bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of poly(enaminonitriles) containing arylate and aramide units, and their thermal properties
Authors: Bae Jang‐Soon , Gong Myoung‐Seon 
Published: April 2003

AbstractVarious aromatic diamines with preformed arylate and aramide linkages were obtained by the reaction of p‐nitrobenzoyl chloride with aromatic diols and diamines, and terephthaloyl chloride with p‐nitrophenol and p‐nitroaniline, followed by hydrogenation. New poly(enaminonitriles) containing arylate or aramide units in the main chain were prepared by reacting p‐bis(1‐chloro‐2,2‐dicyanovinyl)benzene (2) with the corresponding ester‐ or amide‐containing aromatic diamines. These polymers possess intrinsic viscosities of 0.38–0.53 dL/g. They are easily soluble in polar aprotic solvents such as dimethyl sulfoxide, N,N‐dimethylformamide and N‐methyl‐2‐pyrrolidone. Hard and brittle films were easily cast from DMF solutions. These polymers show a broad exothermic peak in differential scanning calorimetry and undergo a curing reaction around 350°C to form insoluble materials. Almost all the poly(enaminonitriles) exhibited no appreciable decomposition below 400°C, 10% weight loss being recorded above 450°C, and a good thermal stability of 83–92% residual weight at 500°C.
Scattering properties of multicomponent polymer solutions: polyelectrolytes, homopolymer mixtures and diblock copolymer
Authors: Borsali Redouane 
Published: April 2003

AbstractThis article reviews the understanding of static and dynamic scattering properties of multicomponent polymer systems in solution achieved during the past decade. We shall describe particularly ternary polymer systems which include polyelectrolyte solutions (polyion/counter‐ions/water), mixture of homopolymers (A and B)/solvent and the case of diblock copolymer (A‐B, linear or cyclic) solutions. The purpose of this paper is not an extensive survey of theoretical and experimental results obtained on the scattering behavior of these systems but rather an updating of recent results. For polyelectrolyte systems we shall focus, by means of scattering techniques, on the conformation of the polyelectrolyte chain and on the structure of the system induced by the dominant electrostatic interactions in solution involving polyions, counter‐ions and solvent. As for the mixture of homopolymers in solution and diblock copolymer/solvent systems, we shall mainly discuss their dynamic behavior and show that using linear response theory and the Random Phase Approximation (RPA), two relaxation modes describe the autocorrelation functions as revealed using dynamic light scattering (DLS) or/and Neutron Spin Echo (NSE) techniques: the first mode characterizes the concentration fluctuations and the second one the composition fluctuations. We shall discuss the scattering properties of these systems on the basis of recent developments with emphasis on possible coiling of the polyelectrolyte chain at low charge density and also how important parameters such as the mobility of the chain (diffusion process) and the interaction parameter (compatibility), which control the dynamics and the thermodynamics in homopolymer mixtures and diblock copolymer systems, could be deduced from scattering experiments.
On the stereoisomerization in thermal degradation of isotactic poly(propylene)
Authors: Sawaguchi Takashi , Seno Manabu 
Published: April 2003

