bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and characterization of fluorine‐containing aromatic condensation polymers, 4. Preparation and characterization of fluorine‐containing aromatic polyazomethines and copolyazomethines from perfluoroisopropylidene group‐containing aromatic diamines and/or isopropylidene group‐containing aromatic diamines and phthaladehydes
Authors: Saegusa Yasuo , Kuriki Minoru , Nakamura Shigeo
Published: April 2003

A series of novel fluorine‐containing aromatic homopolyazomethines and copolyazomethines were synthesized by solution polycondensation of perfluoroisopropylidene (perfluoropropane‐2,2‐diyl) group‐containing aromatic diamines, 2,2‐bis[4‐(4‐aminophenoxy)phenyl]‐1,1,1,3,3,3‐hexafluoropropane (4,4′‐[1,1,1,3,3,3‐hexafluoropropane‐2,2‐diylbis(1,4‐phenyleneoxy)]dianiline (1a)) and 2,2‐bis(4‐aminophenyl)‐1,1,1,3,3,3‐hexafluoropropane (4,4′‐(1,1,1,3,3,3‐hexafluoropropane‐2,2‐diyl)dianiline (1b)), and/or the corresponding analogous isopropylidene group‐containing aromatic diamines, 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane (4,4′‐[isopropylidenebis(1,4‐phenyleneoxy)]dianiline (1c)) and 2,2‐bis(4‐aminophenyl)propane (4,4′‐isopropylidenedianiline (1d)), with terephthalaldehyde (2a) and isophthaladehyde (2b). The effect of fluorine substitution on the synthesis and properties of these polymers was investigated by comparison with those of the corresponding homopolyazomethines but without fluorine. Film‐forming fluorine‐containing polyazomethines with reduced viscosities up to ηred= 0,44 dL · g−1were obtained in high yields by usingm‐cresol as reaction medium. Incorporation of perfluoroisopropylidene groups in the polyazomethine backbone greatly enhanced the solubility of the polymers in various organic solvents including chloroform and tetrahydrofuran. Their thermal stability was also successfully improved by the introduction of fluorine, and both the temperatures of 5% and 10% weight loss in air increased monotonically with the increase of the fluorine content. The surface properties of the films or the contact angles formed by water and diiodomethane were, however, scarcely affected by fluorine substitution. The mechanical properties of the films, such as tensile strength and initial modulus, fairly decreased by the modification.
Ferroelectric liquid‐crystalline elastomers
Authors: Brehmer Martin , Zentel Rudolf , Wagenblast Gerhard , Siemensmeyer Karl
Published: April 2003

Oriented liquid‐crystalline (LC) elastomers (polar monodomains, concerning the direction of polarisation) have been prepared from polar monodomains of ferroelectric LC‐polysiloxanes by a radical photocrosslinking process. Attempts to perform ferroelectric switching lead in these soft elastomers to an elastic stress which prohibits—for low voltages—a complete reorientation of the polar axis (ferroelectric switching). A ferroelectric switching can, however, be observed for high voltages. The loop of hysteresis of this switching is asymmetric concerning the zero point of the driving voltage. Piezoelectric measurements show that these elastomers combine an elastic memory for one polar state with enough flexibility to allow a reorientation of the polar axis.
Soluble polyimides containing perylene units
Authors: Dotcheva Dobrinka , Klapper Markus , Müllen Klaus
Published: April 2003

Novel soluble polyimides containing perylene units have been synthesized. The polymers were prepared in a one‐step polycondensation reaction from 1,6,7,12‐tetrakis(4‐tert‐butylphenoxy)‐3,4:9,10‐perylenedianhydride and aliphatic and aromatic diamines. The amorphous polyimides have a very good solubility in a wide range of organic solvents and exhibit thermal stability up to 350°C. The polymers consist of 10 to 30 monomer units and show a narrow molecular weight distribution. The dark red materials can be used as polymeric dyes (absorption wavelength: λmax = 590–610 nm) and exhibit fluorescence near 620 nm.
Ionic conduction in polyphosphazene containing oligo(oxyethylene) side chains with cyclic carbonate as terminal groups
Authors: Tada Yuji , Sato Moriyuki , Takeno Noboru , Inubushi Akiyoshi , Nakacho Yoshifumi , Shigehara Kiyotaka
Published: April 2003

Novel comb‐type polyphosphazene derivatives with cyclic carbonate groups as the terminal function of oligo(oxyethylene) side chains [CEP] were prepared for the achievement of high ionic conductivity, when they were hybridized with LiCIO4, in accordance with increase of permittivity. The relative permittivity of CEP turned out to be extraordinarily high, i.e. 24,6, whereas that of a similar comb‐type polyphosphazene with methyl ether terminal function of side chains was less than 10 at 25°C. The [LiCIO4(5)/CEP (95 wt.‐%)] hybrid showed relatively high ionic conductivity of 7,3 · 10−6 at 25°C and 9,6 · 10−5 S · cm−1 at 60°C, respectively. From the observation of the temperature dependence of ionic conductivity at 10–60°C, it was revealed that the ionic conduction obeys the Vogel‐Tamman‐Fulcher and Williams‐Landel‐Ferry equations based on the free volume theory.
Poly(2,5‐dialkoxy‐p‐phenylene)s—synthesis and properties
Authors: Vahlenkamp Thomas , Wegner Gerhard
Published: April 2003

The synthesis of poly(2,5‐dialkoxy‐p‐phenylene)s (PPP) by palladium‐catalyzed polycondensation of 2,5‐dialkoxy‐4‐bromophenylboronic acids is described. Number‐average degrees of polymerization of ca. 30 have been reached at best. The characterization of the polymers by NMR, IR, UV‐VIS and fluorescence spectra, data on the bulk structure obtained by X‐ray methods, melting behavior and thermal stability are reported. PPP's with long alkoxy side chains exhibit a layered phase structure, those with short or branched alkoxy side chains, cylindrical packing. Poly(2,5‐dibutoxy‐p‐phenylene) was prepared with chain lengths 7 ≤Pn≤ 30. The polymer withPnof 30 shows thermal transitions in the bulk phase at 182°C and 227°C. It forms an anisotropic melt above 227°C which only starts decomposing if heated above 300°C. The polymers of shorter chain length show isotropic melts, with the melting point strongly depending on chain length.
Investigation of poly(vinyl alcohol)/poly(N‐vinyl‐2‐pyrrolidone) blends, 3. Permeation properties of polymer blend membranes
Authors: Ping Zhenghua , Nguyen Quang Trong , Néel Jean
Published: April 2003

