bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, characterization, and curing of hyperbranched allyl ether–maleate functional ester resins
Authors: Johansson Mats , Malmström Eva , Hult Anders
Published: April 2003

A model two‐step synthesis of a saturated hyperbranched hydroxyl‐terminated ester has been developed to show a synthesis route. Three different series of hyperbranched esters with different terminations have been synthesized to relate some of their properties to their structures. This route has then been used to synthesize three different allyl ethermaleate functional hyperbranched ester resins in a two‐step procedure. The resins have been characterized with respect to rheology, structure, and properties, and the differences are discussed. The allyl ether‐maleate functional resins have also been studied with respect to curing performance and final film properties. © 1993 John Wiley & Sons, Inc.
Curing reaction of o‐cresol novolac epoxy resin according to hardener change
Authors: Kim Whan Gun , Lee Ji Yoon , Park Kyung Y.
Published: April 2003

The investigations of cure kinetics and glass transition temperature (Tg) versus reaction conversion (α) of o‐cresol novolac epoxy resin with the change of hardener were performed. All kinetic parameters of the curing reaction such as the reaction rate order, activation energy, and frequency factor were calculated. The curing mechanisms were classified into two types. One was an autocatalytic mechanism and the other was a nth order kinetic mechanism. The constants related to the chain mobility of polymer segments were obtained by using the DiBenedetto equation. We have tried to correlate the relationships between curing mechanism and molecular structures of hardeners from these results. © 1993 John Wiley & Sons, Inc.
A systematic nomenclature for cascade polymers
Authors: Newkome George R. , Baker Gregory R. , Young James K. , Traynham James G.
Published: April 2003

Cascade (dendritic) polymers are discrete, highly branched, monodisperse polymers that possess branching patterns described by a mathematical progression. A systematic nomenclature that accurately represents these molecules is described. © 1993 John Wiley & Sons, Inc.
S‐benzoyl O‐ethyl xanthate as a new photoinitiator: Photopolymerization and laser flash photolysis studies
Authors: Ajayaghosh A. , Das S. , George M. V.
Published: April 2003

A new sulfur‐containing photoinitiator, S‐benzoyl O‐ethyl xanthate (2) has been prepared and used for the photopolymerization of methyl methacrylate (MMA). The photoinitiation property of 2 has been examined by conventional polymerization methods and nanosecond laser flash photolysis studies. Upon 308 nm laser pulse excitation, 2 gave rise to transients with absorption maxima at 350 and 650 nm, assigned to the benzoyl radical (3) and (ethoxythiocarbonyl)thiyl radical (4), respectively, on the basis of their quenching by nitroxy radicals and spectral similarity to analogous species, reported in the literature. © 1993 John Wiley & Sons, Inc.
Thermal degradation behavior of polyamides having 2‐ and 4‐hydroxycinnamic acid dimer components
Authors: Yonezawa Noriyuki , Kanoe Toshio , Saigo Kazuhiko , Hasegawa Masaki
Published: April 2003

Two new types of polyamides having anti head‐to‐tail hydroxycinnamic acid dimer component in the main chain were synthesized. Their thermal degradation behavior was investigated by TG‐DSC analysis in comparison with those of their model compounds and the polyamides derived from anti head‐to‐head coumarin dimer. The key reactions in the thermal degradation were clarified to be lactonization and cyclic imide formation. The polyamide, derived from 4‐hydroxycinnamic acid dimer and hexamethylenediamine, showed good heat stability. © 1993 John Wiley & Sons, Inc.
Linear all‐ortho oligomers of phenol–formaldehyde resins. I. Preparations, characterizations, and solution properties
Authors: Yamagishi T. , Enoki M. , Inui M. , Furukawa H. , Nakamoto Y. , Ishida S.
Published: April 2003

Three kinds of all‐ortho methylene‐linked phenolic oligomers, i.e., 4‐tert‐butylphenol (BP), phenol (AO), and O‐methylated BP (BPM), were prepared with good yields and their dilute solution properties were studied. In acetone, all of these oligomers are highly solvated and molecularly dispersed. In chloroform, however, AO and BP molecules strongly form hydrogen bonds among themselves. By intramolecular and intermolecular hydrogen‐bondings, a large portion of the dimers and the trimers of AO and BP associate to form bimolecular aggregates in chloroform, assuming pseudo‐cyclic conformations analogous to calix [4] arene and calix [6] arene, respectively. By intramolecular hydrogen‐bonding, the tetramers and the hexamers also form pseudo‐cyclic conformations by themselves in chloroform. © 1993 John Wiley & Sons, Inc.
Chemiluminescence of anhydride‐cured epoxy networks: Influence of the anhydride structure
Authors: Tcharkhtchi A. , Audouin L. , Verdu J.
Published: April 2003

