bluuebunny/crossref_metadata_2025 huggingface dataset:
Extended cooperative electronic effects in poly((E,E)‐[6.2]paracyclophane‐1,5‐diene)
Authors: Glatzhofer Daniel T. , Longone Daniel T.
Published: April 2003

Fluorescence spectroscopy of poly((E,E)‐[6.2]paracyclophane‐1,5‐diene) shows the existence of several emission maxima which appear at wavelengths longer than that of the [3.2]paracyclophane repeat‐unit excimer. These maxima appear to be emission bands due to “extended excimer” fluorescence from multiples of electronically interacting repeat units. Oxidation of the polymer by exposure to iodine vapor results in a material which exhibits a strong, asymmetric electron‐spin‐resonance spectrum with g = ca. 2.00 and a DC conductivity of 5 X 10—4 S‐cm—1. These results are interpreted by a model in which segments of interacting radical cation salts occur pendant to and along the polymer chains but are of random length and orientation in the bulk polymer. Similar results were obtained for a structurally related polymer containing [3.3]paracyclophane rings.
Functional polymers and sequential copolymers by phase transfer catalysis. 18. Synthesis and characterization of α,ω‐bis(2,6‐dimethylphenol)–poly(2,6‐dimethyl‐1,4‐phenylene oxide) and α,ω‐bis(vinylbenzyl)–poly(2,6‐dimethyl‐1,4‐phenylene oxide) oligomers
Authors: Nava Hildeberto , Percec Virgil
Published: April 2003

A novel and convenient synthetic method for the preparation of α,ω‐bis(2,6‐dimethylphenol)–poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO‐2OH) is presented. It is based on the oxidative copolymerization of 2,6‐dimethylphenol (DMP) with 2,2′‐di(4‐hydroxy‐3,5‐dimethylphenyl propane) (TMBPA) in a mixture of water–methanol or chlorobenzene–methanol. By using a 4/1 mole ratio of DMP to TMBPA and different solvent mixtures, it was possible to obtain bifunctional PPO‐2OHs with number average molecular weights between 1000 and 5000. A phase‐transfer‐catalyzed etherification of PPO‐2OH chain ends with a mixture of m‐ and p‐chloromethylstyrene was used to synthesize α,ω‐bis(vinylbenzyl)‐poly(2,6‐dimethyl‐1,4‐phenylene oxide)s (PPO‐2VBs). The thermal polymerization of the PPO‐2VBs was studied by differential scanning calorimetry, and has demonstrated a very high thermal reactivity for this new class of reactive oligomers.
Rhodium and platinum complexes as catalysts for the polymerization of phenylacetylene
Authors: Furlani A. , Licoccia S. , Russo M. V. , Camus A. , Marsich N.
Published: April 2003

In polymerization reactions of phenylacetylene three different types of polyphenylacetylene (PPA) were prepared by using Rh and Pt complexes as catalysts in different reaction conditions. Type I PPA is obtained with [Rh (COD) Chel] PF6complexes (COD =cis,cis‐cycloocta 1,5‐diene; chel = 2,2′‐bipyridine, 1,10‐phenanthroline, 2,9‐dimethyl‐1,10‐phenanthroline, 5,6‐dimethyl‐1,10‐phenanthroline, 3,4,7,8‐tetramethyl‐1,10‐phenanthroline) in bulk, benzene methanol, while type II PPA is obtained with the same catalysts inp‐dioxane and type III PPA in the presence of [Pt (CCPh)2(PPh3)2] in bulk. Type I, II, and III PPA exhibit different IR and1H‐NMR spectra, which have been compared with literature data. Correlations proposed by different Authors between spectral properties of PPA and chain structures are also discussed.
Spectroscopic studies on the oligomers of bromotrifluoro ethylene
Authors: Rao M. Rama , Radhakrishnan T. S. , Ravindran P. V.
Published: April 2003

The photo‐initiated oligomerization of bromotrifluoroethylene in chlorotrifluoromethane medium was found to yield a complex mixture of products. 19F‐nmr, infrared and GC‐MS spectra revealed the presence of ‐CF2Br and —CF = CF2 and the absence of —CF Br2 and —CF3 end groups in the products. Oligomers up to pentamers were identified and their structures elucidated by GC‐MS. A plausible mechanism for their formation is suggested.
Photocrosslinkable polyesters with conjugated double bonds: Reciprocity effect in laser recording
Authors: Iwata Kaoru , Hagiwara Tsuneo , Matsuzawa Hiroshi
Published: April 2003

The reciprocity effect under intense illumination was studied with photocrosslinkable polyesters of p‐phenylenebis(α‐cyanobutadiene carboxylic acid) (I), m‐phenylenebis(α‐cyanobutadiene carboxylic acid) (II), and p‐phenylenebis(acrylic acid) (III), with an argon ion laser as a light source. The reciprocal sensitivities of I, II, and III were 5.0, 1800, and > 105 mJ/cm2, respectively. II and III required sensitization to enhance their sensitivities to a level at which reciprocity effects could be measured. I obeyed the reciprocity law over a wide range of exposure times from seconds to microseconds. Both II′, a copolyester of II, and III showed a dramatic decrease of sensitivity in high‐intensity/short‐time exposure when sensitized by 9,10‐phenanthraquinone and pyrylium salts.
Dual‐functional catalysis for ethylene polymerization to branched polyethylene. II. Kinetics of ethylene polymerization with a mixed homogeneous–heterogeneous Ziegler–Natta catalyst system
Authors: Kissin Yury V. , Beach David L.
Published: April 2003