Dense membranes made of poly(vinyl alcohol) (PVA) and poly(N‐vinyl‐2‐pyrrolidone) (PVP) blends of different compositions were studied in gas‐sweeping permeation of a water‐ethanol mixture containing 10 wt.‐% of water. When the PVP content increases, the steady‐state permeation flux and the water content in the permeate show sudden changes at ca. 30–40 wt.‐% of PVP in the membrane: the flux increases drastically, while the water selectivity of the membrane falls to a much lower level. The diffusion coefficients of both water and ethanol, as determined from the permeation flux changes in the transient regime, exhibit a large increase when the PVP content exceeds 30 wt.‐%, and this accounts for the flux increase. The fall in the permeation selectivity is shown to be due to a strong decrease in the sorption selectivity. The threshold of the change corresponds approximately to the PVP content at which PVA crystallites no longer exist in the blend. A further study on the states of water in the blend membranes by differential scanning calorimetry made it possible to relate these changes with a change in the interactions of water with hydrophilic sites in the polymer blend when the PVP content changes.
Radically initiated copolymers of styrene with 4‐vinylbenzylamine and its trifluoroacetamide derivative, 1. Kinetic studies of solution polymerization
Authors: Charreyre Marie‐Thérèse , Razafindrakoto Vanghi , Veron Laurent , Delair Thierry , Pichot Christian
Published: April 2003

Kinetics of radically initiated solution homopolymerization of 4‐vinylbenzylamine (VBA) and its trifluoroacetamide derivative (VBAF), and their copolymerization with styrene (S), have been investigated at 60°C in toluene and DMSO, respectively, using AIBN as initiator. kp/kt1/2 values were first estimated, showing a higher value for VBAF than for VBA and styrene. The reactivity ratios were determined to be rVBA = 2,15, rS = 0,45 for the VBA/S system and rVBAF = 0,93, rS = 1,03 for the VBAF/S one. This indicates that the reactivity of VBA is higher than that of styrene, but it is significantly lower when VBA is in its protected form (i.e. VBAF), which is well reflected in the Q, e values. Average copolymer compositions, as characterized by 1H NMR and elemental analysis, are in good agreement with the theoretical ones; in addition, comparison of the molecular weights of both series of copolymers, as obtained from GPC, suggests that the VBA monomer can act as a relatively efficient chain transfer agent.
The electron transfer behavior of some new polymers with viologen structure on the reduction of azobenzene in heterophases
Authors: Liu Fu‐Tian , Song Ning , Yu Xian‐Da , Li Shu‐Ben
Published: April 2003

Several polymers with viologen structure were prepared by polymer analogous reaction with poly(vinyl alcohol) (PVA) and ethylcellulose (EC). The polymers were used as electron‐transfer catalysts (ETC) for the reduction of azobenzene, either in a Zn‐PV2+ system (reductant: Zn, in CH3CN/H2O) or a Na2S2O4‐PV2+ system (reductant: Na2S2O4, in CH2Cl2/H2O). It was found that all the polymers used in our work had the ability to mediate the reduction of azobenzene. Two factors (polymeric carrier and viologen group) are believed to affect the reduction.
High performance aromatic polyimide fibers, 3. A polyimide synthesized from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and 2,2′‐dimethyl‐4,4′‐diaminobiphenyl
Authors: Eashoo Mark , Wu Zongquan , Zhang Anqiu , Shen Dexing , Tse Cecilia , Harris Frank W. , Cheng Stephen Z. D. , Gardner Kenncorwin H. , Hsiao Benjamin S.
Published: April 2003

A new high molecular weight aromatic polyimide has been synthesized from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 2,2′‐dimethyl‐4,4′‐diaminobiphenyl (DMB) in p‐chlorophenol at elevated temperature. BPDA‐DMB fibers have been spun by a dry‐jet wet spinning method. The fibers were elongated and annealed at elevated temperatures above 400°C to achieve excellent mechanical properties. In seven times drawn fibers, the BPDA‐DMB molecule packs into a triclinic unit cell with dimensions of a = 2,10(2) nm, b = 1,523(8) nm, c = 4,12(7) nm, α = 61,2(6)°, β = 50,7(7)°, and γ = 78,9(6)° with the number of chain repeating units per unit cell (Z) is sixteen. After annealing at elevated temperatures, the fibers produce a small modification of the unit cell [a = 2,048(6) nm, b = 1,529(5) nm, c = 4,00(2) nm, α = 62,1(3)°, β = 52,2(3)° and γ = 79,6(3)°]. By increasing the draw ratio, both the crystallinity and crystal orientation increase. The BPDA‐DMB fibers possess a decomposition temperature of 530°C in nitrogen and 500°C in air at a 5% weight loss when the heating rate is 10°C/min. After extensive drawing, BPDA‐DMB fibers exhibit a tensile strength of 3,3 GPa and a tensile modulus of over 130 GPa. Dynamic mechanical behavior of the fibers show both α (glass transition) and β (sub‐glass transition) relaxations above room temperature. The nature of the sub‐glass transition behavior is described as a noncooperative motion attributed to the diamine portion of the molecule. The activation energy for this relaxation in as‐spun fibers is 109 kJ/mol and increases to 144 kJ/mol by increasing the draw ratio. This β relaxation is found to be crystallinity dependent. The α transition is also suppressed by crystallinity which increases with draw ratio.
Thermotropic liquid‐crystalline aromatic‐aliphatic polyimides, 4. Poly(imide‐urethane‐carbonate)s based on pyromellitdiimide and 3,4:3′,4′‐biphenyldicarboximide
Authors: Hirata Tomohiro , Sato Moriyuki , Mukaida Ken‐ichi
Published: April 2003

