bluuebunny/crossref_metadata_2025 huggingface dataset:
Low glass transition temperature fluorocarbon ether bibenzoxazole polymers
Authors: Evers Robert C.
Published: April 2003

Fluorocarbon ether bis(o‐aminophenol) monomers were prepared by a multistep synthetic route based on the copper‐promoted coupling of 4‐iodophenyl acetate with 1,8‐diiodoperfluoro‐3,6‐dioxaoctane, 1,11‐diiodoperfluoro‐3,9‐dioxaundecane, 1,14‐diiodoperfluoro‐5,10‐dimethyl‐3,‐6,9,12‐tetraoxatetradecane, and 1,17‐diiodoperfluoro‐3,6,9,15‐tetraoxaheptadecane. Acetic acidpromoted polycyclocondensations of the monomers with long‐chain fluorocarbon ether‐diimidate esters and ‐dithioimidate esters led to linear fluorocarbon ether‐bibenzoxazole polymers soluble in 1,1,1,3,3,3‐hexafluoroisopropanol and 1,1,2‐trichloro‐1,2,2‐trifluoroethane. Polymer structures were verified by elemental and infrared spectral analysis. The polymers were rubbery gums and could be obtained in the inherent viscosity range of 0.20–0.79 dlg−1. Selection of monomers governed the glass transition temperatures of the resultant polymers. As expected, the polymers exhibited lower glass transition temperatures with increased fluorocarbon ether content, a minimum value of −58°C being achieved. None of the polymers exhibited crystalline melt temperatures. Based on thermogravimetric analysis data, the thermooxidative stability of the polymers tended to decrease with increased fluorocarbon ether content. Onset of breakdown during thermogravimetric analysis in air occurred in the 350–400°C range. Isothermal aging of the polymers in air indicated good thermooxidative stability at 260°C; only 5% weight loss was recorded after 200 hr.
Kinetic studies of the radiation‐induced graft polymerization of butadiene onto poly(vinyl chloride) powder
Authors: Omichi Hideki , Yoshida Kenzo , Suzuki Kazuya , Araki Kunio
Published: April 2003

The radiation‐induced graft polymerization of butadiene onto poly(vinyl chloride) powder was studied. By the kinetic treatment of elementary reactions the values of kp and kt[Z] of the graft polymerization were obtained. The activation energy of the propagation was calculated as 16.0 kcal mole−1. The value of kp was proportional of the 0.42 power of the dose rate and that of kt[Z] was proportional to the 0.84 power of the dose rate.
Improved methods of estimating monomer reactivity ratios in copolymerization by considering experimental errors in both variables
Authors: Van Der Meer R. , Linssen H. N. , German A. L.
Published: April 2003

Existing methods of calculating monomer reactivity ratios in copolymerization are reviewed briefly, evaluated, and classified according to their mathematical and computational similarities. More attention is paid to procedures based on the integrated copolymer equation with which calculation of r values is performed most often by electronic computer. Unfortunately, until now all procedures have shown shortcomings because the real‐error structure of the observations has not been taken into account. A new algorithm that does account correctly for measurement errors in both variables is described. A computational method is illustrated for copolymerization data obtained from quantitative gas chromatographic analysis of the monomer feed throughout the reaction. It is shown that the actual error structure of the variables corresponds to the assumed error structure. Reliability of the estimates is substantially increased, compared with the existing methods. Standard deviations of the monomer reactivity ratios are given and appear to be in good agreement with reality.
Alternating copolymerization of benzofuran and acrylic monomers in the presence of organoaluminum compounds
Authors: Furukawa Junji , Kobayashi Eiichi , Nagata Shiro
Published: April 2003

The copolymerization of benzofuran and acrylic monomers, such as acrylonitrile, methacrylonitrile, methyl acrylate, and methyl methacrylate, was investigated in the presence of aluminum compounds as complexing agents for acrylic monomers. Among the various kinds of aluminum compound, ethylaluminum sesquichloride is the most suitable for alternating copolymerization, whereas ethoxyaluminum compounds of low acidity allow the incorporation of excess acrylic monomer and dichloride of strong acidity is likely to induce cationic homopolymerization of benzofuran as a side reaction. The equimolar amount of sesquichloride with respect to acrylic monomer is necessary for alternating copolymerization. Azobisisobutylonitrile (AIBN) is an effective initiator but benzoyl peroxide is not. Nuclear magnetic resonance (NMR) of the copolymer indicates that the copolymer is essentially alternating, although some block sequences of acrylic monomer sometimes exist. As a mechanism the copolymerization via a ternary complex of acrylic monomer, aluminum compound, and benzofuran is considered.

Free acrylic monomer participates in copolymerization when the amount or acidity of the complexing agent is insufficient. A quantitative relation between monomer and copolymer composition is derived from a scheme based on the copolymerization of the donor monomer‐acceptor monomer complex with free acrylic monomer.
13C NMR spectroscopic study of epoxidized 1,4‐polyisoprene and 1,4‐polybutadiene
Authors: Gemmer Robert V. , Golub Morton A.
Published: April 2003

Partly epoxidized cis‐ and trans‐1,4‐polyisoprenes and cis‐and trans‐1,4‐polybutadienes were prepared, and their 13C NMR spectra examined. All the prominent resonances in the spectra of the epoxidized polymers were assigned by using lanthanide shift reagent and off‐resonance decoupling experiments. A 13C NMR method of quantitative assessment of the epoxide content was developed following determination of relative spin‐lattice relaxation time (T1) and nuclear Overhauser effect (NOE) parameters of the various carbons in the epoxidized polyisoprenes and polybutadienes.
Radical block polymerization of vinyl chloride. III. Physical properties and morphology of block copolymers of PVC
Authors: Overbergh N. , Weinand G. , Smets G.
Published: April 2003