The previous paper in this series described several catalytic systems which can be used for simultaneous ethylene dimerization to 1‐butene and copolymerization of the in situ‐formed olefin with ethylene to form branched polyethylene. Such catalytic systems allow the synthesis of linear low‐density polyethylene from a single monomer source. This article presents a more detailed description of one of the dual‐functional catalyst systems studied, a mixed homogeneous–heterogeneous Ziegler–Natta catalyst, Al(C2H2)3–Ti(Oi‐C3H7)4–TiCl4/MgCl2/polyethylene, at 90°C. Discussed are kinetics of ethylene dimerization with the soluble component, Al(C2H5)3–Ti(Oi–C3H7)4, and the effects of aluminum alkoxides on the system. Addition of the ethylene dimerization catalyst to the solid component, Al(C2H5)3–TiCl4/MgCl2/polyethylene, results in a partial decrease in polymerization activity. Some of the decrease can be attributed to the presence of 1‐butene in the reaction medium. Measurement of the reactivity ratio kEE/kEB for two catalytic systems, the solid component and the title dual‐functional catalyst, demonstrated that the presence of the dimerization component results in a twofold increase in the reactivity ratio, from 20 to ca. 40.
Kinetics of thermal depolymerization of trimethylsiloxy end‐blocked polydimethylsiloxane and polydimethylsiloxane‐N‐phenylsilazane copolymer
Authors: Kang D. W. , Rajendran G. P. , Zeldin M.
Published: April 2003

The thermal degradation of Me3SiO end‐blocked polydimethylsiloxane (eb‐PDMS) and polydimethylsiloxane‐N‐phenylsilazane (eb‐PDMS–NPhSz) copolymer was studied. For both polymers relative degree of polymerization (DP/DP0) as a function of conversion (1 – W/W0) data were obtained. For eb‐PDMS the results were consistent with a mechanism involving a rate determining random siloxane bond cleavage initiation step followed by a rapid and complete depropagation of the active fragments evolving volatile cyclic oligomers. Rate constants (k) for initiation were obtained at four temperatures from plots of DP−1 vs. time. An Arrhenius activation energy of approximately 80 kcal/mol was determined and is consistent with a SiOSi scission transition state. The degradation of eb‐PDMS–NPhSz appears to follow the same depolymerization process evolving cyclic oligomers. Although DP/DP0 vs. C data suggest a random cleavage–complete depolymerization mechanism, an Arrhenius plot suggests a more complex degradation mechanism. The role of impurities as degradation catalysts is discussed.
Degradation of dehydrochlorinated poly(epichlorohydrin) using photo‐generated cationic catalysts
Authors: Nishikubo Tadatomi , Iizawa Takashi , Sugawara Yoshihiko , Shimokawa Tsutomu
Published: April 2003

The photochemical reaction of polymer containing vinyloxy group (P‐1), which was prepared from treating poly(epichlorohydrin) with base using a phase transfer catalyst, was investigated in the presence of a photo‐generated cationic catalyst (PGCC). When the polymer with PGCC was irradiated, the vinyloxy group in the polymer disappeared rapidly. The rate of disappearance of the vinyloxy group in P‐1 was strongly influenced by its content in the polymer and the kind of PGCC. P‐1, containing about 65 mol% of vinyloxy group, had the highest photochemical reactivity, and PGCC with PF6− and SbF6− as counterions showed higher catalytic activity than those with BF4− The photochemical reaction of P‐1 involved a number of reactions such as degradation, rearrangement, and crosslinking reaction competitively; however, P‐1 with less vinyloxy group than 60 mol% degraded preferentially. These results suggested that P‐1 is an excellent photodegradating polymer using PGCC. The thermal degradation of P‐1 was also investigated.
Wholly aromatic polyamide‐hydrazides. IV. Structure–property relationships for polymers containing p‐phenylene and m‐phenylene units
Authors: Dvornic Petar R.
Published: April 2003

A series of wholly aromatic polyamide‐hydrazides was investigated in order to acquire clear understanding of the influence exerted by controlled structural variations in these polymers upon some of important properties, such as chain flexibility, membrane permselectivity, and thermal as well as thermo‐oxidative stability. For that reason, the content of para and meta phenylene units was varied within this series so that the changes in the latter were 12.5 mol % from polymer to polymer, starting from an overall content of 0–50 mol %. The polymers were prepared by a low‐temperature solution polycondensation reactin of p‐aminobenzhydrazide (ABH) and terephthaloyl chloride (TCI), isophthaloyl chloride (ICI), and their appropriate combinations in N,N‐dimethylacetamide (DMA) as solvent and all of these preparations were monitored viscometrically in order to prepare the products with as similar as possible average molecular weights. Polymer structures were characterized by elemental analysis, infrared spectrometry, and 13C NMR spectroscopy, while their molecular weights were determined by light scattering and dilute‐solution viscometry. Polymer properties were evaluated by solution viscometry, reverse osmosis tests, and thermal gravimetric analysis. The results obtained during the preparation of these materials, their subsequent structural characterization, and their property evaluations are discussed. They clearly indicate that substitution of m‐phenylene units for p‐phenylene ones within this polymer series led to an increase in polymer chain flexibility (from what is usually referred to as semiflexible or semirigid to typically flexible macromolecules), disrupted selectivity of the asymmetric thin membranes under reverse osmosis conditions and decreased stability at elevated temperatures in inert as well as in oxidative atmospheres.
Effects of chemical structure on low‐temperature modulus for UV‐curable polybutadiene acrylates as an optical fiber coating material
Authors: Kimura T. , Yamakawa S.
Published: April 2003

The relationship between chemical structure and low‐temperature modulus of ultraviolet(UV)‐radiation‐cured optical‐fiber coating materials has been investigated. The coating materials are low‐viscosity liquid compounds consisting of a 1,4‐polybutadiene diacrylate oli‐gomer, a monomer, and a photoinitiator. Dynamic mechanical test results show that low‐temperature modulus and glass transition temperature (Tg) are affected by the monomer structure and monomer concentration in the coating material in cases where the same oligomer is used. With increasing alkyl group chain length of the alkylacrylate monomer, the Tg value is shifted to lower temperatures. Low‐temperature modulus increases with increasing monomer concentration in the coating material. Low‐temperature excess optical losses of coated fibers have been found to be closely related to low‐temperature modulus of the coating.
A pyrolysis/GC/MS study of plasma‐polymerized toluene—evidence for carbon atom scrambling in the plasma
Authors: Kaplan S. , Dilks A. , Crandall R.
Published: April 2003