The chemiluminescence of three epoxy networks based on diglycidyl ether of biphenol A (DGEBA) crosslinked by respectively the phthalic anhydride (PA), hexahydrophthalic anhydride (HHPA), and methyl tetrahydrophthalic anhydride (MTHPA), was studied in the 180–240°C temperature range. Isothermal stationary and nonstationary (perturbed) experiments revealed that the behavior depends sharply on the anhydride structure. The higher emissivity of cycloaliphatic systems (MTHPA and HHPA) is explained in terms of hydrogen abstractibility on the hardener's moiety. The main difference between MTHPA and HHPA (intensity initially decreases for the former, increases for the latter) is explained by the consumption of the MTHPA double bonds in oxidative crosslinking processes. The results of perturbed experiments were essentially attributed to changes of alkyl radical concentration during the exposure under nitrogen. These changes can be modelled by a simple kinetic model taking into account the observed differences between the systems under study. © 1993 John Wiley & Sons, Inc.
Copolymers of nylon 266 and nylon 66: Synthesis and characterization
Authors: Gonsalves Kenneth E. , Chen Xiaomao
Published: April 2003

Copolymers of nylon 266 and nylon 66 were prepared by interfacial polymerization of N‐glycyl hexanediamine and hexanediamine with adipoyl chloride. According to the results of intrinsic viscosity measurements and GPC analysis, the molecular weights of the copolymers were relatively high. The structure of the copolymers was confirmed by FTIR, and the compositions were determined by 1H‐NMR spectroscopy. The copolymers have similar solubility features as nylon 66. Both melting and glass transition temperatures showed a minimum at around 20–30% nylon 66 content. The copolymers are semicrystalline. Copolymers with lower Tm could be melt‐spun into fibers without appreciable thermal degradation. © 1993 John Wiley & Sons, Inc.
Determination of the degree of N‐deacetylation in chitin and chitosan as well as their monomer sugar ratios by near infrared spectroscopy
Authors: Rathke Thomas D. , Hudson Samuel M.
Published: April 2003

Chitin and its derivative chitosan are rapidly becoming of commercial interest in the biomedical, wastewater treatment, and fiber industries. One of the most important properties of these copolymers is the degree of N‐acetylation. Presently there is no rapid accurate method to determine this value. We propose near infrared spectroscopy for such a method. Using a primary method such as hydrobromic acid titration or 1H‐NMR, standards can be established. Once a model calibration equation has been developed, unknown samples can be analyzed by near infrared spectroscopy in less than 5 min. This is demonstrated by examining representative structural monomers of chitosan, N‐acetyl‐D‐glucosamine and D‐glucosamine hydrochloride, as model compounds as well as actual chitin and chitosan samples. © 1993 John Wiley & Sons, Inc.
Electrophilic aromatic substitution in the curing of brominated poly(isobutylene‐co‐4‐methylstyrene): A mechanistic model study with zinc salts
Authors: Bielski R. , Fréchet J. M. J. , Fusco J. V. , Powers K. W. , Wang H. C.
Published: April 2003

The crosslinking chemistry of a new elastomer based on brominated poly(isobutylene‐co‐4‐methylstyrene) has been investigated using model compounds. In order to mimic the conditions that prevail within the highly allphatic rubber, the study was carried out in mineral oil using catalysts that are compatible with such low polarity media. Electrophilic aromatic substitution reactions occur in a system consisting of p‐isopropylbenzyl bromide and p‐isopropyl toluene in the presence of zinc oxide and zinc stearate. The reaction proceeds after a significant induction period while no induction period is seen for a similar reaction with zinc bromide as the catalyst. The in situ formation of reactive species containing ZnBr bonds appears to be an important step in the overall process. The stoichiometric ratio of zinc salt to benzylic bromide is important. High ratios lead to the accumulation of benzylic stearate or benzylic alcohol in the system which retards the alkylation reaction. The model study emphasizes the importance of stoichiometry of reagents in this reaction and provides insight into the crosslinking mechanism. © 1993 John Wiley & Sons, Inc.
Polymerization of coordinated monomers. XXII. Ab initio molecular orbital study on the binary radical complexes of 2‐methoxycarbonyl propyl radical with boron trichloride and with boron trifluoride as a model of growing radical end
Authors: Sato Kota , Goto Tatsuo , Iwabuchi Susumu , Hirai Hidefumi
Published: April 2003