Some physical properties of the block copolymers with PVC, described in Parts I and II, are discussed. The effect of chemical composition, molecular architecture, and film preparation conditions on their two‐phase structure is shown. Especially in the case of high PVC content, the morphological aspect is largely influenced by the molecular architecture—pronged‐fork polymer chains—and the nature of the solvent for casting. The incorporation of rubbery poly(alkyl acrylate) particles in the PVC matrix leads to an interesting stress–strain behavior. A relation between this behavior and the morphology is established.
Thermal degradation studies of PVC with time‐resolved pyrolysis GC and derivative TGA
Authors: Liebman S. A. , Ahlstrom D. H. , Foltz C. R.
Published: April 2003

This thermal degradation study reports the application of “time‐resolved” pyrolysis gas chromatography (PGC) in addition to derivative thermogravimetric analysis (DTGA) to a series of PVC homopolymers with differing branch content and to a model copolymer series with low amounts of propylene in an otherwise vinyl chloride chain. Benzene and toluene generation and decay envelopes were determined during the controlled thermal degradation and related to the derivative TGA experiments. These data allowed interpretation as to the microstructure of the respective polymers and its effect on the degradative pathways. It was concluded that the branch content was not a dominant factor in the initiation of thermal degradation, although it was a factor in other stages of the complex mechanism. A unique fragmentation step was noted only under oxidative thermal exposures, which gave additional support for the theory of low‐level unsaturation sites as being significant triggers in the decomposition mechanism.
Chemical stability and electroconductivity of 7,7,8,8‐tetracyanoquinodimethane salts containing polycation polymers
Authors: Mizoguchi Katsuhiro , Tsuji Shoichi , Tsuchida Eishun , Shinohara Isao
Published: April 2003

The chemical and electrical stabilities of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) salts composed of neutral TCNQ (TCNQˆ), anion radicals of TCNQ(TCNQ−·), and polycation polymers were studied by measuring their electronic spectra and resistivities (ρ). The results of spectral and chemical analyses confirmed that TCNQ−· in TCNQ salts was decomposed to α,α‐dicyano‐p‐toluoylcyanide (DTC−) as the final product by the intermediate formation of TCNQˆandp‐phenylenediamalononitrile (H2TCNQ) and that H2O played an important part in the reaction. From these results it was concluded that TCNQ salts are decomposed by two reaction processes:The resistivity of TCNQ salts increases with the decomposition of TCNQ−·. Studies on electroconductivity of TCNQ salts assume that the change in resistivity arises from the loss of unpaired electrons which become conduction carriers and also from the disintegration of the TCNQˆand TCNQ−· complex which forms the conduction path.
Emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. II. Effects of reaction conditions on polymer particle size and number
Authors: Suwa Takeshi , Watanabe Terutaka , Seguchi Tadao , Okamoto Jiro , Machi Sueo
Published: April 2003

The size, distribution, and number of PTFE particles formed by radiation‐induced emulsifier‐free polymerization were measured by electron microscope and automatic particle analyzer (centrifugation method). From the electron micrographs we found that the particles are formed within 5 min. The change in the number of polymer particles (np) with reaction time (t) depends on the relative concentration of growing polymer chains to stabilizing species produced by the radiolysis of water and monomer; that is, it was governed by TFE pressure/dose rate ratio and classified into three cases: case I, dnp/dt = 0 (e.g., at 3 × 104 rad/hr and 20 kg/cm2); case II, dnp/dt < 0 (e.g., at dose rate below 1.9 × 104 rad/hr and 20 kg/cm2); case III, dnp/dt > 0 (e.g., at 3 × 104 rad/hr and 2 kg/cm2). The polymer molecular weight above 106 is almost independent of the particle size. The polymerization loci are mainly on the surface of polymer particles dispersed in the aqueous phase in cases I and II except in the initial stage. In case III new particles are formed successively during polymerization. Therefore the polymerization loci are mainly in the aqueous phase. Especially in case I, we concluded that after the generation of particles the propagation proceeds mainly on the surface of polymer particles like the core shell model proposed by Granico and Williams.
1H‐NMR spectra of poly(ethylene glycols) in the presence of shift reagent
Authors: Okada Tadashi
Published: April 2003

To determine the content of trans‐gauche‐trans (TGT) conformation in poly(ethylene glycol) (PEG) 1H‐NMR spectra were measured with tris(1,1,1,2,2,3,3‐heptafluoro‐7,7‐dimethyl‐1,4,6‐octanedinato)europium(III) [Eu(fod)3] as a shift reagent. As a result the peaks assigned to the ethylene protons in the polymeric segments separated from those assigned to four ethylene protons as the “near‐end” groups, and the singlet peak in the former at the lowest field was assigned to the TGT conformation of the COCCOC sequence. It was confirmed that the conformation of the polymeric segments in PEG complexed with Eu(fod)3 remained unchanged with benzene‐d6 content as the solvent. The concentration of TGT conformation increased with the number‐average molecular weight (Mn): it increased rapidly until about 70% at Mn = 1500.
Effect of structure on properties of aromatic‐aliphatic polybenzimidazoles. II
Authors: Varma I. K. , Veena
Published: April 2003