Mass spectral analysis of the gas‐chromatography‐separated pyrolysis products of the solid polymer formed in a toluene plasma has shown the presence of a number of phenyl‐containing structures. Of particular interest is the biphenyl product, whose isotopic distribution patterns are very different for the polymers prepared from natural 13C abundance and 13CH3‐labeled toluene. This result is interpreted in terms of carbon atom scrambling via seven‐membered‐ring intermediates in the gas phase during plasma polymerization. A comparison of measured isotopic patterns with calculated patterns reveals that 34 ± 10% of the toluene molecules scramble prior to polymer formation. This value is similar to an upper bound on scrambling determined here but based on earlier NMR results1 and reinforces a model for the structure of plasma‐polymerized toluene established in that work.
Diacetylenic liquid‐crystalline polymers and copolymers. I. Derivatives of diphenyldiacetylene
Authors: Ozcayir Y. , Blumstein A.
Published: April 2003

The diphenyldiacetylene moiety is highly mesogenic and liquid‐crystalline mesophases were observed in polymers incorporating such moieties in the main chain of polyesters with regularly alternating mesogenic groups and flexible spacers. Extensive crystallinity, polymorphism and high values of transition temperatures characterize these polymers. The reactivity of the conjugated triple bond at the temperature of mesophase formation impedes the stability of LC mesophases. Methyl substitution in the benzene ring lowers the transition temperatures significantly.
Photochemically active modification of polymers I. Preparation and reaction of photocrosslinkable poly(vinyloxycarbonylchalcone)
Authors: Watanabe Shoji , Harashima Susumu , Tsukada Noriaki
Published: April 2003

Photocrosslinkable polymers containing pendant chalcone groups were prepared by the reaction of 4′‐substituted‐4‐carboxychalcone (4‐R‐CC) with poly(vinyl alcohol) (PVA) in homogeneous dimethylacetamide (DMA) solutions using 2,4,6‐trinitrochlorobenzene (TNCB) as condensing agents. The mechanism of ester formation is mainly discussed for 4‐carboxychalcones on the basis of the isolated intermediates and mass spectrometry. The modified polymers showed excellent properties as photocrosslinkable polymers and the photosensitivity was confirmed in the range of about 1 to 5 mJ/cm2.
Polydimethylsiloxane–vinyl block polymers. II. The synthesis and characterization of block polymers by the thermolysis of polydimethylsiloxane macroinitiators containing bis(silyl pinacolate) groups
Authors: Crivello J. V. , Lee J. L. , Conlon D. A.
Published: April 2003

The thermolysis of polydimethylsiloxanes containing thermally labile bis(silyl pinacolate) groups in the backbone in the presence of various vinyl monomers leads to the direct synthesis of block polymers. Depending on the monomer chosen, simple triblock or multisequence block polymers can be readily prepared. Analysis of the products of the block polymerizations using various styrenic‐type monomers shows that only block polymers are obtained, i.e., no homo‐polymers are formed. These block polymers display evidence of phase separation such as intense iridescence and solvent‐dependent mechanical properties. The mechanical properties of these block polymers have been measured and found to be highly composition dependent. Depending on the block length and the relative portions of the hard (vinyl) and soft (polydimethylsiloxane) blocks, one can produce either thermoplastic elastomers or rubber‐modified thermoplastics.
Polymerization of vinyl chloride at reduced monomer accessibility. III. Polymerization kinetics and molecular structure using PVC latex as seed
Authors: Hjertberg Thomas , Sörvik Erling M.
Published: April 2003

Vinyl chloride was polymerized at 53–97% of the saturation pressure in a water‐suspended system at 55°C with an emulsion PVC latex as seed. A water‐soluble initiator was used in various concentrations. The monomer was continuously charged as vapor from a storage vessel kept at lower temperature. Characterization included determination of molecular weight distribution and degree of long‐chain branching by gel chromatography and viscometry and by thermal dehydrochlorination. To avoid diffusion control intense agitation was necessary. At a certain conversion, aggregation of primary particles resulted in restricted polymerization rate. Before aggregation, formation of new particles did not occur as the number of particles was high enough to ensure capture of all oligoradicals. The kinetic equation accepted for ordinary emulsion polymerization of vinyl chloride was qualitatively found to be valid after the pressure drop as well. Decreased termination rate may result in increased polymerization rate at reduced monomer concentration, i.e., a gel effect, especially at low particle numbers and high polymer contents. The molecular weight decreased with decreasing monomer concentration. This is in accordance with the new mechanism suggested for chain transfer to monomer starting with occasional head‐to‐head additions.
Poly(alkyl α‐bromoacrylate)s. III. Tacticity analysis from 19 mHz 13C‐NMR spectroscopy
Authors: Saunders K. G. , Macknight W. J. , Lenz R. W.
Published: April 2003

Polymer tacticity was determined by 19 mHz 13C‐NMR spectroscopy for isotactic, atactic, and syndiotactic samples of six poly(alkyl α‐bromoacrylate)s. Included in this series were the methyl, ethyl, n‐propyl, i‐propyl, n‐butyl, and n‐pentyl esters. Complete assignments for the 10 pentad peaks of the carbonyl carbon resonance were achieved for all but the i‐propyl ester while a complete analysis of tetrad tacticity from the backbone methylene carbon resonance was possible for all but the methyl ester. The tetrad values calculated from the experimentally determined pentad contents were found to agree with the experimental tetrad values. As a result of insufficient peak separation of the quaternary carbon resonance, complete pentad assignments were possible in only a few instances. The polymerization reaction mechanisms were discussed in terms of the propagation statistics calculated from the experimentally determined tetrads and pentads. Both the atactic and syndiotactic polymers that were synthesized by free radical techniques displayed Bernoullian or random statistics while the stereochemical statistics of the isotactic polymers synthesized by a modified Grignard complex were more consistent with nonrandom or first‐order Markovian statistics.
Preparation of plasma‐films containing carboxylate anions by hydrolysis with octylbromide
Authors: Inagaki N. , Oh‐Ishi K.
Published: April 2003