AbstractThe terminal microstructure of the hydrogenated α,ω‐diisopropenyloligo(propylene) prepared by thermal degradation of isotactic poly(propylene) at 370°C was determined by means of 13C NMR spectroscopy, and therefrom the stereoisomerization reaction of the reacting polymer segment is discussed in relation to polymer dynamics. With respect to the asterisked carbons of the propyl end group CH3CH2*CH2(n‐Pr) and of the isopropyl end group (*CH3)2CH (i‐Pr) formed by hydrogenation, the mole fractions of triads (m meso, r racemo) Fmm = 0.64, Fmr = 0.09, Frr = 0.12 of n‐Pr‐*CH2 differ from the microtacticity of the main chain of telechelic oligomers, and the mole fraction of i‐Pr‐*CH3 is as follows: F(δtζt) + F(δeζe) = 0.74 (m); F(δtζe) + F(δeζt) = 0.26 (r). These results clearly show that the stereoisomerization occurs only at the asymmetric carbon near the end group of the telechelic oligomer. The value of the mole fraction of i‐Pr‐*CH3 is consistent with Fm = 0.73 (Fmm + Fmr) and Fr = 0.27 (Frr + Frm) of n‐Pr‐*CH2 at the outer position of the main chain rather than with Fm = 0.79 (Fmm + Frm) and Fr = 0.21 (Frr + Fmr) at the inner position. These results could be consistently traced by a simulation based on a reaction model including stepwise intramolecular hydrogen abstraction of the tertiary on‐chain macroradical near the center of the main chain before the successive β‐scission. This stepwise back‐biting is estimated to occur once (20%) and twice (80%) via a quasi six‐membered cyclic structure in a transition state, and occurs in a very limited part of the molecular chain.
Novel perylene‐containing polymers
Authors: Quante Heribert , Schlichting Peter , Rohr Ulrike , Geerts Yves , Müllen Klaus 
Published: April 2003

AbstractNovel perylene‐containing polymers have been synthesized. They exhibit good solubilities in organic solvents and have good film forming properties. A water‐soluble perylene‐containing polyimide was obtained via sulfonation of the corresponding polyimide. Solubilities and spectral characteristics of these polymers are discussed as a function of their structures.
Polysiloxanes with benzophenone side groups: factors affecting their efficiency as free radical polymerization photoinitiators
Authors: Pouliquen Lydie , Coqueret Xavier 
Published: April 2003

AbstractFunctionalized silicone copolymers containing 2‐benzoylbenzoic acid (2‐BBA) ester side groups were evaluated as radical polymerization photoinitiators in the presence of an amine co‐reactant. Following up previous reports, the study of their efficiency conducted at various concentrations of the photoinitiating system in a model acrylate formulation was compared to that of the low molecular weight 2‐BBA ester. The photosensitive polysiloxanes were confirmed to exhibit a clear polymer effect, the type II photoinitiating efficiency being enhanced when the chromophores are present as pendant groups on polymer chains and when the tertiary amine (ethyl 4‐dimethylaminobenzoate) is free in the medium and with r = [amine]0/[2‐BBA]0 = 1. The influence of the increase of r in the range 0.5‐2 on the initial polymerization rate at constant concentration of BBA was shown to improve the initial rate of polymerization as well as the limiting conversion. N,N‐Dimethyl and N,N‐diethyl aliphatic or aromatic low molecular weight aminoesters were studied as co‐initiators to gain a deeper insight into the process. The effect of the incident UV beam wavelength was also examined and showed the complex influence of the amine structure on reactivity. Light absorption characteristics, reducing power and aptitude to charge transfer initiation of acrylate polymerization seem to contribute to various extents to overall efficiency.
The crystal structure and drawing‐induced polymorphism in poly(aryl ether ketone)s, 1. Poly(oxybiphenyl‐4‐4′‐diyloxy‐1,4‐phenylenecarbonyl‐1,3‐phenylenecarbonyl‐1,4‐phenylene)
Authors: Wang Shanger , Wang Junzuo , Mo Zhishen , Zhang Hongfang , Wu Zhongwen 
Published: April 2003