Main‐chain types of thermotropic liquid‐crystalline (LC) poly(imide‐urethane‐carbonate)s were synthesized by melt polycondensation of N,N′‐bis(6‐hydroxyhexyl)pyromellitdiimide or N,N′‐bis(6‐hydroxyhexyl)‐3,4:3′,4′‐biphenyldicarboximide with diphenyl hexamethylenedicarbamate and/or diphenyl hexamethylenedicarbonate. The poly(imide‐urethane)s were also obtained from the dihydroxyalkylene diimide derivatives and hexamethylene diisocyanate by polyaddition. Yields and molecular weights of the resulting polymers tended to decrease with increasing urethane units. Differential scanning calorimetry (DSC) measurements, polarizing microscopic observations and powder X‐ray analyses at various temperatures demonstrated that the carbonaterich copolymers comprising the 3,4:3′,4′‐biphenyldicarboximide derivative formed a nematic mesophase. Temperature‐dependent Fourier‐Transform infrared measurements suggest that hydrogen bonding of urethane linkages affects the formation of LC mesophases.
Heterochain polymers based on natural amino acids. Synthesis and enzymatic hydrolysis of regular poly(ester amide)s based on bis(L‐phenylalanine) α,ω‐alkylene diesters and adipic acid
Authors: Arabuli Natia , Tsitlanadze George , Edilashvili Lamara , Kharadze Darejan , Goguadze Tsisana , Beridze Vakhtang , Gomurashvili Zaza , Katsarava Ramaz
Published: April 2003

Novel biodegradable regular poly(ester amide)s were synthesized by polycondensation of p‐toluenesulfonic acid salts of bis(phenylalanine) α,ω‐alkylene diesters (1) with bis(p‐nitrophenyl) adipate under mild conditions in organic solvents in the presence of triethyl amine as acid acceptor. Enzymatic hydrolysis (α‐chymotrypsinolysis) of the starting salts 1, the model bis(ester acetamide)s 2 and the obtained poly(ester amide)s 3 was investigated at 37°C and pH 8 using potentiometric titration. It was established that the hydrolysis rate increased with elongation of the α,ω‐alkylene chain. A strong noncovalent immobilization of the enzyme on the polymeric surface was observed.
Light controlled solubility change of polymers: Copolymers of N,N‐dimethylacrylamide and 4‐phenylazophenyl acrylate
Authors: Kröger Rainer , Menzel Henning , Hallensleben Manfred L.
Published: April 2003

Copolymers of N,N‐dimethylacrylamide (DMA) and 4‐phenylazophenyl acrylate (PAPA) have been prepared by free‐radical copolymerization in dioxane (DMAP‐x). The molecular weights of the copolymers show a strong decrease with increasing azobenzene content due to the retardation effect of the azobenzene group. An analogous decrease in molecular weight was found with a number of polymers of DMA which were polymerized in the presence of the non‐polymerizable model 4‐phenylazophenyl propionate (PAPP). We were able to induce a lower critical solution temperature (LCST) above a certain content of azobenzene moieties in the copolymers (DMAP‐x) in contrast to the good water solubility of poly(DMA). Due to the reversible photoisomerization and the concomitant change in the dipole moment of the azobenzene moieties, the LCST depends not only on the content of azobenzene but also on the degree of isomerization. A difference in the LCST up to 20°C was found for dark adapted polymer solutions (0% Z‐isomer) and polymer solutions in the photostationary state (ca. 85% Z‐isomer). Within this temperature range the polymer can be precipitated by irradiation with light.
Liquid crystalline epoxy resins containing binaphthyl group as rigid block with enhanced thermal stability
Authors: Carfagna Cosimo , Amendola Eugenio , Giamberini Marta
Published: April 2003

The synthesis and characterization of a novel liquid crystalline difunctional epoxy compound, 6,6′‐bis(2,3‐epoxypropoxy)‐2,2′‐binaphthyl (4), is presented. This epoxide, obtained by glycidyl termination of 2,2′‐binaphthyl‐6,6′‐diol, shows a nematic phase between 240 and 270°C. The curing reaction was carried out in the DSC pan by mixing the epoxy monomer with 4,4'‐diaminodiphenyl sulfone (DDS) or phthalic anhydride (FA). The thermal analysis of the cured resins indicated high thermal resistance.
Lamellar structure formation in the mixture of two cylinder‐forming block copolymers
Authors: Vilesov Alexander D. , Floudas Georg , Pakula Tadeusz , Melenevskaya Elena Yu. , Birshtein Tatiana M. , Lyatskaya Yulia V.
Published: April 2003

Two cylinder‐forming polystyrene‐block‐polybutadiene block copolymers of type A‐B with antisymmetric composition (polymer P1 with A : B = 3 : 1 (w/w) and polymer P2 with A : B = 1 : 3 (w/w)) and their binary mixture were studied by small‐angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) in order to determine the microphase structure. The cylindrical microstructure is confirmed for both copolymers, whereas, in the mixture, both techniques have unambiguously shown that a regular lamellar structure is obtained at the polymer‐polymer composition P1 : P2 = 1 : 1 (ratio of the numbers of chains). Qualitatively, the same results are obtained for corresponding systems simulated by the cooperative motion algorithm (CMA). Direct observations of the structure as well as the cooperative structure factors determined in the strong segregation limit for the simulated systems indicated lamellar structures in the blend of composition P1 : P2 = 1 : 1, in contrast to the microfibrillar morphology of the copolymers. The simulation additionally indicated a polymer‐polymer microseparation. The experimental and simulation results are compared with theoretical predictions based on the self consistent field theory.
Cationic polymerization of hexamethylcyclotrisiloxane by trifluoromethanesulfonic acid and its derivatives, 1. Initiation by trifluoromethanesulfonic acid
Authors: Nicol Pascal , Masure Michèle , Sigwalt Pierre
Published: April 2003