Polybenzimidazoles (PBI) with p‐phenylene and/or cis‐vinylene groups in the backbone were prepared from terephthalic acid (T), maleic acid (M), and 3,3′ diamino‐benzidine tetrahydrochloride dihydrate (DAB) in poly(phosphoric acid) (PPA). Five polymer samples were prepared by varying the M:T molar ratios in the following order: 1:0, 1:1, 2:1, 1:2, and 1:4. The polymers were characterized by intrinsic viscosity, density, electronic fluorescence, and IR spectra. The effect of composition on the solubility of the polymers in various organic solvents was also investigated. The relative thermal stability of the polymers was evaluated by dynamic thermogravimetry in air and polybenzimidazoles (PBI) with cis‐vinylene groups were found to be less stable.
Ferrocene‐containing polymers. I. Radiation‐induced polymerization of ferrocenylmethyl methacrylate
Authors: Tsubakiyama Kyoji , Matsuo Togoro , Sasaki Takashi , Yoshida Kenzo , Fujimura Takashi , Araki Kunio
Published: April 2003

γ‐Ray‐induced polymerizations of ferrocenylmethyl methacrylate (FMMA) in crystalline and amorphous states were investigated with kinetical and ESR methods. In the crystalline state the polymerization of FMMA proceeded slowly and gave low‐molecular‐weight polymers, whereas in the amorphous state it proceeded rapidly and gave polymers of much higher molecular weight. Molecular weight distributions of these polymers were binodal. The temperature dependence and the dose‐rate dependence of the polymerization rates were different between the two states. Wide‐line nuclear magnetic resonance (NMR) spectra of the amorphous monomer suggested that the polymerization proceeded in a supercooled state. Electron spin resonance (ESR) spectra of γ‐irradiated FMMA and 1,1′‐ferrocenyl‐di(methyl methacrylate) showed that ferrocene radicals and methacrylic radicals were formed simultaneously at low temperature; with increasing temperature the former radicals disappeared, whereas the latter changed into growing chain radicals. The yields of radicals were relatively low; this means that ferrocene groups in the monomers behave as a radiation energy absorber.
Ring retention in the homopolymerization of cyclic olefins by rhenium olefin metathesis catalysts
Authors: Tsonis Christos , Farona Michael F.
Published: April 2003

The homogeneous catalyst system, Re(CO)5Cl/C2H5AlCl2, was found to promote the homopolymerization of cyclic olefins containing 5‐, 6‐, 7‐, and 8‐member rings to low‐molecular‐weight materials. The final compounds, which polymerize only at elevated temperatures, were found by nuclear magnetic resonance (NMR) and infrared (IR) studies to be totally saturated systems. Various bands in the IR spectra indicate that the ring systems are preserved and that the final products are made up of repeating 1,2‐, or a combination of 1,2‐ and isomerized single‐bond units. Although the active catalyst initially contains a coordinated carbene, a mechanism similar to that of polymerization by a Ziegler—Natta catalyst is proposed.
Thermal decomposition of poly(butylene terephthalate)
Authors: Lum Richard M.
Published: April 2003

Detailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex multistage decomposition mechanism was observed which involves two major reaction pathways. Initial degradation occurs by an ionic decomposition process that results in the evolution of tetrahydrofuran. This is followed by concerted ester pyrolysis reactions that involve an intermediate cyclic transition state and yield 1,3‐butadiene. Simultaneous decarboxylation reactions occur in both decomposition regimes. Finally, the latter stages of polymer decomposition were characterized by evolution of CO and complex aromatic species such as toluene, benzoic acid, and terephthalic acid. Activation energies of formation for the main pyrolysis products were determined from the dynamic measurements of the major ion species and indicate values of E = 27.9 kcal/mole for the production of tetrahydrofuran and E = 49.7 kcal/mole for the production of butadiene.
Copolymerization of carbon disulfide and N‐(β‐cyanoethyl)ethylenimine
Authors: Soga Kazuo , Hattori Iwakazu , Sato Masaru , Ikeda Sakuji
Published: April 2003

It was found that carbon disulfide copolymerizes with N‐(β‐cyanoethyl) ethylenimine by using water as a catalyst. The copolymerization was conducted in detail by using water as a catalyst in the temperature range between 0 and 50°C with various initial concentrations of carbon disulfide and N‐(β‐cyanoethyl)ethylenimine in the absence of solvent. The copolymer obtained was always composed of the two monomers: 1:1 ratio, independent of the initial concentration of the monomers. The copolymer was white solid material soluble in dimethyl sulfoxide, insoluble in other usual organic solvents and decomposed at 155°C. Spectroscopic analysis of the copolymer combined with the results of elemental analysis indicates that the copolymer had the following structure:
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Photocrosslinking of poly(methyl acrylate)s containing the 1,3‐dioxolane structure as a pendant group
Authors: Nakashima Yoshihiro , Fukuda Hiroyuki
Published: April 2003

(2‐Ethyl‐2‐methyl‐1,3‐dioxolan‐4‐yl)methyl‐ and (2‐methyl‐2‐phenyl‐1,3‐dioxolan‐4‐yl) methyl acrylates were synthesized and polymerized. The photochemical behavior of the resulting polymers was investigated to determine whether the polymers pending on the 1,3‐dioxolane structure were readily crosslinked with ultraviolet (UV) irradiation. The degree of crosslinking was estimated by the weight‐loss method by immersion in acetone, with the result that the polymer with an aromatic substituent was more photocrosslinkable than the polymer that bore the aliphatic substituent. The catalytic effect on photocrosslinking of polymers was also studied by using benzoin and cobalt naphthenate. The infrared (IR) spectra of polymers irradiated in air that showed the new band at 3450 cm−1 were attributed to a hydroxyl group; however, the spectra of polymers irradiated in vacuum displayed little absorption at 3450 cm−1. To explain the mechanism of crosslinking model compounds were prepared and irradiated with UV light. It was concluded that crosslinking proceeds mainly from the fission of the 1,3‐dioxolane ring and the coupling of the yielding radicals, together with autooxidation by atmospheric oxygen.
A new organic semiconducting polymer from Cu2+ chelate of poly(vinyl alcohol)and iodine
Authors: Higashi Fukuji , Cho Chong Su , Kakinoki Hideo , Sumita Osao
Published: April 2003