The geometrical and electronic structures of the binary radical complexes of 2‐methoxycarbonyl propyl radical with boron trichloride and with boron trifluoride were determined by using an ab initio molecular orbital method. The 2‐methoxycarbonyl propyl radical complex was a model of the growing radical end in the copolymerization of methyl methacrylate in the presence of boron halides. The most stable structure of the binary radical complex composed of 2‐methoxycarbonyl propyl radical with boron trichloride was a twisted form in which the dihedral angle between the vinyl group and the ester group was 32°, while that of the binary radical complex composed of methyl methacrylate radical with boron trifluoride was a planar form as the free radical. The frontier orbital energy of 2‐methoxycarbonyl propyl radical was lowered by 0.06 au by the coordination of boron trichloride, while that was lowered only by 0.02 au by the coordination of boron trifluoride. The polymerization mechanism was elucidated on the basis of these predictions. © 1993 John Wiley & Sons, Inc.
Polymerization of ethylene at high temperature by vanadium‐based heterogeneous Ziegler–Natta catalysts. I. Study of the deactivation process
Authors: Adisson E. , Deffieux A. , Fontanille M.
Published: April 2003

Kinetics of the polymerization of ethylene initiated by heterogeneous vanadium‐based Ziegler‐Natta catalysts (VCI3‐1/3 AICI3) have been studied at high temperature (160°C, 5 bars) and compared with a titanium‐based system. For the V catalyst, the dependence of the polymerization activity versus time, with the nature and the concentration of the associated aluminum alkyl, has been investigated. Kinetic results have also been correlated with the oxidation state of vanadium in the polymerization conditions. Despite the relatively high initial activity a low productivity is obtained; it can be attributed to a very fast deactivation of the active sites due to the reduction of vanadium III into vanadium II. The effect of the nature of the alkyl aluminum component of the catalytic system on the reduction process is shown. A kinetic model for the polymerization is proposed. © 1993 John Wiley & Sons, Inc.
Hydrogenated polybutadiene–polymethyl methacrylate (HPB–PMMA) block copolymer. I. Synthesis of polybutadiene–polymethyl methacrylate (PB–PMMA) block copolymer
Authors: Ren Qin , Zhang Hong Jin , Zhang Xiao Kang , Huang Bao Tong
Published: April 2003

To get hydrogenated polybutadiene‐polymethyl methacrylate (HPB‐b‐PMMA) block copolymer to be used as a compatibilizer for blends of polyolefin/polar polymer, PB‐b‐PMMA was synthesized by anionic‐free radical mechanism transformation polymerization. Selective extraction, gradient elution thin layer chromatography, and oil‐oil emulsion separation techniques were tried to attempt to separate the copolymerization products. Hydrogenation of the PB sequence in PB‐b‐PMMA yielded HPB‐b‐PMMA. The compatibilizing function of PB‐b‐PMMA was shown in blending experiments. © 1993 John Wiley & Sons, Inc.
Synthesis and Ni(0)‐catalyzed oligomerization of isomeric 4,4‴‐dichloroquaterphenyls
Authors: Percec Virgil , Okita Shigeru
Published: April 2003

4,4‴‐Dichloro‐1,1′ : 2′,1″ : 2″,1‴‐quaterphenyl (9), 4,4‴‐dichloro‐1,1′ : 3′,1″ : 3″,1‴‐quaterphenyl (10), and 4,4‴‐dichloro‐1,1′ : 4′,1″ : 4″,1‴‐quaterphenyl (11) were synthesized by Pd (0) catalyzed cross‐coupling reaction of 4‐chlorobenzeneboronic acid with 2,2′‐, 3,3′‐, and 4,4′‐bis (trifluoromethanesulfonyloxy)biphenyl respectively. 4,4‴‐Dichloro‐1,1′ : 2′,1″ : 2″,1‴‐quaterphenyl (9) and 4,4‴‐dichloro‐1,1′ : 3′,1″ : 3″,1‴‐quaterphenyl (10) were oligomerized by Ni(0) catalyzed homocoupling reaction to yield white and soluble oligophenylenes. © 1993 John Wiley & Sons, Inc.
Monomer‐isomerization radical polymerization of di‐tert‐butyl maleate and preparation of poly(fumaric acid) via pyrolysis
Authors: Otsu Takayuki , Shiraishi Kohei , Matsumoto Akikazu
Published: April 2003

Di‐tert‐butyl maleate (DtBM) did not polymerize with 2,2′‐azobis(isobutyronitrile) as a radical initiator, but DtBM easily homopolymerized via a monomer‐isomerization radical polymerization mechanism to give a high molecular weight polymer when morpholine was added into the polymerization system as an isomerization catalyst. The feature of the monomer‐isomerization polymerization of DtBM was investigated in detail. The polymer obtained was confirmed to consist of a poly(tert‐butoxycarbonylmethylene) structure similar to that from di‐tert‐butyl fumarate. Subsequent pyrolysis of the resulting polymer at 180°C is a useful route to synthesis of a high molecular weight poly(fumaric acid). © 1993 John Wiley & Sons, Inc.
Investigation of the free radical polymerization of styrene in the presence of several 1,1‐disubstituted ethylenes
Authors: Dais Virginia A. , Priddy D. B. , Bell Bruce , Sikkema Kevin D. , Smith Pat
Published: April 2003