Polymerization of hexamethylcyclotrisiloxane (D3) initiated by trifluoromethanesulfonic acid (triflic acid TfOH) was carried out under vacuum, in methylene chloride solution at 20°C. The reaction rate is first order in [D3] and the constant active sites concentration [P*] varies as [P*] = k · [TfOH] · [D3]. The two main products of the reaction, both formed in similar amount from the beginning, are the dimer D6 and a high‐molecular‐weight polymer (HP). The other cyclic products also formed are the multiples of D3 (D9, D12, …), macrocycles MC (number‐average molecular weight M̄n ≈ 104) and small amounts of D4, D5 … (with [D5] > [D4]). The concentration of HP, MC, D6, D9, D12, … and the M̄n of the high polymer grow proportionally to conversion. The main reaction giving the high polymer and D6 is interpreted as a chain reaction, the growing HP bearing at each end potentially reactive silyl triflates which may be activated by the residual acid. D6 is mainly formed by a special type of back‐biting reaction involving transitory tertiary siloxonium ions. The other cycles D3x and the macrocycles mainly result from cyclization reactions of a second population of growing macromolecules which bear a silyl ester at one end and a nucleophilic silanol group at the other end.
Synthesis of polymers with pendant spiro orthoester groups
Authors: Zamzow Manfred , Höcker Hartwig
Published: April 2003

This paper describes the synthesis of polymers having spiro orthoester side groups, starting from lactones with methacrylate side groups. The spiro orthoester polymers are synthesized by a reaction with an oxirane. The hydroxy‐functional lactones 3‐hydroxy‐4,4‐dimethyl‐2‐oxotetrahydrofuran (1) and 5‐hydroxymethyl‐2‐oxotetrahydrofuran (13) were esterificated with methacryloyl chloride. The esterification of 5‐oxotetrahydrofuran‐2‐carboxylic acid (6) and 2,2‐dimethyl‐5‐oxotetrahydrofuran‐3‐carboxylic acid (11) with 2‐hydroxyethyl acrylate and 2‐hydroxyethyl methacrylate yielded the functionalized precursors for the synthesis of polymeric spiro orthoesters. These monomers were polymerized and copolymerized with methyl methacrylate and characterized. Furtheron, the obtained polymers with lactone groups were converted to the corresponding spiro orthoesters using 2,3‐epoxypropyl phenyl ether in the presence of boron trifluoride.
Ring‐opening polymerization of ε‐caprolactone in the presence of dicarboxylic acids
Authors: Zhang Qijin , Wang Bin , Hong Kulun , Zhu Qingren
Published: April 2003

The ring‐opening polymerization of ε‐caprolactone (ε‐CL) has been investigated in the presence of succinic acid in nitrogen atmosphere at 225°C. Analysis of the resultant polymers suggests that the poly(ε‐caprolactone) (PCL) obtained has two terminal carboxylic groups. VPO, 1H NMR and titration are used to determine the number‐average molecular weight of the PCL obtained at ε‐CL to acid molar ratios of 4, 8, 12, 14, 16 and 20, respectively. It is found that the molecular weight of the PCL is not related to the ratio of ε‐CL to succinic acid except for low ε‐CL concentrations. At a molar ratio of 14, the molecular weight of PCL reaches a maximum at a reaction time of 3 h. Beyond 3 h the ester exchange reaction becomes predominant, and the molecular weight approaches the equilibrium value (M̄e) due to the ratio of ε‐CL to succinic acid in the feed.
Renewable resources, 2. Poly‐Diels‐Alder additions with disorboylamides as bisdienes and a dimaleoylamide as bisdienophile
Authors: Reinecke Martin , Ritter Helmut
Published: April 2003

The poly‐Diels‐Alder reactions between the disorboylamides 1 and 7 and the dimaleoylamide 9, yielding the oligomers 13 and 14, are described. The applicability of the maleoyl and the sorboyl system for poly‐Diels‐Alder additions is demonstrated in a low‐molecular‐weight model cycloaddition between the monodiene 10 and the monodienophile 11. All presented compounds contain a high amount of molecules derived from renewable resources.
Studies on microgels, 1. Microgel formation studied by gel‐permeation chromatography with an on‐line light scattering detector
Authors: Pille Ludger , Solomon David H.
Published: April 2003

The previously described microgel synthesis in which living poly(4‐tert‐butylstyrene) was reacted with 1,4‐divinylbenzene was studied. Samples were taken after the addition of the crosslinker and characterized by gel‐permeation chromatography (GPC) with an on‐line multi angle laser light scattering (MALLS)‐ and a differential refractive index (DRI) detector. Primary particle formation was found early in the reaction followed by interparticular crosslinking. The GPC calibration curves allowed the derivation of a branching plot. The branching plots showed, that in addition to interparticular crosslink reactions also intraparticular crosslink reactions are occurring. The plots also showed that the primary particles scale like linear polymers, which led to the conclusion that they consist of comb‐like structures with poly(4‐vinylstyrene) as the backbone and poly(4‐tert‐butylstyrene) as branches.
TiCl4/MgH2‐supported Ziegler‐type catalyst system, 3. New findings on the concentration of active sites in ethylene/1‐hexene copolymerization
Authors: Jaber Isam A. , Fink Gerhard
Published: April 2003

The effect of 1‐hexene on the rate constant of ethylene polymerization and on the number of active centres in the copolymerization of ethylene with 1‐hexene is reported. Using three TiCl4/MgH2Al(C2H5)3 catalysts, of different Ti contents and surface area in the polymerization reveals that the addition of small amounts of the comonomer 1‐hexene results in a two‐ to three‐fold increase in the rate of ethylene consumption when a low‐Ti‐content catalyst is used. In contrast, no fundamental change in the catalytic activity was observed when a high‐Ti‐content catalyst is employed. The determination of the concentration of active centres C* by means of the 14CO radio‐labelling technique, shows that C* in ethylene/1‐hexene copolymerization is more or less the same as in ethylene homopolymerization.
Preparation and properties of poly(amide‐imide)s derived from trimellitic anhydride, α‐amino acids, and aromatic diamines
Authors: Hsiao Sheng‐Huei , Yang Chin‐Ping , Wu Feng‐Yueh
Published: April 2003