AbstractCrystal structure and polymorphism induced by uniaxial drawing of a poly(aryl ether ketone) [PEDEKmK] prepared from 1,3‐bis(4‐fluorobenzoyl)benzene and biphenyl‐4,4′‐diol have been investigated by means of transmission electron microscopy (TEM), electron diffraction (ED), wide‐angle X‐ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The melting and recrystallization process in the temperature range of 250‐260°C, far below the next melting temperature (306°C), was identified and found to be responsible for the remarkable changes in lamellar morphology. Based on WAXD and ED patterns, it was found that crystal structure of isotropic‐crystalline PEDEKmK obtained under different crystallization conditions (melt‐crystallization, cold‐crystallization, solvent‐induced crystallization, melting‐recrystallization, and crystallization from solution) keeps the same mode of packing, i.e., a two‐chain orthorhombic unit cell with the dimensions a = 0.784 nm, b = 0.600 nm, and c = 4.745 nm (form I). A second crystal modification (form II) can be induced by uniaxial drawing above the glass transition temperature, and always coexists with form I. This form also possesses an orthorhombic unit cell but with different dimensions, i.e., a = 0.470 nm, b = 1.054 nm, c = 5.064 nm. The 0.32 nm longer c ‐axis of form II as compared with form I is attributed to an overextended chain conformation due to the expansion of ether and ketone bridge bond angles during uniaxial drawing. The temperature dependence of WAXD patterns for the drawn PEDEKmK suggests that form II can be transformed into the more stable form I by relaxation of overextended chains and relief of internal stress at elevated temperature in absence of external tension.
High‐pressure free‐radical copolymerization of ethene and 2‐ethylhexyl acrylate
Authors: Buback Michael , Dröge Thomas , Herk Alex Van , Mähling Frank‐Olaf 
Published: April 2003

AbstractThe free‐radical copolymerization of ethene (E) and 2‐ethylhexyl acrylate (EHA) is studied between 150 and 250°C and at pressures from 1500 to 2500 bar. The reactions which were induced either thermally or laser‐photochemically are carried out in two types of continuously operated devices and also within a batch reactor. The precision in the determination of reactivity ratios is considered in detail for the continuous experiments taking the error structure of the copolymer composition measurement into account. The reactivity ratios rE and rEHA at 220°C and 2000 bar are found to be 0,050 ± 0,002 and 3,9 ± 0,9, respectively. From the ethene rich reaction mixtures rE is available with higher precision than is rEHA. The E/EHA reactivity ratios are found to be very close to literature data for the E/butyl acrylate (BA) copolymerization. Fitting of the combined data set, for E/EHA and E/BA, yields for the activation energy and activation volume of the ethene reactivity ratio EA(rE) = (11,9) kJ · mol−1 and ΔV≠(rE) = ‐(8,2 ± 3,5) cm3 · mol−1, respectively.
High and low molar mass 3‐alkyl‐1,4‐pentazadienes. Synthesis and photolysis
Authors: Baindl Andreas , Lang Armin , Nuyken Oskar 
Published: April 2003

AbstractHigh and low molar mass compounds containing the 3‐alkyl‐1,4‐diarylpentazadiene group were synthesized in the reaction of aromatic diazonium salts with primary amines. These high nitrogen compounds are characterised by high photosensitivity and thermostability. The photolytic decomposition was studied in detail with respect to the substitution at the aromatic moieties and at N3 of the pentazadiene chromophore. Electron donating aromatic substituents were found to increase photosensitivity and decrease thermostability whereas electron withdrawing aromatic substituents cause higher photolytic and thermolytic stability. A little influence of the alkyl group at N3 on the photosensitivity of the pentazadiene group was observed. Photolysis was investigated by means of UV/Vis spectroscopy and obeys first order kinetics for some compounds under investigation. Gel permeation chromatography (GPC) measurements during photolysis of pentazadiene polymers prove that irradiation with UV light causes irreversible chain degradation. Thermolysis in bulk was studied for all compounds by differential scanning calorimetry (DSC). In contrast to the results of the photolysis the alkyl substituent at N3 has an effect on the thermostability of the pentazadiene chromophore.
Liquid‐crystalline polyimides, 28. Thermoplastic elastomers with smectic hard phase based on 3,5:3′,5′‐biphenyltetracarboximides
Authors: Kricheldorf Hans R. , Linzer Volker 
Published: April 2003