To obtain thin films containing carboxylate anions, hydrolysis of amido groups in films plasma‐polymerized from trimethylsilyldimethylamine (TMSDMA) and bis(dimethylamino)methylvinylsilane (BDMAMVS) has been investigated by infrared spectroscopy and ESCA. The thin films from TMSDMA and BDMAMVS were hydrolyzed at 80–100°C for 3–16 h to transform amido groups to carboxyl groups. The products hydrolyzed from the TMSDMA–plasma‐polymers were mixtures of carboxylate ester and carboxylic acid, and that from the BDMAMVS–plasma‐polymers was carboxylic acid. The hydrolysis reaction was restricted at regions near polymer surfaces.
Synthesis of bifunctional monodisperse poly(N‐isovaleryl ethyleneimine)
Authors: Swamikannu A. Xavier , Hsiue Ging‐Ho , Litt Morton H. , Balasubramanian M.
Published: April 2003

A bifunctional initiator, ethanediyl 1,2‐bis(2‐isobutyl oxazolinium trifluoromethane sulfonate) was prepared and used for the ring opening polymerization of 2‐isobutyl oxazoline. Polymerizations were run in CH3CN at 80 and 60°C and in sulfolane at 80°C. The molecular weight distributions of the poly(N‐isovaleryl ethyleneimine)s produced, M/I ≤ 45, approached Poisson distribution.
Preparation and structural characterization of poly(4‐vinylphenylacetate‐co‐maleic anhydride)
Authors: Jones J. A. , Ottenbrite R. M.
Published: April 2003

Poly(4‐vinylphenylacetate‐co‐maleic anhydride) was synthesized by free‐radical initiation to yield a 1:1 copolymer over a 0.2‐0.8 mole fraction range of monomer feed in maleic anhydride. Evidence of 1:1 charge transfer complex between 4‐vinylphenylacetate and maleic anhydride was obtained in the UV region at 355 nm. The 13C NMR chemical shifts and 1H NMR integration data indicate that poly(4‐vinylphenylacetate‐co‐maleic anhydride) has an alternating and stereoregular structure. The molecular weight of poly(4‐vinylphenylacetate‐co‐maleic anhydride) was controlled by using specific solvents and initiator concentrations.
Long‐lived polymer radicals. VIII. Easy formation of long‐lived propagating radicals of vinyl monomers at room temperature
Authors: Sato Tsuneyuki , Yamamoto Tsuyoshi , Ogawa Tetsuo , Otsu Takayuki
Published: April 2003

Poly[acryloyl‐L‐valine (ALV)] microspheres containing peroxy ester groups were prepared by radical copolymerization of ALV with a small amount of di‐tert‐butyl peroxyfumarate. When the microspheres were irradiated in the presence of second vinyl monomers, long‐lived propagating radicals of the second monomers were formed in the microspheres by the reaction of microsphere polymer radicals with the monomers. The presence of a minute quantity of ethyl alcohol served to soften the microspheres and made the polymer radicals more mobile in the microspheres. As a result, sharper ESR spectra of the propagating radicals were observed although their lifetimes became shorter. This microsphere method also yielded easily the stable propagating radicals of a‐methylstyrene and 1,1‐diphenylethylene which have no homopolymerizability in usual radical polymerization. When N‐n‐propyldimethacroylamide and N,N′‐dimethyl‐N,N′‐dimethacroylhydrazine, which undergo cyclopolymerization, were used as second monomer, uncyclized polymer radicals were only observed. Some discussions were given on the propagation mechanism of the cyclopolymerization.
Ceric‐ion‐initiated grafting of methyl methacrylate onto (1 → 5)‐α‐D‐ribofuranan and (1 → 5)‐α‐D‐xylofuranan
Authors: Chen Yen‐Yuan , Oshima Ryuichi , Hatanaka Kenichi , Uryu Toshiyuki
Published: April 2003

We report herein studies of grafting of MMA onto (1 → 5)‐α‐D‐ribofuranan and (1 → 5)‐α‐D‐xylofuranan by ceric ion initiation both in water and in dimethyl sulfoxide (DMSO). In aqueous medium, the graft polymer having high grafting (%) can be obtained easily without adding any nitric acid. The degradation of polysaccharide by the acidic ceric ion solution is not serious; 73–82% of its original molecular weight remained after the polymerization. In DMSO, graft polymers having lower grafting (%) and lower molecular weight of grafts were obtained.
Photolysis of polymeric organosilicon systems. III. Synthesis and photochemical behavior of polysiloxanes containing phenyldisilanyl units
Authors: Nate Kazuo , Ishikawa Mitsuo , Imamura Naoya , Murakami Yoshihide
Published: April 2003

The synthesis and photochemical behavior of three types of polysiloxanes containing phenyldisilanyl units as chromophore have been reported. Irradiation of thin liquid films of the polymer (2) prepared from copolymerization of octamethylcyclotetrasiloxane and 1,3,5‐triphenyl‐1,3,5‐tris(trimethylsilyl)cyclostrisiloxane (1) with a 500‐W Xe‐Hg lamp afforded transparent solid films which are insoluble in common organic solvents. Similar irradiation of thin liquid films of polysiloxane (8) containing both phenyldisilanyl units and vinyl groups resulted in formation of crosslinked solid films. When thick films of the polymers 2 and 8 were irradiated with a Xe‐Hg lamp, crosslinking occurred only on the surface of the films, but inside remained as liquid. Irradiation of the films prepared from the polysiloxane involving the phenyldisilanyl units and butenyl groups, however, gave crosslinked solid films, whatever thickness of the films. The mechanism of photochemically induced crosslinking of the copolymers is discussed on the basis of the results obtained from the photolysis of 1,1‐bis(trimethylsiloxy)‐1‐phenyl(trimethyl)disilane as a model compound.
Synthesis of N‐substituted phenoxazine polymers bearing vinyl backbone
Authors: Kamogawa Hiroyoshi , Kobayashi Masahiko , Yoshihara Shigeki
Published: April 2003