Four dicarboxylic acids containing one preformed imide ring were prepared by condensation of trimellitic anhydride with α‐amino acids such as glycine, DL‐alanine, DL‐valine, and DL‐lcucinc. These diacids were subsequently directly polycondensated with various aromatic diamines using triphenyl phosphite (TPP) and pyridine as condensing agents in N‐methyl‐2‐pyrrolidone (NMP) containing calcium chloride, producing various aliphatic‐aromatic poly(amide‐imide)s with pendant alkyl groups. The resultant polymers have inherent viscosities in the range of 0,58–2,15 dL/g and were amorphous, as revealed by wide‐angle X‐ray diffractograms. All polymers were readily soluble in a variety of solvents such as N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), and NMP, and could be cast from their DMAc solutions into transparent, flexible, and tough films. All poly(amide‐imide)s showed clear glass transition temperatures in the range of 181–313°C on the heating traces of differential scanning calorimetry (DSC). Almost all the poly(amide‐imide)s exhibited no appreciable decomposition below 370°C, with 10% weight loss being recorded above 400°C in nitrogen and air. The polymers with larger side chain attached exhibited higher solubility, but lower glass transition temperature and initial decomposition temperature.
Acoustic properties of poly(phenylene sulfide) crystallized in the presence of sorbed nitrous oxide
Authors: Böhning Martin , Schultze J. Dirk , Springer Jürgen , Lukashov Alexander , Kuzaev Oleg , Feofanov Valentin
Published: April 2003

Poly(phenylene sulfide) annealed thermally and under the influence of nitrous oxide pressure is investigated using the acoustic vibrating reed technique. The acoustic parameters velocity of sound, c, and loss tangent, tan δ, are calculated. The discussion concerning the structural changes of the polymer during the applied annealing procedures is based on the temperature dependence of these parameters and the transition temperatures TG and T' determined therefrom.
Polymerization of olefins with the TiCl4/SiO2 catalyst system modified with MgCl2
Authors: Maria Luiz Claudio de Santa , Soga Kazuo , Shiono Takeshi
Published: April 2003

MgCl2/TiCl4/SiO2 catalysts were prepared by treating TiCl4/SiO2 with MgCl2 · 2THF (THF: tetrahydrofuran) at different Mg/Ti ratios. The catalysts were analysed by X‐ray, electron spin resonance (ESR), atomic absorption spectrometry to determine the crystal structure, oxidation state of titanium and also contents of Ti, Al and Mg. Homo‐ and copolymerizations of ethylene and propene were conducted with them using Al(i‐C4H9)3 as a cocatalyst. The results of polymerization were correlated with the analytical data of the catalyst.
Synthese und charakterisierung von butadien/ethen/propen terpolymeren
Authors: Arnold Manfred , Reußner Jens , Utschick Hermann , Fischer Hartmut
Published: April 2003

Butadiene/ethene/propene terpolymers are synthesized by Ziegler‐Natta polymerization with the catalyst system VO(O‐neopentyl)2Cl/Al(i‐Bu)3 in toluene at −10°C. Variation of the amounts of propene and ethene leads to products with propene contents between 5 and 30 mol‐% (referring to monomeric unit) in the polymer. These polymers are terpolymers with alternating units of butadiene‐ethene and butadiene‐propene sequences as shown by means of nuclear magnetic resonance investigations. The degree of crystallinity can be varied between 10 and 51 mol‐% by different incorporation of propene into the terpolymer (X‐ray diffraction). The thermal behaviour was characterized using differential scanning calorimetry investigations. Depending on the propene content in the terpolymer the degree of crystallinity significantly influences the parameters of glass transition and the melting process.
Surface studies on copolymers having pendant monosaccharides
Authors: Nakamae Katsuhiko , Miyata Takashi , Ootsuki Norihito , Okumura Masakazu , Kinomura Keisuke
Published: April 2003

Copolymers having pendant monosaccharide groups were synthesized by copolymerizing 2‐(glucosyloxy)ethyl methacrylate (GEMA, 1), with methyl methacrylate (MMA) or styrene (St). The surface characteristics of the copolymer films were investigated by means of contact angle measurements, X‐ray photoelectron spectroscopy (XPS), and protein adsorption. The surface free energy of the GEMA/St copolymer films was constant in the range of a GEMA content from 10 mol‐% to 60 mol‐%. Insertion of GEMA of over 60 mol‐%, however, caused an increase of the surface free energy of the copolymer films. The surface composition determined by means of XPS supported the result from surface free energy measurements. There was a significant difference between the GEMA/St and GEMA/MMA copolymer films in the effect of the GEMA content on the surface characteristics of the films. The differences could be explained on the basis of the sequence of monomeric units in each copolymer. Immersing the copolymer films in hot water made the copolymer surface more hydrophilic. This is because each component migrates to the surface or the bulk in order to minimize the surface free energy of the copolymer films. The introduction of GEMA to the copolymer suppressed fibrinogen adsorption onto the copolymer films.
Assignment of finely resolved 13C NMR spectra of poly(methyl methacrylate), 2. Methylene carbon
Authors: Kawamura Tokiji , Toshima Naoki , Matsuzaki Kei
Published: April 2003

The 13C methylene carbon absorptions of poly(methyl methacrylate) with a random structure were assigned in terms of tetrad sequences using the 2D COSY (1H‐13C) NMR spectrum and by comparison with the absorptions of isotactic‐rich and syndiotactic‐rich poly(methyl methacrylate)s. The rrr, rmr and mmr tetrads were further assigned in terms of hexad sequences.
Influence of spacer length between interacting group and polymer backbone on the glass transition temperature of electron‐donor/electron‐acceptor blends
Authors: Bolsinger Michael , Schneider Hans Adam
Published: April 2003