AbstractTwo series of copoly(ether‐imide)s were prepared by polycondensation of 3,5:3′,5′‐biphenyltetracarboxylic anhydride (BTCA) and mixtures of 4,4′‐(nonamethylenedioxy)dianiline and polytetrahydrofuran (polyTHF) containing two amino end groups. Two samples of polyTHF were used, one sample with a number‐average molecular weight Mn = 750 and another sample with Mn around 2100. All polycondensations were conducted in the form of a “one‐pot procedure” in refluxing m‐cresol. The mole ratio of poly‐THF and 4,4′‐(nonamethylenedioxy)dianiline was varied, so that the length of the hard segments varied.Wide‐angle X‐ray scattering (WAXS) powder patterns proved that at least the hard phase of those poly(ether‐imide)s with relatively long hard segments possesses a smectic‐crystalline layered structure analogous to that of the homopolymer derived from BTCA and 4,4′‐(nonamethylenedioxy)dianiline. Only one polyimide showed highly elastic behavior.
Calorimetric study of tetrahydro‐1,3‐oxazin‐2‐one and poly(oxy‐1,3‐propanediyliminocarbonyl), and the polymerization/depolymerization equilibrium
Authors: Lebedev Boris V. , Smirnova Natal'ya N. , Kiparisova Elena G. 
Published: April 2003

AbstractIn adiabatic vacuum and dynamic calorimeters the temperature dependence of the heat capacity Cp0 of tetrahydro‐1,3‐oxazin‐2‐one (THO) and poly(oxy‐1,3‐propanediyliminocarbonyl) (PTHO) was studied between 5 and 500 K. The melting temperature of the monomer and the polymer, the enthalpies of melting of THO and the glass transition temperature of PTHO were determined. In a calorimeter with a static bomb and an isothermal shield the energies of combustion ΔUcomb of the monomer and the polymer were measured. From the experimental data the thermodynamic functions Cp0, H0(T) – H0(O), S0(T), G0(T) – H0(0) were calculated in the range of 0 to 450 K, and enthalpies of combustion ΔHcomb0 and thermochemical parameters of formation ΔHf0, ΔSf0, ΔGf0 of the compounds studied were estimated at T = 298.15 K and standard pressure. The results obtained were used to estimated the thermodynamic characteristics of the equilibrium of THO polymerization in bulk (ΔHpol0, ΔSpol0, ΔGpol0), with opening of the six‐membered ring and formation of the linear polymer PTHO, in the range 0 to 450 K. It was found that the ΔGpol0 values are always negative and change from −18 kJ · mol−1 at 0 K to −14 kJ · mol−1 at 450 K. Thus, the process equilibrium is everywhere shifted towards the formation of the polymer. The upper (ceiling) limiting temperature of THO polymerization in bulk at standard pressure is Tceil = 750 K, that is, considerably higher than the temperature of the onset of the thermal polymer decomposition (450 K).
Infrared temperature studies of a simple polyurea
Authors: Coleman Michael M. , Sobkowiak Maria , Pehlert George J. , Painter Paul C. , Iqbal Tahir 
Published: April 2003

AbstractInfrared temperature studies of a polyurea formed from 2‐methylpentane‐1,5‐diamine and 4,4′‐methylenebis(phenyl isocyanate) are presented, together with those of two model diureas, 2‐methylpentane‐1,5‐diphenylurea and ethylene diphenylurea. The main thrust of the work concerns the interpretation of the infrared changes that are observed in ordered and disordered hydrogen bonded ureas.
Polymers by “criss‐cross”‐cycloaddition, 7. Segmented block copolymers
Authors: Maier Gerhard , Fenchl Andrea , Sigl Gerhard 
Published: April 2003

Abstract“Criss‐cross”‐cycloaddition of 4,4′‐diisocyanatodiphenyl ether and 4‐methoxybenzaldazine was used to synthesize α,ω‐diisocyanato telechelics of molecular weights between 1 600 and 3 900. These precursors were reacted with different α,ω‐dihydroxy functionalized aliphatic polyethers to produce segmented block copolymers in which the precursors obtained by cycloaddition reaction provide hard segment domains embedded in a polyether soft segment matrix. The resulting materials were soluble in common organic solvents such as tetrahydrofuran and chloroform and were characterized by spectroscopic techniques (1H‐, 13C NMR, IR spectroscopy) as well as gel permeation chromatography (GPC) for molar mass determination. The block copolymers were molded in a hot stage press, and the resulting samples were characterized by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and stress‐strain measurement. The materials with a hard segment fraction below 0.36 and a molecular weight above M̄n = 90 000 were elastomers with ultimate elongations above 700%.
Thermal and mesogenic properties of semirigid polyamides based on mono‐ or trimethylsubstituted 1,3‐diaminobenzenes
Authors: Sato M. , Ujiie S. 
Published: April 2003

