained polysulfones with pendant alkylamido groups show a strong dependence of the glass transition temperature on the side chain length.
Anisotropic binders for polymer/liquid crystal dispersions
Authors: Cada Leonorina G. , Chien Liang‐Chy 
Published: April 2003

AbstractThe synthesis and phase behavior of linear and crosslinked side‐group epoxy polymers are described. These polymers are used in dispersons with low‐molecular‐weight liquid crystals, and the observation of phase separation in these systems is demonstrated.
Cationic polymerization of bis(1‐alkylvinyl)benzene and related monomers, 7. Copolymers
Authors: Maier Gerhard , Nuyken Oskar , Leitner Michael B. 
Published: April 2003

AbstractPolyindanes with long alkyl side chains have been prepared by reaction of 1,4‐bis(2‐hydroxy‐2‐propyl)benzene (3) and 1,4‐bis(2‐hexadecen‐2‐yl)benzene (4) in various ratios. All copolymers are soluble in common organic solvents and have been characterized by NMR, IR, GPC, DSC and TG. The variation of the glass transition temperature Tg with the composition of the copolymers can be described satisfactorily by Couchman's equation, which describes the dependence of the Tg's of copolymers on the Tg's and heat capacities of the homopolymers and the weight fractions of the comonomers in the copolymers. A very important feature of this step‐growth copolymerization is the ability of all possible end‐groups of monomers and oligomers to react with each other. Therefore the composition of the copolymers is not governed by the composition of the feed, because there is no need for high conversion to obtain high molar mass. It was found that 3 was twice as reactive as 4. The experimentally determined composition of the copolymers is in good agreement with the calculations based on the differences in the reactivity of the monomers.
Novel structural and thermotropic behavior of poly(diphenylphosphazene)
Authors: Kojima Morio , Magill Joseph H. , Cypryk Marek , White Michael L. , Franz Uli , Matyjaszewski Krzysztof 
Published: April 2003

AbstractPoly(diphenylphosphazene) (PDPhP) was synthesized by a reaction of 2,2,2‐trifluoroethyl diphenylphosphinite with trimethylsilyl azide. Characteristics of the polymer exhibit a marked molecular weight dependency. DSC measurements showed that the PDPhP undergoes a mesophase T(1) type transition in the range 180 ∼ 190°C and another at 240 ∼ 255°C depending upon the molecular weights of the polymers. Upon heating and cooling through T(1) the higher molecular weight PDPhP transforms to a 3D orthorhombic (γ‐form) with a = 1,99 nm, b = 1,05 nm and c = 0,995 nm from its original form (α‐form) in which a = 1,01 nm, b = 1,01 nm and γ = 101° after passing through the disordered mesophase (δ‐form). Another 3D form (β‐form) with c = 1,25 nm is formed from the lower molecular weight PDPhP after heat treatment of the 2D phase (δ‐form) that is obtained by quenching the specimens into ice‐water (4°C) from above T(1). The conditions for the formation of the β‐form depend strongly on the polymer molecular weight and its history. Lath‐shaped crystals were grown from dilute dichlorobenzene solution by adding p‐xylene (a non‐solvent). Electron diffraction patterns of solution grown PDPhP specimens exhibit unusual hexatic triple reflections associated with the mesophase. (100) twinning due to the thermal history of the specimens has been established. A complex (multistep) heat treatment process was required to elucidate the transformation behavior in PDPhP.