Charge transfer Interaction (CT‐I) between electron‐donor/electron‐acceptor groups contributes to an enhancement of the miscibility in polymer blends. Typical of polymer blends with charge transfer interaction is an increase of the glass transition temperature, suggesting a decrease of the free volume during mixing of the blend components. Both, “zip”‐like orientation effects of the CT‐I onto the polymer backbones and temporary crosslink formation may contribute to the reduction of the free volume. The effect generally decreases with increasing spacer length between the interacting groups and the polymer backbone, although an increased probability of electron‐donor/electron acceptor (EDA) association may be accepted due to the enhanced mobility of the interacting endgroups. Thus the increased probability of EDA association is overcome both by the increased mobility of the temporary crosslinks and by the decrease of the induced orientation effect on the polymer backbone of the CT‐I due to the enhanced decoupling of the mobile interacting groups from the less mobile polymer backbone. Because of the possibility of D/2A association of the carbazolyl end‐group the effect is more complicated. For the same overall spacer length of the interacting EDA groups the deviation from the additivity of the glass transition temperatures of the polymer blend components is always the larger the longer the donor‐spacer.
Synthesis and properties of amphiphilic “dumbbell”‐shaped grafted block copolymers, 1. Anionic synthesis via a polyfunctional initiator
Authors: Bayer Uwe , Stadler Reimund
Published: April 2003

Two poly(ethylene oxide) stars linked by a long polystyrene chain represent a novel amphiphilic architecture (dumbbell), which is available by anionic grafting of ethylene oxide from a hydroxylated polybutadiene‐block‐polystyrene‐block‐polybutadiene triblock copolymer. The short butadiene end‐blocks (DPB = 36) of a BSB triblock copolymer with a long styrene middle block (DPS = 650) was first modified by hydroboration and oxidation. A multifunctional alkoxide initiator is thus prepared by titration of the hydroxyl groups of the “polybutadiene” end‐block with cumylpotassium. Gelation and precipitation of the polyfunctional initiator in THF could be avoided by complexing the cation (K+) with a suitable cryptand (Kryptofix[2.2.2]TM). This multifunctional macroinitiator was used to polymerize ethylene oxide. Dumbbell‐shaped molecules with various number and length of PEO branches were synthesized. Some first results about their solution properties are presented and discussed based on viscosity and light scattering measurements.
Spectroscopic study of 1‐decene oligomers obtained with AlCl3 as catalyst
Authors: Doskočilová Danica , Pecka Jan , Dybal Jiří , Kříž Jaroslav , Mikeš František
Published: April 2003

The product of 1‐decene oligomerization with AlCl3 as catalyst was fractionated by vacuum distillation, with the highest fraction consisting predominantly of the hexamer. The structure of the fractions was characterized by 1H and 13C NMR and Raman spectroscopy. The oligomers contain predominantly long branches (7 carbons and longer) and always one double bond per molecule, with strong predominance of tri‐ and tetra‐substituted types. The minority structures are analyzed, and the polymerization and isomerization mechanisms are discussed.
Characterization of the network structure in amine‐cured epoxy resins by selective degradation
Authors: Stutz Herbert , Mäder Hans‐Joachim , Simak Petr , Voelkel Rüdiger
Published: April 2003

A special model system based on a diglycidylester (1) and 4,4′‐diaminodiphenylmethane (2) was used to characterize the network structure of epoxy resins. Networks with cure degrees of 0,72 to 0,82 were prepared. These networks could be cleaved by hydrolysis after curing, and the network functionality and its distribution were characterized by chromatography. The results are in good agreement with predictions from branching theory, no indication of a deviation from statistics could be found.
Compatibilizing effect of a thermotropic liquid‐crystalline compatibilizer on liquid‐crystalline polycarbonate/poly(p‐phenylene oxide) blends
Authors: Kobayashi Takanori , Sato Moriyuki , Takeno Noboru , Mukaida Ken‐ichi
Published: April 2003

The compatibilizing effect of a thermotropic block‐graft copolymer (LCBG) as a compatibilizer on thermotropic liquid‐crystalline (LC) polycarbonate (LCPC)/poly(p‐phenylene oxide) (PPO) blends was studied. Compatibility, morphology and mechanical properties of the blend systems were investigated by differential scanning calorimetry (DSC), thermal mechanical analysis (TMA) and scanning electron microscopy (SEM). The blend without the compatibilizer formed thermotropic LC phases, based on LCPC domains, and had a phase‐separated structure. The LC temperature ranges of the blends with LCBG were wider than that of the blend without the compatibilizer. DSC, SEM and TMA data showed that in the blends containing the compatibilizer the compatibility and the viscoelasticity were improved, because LCBG segments penetrate into both the PPO matrices and the LCPC domains in the blends. These results suggest that LCBG acts as a good compatibilizer for blends.
Use of different alkoxysilanes as external donors in MgCl2‐supported Ziegler‐Natta catalysts to obtain propene/1‐butene copolymers with different microstructure
Authors: Sacchi Maria Carmela , Fan Zhi‐Qiang , Forlini Fabrizio , Tritto Incoronata , Locatelli Paolo
Published: April 2003

The effects of different alkoxysilane donors (Ph(EtO)3Si, Me(EtO)3Si and Ph2(EtO)2Si) have been compared in propene/1‐butene copolymerization with MgCl2‐supported Ziegler‐Natta catalysts. The copolymers obtained were fractionated and the fractions characterized by 13C NMR analysis. The influence of the different alkoxysilanes on the yield, the fraction distribution and the composition, the reactivity ratios and the number‐average sequence lengths of all the fractions were analyzed. The results obtained show that it is possible to vary the characteristics of propene/1‐butene copolymers by varying the bulkiness of the hydrocarbon substituent and/or the number of the alkoxy groups of the silane donor. It was also possible to correlate the effect of the silane donor on the homopolymerization stereochemistry and on the characteristics of the copolymers.
Preparation and properties of “thread‐through” copolymers of polyethylene with polyisoprene
Authors: Zhang Xuequan , Li Weidong , Huang Baotong
Published: April 2003