AbstractThermal and mesogenic properties of semirigid polyamides composed of one benzene ring with a kinked linkage and various aliphatic chains in the repeating unit, which are derived from three 1,3‐diaminobenzenes and aliphatic dicarboxylic acids, were examined. Only two polyamides with a long aliphatic chain (C18H36), based on 4‐methyl‐ and 2,4,6‐trimethyl‐1,3‐diaminobenzenes, form mesophases although the polymers exert nontraditional mesogenic units. Formation of the mesophase in the latter case depends on the inherent viscosity, i.e., polymers with lower inherent viscosity (⩽1,47 dL/g) form a layered structure by intermolecular interaction via hydrogen bonding of the amide linkage.
Interpolyelectrolyte complexes of poly[4‐(but‐3‐en‐1‐ynyl)‐1‐methylpiperidin‐4‐ol] with poly(carboxylic acids)
Authors: Kudaibergenov Sarkyt E. , Nurkeeva Zauresh S. , Sigitov Vladimir B. , Zh. Akimbekova K. , Ushanov Valerii Zh. 
Published: April 2003

AbstractThe formation of polyelectrolyte complexes (PEC) between linear or crosslinked poly[4‐(but‐3‐en‐1‐ynyl)‐1‐methylpiperidin‐4‐ol] and linear as well as crosslinked poly(acrylic acid) and poly(methacrylic acid) was studied by potentiometric, conductimetric, turbidimetric, viscometric and volumetric methods in aqueous solution. The composition of PEC particles depends on the conformational state of the interacting macromolecules. The destruction of PEC particles into the individual components takes place at an ionic strength μ > 1 × 10−2 mol/L. The addition of organic solvents causes the conformational transition of PEC particles from the compact structure to an extended one. The sorption of linear polyelectrolytes by networks is accompanied by the shrinking of the polyelectrolyte gels. The kinetics of sorption increases with increasing temperature, ionic strength of the solution and ionization degree. The destruction of PEC consisting of oppositely charged linear and crosslinked polyelectrolytes takes place at high ionic strength of the external solution. The completeness of interpolyelectrolyte reactions with participating of linear and crosslinked poly[4‐(but‐3‐en‐1‐ynyl)‐1‐methylpiperidin‐4‐ol] was detected by the disappearance of the Bohlman band at 2 800 cm−1. The kinetics of sorption of linear polyelectrolytes by crosslinked polyelectrolytes as well as of the competition reaction which is accompanied by the destruction of PEC composed of oppositely charged linear and crosslinked polyelectrolytes was also studied.
Synthesis and characterization of monomethacrylate‐functionalized self‐organizing crown ether compounds
Authors: Percec Virgil , Zipp Gabriela , Johansson Gary , Beginn Uwe , Möller Martin 
Published: April 2003

AbstractSynthesis and characterization of methacrylate‐monofunctionalized crown ether compounds based on derivatives of 2‐hydroxymethyl‐1,4,7,10,13‐pentaoxacyclopentadecane and 4′‐hydroxymethyl‐1,4,7,10,13‐pentaoxabenzocyclopentadecane is described. By differential scanning calorimetry (DSC) and thermooptical analysis (TOA) it is shown that the synthesized compounds and their sodium triflate complexes exhibit columnar mesophases.
Hydrolysis and release behavior of hydrolyzable poly(etherurethane) gels derived from saccharide‐, L‐lysine‐derivatives, and poly(propylene glycol)
Authors: Wibullucksanakul Sirinat , Hashimoto Kazuhiko , Okada Masahiko 
Published: April 2003