Vinyl monomers bearing N‐substituted phenoxazine or 2,8‐dimethylphenoxazine units were synthesized starting with the corresponding phenoxazines. N‐substituents were 2‐vinylbenzyl‐oxycarbonylethyl group prepared via 2‐carboxyethyl group, 3‐methacrylamido‐, 3‐acrylamido‐, or 3‐(4‐styrenesulfonamido)‐propyl group prepared via 3‐aminopropyl group, vinylbenzyl, or 2‐vinyloxyethyl group attached by the displacements of sodium salts of the phenoxazines to the chlorides, and 2‐methacryloyl‐ or 2‐acryloyl‐oxyethyl group prepared via 2‐hydroxyethyl group. Free‐radical polymerixations of these novel monomers proceeded smoothly, except those with 2‐vinyloxyethyl group, which were susceptible to BF3‐etherate. Changes of the visible absorption spectrum of iodine in THF with addition of the monomers and polymers were considerable, with the appearance of new absorption peaks or shoulders in major cases.
A brief report on novel polyazobenzoxazinones
Authors: Gopal Jayalakshmi , Srinivasan M.
Published: April 2003

Polybenzoxazinones were synthesized by solution polycondensation from five different aromatic diacidchlorides and 3,3′‐diaminoazobenzene‐4,4′‐dicarboxylic acid through a polyamic acid precursor which was further cyclodehydrated to polybenzoxazinones. The amic acid and the benzoxazinones were obtained in 85–93% and 56–63% yield, respectively. The polymers were characterized by physical and thermal analysis.
Selective separation of water–ethanol mixture through synthetic polymer membranes having carboxylic acid as a functional group
Authors: Yoshikawa Masakazu , Yukoshi Takashi , Sanui Kohei , Ogata Naoya
Published: April 2003

Separation of water–ethanol mixture through a membrane was carried out by pervaporation using a membrane which provided a hydrogen‐bonding interaction. A membrane obtained from poly(acrylic acid‐co‐acrylonitrile) was effective for a selective separation of water from aqueous ethanol solution by pervaporation technique. Spectroscopic and flux analyses verified that this high selectivity toward water was attributed to the hydrogen‐bonding interaction between water and acrylic acid (carboxylic acid) unit in the membrane. On the other hand, a membrane from poly(acrylic acid‐co‐styrene) preferentially permeated ethanol in the low water feed concentration region.
Segmented poly(ether urethane) films containing ferrocene units in the hard segments
Authors: Gonsalves Kenneth E. , Rausch Marvin D.
Published: April 2003

Segmented poly(ether urethanes) were synthesized from polypropylene glycol (PPG) and 4,4′‐methylene‐bis(phenyl‐isocyanate) (MDI), using 1,1′‐bis(β‐aminoethyl)ferrocene (BAF) and 1,1′‐bis(β‐hydroxyethyl)ferrocene (BHF) as chain extenders. These polymers were characterized by infrared and 13C‐NMR spectroscopy. Mass spectrometry was also utilized to determine the linkage of BAF and BHF in these polymers.
Electrical conductivity in vinyl chloride during polymerization
Authors: Uustalu Joan M.
Published: April 2003

Vinyl chloride of good polymerization quality showed a measurable electrical conductivity. The ionic strength of redistilled VCM appeared to be independent of temperature in the range from 20 to 50°C, and to decrease at higher temperatures. Conductivity measurements during bulk polymerization of VCM showed that the conductivity decreased with conversion. Other results indicated that electrolytically active species, formed during the polymerization, were trapped in the polymer matrix.
Monomer‐isomerization polymerization. XXII.. Isomerization and polymerization of propenylbenzene with various ziegler–natta catalysts
Authors: Endo Kiyoshi , Otsu Takayuki
Published: April 2003

The isomerization and polymerization of propenylbenzene (PB) with various Ziegler–Natta catalyst systems have been investigated. With the TiCl3–(C2H5)3Al (Al/Ti > 2.0) catalyst at 80°C, PB polymerized to give a polymer exclusively consisting of allylbenzene (AB) unit. During the polymerization, AB, which polymerized readily with the catalyst, was produced through isomerization of PB, indicating that PB underwent monomer‐isomerization polymerization. PB also polymerized with isomerization to AB in the presence of TiCl3−(C2H5)2AlCl−NiCl2 catalyst system, and a copolymer with PB and AB units was obtained. With TiCl3−C2H5AlCl2 catalyst, poly(PB) was formed via ordinary vinylene polymerization without isomerization. From these facts, it was concluded that the structure of the polymers produced from PB widely changed, depending on the catalyst systems used, which determine the rate of isomerization to AB and the polymerization reactivity of the PB and AB isomers formed.
Poly[amino‐p‐(hydroquinone or benzoquinone)]amides and poly(p‐benzoquinono)diimidazoles of aliphatic dicarboxylic acids. V.
Authors: Kehayoglou A. H. , Sideridou‐Karayannidou I.
Published: April 2003

Poly(amino‐p‐hydroquinone)amides prepared from 2,3,5,6‐tetraamino‐p‐hydroquinone and adipic, suberic, or sebacic acid dichloride were converted by mild oxidation to the corresponding poly(amino‐p‐benzoquinone)amides. The latter, prepared also directly from 2,3,5,6‐tetraamino‐p‐benzoquinone, were converted by thermal cyclodehydration to the corresponding thermally stable poly(p‐benzoquinono)diimidazoles. The prepared new redox polymers were characterized by elemental analysis, UV and IR spectral study, inherent viscosity, solubility, and thermal analysis (DSC, TGA).
Monomer‐isomerization polymerization. XXIII.. Monomer‐isomerization polymerization of 5‐phenyl‐2‐pentene with ziegler–natta catalysts
Authors: Endo Kiyoshi , Tsujikawa Hajime , Otsu Takayuki
Published: April 2003