A new, easily processed, organic semiconductor was prepared from poly(vinyl alcohol) (PVA). The Cu2+ chelate of PVA exhibited excellent surface resistivity around 103 Ω cm−2 when modified with iodine. Favorable conditions for preparing the chelate effective for the conduction were investigated. The resistivity was significantly affected by the amounts of cupric salts and iodine, satisfactory results being given by more than 15 wt% of cupric salts and about 4 wt% of iodine. Effects of molecular weight of PVA and the chelate structure were also studied.
Vinyl polymerization. 361. Polymerization of 2,2,4‐trimethyl‐3‐on‐1‐pentyl methacrylate
Authors: Ouchi Tatsuro , Arita Yoshitaka , Imoto Minoru
Published: April 2003

2,2,4‐Trimethyl‐3‐on‐1‐pentyl methacrylate (TMPM) was first synthesized from the condensation reaction of 2,2,4‐trimethyl‐1‐pentanol‐3‐on with methacrylic acid. Second, the polymerization of TMPM and the copolymerization of TMPM with styrene (St) were carried out in benzene at 60°C, using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. As the result of kinetic investigation, the rate of polymerization (Rp) could be expressed by: Rp = k[AIBN]0.5 [TMPM]1.0. Kinetic constants of polymerization of TMPM were obtained as follows: kp/k = 0.27 dm3/2 mole−1/2 sec−1/2, 2fkd = 1.23 × 10−5 sec−1, f = 0.73, Cm = 2.6 × 10−5, Cs = 1.1 × 10−5. From the results the reactivity of TMPM was found to be larger than that of methyl methacrylate. The overall activation energy was calculated to be 110 kJ mole−1. The following monomer reactivity ratios and Q, e values were obtained: TMPM(M1) − St(M2): r1 = 1.50, r2 = 0.14, Q1 = 2.63, E1 = 0.45.
Effect of amount of monomer on radiation‐induced polymerization of styrene adsorbed on silica gel
Authors: Kusama Yasuo , Udagawa Akira , Takehisa Masaaki
Published: April 2003

The effect of amount of monomer on radiation‐induced polymerization of styrene adsorbed on silica gel was investigated with the monomer amounting from less than monolayer adsorption to more than the equilibrium adsorption. The rate of graft polymerization and the molecular weight of the polymer changed with the amount of monomer adsorbed on silica gel. Maximum grafting efficiency was obtained at monolayer adsorption. The molecular weight of graft polymer was higher than that of homopolymer in both radical and cationic polymerizations, and the ratio in molecular weight of graft polymer to that of homopolymer tends to be unity with increasing amount of adsorbed monomer. These results can mainly be explained in terms of the number of initiating species (radical and cation) that change in relation to the amount of adsorbed monomer. Propagation and termination change with amount of adsorbed monomer in relation to the molecular mobility of adsorbed monomer. A very high‐molecular‐weight graft polymer is formed only with a small amount of adsorbed monomer in the initial stage. The grafting percent with a large amount of adsorbed monomer increased after most of the monomer has been polymerized. Secondary effect of radiation on the graft and homopolymers due to energy transfer from silica gel is suggested from the complicated phenomena in the later stage of the reaction.
Stabilization of high nitrile polymers. II. Effects of metal ions and oxygen on the stabilization reaction of dienophiles
Authors: Marien Bruce A.
Published: April 2003

The color stability of high nitrile polymers is increased by dienophilic stabilizers; however, the stabilization reaction is greatly affected by the presence of residual metal ions. This effect is correlated with electronegativity considerations of the metal ion. Metal ions affect the stability of the polymer whether they are used to coagulate the latex or postadded to the dry resin. Coagulation with group IIA metal ions results in polymer capable of stabilization by dienophiles. The mechanisms of stabilization and degradation in the presence of residual metals are discussed.
Emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. V. Effect of reaction conditions on the stability of polytetrafluoroethylene latex
Authors: Suwa Takeshi , Watanabe Terutaka , Okamoto Jiro , Machi Sueo
Published: April 2003

The stability of PTFE latex prepared in the absence of emulsifier by radiation‐induced polymerization was investigated by electrophoresis and conductometric titration. The storage stability depends on total dose rather than dose rate, and the stable latex can be obtained in the region log D > 0.026 V1 − 0.6, where D is the total dose (104 rad) and V1 is a polymer concentration in latex (g/liter). The stability increases only during polymerization in the presence of enough TFE monomer. The ζ potential of the latex particles lies in the region from −25 to −50 mV in an as‐polymerized state (near pH 3) and from −50 to −65 mV at pH 10. The number of carboxyl end groups and surface charge density were examined by conductometric titration with NaOH and calculation from the G values of radiolysis of water. All the surface charge densities measured by conductometric titration are larger than those calculated from the G values. These results suggest that some acids have been formed on the surface of the particles. The acids may be the carboxyl end groups of polymer chains or hydrofluoric acid (HF) adsorbed on the surface. PTFE particles prepared in this polymerization system are stabilized mainly due to the carboxyl end groups and adsorptions of OH− and HF on the particles.
Radiation‐induced copolymerization of hexafluoroacetone with 2‐methyl‐1‐pentene
Authors: Watanabe Shojiro , Matsuda Osamu , Okamoto Jiro , Machi Sueo , Ishigure Kenkichi , Tabata Yoneho
Published: April 2003