Graft copolymers of polyethylene (PE) with polyisoprene (PI) were synthesized through polymerization of ethylene in toluene solution of PI (cis‐1,4‐:95%; 3,4‐:5%) using a homogeneous V(acac)3/Et3Al2Cl3 catalyst. Copolymers are formed when the growing polyethylene chains thread through the external and/or internal double bonds of the dissolved polyisoprene, giving copolymers with proliferating chain structures. Compared to the corresponding PI/PE blends, “thread through” copolymers had lower crystallization temperature, much lower crystallinity, and smaller microcrystallite sizes, indicating that the PI component hampered the crystallization of PE due to the chemical bonding between them. This chemical bonding between PE and PI was substantiated by a 11°C higher Tg of PI, 13°C lower α‐relaxation and the presence of a β‐relaxation, as compared to the corresponding PI/PE blends. Moreover, the PI/PE “thread through” copolymer with higher PI content had lamellar phase morphology, whereas the PI/PE blends with similar composition showed quite broadly dispersed PI domains. Much better mechanical properties of the “thread through” copolymers than of the PI/PE blends indicate that there is a great difference in their chain structures.
Monofunctional polydimethylsiloxane oligomers for graft copolymerisation
Authors: Holohan Aidan T. , George Maurice H. , Barrie James A. , Parker David G.
Published: April 2003

Well defined, narrow molecular weight distribution polydimethylsiloxane (PDMS) oligomers containing single, terminal, reactive end groups were synthesised by the anionic polymerisation of hexamethylcyclotrisiloxane (D3). A variety of functionalities were obtained by termination with an appropriate silyl chloride end blocker, e.g. styryl, allyl, silyl chloride, silane, hexenyl etc. Certain monomeric end blockers were also synthesised where necessary. The resulting oligomers were subjected to detailed characterisation using 1H NMR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and IR spectroscopy.
Study of the propagation centre in the anionic polymerization of acrylic monomers, 1. Spectroscopic study of methyl 2‐lithioisobutyrate, an initiator for the anionic polymerization of acrylic monomers
Authors: Kříž Jaroslav , Dybal Jiří , Vlček Petr , Janata Miroslav
Published: April 2003

As the simplest model for the propagation centre in the anionic polymerization of methyl methacrylate, the solution of methyl 2‐lithioisobutyrate (1) in tetrahydrofuran was studied by means of 1H, 6Li, 7Li and 13C nuclear magnetic resonance (NMR), and Raman spectroscopy at various concentrations and temperatures. A system of equilibria of differently solvated dimeric, tetrameric and two isomeric trimeric aggregates was found and their thermodynamic constants were established. On the basis of the analysis of NMR chemical shifts, heteronuclear nuclear Overhauser effect correlation spectroscopy (NOESY) spectra and relaxation data, structures of the aggregates are suggested. The kinetics of the exchange between the aggregates and the lifetime of individual aggregates was established. The results suggest that the aggregation can interfere with initiation in the early steps of anionic polymerization of acrylics.
A master curve for tensile properties of thermoplastics
Authors: Elias Hans‐G.
Published: April 2003

Ultimate mechanical properties of polymers can be characterized by a dimensionless Hooke number He ≡ σb/(Eϵb), where σb is the ultimate tensile strength, E the tensile modulus, and ϵb the elongation at break. Hooke numbers are found to be a smooth function of ultimate elongations, independent of the chemical and physical structure of common thermoplastics. This master curve for fracture strengths and elongations can be described by He = [1 + (ϵb/ϵcrit)ab]−1/b with empirically found parameters ϵcrit = 0,0168, a = 0,918, and b ≈ 4. The decrease of He with increasing ϵb at ϵb > ϵcrit reflects the shear flow on deformation. Hooke numbers depend on entanglement densities ve according to He = 1,285·1036 (ve/cm−3)−1,846 for ve > 3,65·1019 cm−3. A correction for additional segment orientation during tensile testing brings the exponent to −1,846/0,918 = −2,01; i. e., a dependence of Hooke numbers on the reciprocal square of entanglement densities.
Entanglement of poly(ethylene terephthalate): A reevaluation
Authors: Elias Hans‐G.
Published: April 2003

The mass‐average based critical molar mass Mc = 9200 g·mol−1 and the entanglement density ve = 17,0·1019 cm−3 of poly(ethylene terephthalate) PETP were calculated for 280°C from literature data on PETP melts, using appropriate corrections for polymolecularities.
Elastomers based on poly(hexafluoropropylene oxide) crosslinked via triazine groups
Authors: Ding Ji‐Feng , Khan A. Rasheed , Proudmore Martin , Mobbs Richard H. , Heatley Frank , Price Colin , Booth Colin
Published: April 2003

Poly(hexafluoropropylene oxide), poly(HFPO), networks were prepared from functional polymers by end‐linking via triazine groups. The networks were characterised by NMR spectroscopy and by determination of the number of network chains from the shear modulus, and were shown to contain both triazine crosslinks and imidoylamidine links. The mechanical, thermal and chemical properties of the networks were investigated by a range of techniques. A network formed from fully difunctional poly(HFPO) had excellent elastomeric properties above −15°C, and was thermally stable up to 270°C.
Assignment of 13C nuclear magnetic resonance spectra of poly(methacrylonitrile)
Authors: Kawamura Tokiji , Toshima Naoki , Matsuzaki Kei
Published: April 2003

13C Nuclear magnetic resonance (NMR) spectra of atactic and syndiotactic‐rich poly(methacrylonitrile) (PMAN) were determined. In addition, 2D (1H‐13C COSY)

COSY = COrrelated SpectroscopY.