5‐Phenyl‐2‐pentene (5Ph2P) was found to undergo monomer‐isomerization polymerization with TiCl3–R3Al (R = C2H5 or i‐C4H9, Al/Ti > 2) catalysts to give a polymer consisting of exclusively 5‐phenyl‐1‐pentene (5Ph1P) unit. The geometric and positional isomerizations of 5Ph2P to its terminal and other internal isomers were observed to occur during polymerization. The catalyst activity of alkylaluminum examined to TiCl3 was in the following order: (C2H5)3Al > (i‐C4H9)3Al > (C2H5)2AlCl. The rate of monomer‐isomerization polymerization of 5Ph2P with TiCl3–(C2H5)3Al catalyst was influenced by both the Al/Ti molar ratio and the addition of nickel acetylacetonate [Ni(acac)2], and the maximum rate was observed at Al/Ti = 2.0 and Ni/Ti = 0.4 in molar ratios.
Thermal decomposition mechanisms of sequential bipolyesters based on propeneglycol and hydroxybenzoic/phthalic diacid derivatives
Authors: Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio , Chiellini Emo
Published: April 2003

Some bipolyesters consisting of 1,2‐propene glycol residue (P) and symmetric aromatic diacid residue constituted by two p‐oxybenzoyl groups coupled by a terephthaloyl (HTH), phthaloyl (HOH) and isophthaloyl (HIH) group, and a nonsymmetric diacid residue constituted by a p‐oxybenzoyl and a terephthaloyl group (HT), have been investigated by direct pyrolysis–mass spectrometry. The results show that intramolecular exchange reactions occurring at the pyrolysis stage cause a reorganization of the copolymer sequences. Sequential bipolyesters I–IV are ideal materials for the investigation of the extent of thermal reorganization induced in the bipolymer sequences by the pyrolytic process.
Addition reactions of pendant epoxide group in poly(glycidyl methacrylate) with various active esters
Authors: Nishikubo Tadatomi , Iizawa Takashi , Saita Seiji
Published: April 2003

Addition reactions of pendant epoxide groups in poly(glycidyl methacrylate) (PGMA) with various active esters such as 1‐benzotriazolyl benzoate, S‐(2‐benzoxazolyl) thiobenzoate, S‐(2‐benzothiazolyl) thiobenzoate, 4‐nitrophenyl benzoate (4NPB), and S‐phenyl thiobenzoate (PTB) were carried out using quaternary salts as catalysts. The reactions of PGMA with those active esters proceeded in diglyme at 100°C for 24 h quantitatively without the formation of 2‐hydroxyl pendant groups in the polymer when 10 mol % of tetraethylammonium bromide was used as a catalyst. Furthermore, it was found that the respective quaternary salts have higher catalytic activity than tertiary amines in the reaction of PGMA with the active esters, and the reaction of PGMA with 4NPB gave the corresponding polymer with the highest conversion by addition of tetrabutylammonium bromide as a catalyst, while tetraethylammonium chloride showed the highest activity for the reaction of PGMA with PTB. In addition, the rate of reaction of PGMA with 4NPB was proportional to third order kinetics of the epoxide concentration, the ester concentration and the catalyst concentration as follows: −d[Epoxide]/dt = −[Ester]/dt = k3[Epoxide] [Ester] [Catalyst].
Direct polycondensation of hydroxybenzoic acids with thionyl chloride in pyridine
Authors: Higashi Fukuji , Mashimo Toshio
Published: April 2003

The reaction promoted by thionyl chloride and pyridine could selectively activate carboxyl groups of hydroxybenzoic acids to give polyesters of high inherent viscosities up to 3.8. Favorable conditions were studied in terms of the temperatures for the initial reaction with the acids and subsequent aging at room temperature. Copolymers of several combinations of hydroxybenzoic acids with high molecular weights were obtained in quantitative yield by carrying out the polycondensation at 80°C for 3 h. The reaction could also produce high molecular polyesters in a simpler process without the initial activation of dicarboxylic acids by adding a mixture of these monomers to the condensing agent, and a tough film‐ and fiberforming polymer was obtained from 4,4′‐dihydroxyphenylsulfone of low nucleophilicity whose polymer of high molecular weight is difficult to obtain. The process was also successfully applied to the direct copolycondensations of hydroxybenzoic acids, aromatic dicarboxylic acids, and bisphenols to produce polyesters of ηinh up to 5.6.
Kinetics of polymerization of vinyl monomers initiated by lead tetraacetate
Authors: Balakrishnan T. , Kasilingam E. K.
Published: April 2003

A systematic study of the thermal polymerization of α‐chloroacrylic acid and α‐bromoacrylic acid in aqueous nitric acid was carried out. The effect of variation of monomer concentration lead tetraacetate concentration, hydrogen ion concentration, ionic strength, and temperature on the rate of monomer disappearance was carried out. Based on the experimental observations, suitable reaction schemes were proposed for the polymerization of the above monomers. The rate constants and the thermodynamic parameters were evaluated.
Characterization of large water‐soluble macromolecules by size exclusion chromatography
Authors: Lundy Charles E. , Hester Roger D.
Published: April 2003

A method for characterizing very large, water‐soluble polymers by size exclusion chromotography (SEC) has been developed. Sephacryl S1000 packing material, a precision syringe pump, and an eluent pressure detector have been utilized to produce highly accurate chromatograms of polymers having molecular hydrodynamic diameters up to 250 nm. Previous SEC analysis has been limited to polymers having hydrodynamic diameters of less than 120 nm.
Polymerization of 1‐(trimethylsilyl)‐1‐propyne homologs containing two silicon atoms by tantalum‐ and niobium‐based catalysts
Authors: Isobe Eiji , Masuda Toshio , Higashimura Toshinobu , Yamamoto Akira
Published: April 2003