Copolymerization of hexafluoroacetone (HFA) with 2‐methyl‐1‐pentene (2MP) in trichlorotrifluoroethane (R‐113) was carried out by γ‐ray irradiation in a low‐temperature region of −100 to 0°C. Though HFA does not homopolymerize and 2MP scarcely does, the copolymerization took place at various monomer compositions. The copolymerization rate and the molecular weight in the low‐temperature region were much higher than those at 0°C. Above room temperature the copolymerization did not take place and only the adduct of monomers was formed. The copolymerization was inhibited to some extent by cation scavengers, but not by radical or electron scavengers. Elemental analysis and nuclear magnetic resonance (NMR) spectra show that the copolymer consists of almost equimolar monomer units and has two types of structure, head to tail and head to head or tail to tail. It has been concluded that copolymerization probably proceeds via a cationic mechanism to form an alternating copolymer.
Effect of pyridine on the kinetics of polymerization of styrene initiated by benzoyl peroxide and azobisisobutyronitrile at 60°C
Authors: Ghosh P. , Mukhopadhyay G.
Published: April 2003

Kinetics of solution polymerization of styrene was studied using pyridine as solvent and BZ2O2 and azobisisobutyronitrile (AIBN) as initiators at 60°C. Normal kinetic features (Rp ∝ [AIBN]0.5 · [styrene]1.0) were observed for the AIBN‐initiated polymerization, with pyridine playing the role of an inert diluent; but in the BZ2O2‐initiated polymerization, the monomer exponent was found to vary from a low value of 0.45 at a relatively low initiator concentration (1 × 10−2 mole/liter) to a value higher than the usual value of unity (1.18) at a much higher concentration of the initiator (16 × 10−2 mole/liter). The initiator exponent value was found to be 0.5 (usual) up to 20% v/v dilution with pyridine, but it showed a tendency to decrease with increase in pyridine content beyond 20% v/v. The k/kt value for each initiator system, however, was found to remain constant over the whole concentration range of pyridine. The unusual kinetic features were explained on the basis of predominance of one or the other of two competitive reactions in BZ2O2‐initiated system: (a) higher rate of decomposition of BZ2O2 in pyridine and (b) primary radical depletion by reaction with pyridine, depending upon the concentration of BZ2O2 and pyridine.
Small‐angle x‐ray scattering measurements on dilute solutions of polyisobutene by use of kratky cone collimation
Authors: Lederer K. , Klapp H. , Zipper P. , Wrentschur E. , Schurz J.
Published: April 2003

SAXS measurements on dilute solutions of polyisobutene inn‐hexane (Mν= 25,600−3.55 × 106,c< 53 g/liter) were carried out by combining conventional slit collimation with the new cone collimation technique. With a fractionated sample (Mν= 25,600;U< 0.2) the radius of gyration (R= 48 Å), the cross‐sectional radius of gyration (Rq= 3.9 Å), the molecular weight per unit length (M/L= 22.8 Å−1), and the Porod persistence length (a*= 8.1 Å) are found. The persistence length appears to be dependent on the molecular weight. The partial specific volumeνof polyisobutene inn‐hexane also depends on the molecular weight according toν= 1.025 + 105/Mν(cm3/g).
Thermoelastic properties of crosslinked polyurethanes
Authors: Dzierża W.
Published: April 2003

Thermoelastic (stress–temperature) measurements in elongation have been carried out on polyurethane elastomers obtained from poly(ethylene adipate), poly(ethylene maleate), poly(ethylene glycol), and 4,4′‐diphenylmethane diisocyanate. The elastomers were crosslinked by an excess of diisocynate and some of them were additionally crosslinked by dicumyl peroxide. Values of the temperature coefficient d ln r/dT of the unperturbed dimensions of the network chains and the fraction fe/f of the stress, which is due to energetic effects, were calculated from measurements of unswollen samples and samples swollen in benzene to a constant volume fraction ν2 of about 0.6. The coefficient d ln r/dT and the ratio fe/f for unswollen samples were positive but dependent on the extension ratio α and crosslinking density. The fe/f ratio displayed a tendency to decrease with increasing α and this decrease was smaller for elastomers of higher crosslinking density. Additional crosslinking due to dicumyl peroxide reduced the dependence of fe/f on α. Swollen samples had lower positive values of fe/f; which were somewhat independent of α and crosslinking density. Departures from the molecular theories of rubberlike elasticity are explained by intermolecular effects, which, in general, are influenced by crosslinking.
Singlet oxygen reactions with model compounds of cis‐ and trans‐polyisoprene containing one unit. Kinetic aspects
Authors: Tanielian C. , Chaineaux J.
Published: April 2003

We have studied the rose bengal‐sensitized photooxygenation of cis‐ and trans‐polyisoprene model compounds that contain one unit in methanolic solution, characterized the resulting monohydroperoxides, and determined their yield. We have also demonstrated the possibility of a second addition of singlet oxygen on the same unit and have undertaken a kinetic study to determine the rate constants of all the reactions of 4‐methyl‐4‐octene.
Functional monomers and polymers. XXXXI. Template polymerization of methacryloyl‐type monomers containing nucleic acid bases
Authors: Akashi M. , Takada H. , Inaki Y. , Takemoto K.
Published: April 2003