A variety of 1,1‐disubstituted ethylenes, having an electron‐withdrawing (capto) and an electron‐donor (dative) substituent on the same carbon, were synthesized and added to styrene polymerizations. The dative substituents investigated were alkoxy or alkylcarbonate. After the addition of a polystyryl radical to a disubstituted ethylene, the resulting alkoxy or carbonate radicals could potentially fragment, resulting in chain termination and the formation of alkyl radicals. This process is called addition‐fragmentation chain transfer (AFCT). The polymers produced during this study were examined for evidence of copolymerization and AFCT. The relative stability of the radicals generated by the fragmentation process appears to be the predominant factor controlling the ratio of copolymerization versus AFCT. © 1993 John Wiley & Sons, Inc.
Effects of diamine monomer structure on the gas permeability of polyimides. I. Bridged diamines
Authors: Langsam Michael , Burgoyne William F.
Published: April 2003

Permeability measurements for oxygen and nitrogen were carried out on a series of structurally similar polyimides in order to define structure/permeability relationships. The polyimides were prepared from 5,5′‐[2,2,2‐trifluoro‐1‐(trifluoromethyl) ethylidene] bis‐1,3‐isobenzofuranedione (6FDA) and a variety of substituted methylene dianilines and benzidines. A correlation between the diamine monomer structure and polymer permeability was found, particularly with diamine monomer variations at the ortho positions of the diamine relative to the amino moiety. These correlations were semilogarithmic, relative to the summation of the substituent volumes. Direct correlations were observed between the measured properties of polymer density and interchaind‐spacings and the oxygen permeability value of each of these polyimides. In addition, we observed that the calculated values of fractional free volume were related to oxygen permeability in a manner which enabled us to identity a polar component in the effects of these ortho substituents. © 1993 John Wiley & Sons, Inc.
Nucleophilic substitution reactions of 1,4‐dichlorobenzene chromium tricarbonyl with mono‐ and diphenoxides
Authors: Percec Virgil , Okita Shigeru
Published: April 2003

The nucleophilic substitution reactions of 1,4‐dichlorobenzene chromium tricarbonyl (1) with the phenoxide anion were investigated. The substitution of the first chlorine was very fast and gave the mono‐substituted product in high yield. The substitution of the second chlorine group was significantly retarded by the presence of the phenoxy group incorporated during the first reaction and also due to the competing decomplexation reaction. The application of 1,4‐dichlorobenzene chromium tricarbonyl (1) to the synthesis of new monomers was demonstrated by the preparation of 2,2′‐bis[4‐(4‐chlorophenoxy)phenyl]propane (9). 2,2′‐Bis[4‐(4‐chlorophenoxyl)phenyl]propane (9) was synthesized by a nucleophilic substitution reaction of 4,4′‐isopropylidenediphenolate with 1,4‐dichlorobenzene chromium tricarbonyl (1) followed by decomplexation with I2. 2,2′‐Bis[4‐(4‐chlorophenoxy)‐phenyl]propane (9) was also synthesized via a three‐step reaction starting from the nucleophilic substitution reaction of 4,4′‐isopropylidenediphenol (7a) with 1‐chloro‐4‐nitrobenzene (10). 2,2′‐Bis[4‐(4‐chlorophenoxy)phenyl]propane (9) was polymerized by a Ni(0)‐catalyzed reaction to yield amorphous aromatic polyethers with number‐average molecular weights of up to 11,200 g/mol. © 1993 John Wiley & Sons, Inc.
Insoluble polystyrene‐bound quaternary onium salt catalysts for the synthesis of cyclic carbonates by the reaction of oxiranes with carbon dioxide
Authors: Nishikubo Tadatomi , Kameyama Atsushi , Yamashita Jun , Tomoi Masao , Fukuda Wakichi
Published: April 2003