Polymerization of new 1‐(trimethylsilyl)‐1‐propyne homologs containing two silicon atoms [CH3CCSi(CH3)2CH2Si(CH3)3 and CH3CCSi(CH3)2CH2CH2Si(CH3)3] was investigated by use of Ta and Nb catalysts. CH3CCSi(CH3)2CH2Si(CH3)3 was polymerized quantitatively by TaCl5 alone to provide a polymer having molecular weight over 106. CH3CCSi(CH3)2CH2CH2Si(CH3)3 was polymerized in good yield by an equimolar mixture of TaCl5 with an appropriate organometallic cocatalyst such as Ph4Sn to give a polymer with molecular weight of ca. 4 X 105. Nb catalysts were less active toward these monomers than the corresponding Ta catalysts. These two kinds of polymers had alternating double bonds along the main chain according to IR and 13C‐NMR spectra. Both polymers were white solids completely soluble in low‐polarity solvents like toluene, and solution casting afforded uniform, tough films. These polymers were thermally fairly stable, and their softening points were above 350°C. Films of these polymers showed smaller oxygen permeability coefficients [P = 4 × 10−9 – 8 × 10−9 cm3(STP) · cm/(cm2·sec·cmHg)] but larger separation factors [(P/P) = 3.4 – 3.6] than a poly[1‐(trimethylsilyl)‐1‐propyne] film.
Thermooxidatively stable articulated benzobisoxazole and benzobisthiazole polymers
Authors: Evers Robert C. , Moore George J.
Published: April 2003

Articulated all‐para polymers with 2,6‐benzobisoxazole and 2,6‐benzobisthiazole units in the backbone weree synthesized by copolycondensation in polyphosphoric acid of 4,6‐diamino‐1,3‐benzenediol dihydrochloride and 2,5‐diamino‐1,4‐benzenedithiol dihydrochloride, respectively, with terephthalic acid and reactive 3,3′‐biphenyl or 4,4′‐(2,2′‐bipyridyl) monomers. Inherent viscosities of up to 13.18 dL/g (CH3SO3H, 25°C, 0.2 g/dL) were achieved. The average length of the rodlike all‐para segments between the relatively flexible biphenyl or bipyridyl units was controlled by the stoichiometry of the copolycondensation reactions. Dependent upon the solids content of the polymerization mixture and the mole proportion of the flexible units in the polymer backbone, copolycondensation proceeded in the liquid‐crystalline state to give polymerization mixtures which exhibited lower bulk viscosities than comparable copolycondensation reactions that remained in the isotropic state. Films which exhibited optical birefringence under crossed polars could be cast from methanesulfonic acid solutions of the polymers. Thermooxidative stability of the articulated polymers was evaluated by isothermal aging in air at 371°C. Stability for the polymers was found to decrease slightly with increased content of the flexible biphenyl structure in the polymer backbone. The biphenyl structure was found to be more thermooxidatively stable than the bipyridyl structure.
Photolysis of aromatic diisocyanate‐based polyurethanes in solution
Authors: Hoyle Charles E. , Kim Kyu‐Jun
Published: April 2003

Fluorescence analysis has been employed as an analytical technique to elucidate the photolysis mechanism of several aromatic diisocyanate‐based polyurethanes in solution. Based on a comparison with model arylmonocarbamates and arylbiscarbamates, the photo‐Fries rearrangement and cleavage‐type products found for the small‐model arylcarbamates were also identified for the photolyzed polyurethanes in solution. Viscosity and absorbance change results for photolysis of both air and nitrogen‐saturated polyurethane solutions are consistent with a general two‐step mechanism for the photolysis of aromatic diisocyanate‐based polyurethanes.
Radiation‐induced graft polymerization of acrylamide I. Preparation conditions and gel determination for polyethylene‐grafted films
Authors: Hegazy El‐Sayed A. , Dessouki Ahmed M. , El‐Boohy Hussain A.
Published: April 2003

Radiation‐induced graft polymerization of acrylamide (AAm) onto low‐density polyethylene(LDPE) film has been investigated. The appropriate reaction conditions at which the graft polymerization was carried out successfully were selected. It was observed that the grafting process was enhanced remarkably by using distilled water as diluent. In this grafting system ammonium ferrous sulphate (Mohr's salt) was used as inhibitor to minimize the homopolymerization of AAm and the suitable concentration of such inhibitor was found to be 3 wt %. The dependence of the grafting rate on the monomer concentration was calculated to be 2.9 order, regardless of the irradiation atmosphere (N2 gas or under vacuum). When the radiation grafting process was carried out under vacuum, higher degrees of grafting were obtained as compared to those in nitrogen gas or in air atmosphere. Network structure was formed in the graft copolymer and the gel formation was determined in the p‐xylene‐extracted grafted films. Results showed good evidence that the grafting process takes place by the front mechanism.
Organosilane polymers: Synthesis and photochemical and photophysical behavior of poly[dimethyl‐co‐methyl(1‐naphthyl)silylene]
Authors: Todesco R. V. , Basheer R.
Published: April 2003

A meltable, partially crystalline silane copolymer, PSN, containing dimethylsilylene and methyl(1‐naphthyl) silylene units was synthesized and characterized. The polymer has a high molecular weight, is appreciably soluble in common solvents and is photoactive. The emission properties of PSN, under stationary and nonstationary conditions, were studied in dilute THF solution. PSN is the first organosilane polymer showing an intense intramolecular excimer emission in addition to monomer and intramolecular charge transfer (CT) fluorescence. It is shown that the ratio of excimer to monomer fluorescence can be used to monitor the UV induced degradation of the polymer.
Synthesis and characterization of the novel type of polymerizable bisphthalonitrile monomers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

Three new bisphthalonitrile derivatives are prepared by the nucleophilic displacement of the nitrosubstituent from 4‐nitrophthalonitrile with 9,9‐bis(4‐hydroxyphenyl)fluorene; 9,9‐bis(3,5‐dimethyl‐4‐hydroxyphenyl)fluorene, and phenolphthalein in the presence of potassium carbonate. The reaction has been carried out in dimethylsulfoxide solvent. These monomers are characterized by elemental analysis, FT‐IR, 1H NMR, TGA, DSC, and mass spectral studies. A tentative mechanism for the fragmentation of the compounds is given to explain the mass spectral data. The compounds are expected to be useful to prepare thermally stable thermosetting phthalocyanine polymers.
Crystallization and melting behavior of isotactic polybutene‐1 at high pressures
Authors: Kishore K. , Vasanthakumari R. , Ramesh T. G.
Published: April 2003