In due consideration of the specific base–base interaction that exists between nucleic acid molecules, the free radical polymerization of N‐β‐methacryloyloxyethyl derivatives of adenine, thymine, and theophylline initiated by azobisisobutyronitrile (AIBN) was studied in the presence of N‐β‐methacryloyloxyethyl‐type polymers which have complementary nucleic acid bases as template polymers. The rate of polymerization of N‐β‐methacryloyloxyethyladenine was accelerated when poly(N‐β‐methacryloyloxyethyluracil) or ‐thymine was present in the polymerization system. The effect of the stereoregularity of the template polymers, as well as polymerization temperature and the sort of solvents used on the rate of polymerization, was studied and discussed in some detail. The results suggest that the interaction between complementary bases plays a role in template polymerization behavior.
The radiation‐induced copolymerization of tetrafluoroethylene and styrene at high pressure
Authors: Brown Daniel W. , Lowry Robert E.
Published: April 2003

The radiation‐induced copolymerization of tetrafluoroethylene (A) and styrene (B) was studied in bulk and in perfluorotoluene at 22°C at autogenous pressure and 260 and 510 MPa. The reactivity ratio for addition to A‐ended radicals, rA, is effectively zero at the two lower pressures and is in the range 0.002–0.008 at 510 MPa. The other reactivity ratio, rB, is 6 at autogenous pressure and also at 260 and 510 MPa if the A content of the charge is less than 50%. If the A content is greater than 95%, rB appears to be 100 at pressures of 260 and 510 MPa. The apparent variation in rB cannot be explained by invoking a penultimate unit effect for B‐ended radicals. Polymerization rates scatter somewhat, but all rates are quite small when the A content of the charge is in the range 95–99.8%. Polymers containing as much as 66% A appear to be inherently benzene soluble but frequently contain some gel because of radiation‐induced crosslinking after their formation. No very high polymers were formed that contained more than a few percent A, even at high pressure. Features that complicated the study were immiscibility of the liquid monomers, extreme variation of the monomer—copolymer compatibility with charge composition, and freezing of B at high pressure.
Synthesis of polyamides from linear bisanhydrides and diamines
Authors: Ueda Mitsuru , Hara Osamu , Sato Akira , Imai Yoshio
Published: April 2003

The aminolysis of benzoic mesitoic anhydride was studied in a model system to select the reaction site by steric effect and was found to occur exclusively at the carbonyl group of the benzoic acid. Solution polycondensation of new linear bisanhydrides, terephthalic bis(mesitoic anhydride) and adipic bis(mesitoic anhydride), with aromatic diamines in polar aprotic solvents that contained lithium chloride at room temperature, afforded polyamides with high molecular weight. The interfacial polycondensation in a dichloromethane‐water system also successfully yielded polyamides from aliphatic diamines.
Synthesis of aromatic polyamides by 1‐hydroxybenzotriazole‐catalyzed polycondensation of active aromatic diesters with aromatic diamines
Authors: Ueda Mitsuru , Sato Akira , Imai Yoshio
Published: April 2003

Catalytic actions of various additives were studied in the polycondensation of di(4‐nitrophenyl) isophthalate with bis(4‐aminophenyl) ether in N‐methyl‐2‐pyrrolidone, and 1‐hydroxybenzotriazole (HOBt) was found to be a highly effective catalyst that yielded high‐molecular‐weight polyamide. In addition to the polycondensation of the 4‐nitrophenyl ester, the polymerization of negatively substituted phenyl esters like di(2,4,5‐trichlorophenyl) isophthalate was also accelerated by HOBt. For the HOBt‐catalyzed aminolysis of esters a bifunctional concerted mechanism that involves an eight‐membered transition state was proposed.
A study of the ring size in the copolymer of divinyl ether and maleic anhydride by H‐NMR spectroscopy
Authors: Butler George B. , Chu Y. C.
Published: April 2003

The well‐known alternating 1:2 cyclocopolymer of divinyl ether (DVE) and maleic anhydride (MA) possesses a wide spectrum of biological activities, including antitumor. Recent research on the structure of a variety of cyclopolymers has raised a question about the ring size of this cyclocopolymer. In this article we report on an extensive spectroscopic study of its structure. By use of deuterated monomers the H‐NMR peaks at δ 2.31, 3.47, 4.06, and 4.49 ppm with an area ratio of 2:1:1:1 were assigned to the hydrogens of methylenes, methines on the backbone anhydride unit, methines on the ring anhydride unit, and methines adjacent to oxygen on the cyclic ether ring, respectively. By examination of the possible isomeric structures of the bicyclic ring, the splitting of each peak group was further assigned for cis and trans disubstitutions on the anhydride unit. The splitting pattern from the 300‐MHz NMR spectrum of the DVE‐2,3‐dideuteriomaleic anhydride (DMA) copolymer confirmed the unsymmetrical ring structure. 13C‐NMR spectra were consistent with the conclusion from the H‐NMR spectra. A chair‐form, six‐membered ring with predominantly trans geometry in the anhydride ring was assigned to the structure of DVE–MA copolymer. On the basis of little or no change in the 13C‐NMR spectra of the copolymers prepared at different temperatures it was concluded that there was no significant change in structure with temperature. This led to the assignment of the energetically favored, six‐membered ring structure to the copolymer prepared under these conditions. A mechanism for cyclocopolymerization, based on the HOMO–LUMO interaction of the comonomers and the intramolecular radical addition on the preoriented double bond, was proposed. This mechanism leads to the formation of the six‐membered ring structure of the copolymer as the only product. A 13C‐NMR study of the structure of the copolymer prepared in chloroform by Kunitake and Tsukino is being published as a companion article.
The formation of polyethylene terephthalate in the presence of dicarboxylic acids
Authors: Chegolya A. S. , Shevchenko V. V. , Mikhailov G. D.
Published: April 2003