The addition reaction of oxiranes (26a—e) with carbon dioxide (CO2) was performed using insoluble polystyrene beads containing pendant quaternary ammonium or phosphonium salts as catalysts under atmospheric pressure. The reaction of 26a—e with CO2 proceeded smoothly catalyzed by 1–2 mol % of the polymer‐supported quaternary onium salts to give the corresponding cyclic carbonates (27a—e) in high yields at 80–90°C. In this reaction system, the catalytic activity of the polymer‐supported quaternary onium salts was strongly affected by the following factors: degree of ring substitution (DRS) of the onium salt residues to the polymer, degree of crosslinking (DC) of the polystyrene beads, chain length of the alkylene spacer between the polymer back‐bone and the onium salt, hydrophobicity of the alkyl group on the onium salts, and kind of onium salts. That is, the polymer‐supported quaternary phosphonium salts with low DRS and DC and with long alkylene spacer chain were found to have higher catalytic activity than low molecualr weight quaternary onium salts. The above polymer‐supported catalysts can easily be separated at the end of a reaction by filtration and can be reused for at least seven runs. It was also found that the rate of reaction was proportional to the products of catalyst concentration and oxirane concentration. © 1993 John Wiley & Sons, Inc.
Radical polymerization of 3‐methylene‐5,5′‐dimethyl‐2‐pyrrolidinone: A cyclic analog of N‐substituted methacrylamide
Authors: Ueda Mitsuru , Honda Mutsumi , Sugiyama Jun‐ichi , Ito Hiroshi
Published: April 2003

3‐Methylene‐5,5′‐dimethyl‐2‐pyrrolidinone (α‐MDMP), a cyclic analog of N‐substituted methacrylamide, was synthesized and polymerized with α,α′‐azobis (isobutyronitrile) (AIBN) in solution. Poly(α‐MDMP) is only soluble in dimethyl sulfoxide (DMSO) at room temperature. Thermogravimetry of poly(α‐MDMP) showed 10% weight loss at 355°C in air and 400°C under nitrogen, respectively. The kinetics of α‐MDMP homopolymerization with AIBN was investigated in DMSO. The rate of polymerization (Rp) can be expressed by Rp = k[AIBN]0.49[α‐MDMP]1.0 and the overall activation energy has been calculated to be 73.2 kJ/mol. Monomer reactivity ratios in copolymerization of α‐MDMP (M2) with methyl methacrylate (M1) are r1 = 0.71 and r2 = 0.71, from which Q and e values of α‐MDMP are calculated as 0.75 and ‐0.43, respectively. © 1993 John Wiley & Sons, Inc.
Poly(N‐isopropylacrylamide). II. Effect of polymer concentration, temperature, and surfactant on the viscosity of aqueous solutions
Authors: Tam K. C. , Wu X. Y. , Pelton R. H.
Published: April 2003

The effects of polymer concentration, temperature, and surfactant on the rheological properties of poly(N‐isopropylacrylamide), poly NIPAM, were studied. Below 28°C the viscosity decreased with increasing temperature according to the Arrhenius expression. However, at 29°C the viscosity increased to a maximum value at 32°C, the lower critical solution temperature (LCST) for aqueous polyNIPAM. Higher temperatures gave a much lower viscosity. This unusual rheological behavior was explained by the phase behavior of the polymer. Sodium dodecyl sulfate (SDS) binding to polyNIPAM increased the cloud point temperature (CPT) and attenuated the unusual rheological behavior of polyNIPAM in water. © 1993 John Wiley & Sons, Inc.
Novel surface fixation technology of hydrogel based on photochemical method: Heparin‐immobilized hydrogelated surface
Authors: Nakayama Yasuhide , Matsuda Takehisa
Published: April 2003

This article reports a novel photoinduced surface process technology enabling simultaneous hydrogel formation and its surface fixation on polymeric substrates. The process consists of layering two different types of photoreactive coatings on a polymeric surface, an azidophenyl‐bearing polymer as an adhesive layer and cinnamoylated copolymer as a hydrogel layer, and subsequent UV irradiation. The photoreactive adhesive polymer coated on a substrate is poly(m‐azidostyrene), in which photoreaction of phenyl azido groups is responsible for the chemical bonding between the substrate and hydrogel. N,N‐dimethylacrylamide copolymer containing cinnamate moieties in their side chains, which undergo photocrosslinking via intermolecular dimerization, was applied as an overcoat on the adhesive layer. UV irradiation resulted in the formation of hydrogel chemically bonded onto the substrate. This was confirmed by ESCA measurements. A heparin‐immobilized hydrogelated surface with controlled release characteristics was demonstrated. © 1993 John Wiley & Sons, Inc.
Criteria for living systems with a special emphasis on living cationic polymerization of alkenes
Authors: Matyjaszewski Krzysztof
Published: April 2003