AbstractFour different poly(ether urethane) gels were prepared by polyaddition of saccharide derivatives (1, 2, 3α, or 3β) and poly(propylene glycol) with an L‐lysine‐derived diisocyanate, methyl (S)‐2,6‐diisocyanatohexanoate (4). Dibutyltin dilaurate and triisocyanate 5, that was also derived from L‐lysine, were used as a catalyst and a crosslinking agent, respectively. Hydrogels containing 1, 2 or 3α were hydrolyzed in phosphate buffers (pH 5.5, 7.0, 8.0) at 27°C, while the hydrolysis of the gel bearing 3β did not occur even after immersion for 3 months. Release of 5(6)‐carboxyfluorescein (CF) and magnesium 8‐anilino‐1‐naphthalenesulfonate (ANS) from the hydrogels was investigated in buffers of different pH. The release behavior was significantly controlled by the degree of hydrolysis of the gels. Both hydrolysis and the release behavior of these gels depended on the pH value.
The width of miscibility gaps, measured by scattering
Authors: Hellmann E. H. , Hellmann G. P. 
Published: April 2003

AbstractIncompatible polymers yield two‐phase binary blends at almost all compositions. In equilibrium, the blends consist of two coexisting phases which have frequently very one sided compositions: Much of one component contains little of the other. The small content of the minor component, the so‐called “partial miscibility”, is important for some properties. But it is difficult to measure. Conventional techniques to determine miscibility gaps which rely on transparency and turbidity fail when the gaps are too wide. More reliably, the composition of the coexisting phases can be extracted from X‐ray or neutron scattering data. A series of blends of poly(methyl methacrylate) (PMMA) and random copolymers SxMMAl−x of styrene and MMA, of which the degree of incompatibility was varied via the copolymer composition x, was studied by small angle neutron scattering. The interactions of the polymer components were measured in homogeneous and demixed blends. The demixed blends yield at high wave vectors a scattering equal to the scattering of the two coexisting phases, superposed. The composition of the coexisting phases was extracted from the slope of the Zimm curve which responds very sensitively even when the compositions are extreme. Miscibility gaps as wide as 99.7% could be determined.
Synthesis and characterization of functional polymer films containing trimethylsilyl groups
Authors: Shim Hong‐Ku , Jang Min‐Sik , Hwang Do‐Hoon 
Published: April 2003

AbstractPoly(2‐methoxy‐5‐trimethylsilyl‐1,4‐phenylenevinylene) (PMTSPV) was prepared as thin film via the water‐soluble precursor route, and its electrical and optical properties were studied. The conductivity values of drawn (L/L0 = 7) and undrawn FeCl3‐doped PMTSPV films were 0.1 and 0.5 · cm−1, respectively. The electroluminescence device was fabricated with PMTSPV as an emitting layer, and ITO and aluminium as hole‐injection and electron‐injecting electrodes, respectively. The threshold voltage of the device was about 4 V, and the emission maximum was at about 560 nm, with quantum efficiency of 2 × 10−4% (emitted photons per electron), which corresponds to yellow light emission. The χ(3) for the PMTSPV film was investigated by using the third‐harmonic generation method at 1907 nm fundamental wavelength, and found to be 1.0 × 10−11 esu.
Synthesis and mesomorphic properties of side chain liquid crystalline polymers having thiadiazole ring
Authors: Lee Jaehwan , Hong Sung Il , Hwang Seung Sang 
Published: April 2003

AbstractNew liquid crystalline monomers having 1,3,4‐thiadiazole ring as mesogen were synthesized by using Lawesson's reagents to prepare the thiadiazole ring and acryloyl chloride and methacryloyl chloride to introduce the vinyl group. These monomers were polymerized in the presence of 2,2′‐azoisobutyronitrile as initiator in THF. All monomers and polymers show cholesteric behavior and a broad chiral smectic C* phase. As the spacer length increases, the phase transition temperature is lowered and the polymers show higher phase transition temperatures and improved mesophase stabilities compared to the corresponding monomers.