The process of polyethylene terephthalate (PET) formation in the presence of dicarboxylic acids has been studied. Certain amounts of terephthalic acid (TPA) have two‐ to threefold accelerating efficiency in the polycondensation process. To elucidate the causes of the acceleration the main reactions leading to PET formation in the presence of dicarboxylic acids have been investigated by the use of models. The evaluation of kinetic and equilibrium parameters obtained for model reactions made it possible to conclude that the influence of carboxyl‐containing additives on the apparent rate of polycondensation manifests itself in accelerating direct reactions and facilitating the liberation of the eliminated by‐product; that is, ethylene glycol (EG) from the polymer melt. Carboxylic acid acts as a catalyst on the ester interchange of 2‐hydroxyethyl ester end groups and thus increases the rate of polymer formation in this reaction 10–40 times. The parallel interaction between the 2‐hydroxyethyl ester end group and the carboxyl group of the added acid is also catalyzed by the acid and its rate constant is four times larger than that of the catalytic polycondensation of 2‐hydroxyethyl ester end groups. Unlike EG, the reaction water formed in the process is more readily removed from the reaction system and thus promotes the intensification of the process. In addition, the carboxyl groups react with the eliminated EG to decrease its amount and shift the equilibrium toward polymer formation. The investigation of the consequent parallel reactions on models made it possible to draw a conclusion about the higher reactivity of 2‐hydroxyethyl esters in the esterification processes. This fact has been explained by strengthening the nucleophilicity of the oxygen atom in the hydroxyl of a 2‐hydroxyethyl ester group compared with that of EG; for example, by the formation of an intramolecular cycle involving a hydrogen bond. Simultaneously, it has been found that in the system simulating PET polycondensation in the presence of dicarboxylic acids the reaction mechanism involves the catalysis by a proton formed during the carboxyl group dissociation and accepted by the 2‐hydroxyethyl ester group.
Photoinitiation. IV. The effect of lewis acid on the vinyl monomer polymerization photoinitiated by aromatic hydrocarbons
Authors: Capek Ignác , Barton̆ Jaroslav
Published: April 2003

Polymerization of acrylonitrile photoinitiated by naphthalene, anthracene, phenanthrene, and pyrene is accelerated by an admixture of zinc (II) chloride, acetate, or nitrate. The effect of zinc (II) salts on the rate of pyrene‐photoinitiated polymerization of acrylonitrile leads to an increase in this rate in the order Zn/OCOCH3/2 < ZnCl2 < Zn/NO3/2. The maximum polymerization rate is achieved at the molar ratio [ZnCl2]/([ZnCl2] + [pyrene]) approximately 0.7. In contrast to the photoinitiated polymerization of acrylonitrile, the methyl methacrylate admixture of zinc (II) chloride exerts a smaller effect on the polymerization rate. In the pyrene‐photoinitiated polymerization of styrene an admixture of zinc (II) chloride retards the polymerization rate. Fluorescence of aromatic hydrocarbon in the system acrylonitrile–aromatic hydrocarbon is efficiently quenched by zinc (II) chloride. Stern–Volmer constants determined for pyrene (80 dm3 mole−1), phenanthrene (66 dm3 mole−1), and naphthalene (49 dm3 mole−1) are higher by about 2–3 orders of the Stern–Volmer constants for fluorescence quenching of aromatic hydrocarbons by acrylonitrile in the absence of ZnCl2. The fluorescence of anthracene in acrylonitrile is not quenched by ZnCl2. The acceleration effect of Zn (II) salts on the polymerization of acrylonitrile photoinitiated by aromatic hydrocarbons depends on two factors: an increase in the ratio of the rate constant of the growth and termination reactions, kp/kt, and an increase in the quenching constant of fluorescence of aromatic hydrocarbon, kq, by the complex {acrylonitrile…ZnCl2}. ZnCl2 thus influences both the growth and initiation reactions of the polymerization process.
Photoinitiation. V. Effect of medium polarity on the acrylonitrile polymerization photoinitiated by naphthalene
Authors: Capek Ignác , Barton̆ Jaroslav , Danciger Juraj
Published: April 2003

The heterogeneous polymerization of acrylonitrile photoinitiated by naphthalene is influenced by the polarity of the reaction medium. The rate of initiation increases with the increasing dielectric strength of the reaction medium. A similar trend is observable for Stern–Volmer constants of naphthalene fluorescence quenching by acrylonitrile. The ratio kp/kt1/2 of the rate constant for propagation and termination reactions is not influenced by a change in the polarity of the reaction medium. The effect of viscosity on the value of kp/kt1/2 known for polymerization in a homogeneous medium was not observed in the reaction systems studied.
Solvent resistance of a polymer chain chemically linked onto a solid surface
Authors: Papirer Eugène , Nguyen Van Tao , Donnet Jean‐Baptiste
Published: April 2003

Polystyrene or polystyrene–polyisoprene copolymers have been grafted onto silica by an anionic procedure. The solvent resistance of the grafts has been examined. Linear relationships between the extractable amount of polymer and the solvent extraction temperatures are observed. The extrapolation of these lines leads to temperatures that are in close agreement with the ceiling temperatures of the grafted polymers.
Photoinitiated cationic polymerization by triarylselenonium salts
Authors: Crivello J. V. , Lam J. H. W.
Published: April 2003