A number of new living systems have been reported in recent years. Classic anionic polymerization of nonpolar monomers allows the synthesis of well‐defined high molecular weight polymers (DP > 1000), block copolymers, chains with perfect terminal functionalities and behaves as a true living system. Some new systems abuse the term “living polymerization.” A relatively modest criterion for living systems is proposed “3 X 10,000,” i.e., kp/kt > 104 mol‐1 L, kp/ktr > 104, 1/kt/tr > 104 s (translated to < 10% of chains deactivated at t ≈ 1000 s), which is related to a typical limit of the polymeric chain dimensions (DP ≈ 100) and standard synthetic manipulations (≈ 15 min). New living cationic systems are discussed in detail with special emphasis on exchange phenomena. © 1993 John Wiley & Sons, Inc.
Thermotropic copolyesters of a series of aromatic diols with phenylterephthalic acid and 4,4′‐oxybisbenzoic acid
Authors: Garay Raul O. , Bhowmik Pradip K. , Lenz Robert W.
Published: April 2003

Wholly aromatic, liquid crystalline, main chain copolyesters derived from various linearly substituted aromatic diols with mixtures of 2‐phenylterephthalic acid and a nonlinear aromatic dicarboxylic acid, 4,4′‐oxybisbenzoic acid, were prepared by acidolysis condensation polymerization reactions and characterized for their liquid crystalline properties. The formation of a liquid crystalline phase at elevated temperatures was not prevented by the introduction of up to 50 mol % of the nonlinear diacid in the copolymers, and all of those copolyesters exhibited nematic liquid crystalline phases. Furthermore, the inclusion of a nonlinear monomer was not as effective as was the presence of a phenyl substituent in decreasing the melting transition of these copolymers. All of the copolymers had high glass transition temperatures and high thermal stabilities. © 1993 John Wiley & Sons, Inc.
Polymerization of methyl methacrylate using isatoic anhydride–bromine donor–acceptor complex as the photoinitiator
Authors: Som Pranab Kumar , Banerjee Amar Nath
Published: April 2003

Isatoic anhydride (IA) alone did not initiate photopolymerization of methyl metacrylate (MMA) at 40°C when exposed to visible light for about 180 min. But IA, when used in combination with bromine (Br2) as the initiator, initiated the photopolymerization of MMA readily under the same conditions. This behavior was explained by the formation of a donor‐acceptor type of complex between IA and Br2 in the presence of MMA. The polymerization was found to proceed via a free radical mechanism and the radical generation process was considered to follow an initial complexation reaction between the initiator components and monomer. The complex initiator showed nonideal kinetics for the present system (initiator exponent < 0.5) and was analyzed. The monomer exponents varied from 0.83 to 1.15 normally depending on the nature of solvent used. Initiator‐dependent chain termination was significant as well as the bimolecular mode of chain termination. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of aromatic polyesters with dicyanovinyl substituents
Authors: Kawatsuki Nobuhiro , Dörr Michael , Schmidt Hans‐Werner
Published: April 2003

The synthesis, characterization, and structure—property relations of aromatic polyesters with dicyanovinyl substituents is presented. Two comparable series of polyesters based on 3,4‐dihydroxybenzylidenemalononitrile and 3,4‐dihydroxy‐5‐methoxybenzylidenemalononitrile were prepared. As aromatic diacid components, terephthalic acid, phenylterephthalic acid, isophthalic acid, and 2‐phenylisophthalic acid were used. The polyesters were prepared by solution polycondensation. GPC investigations revealed the existence of substantial amounts of defined cyclic products. These cycles could be isolated by preparative GPC. The polyesters are soluble in common low boiling organic solvents, particularly the phenyl‐substituted ones. The polyesters are amorphous and have glass transition temperatures between 140 and 170°C. The absorption maxima are in the 306–322 nm range. The cut‐off wavelength is between 400 and 428 nm. The polyesters with methoxy substitutent have generally the absorptions at longer wavelength. The refractive index of thin films of these polyesters were between 1.61 and 1.63 at 632.8 nm. © 1993 John Wiley & Sons, Inc.
Cationic polymerization with p‐substituted benzyl p‐hydroxyphenyl methyl sulfonium salts: Effect of substituents and mechanistic aspects of initiation reaction
Authors: Hamazu Fumio , Akashi Sumio , Koizumi Tatsuya , Takata Toshikazu , Endo Takeshi
Published: April 2003

Various p‐substituted benzyl p‐hydroxyphenyl methyl sulfonium salts (2) were synthesized and their initiator activities were evaluated in bulk polymerization of glycidyl phenyl ether (PGE). The order of the activity was found to be 2b (X = CH3) > 2a (X = H) ≈ 2c (X = Cl) > 2d (X = NO2), indicating that the introduction of an electron‐donating group enhanced the activity. In Hammett's plots, the logarithm of the ratio of the polymerization rates (log kx/kH) was correlated with σ+ρ better than with σp and a negative ρ+ value (‐1.18) was obtained. Reaction of 2a with benzyl mercaptan mainly gave dibenzyl sulfide and p‐hydroxyphenyl methyl sulfide. The obtained results seemed to demonstrate that the OH group of the aryl group yielded no proton as initiator for the polymerization, whereas the benzyl group caused the polymerization, which was initiated by the corresponding benzyl cation formed by CS bond cleavage. © 1993 John Wiley & Sons, Inc.
Photopolymerization kinetics of oligo(ethylene oxide) and oligo(methylene) oxide dimethacrylates
Authors: Cook Wayne D.
Published: April 2003