NMR spectra of α‐methyl and methylene regions of atactic PMAN were measured. Values of tetrads and pentads were calculated from triads obtained from α‐methyl carbon absorptions of the samples. By comparing calculated values with the observed ones, and by taking 2D NMR spectra into consideration, both α‐methyl carbon and proton absorptions were assigned by pentads, and methylene carbon absorptions by tetrads (partly by hexads).
Polymerization of propene with highly isospecific. SiO2‐supported zirconocene catalysts activated with common alkylaluminiums
Authors: Soga Kazuo , Kim Hyun Joon , Shiono Takeshi
Published: April 2003

Several types of SiO2‐supported metallocene catalysts were prepared using chemically modified silica gel. Polymerization of propene was conducted with these catalysts combined with methylaluminoxane (MAO) or ordinary alkylaluminiums. Highly isotactic poly(propylene) with high molecular weight was obtained by the catalysts whose zirconocene ligands were chemically immobilized on SiO2. The preparative methods of these catalysts and the results of propene polymerization, together with the analytical data of produced polymers, are reported in some detail.
Raman spectroscopic study of hydrogen bonding of poly(N‐vinyl‐2‐pyrrolidone) in heavy water and dimethyl sulfoxide
Authors: Tanaka Naoki , Ito Kensaku , Kitano Hiromi
Published: April 2003

The Raman spectra of solutions of poly(N‐vinyl‐2‐pyrrolidone) (PVP; M̄w = 1 000, 10 000, 40 000 and 360 000) in D2O and dimethyl sulfoxide (DMSO) were measured at various concentrations. PVP is hydrated by D2O in a manner different from N‐ethyl‐2‐pyrrolidone (NEP) and N‐methyl‐2‐pyrrolidone (NMP), monomer analogues of PVP. The self‐association of DMSO molecules in the solution of PVP was found to be different from that in the solution of NMP by using difference spectroscopy. These phenomena were attributed to a net‐like structure of concentrated solutions of PVP.
Magnesium chloride‐supported catalysts for Ziegler‐Natta propene polymerization: Ethyl formate as internal base
Authors: Noto Vito Di , Zannetti Roberto , Viviani Maria , Cecchin Giuliano
Published: April 2003

MgCl2‐supports for Ziegler‐Natta polymerization processes were prepared by an activation method based on the thermal removal of ethyl formate (EF) from adducts between EF and MgCl2. The various steps of activation were investigated by X‐ray diffraction (XRD) and infrared spectroscopy (FT‐IR) of MgCl2(EF)x adducts having 0 ≤ x ≤ 2. A subsequent titanation process of the above supports gives rise to a decrease of the EF content in the obtained products. By XRD on polycrystalline powders, the effects were investigated of the EF concentration in the titanated adducts used in Ziegler‐Natta polymerization processes and having a composition [MgCl2(EF)k(TiCl4)m]. Moreover, the relationships were investigated between yield and stereospecificity in the propene polymerization tests; a maximum of isospecificity was observed for the mole ratios Ti/Mg ≈ 0,065, EF/Mg ≈ 0,47 and Ti/EF ≈ 0,15. It was also demonstrated that a progressive removal of EF from the adducts gives rise to supports showing a different structural disorder in dependence on the removal time.
Polymerization of 2,2‐dimethyltrimethylene carbonate with tri‐sec‐butoxyaluminium; a kinetic study
Authors: Wurm Birgid , Keul Helmut , Höcker Hartwig
Published: April 2003

The polymerization of 2,2‐dimethyltrimethylene carbonate (DTC, 1) with tri‐sec‐butoxyaluminium (Al(O‐sec‐Bu)3) proceeds with suppression of macrocyclics formation. The propagation of the polymerization proceeds pseudoanionically via insertion. Within the scope of a kinetic treatment, the time‐conversion relationship was determined for the polymerization of DTC with Al(O‐sec‐Bu)3 as initiator and toluene as solvent. For a polymerization temperature between 15°C and 74°C, the apparent rate constant was found to be between 0,1 and 1,0 L · mol−1 · s−1. Using the Arrhenius plot the experimental temperature coefficient (20,6 kJ · mol−1) as well as the frequency factor of the polymerization (1,3 · 103 L · mol−1 · s−1) were determined. Investigation of the dependence of the rate of polymerization on the initiator concentration revealed a degree of aggregation of 2 for the active species.
Investigation of the structural changes in high‐speed spun yarns of polyamide 6 by means of WAXS employing synchrotron radiation
Authors: Schmack Gerhilt , Beyreuther Roland , Häußler Liane , Tidick Peter Joachim , Zachmann Hans Gerhard , Koch Michel Henry Jean
Published: April 2003

The melting and recrystallization of yarns of polyamide 6 spun at different take‐up velocities ranging from 3 500 to 5 600 m/min was investigated by means of wide‐angle X‐ray scattering (WAXS) employing synchrotron radiation and by differential scanning calorimetry (DSC). It was shown that the first peak in the double melting peak of the DSC‐curves is caused by the melting of the γ‐crystals. The melting point is increased by approximately 5°C when the take‐up velocity is increased from 3 500 m/min to 5 600 m/min. The addition of calcium stearate to the material has no effect on the thermal stability of the crystals, but seems to have some effect on the crystallization rate.
Fluorination of polymers containing COOH/COOR‐groups with SF4/HF, 2
Authors: Nuyken Oskar , Dannhorn Wolfgang , Obrecht Werner
Published: April 2003

Carboxyl‐ and ester groups of low molecular‐weight compounds are selectively and quantitatively converted into trifluoromethyl moieties by reaction with SF4/HF as shown in a previous paper. This reaction is now applied to the polymers poly(acrylic acid), poly(acrylic esters) and poly[(acrylic acid)‐co‐(acrylic ester)]. Poly(acrylic acid) yields gelled products whereas poly(acrylic ester) and the copolymers yield highly fluorinated soluble polymers upon reaction with SF4/HF. Under mild reaction conditions the carbonyl groups in acrylic acid/acrylic ester copolymers are selectively fluorinated. Unter vigorous reaction conditions, acid as well as ester moieties of the copolymers are completely fluorinated. Macroscopic gelation during fluorination is most probably associated with intermolecular ether formation. Molecular weights, NMR spectra and glass transition temperatures of the reaction products are given.