An equation has been developed for the study of the kinetics of polymer crystallization at high pressures using differential scanning calorimetry (DSC) in the dynamic mode of operation. The activation energy for the crystallization of isotactic polybutene‐1 (PB‐1) has been determined to be ca. 20 kcals/mol; this has been attributed to the transport of chain segments to the site of crystallization. The melting behavior of form‐I PB‐1 crystals has been studied by using a high‐pressure differential thermal analyzer (DTA) setup and high‐pressure DSC. The melting temperature Tm does not show any significant change with pressure in the low‐pressure region up to 1.2 kbar; beyond this point a large increase in Tm with pressure was observed. This unusual low‐pressure behavior of PB‐1 has been attributed to formation of intermediate form I′, which has a lower melting point than form I.
Preparation and some properties of 2,2,6,6‐tetrahydryl‐F‐heptanedioic acid and its polyester with 1,1,5,5‐tetrahydryl‐F‐1,5‐pentanediol
Authors: Johncock P. , Barnett Susan P. , Rickard Patricia A.
Published: April 2003

2,2,6,6,‐Tetrahydryl‐F‐heptanedioic acid was prepared by hydrolysis of 1,7‐diethoxy‐2,6‐dihydryl‐F‐1,6‐heptadiene, which was obtained by a copper‐induced coupling reaction between 1,3‐di‐iodo‐F‐propane and 1‐ethoxy‐1‐fluoro‐2‐iodethylene. This olefin is obtained almost exclusively as the less thermodynamically stable isomer in the reaction between 1,1‐difluoro‐2‐iodoethylene and soidum ethoxide. Synthesis of the acid via 2,2,6,6,‐tetrahydryl‐F‐heptanedial was unsuccessful, since the latter readily underwent cyclopolymerization. The acid has pK = 2.38 and pK = 3.35, and slowly liberates fluoride ion in aqueous solution. The polyester obtained with 1,1,5,5,‐tetrahydryl‐F‐1,5‐pentanediol is highly crystalline with a mp of 79°C and a history‐dependent Tg of 6 to 75°C. Polymer with a high amorphous content had a reproducible Tg of −35°C. The polyester has good solvent resistance to hydrocarbons, and comparable thermal stability to the corresponding polyester prepared from isophthalic acid.
Synthesis of acryloyl‐type polymer fixing 5‐fluorouracil residues through D‐glucofuranoses and its antitumor activity
Authors: Ouchi Tatsuro , Fujie Hirotoshi , Jokei Satoshi , Sakamoto Yoshiomi , Chikashita Hidenori , Inoi Takeshi , Vogl Otto
Published: April 2003

Acryloyl‐type polymer fixing 1‐β‐carbonylethyl‐5‐fluorouracil residues through D‐glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water‐soluble objective polymer, the copolymerization of the acryloyl‐type monomer with acrylamide was carried out. The extent of release of 5‐FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water‐insoluble homopolymer and water‐soluble copolymer obtained were tested in vivo.
Formation of formal compounds in reaction of dimethyl phenols with formaldehyde
Authors: Yoshimura Yukio
Published: April 2003

Formaldehyde was reacted with both 2,4‐dimethylphenol(2,4‐xyenol) and 2,6‐dimethylphenol(2,6‐xylenol), which are model compounds of monofunctional phenols, and the reaction products were subjected to HLC analysis to elucidate details of the formation process and bonding manner of a formal group, which can greatly affect the performance of phenol–formaldehyde resins. As a result, formal compounds of dimethylphenols were successfully separated by HLC. It was further found, as a result of tracing the reactions by HLC, that the formation of a formal group occurs at either position of the ortho and para positions, and that methylol compounds were formed following formation of the formal compounds. Furthermore, as a result of NMR analysis as well as consideration of solvation on the basis of the relative elution volumes of the nonacetylated and acetylated reaction products it was found that the formal group was added to the phenol nuclei.
An ESR study of radiation damage of bisphenol‐A‐based epoxy resin at low temperature: Selective hydrogen addition to benzene‐ring‐forming cyclohexadienyl‐type radical
Authors: Eda Bunzo , Iwasaki Machio
Published: April 2003

In the γ‐irradiated aromatic epoxy resin, diglycidylether of bisphenol A cured with diaminodiphenylmethane, the cyclohexadienyl‐type radical is produced as one of the main radical species. Although both the resin and the hardener contain benzene rings, it is concluded that the cyclohexadienyl‐type radical is formed by selective addition of the OH hydrogen to the benzene ring on the resin side. The selectivity is accounted for in terms of electron capture by the benzene ring followed by proton transfer from the OH group which is located in front of the benzene ring. This reaction scheme is further supported by the effect of the addition of an electron scavenger on the radical yield as well as by the photobleaching behavior of the radicals involved.
BDMA‐catalyzed DDA‐epoxy resin system: Temperature and composition effects on curing mechanism
Authors: Lin Y. G. , Sautereau H. , Pascault J. P.
Published: April 2003

DSC and IR data on benzyldimethylamine‐catalyzed dicyandiamide‐DGEBA prepolymer system have been utilized to investigate the influences of temperature and composition on the curing mechanism. Etherification as a competitive reaction is favored at lower temperature. On the other hand, the reaction pathway of dicyandiamide (DDA) varies with temperature, especially at the first stage of reaction. At 100°C, the reaction of DDA is shown to be essentially the substitution of the hydrogen atoms by ring‐opening of epoxy groups, giving rise to N‐alkyl cyanoguanidine. But at 140°C or 160°C, the initial reaction of DDA involves a transformation of nitrile groups to imine groups. A greater amount of BDMA and a higher amine‐to‐epoxy ratio favor the etherification. The glass transition temperature Tg is a complex function of these different mechanisms; higher Tg could be reached with a amino‐to‐epoxy ratio equal to 0.6 and after a curing cycle including a precure at 100°C.