The influence of temperature on the photopolymerization kinetics of oligo(methylene) oxide and oligo(ethylene oxide) dimethacrylate series has been investigated by isothermal DSC. The DSC curves showed a rapid rise in rate due to the Trommsdorff effect, and then a slow decline. A shoulder, apparent on many of the DSC curves at low conversions, became more prominent when the cure temperature was lowered. The kinetics were relatively insensitive to the dimethacrylate structure in the early stages of the reaction, but became more dependent as the reaction proceeded. A previously derived mathematical model, which allows for the influence of diffusion on the rate constants, was used to predict the kinetics. The dependence of the maximum rate and conversion on the curing temperature were adequately described by the model. The experimentally observed shoulder on the rate curve was also predicated as was the evolution of the rate/time curves with curing temperature. Similar predictions were found when a nonsteady state version of the model was used. The radiation intensity exponent varied from 0.3 to 0.6 possibly due to chain‐length effects and pseudo‐first order termination, respectively. The final degree of conversion increased with curing temperature (Tcure) and was correlated with the flexibility of the dimethacrylate. These data were fitted to a theoretical expression relating the final conversion to the resin Tg and to the Tcure. © 1993 John Wiley & Sons, Inc.
Kinetics and mechanism of electropolymerization of m‐aminophenol
Authors: Sankarapapavinasam S.
Published: April 2003

The kinetics and mechanism of electropolymerization of m‐aminophenol (mAP) has been investigated in acetonitrile (AN) and methanol (MeOH) media. The rate of polymerization is found to be proportional to [mAP] (current)0.5 at moderate current densities; at higher current densities, the rate of polymerization is independent of current density. A suitable mechanism has been proposed and the rate equation is derived to explain the observed factors. Rotating disc voltametry revealed that at low current densities, the rate of polymerization is charge controlled, while at high current densities it is diffusion controlled. The physicochemical characteristics of AN make it a better solvent than MeOH. © 1993 John Wiley & Sons, Inc.
Studies on the thermotropic liquid‐crystalline polymer. IX. Synthesis and properties of crosslinkable copoly(amide‐ester)s containing conjugated double bonds
Authors: Li Chen‐Hui , Cheng Hsin‐Pei , Chang Teh‐Chou , Chu Tsu‐Yao
Published: April 2003

Four series of copoly(amide‐ester)s containing conjugated double bonds were prepared by using direct polycondensation in the presence of diphenylchlorophosphate (DPCP) and pyridine. Series I–III were prepared from para, meta‐aminophenol, or their mixture with p‐phenylene bis(acrylic acid) (PPBA), p‐carboxylic cinnamic acid (PCCA), and stilbenedicarboxylic acid (SDBA), respectively. Series IV was prepared from a mixture of aminophenols [2‐methyl 4‐aminophenol (MePAP) and m‐aminophenol (MAP)] with a mixture of diacids (PPBA and SDBA). Thermotropic liquid‐crystalline behavior of these polymers was studied by differential scanning calorimetry (DSC), and optical polarizing microscopy equipped with a heating stage. Series I, series II, and P40–P100 of series IV could undergo crosslinking reaction by heating. However, series III could undergo crosslinking reaction only by photoirradiation upon heating. After crosslinking reaction occurred, the properties of these polymers were also examined by DSC, TGA, WAXD, and IR. The synthesized polymers could be crosslinked in the liquid‐crystalline phase with retention of the order in the final crosslinked solid. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new polyesters having tetrahydrofuran rings in their main chains
Authors: Okada Masahiko , Aoi Keigo , Mizuno Wataru , Ito Shinji
Published: April 2003