Triarylselenonium salts with complex metal halide anions such as BF, AsF, and SbF have been prepared and have been shown to be efficient photoinitiators of cationic polymerization. The photolysis rates of these compounds were studied and their quantum yields of photolysis were reported. Use of specific triarylselenonium salts in the polymerizations of cyclohexene oxide, epichlorohydrin, and 2‐chloroethyl vinyl ether are described.
Influence of the conformational state of polymethacrylic acid on the photophysical properties of pyrene in aqueous solution: A fluorescent probe and laser photolysis study
Authors: Chen T. S. , Thomas J. K.
Published: April 2003

The excited state of pyrene observed in fluorescence and pulsed laser techniques is used to show that pyrene is solubilized in the polymer coil of aqueous solution of polymethacrylic acid (PMA) at pH < 4–5. This leads to a decreased access of molecules such as I−, Tl+, CH3NO2, and O2 to excited pyrene in the polymer coil. The protection of the excited state by solubilization in the polymer is sufficient to enable 3‐bromopyrene phosphorescence to be observed at room temperature in these systems. Increasing the pH of the system uncoils the polymer and leads to increased accessibility of excited pyrene to CH3NO2; eventually, at pH >5, the pyrene is ejected into the aqueous phase of the system. In the presence of micellar solutions of surfactants increasing pH transports the pyrene from the polymer to the micellar aggregates. These fluorescence techniques are used to investigate the kinetics of expansion of the polymer coil. The system is suggested as a suitable model for the interaction of pyrene with biopolymers such as DNA.
Friedel–crafts reagents as charring agents in impact polystyrene
Authors: Brauman Sharon K.
Published: April 2003

We have screened various multifunctional Friedel–Crafts alkylation and acylation reagents for their charring ability in impact polystyrene. Only benzyl chloride reagents with Sb2O3–halogen catalysts promoted crosslinking; the result is increased char yields and decreased fuel production and thereby improved fire resistance. Selected systems were evaluated for ignition, extinction, flamespread, and smoke generation; chars were fully characterized.
Oligomeric benzimidazoles with reactive end groups
Authors: Brand Richard A. , Swedo Raymond J. , Marvel C. S.
Published: April 2003

The condensation of aromatic diamines with aromatic dinitriles and the subsequent conversion of the amidines formed to benzimidazole units has been adapted to the preparation of oligomeric benzimidazoles with nitrile and carboxyl end groups. These are promising new dibasic acids for the preparation of heat‐stable condensation polymers.
X‐ray photoelectron spectroscopy of an ethylene–tetrafluoroethylene copolymer
Authors: Pireaux J. J. , Riga J. , Caudano R. , Verbist J. , Gobillon Y. , Delhalle J. , Delhalle S. , Andre J. M.
Published: April 2003

The electronic structure of a clean copolymer of ethylene and tetrafluoroethylene is investigated by measuring the ESCA spectra of the core and valence levels. The chemical composition and alternating (>95%) structure of the copolymer, characterized separately by classical methods, is verified by analyzing the C 1s core‐level spectrum. The comparison of the experimental valence band with an original EHCO band‐structure calculation, and with similar data for a model of polymer with block structure, shows that the combined methods allow us to distinguish between the two compounds through their valence‐band spectra.
Polyimides derived from bismethylolimides. II. Polyamine‐imides from bismethylolimides and diamines
Authors: Kurita Keisuke , Itoh Hiroshi , Iwakura Yoshio
Published: April 2003

Compounds in the N‐methylolimide group reacted smoothly with amines in the presence of water to yield the corresponding condensation products. Polycondensations of bismethylolimides, N,N′‐bismethylolpyromellitic diimide, and N,N′‐bismethylolbenzophenonetetracarboxylic diimide, with amines such as aromatic diamines, piperazine, and n‐butylamine, were carried out in DMAc that contained 1% water to produce linear polyamine‐imides. The polyamine‐imides assumed various colors, from very pale yellow to deep purple, and had inherent viscosities in the 0.07–0.37‐dl/g range. Most of these polymers were soluble in polar solvents such as DMAc and DMSO. The thermal stability of the polymers was examined by thermogravimetric analysis; decomposition started at 210–350°C and weight residue at 500°C was 22–85% in air.
Modification of properties of ion exchange membranes. VI. Electrodialytic transport properties of cation exchange membranes with a electrodeposition layer of cationic polyelectrolytes
Authors: Sata Toshikatsu , Mizutani Yukio
Published: April 2003

When a cation exchange membrane is immersed in a cationic polyelectrolyte solution to form a thin layer on the membrane surface, the membrane properties are changed: permselectivity between cations with different electric charges (a relative transport number of the calcium ions to sodium ions, P), current efficiency, and electric resistance of the membrane. Here the more compact the cationic polyelectrolyte layer, the more outstanding the change in permselectivity. To make a more compact layer, an electrodeposition method was adopted and a change in the permselectivity of the resultant cation exchange membrane was investigated. By using the electrodeposition method a strongly basic polyelectrolyte with a larger molecular weight effectively changed the permselectivity of the cation exchange membrane: the P value dropped to about 0.3 from about 2.5 of the P of the untreated membrane during electrodialysis of the sodium chloride—calcium chloride system, and an increase in the electric resistance of the membrane (i.e., organic fouling) due to a cationic surface‐active agent could be prevented. It is noteworthy that by using the strongly basic polyelectrolyte with a larger molecular weight the electrodeposition method was effective, whereas the immersion method was ineffective. Furthermore, even with the electrodeposition method the cationic polyelectrolyte which had a relatively smaller molecular weight resulted in a more remarkable change in the P value than did that with a larger molecular weight. In the electrodeposition method the amount of polyelectrolyte cohered onto the membrane surface in creased with an increase in the concentration of the polyelectrolyte, and weakly basic polyelectrolyte, and weakly basic polyelectroyte (polyethyleneimine) was also available independent of its molecular weight.