New polyesters 6a–6c consisting of 2,4‐linked tetrahydrofuran rings were synthesized by bulk polycondensation of methyl trans‐ and cis‐4‐hydroxytetrahydrofuran‐2‐carboxylates (5a and 5b) and a stereoisomeric mixture of methyl 4‐hydroxy‐5‐methyltetrahydrofuran‐2‐carboxylate (5c) at high temperature. These monomers were prepared from methyl glycolate or methyl lactate and diethyl maleate through a four‐step reaction sequence. The polycondensation was carried out without solvent at different temperatures ranging from 150 to 220°C. Titanium isopropoxide was most effective among the catalysts examined, giving polyesters with number‐average molecular weights up to 2 × 104. Polyester 6a consisting of trans‐2,4‐linked tetrahydrofuran rings was soluble in trifluoroacetic acid and a mixed solvent of chloroform and methanol (10/1, v/v). Polyester 6b composed of cis‐2,4‐linked tetrahydrofuran rings was soluble in dimethyl sulfoxide and dimethylformamide in addition to the two solvents for 6a. Polyester 6c with 5‐methyl‐substituted tetrahydrofuran rings was composed of a mixture of stereoisomeric units and thus was soluble in a variety of solvents including chloroform, tetrahydrofuran, acetonitrile, dimethyl sulfoxide, and dimethylformamide. The glass transition temperatures of 6a, 6b, and 6c determined by DSC were 109, 88, and 66°C. These polyesters were found to be very slowly hydrolyzed in a neutral phosphate buffer solution at ambient temperature. © 1993 John Wiley & Sons, Inc.
Cationic ring‐opening polymerization of 2‐isopropenyl‐4‐methylene‐1,3‐dioxolane
Authors: Park Jaekyeung , Yokozawa Tsutomu , Endo Takeshi
Published: April 2003

Preparation and cationic ring‐opening polymerization of 2‐isopropenyl‐4‐methylene‐1,3‐dioxolane (VI) was performed. Unsaturated cyclic acetal VI was prepared by dehydrochlorination of 2‐isopropenyl‐4‐chloromethyl‐1,3‐dioxolane, which was easily obtained from methacrolein and epichlorohydrin, with sodium methoxide at ambient temperature. The cationic polymerization of VI with BF3OEt2 or CF3SO3H at −78°C afforded only crosslinked polymers, whereas the polymerization by CH3SO3H gave soluble poly(keto‐ether) which consisted of units VII containing an isopropenyl group in the side chain and units VIII containing a carbon‐carbon double bond in the main chain. The reaction of VI with ethanethiol in the presence of protic acid was also carried out as a model reaction of the polymerization. The reaction initiated by the addition of proton to the 4‐methylene group of VI, and quantitative ring‐opening isomerization followed by the addition of ethanethiol afforded acyclic ketone IX and X. On the basis of the model reaction, the polymerization mechanism is also discussed. © 1993 John Wiley & Sons, Inc.
A study of condensation of trithiane hexaoxide with formaldehyde
Authors: Jeczalik Jerzy
Published: April 2003

The title reaction catalyzed by NaOH in aqueous media was studied. The oligomeric products formed are characterized in terms of their yield, structure, etc. The effects of reaction parameters and media are also discussed. The reaction mechanism is proposed. © 1993 John Wiley & Sons, Inc.
Synthesis and photoconductivity study of phthalocyanine polymers. II. PVK‐co‐CuPc (COOH)3
Authors: Chen Hongzheng , Wang Mang , Feng Linxian , Yang Shilin
Published: April 2003

Cu‐phthalocyanine diimide (Cu‐diPc) was synthesized from a mixture of phthalic anhydride and pyromellitic dianhydride. By the hydrolysis of Cu‐diPc, Cu‐4,4′,5,5′‐tetracarboxy‐phthalocyanine (Cu‐taPc) was obtained. A novel polymer of polyvinylcarbazole‐bonded CuPc(COOH)3 (I) was synthesized by the Friedel–Crafts reaction of polyvinylcarbazole (PVK) with Cu‐phthalocyanine‐4,4′,5,5′‐tetraacid chloride. Polymer (I) contains ca. 5 mol % CuPc(COOH)3 rings, which are covalently bonded to PVK. Polymer (I) shows good photoconductivity, which is much better than that of the corresponding phthalocyanine monomers. The factors that influence the photoconductivity, such as the thickness of IFL, and the types and proportion of CTM, were also studied. © 1993 John Wiley & Sons, Inc.
Preparation and characterization of Co‐ and homopoly(phenylene etherimideketone)s
Authors: Parthiban A. , Sundaram N.
Published: April 2003

Poly(phenylene etherimdeketone)s were prepared by Friedel–Crafts acylation type polymerization using P2O5CH3SO3H 1 : 10 (w/v) mixtures. Most of these polymers were semicrystalline. TgS ranged from 203 to 236°C and crystalline melt temperatures were observed between 306 and 435°C. All of the polymers exhibited high thermal stability and good solvent resistance. © 1993 John Wiley & Sons, Inc.
The conformational stability of tactic poly(2‐hydroxyethyl methacrylate) in aqueous salt solutions
Authors: Kang Seung Koo , Jhon Mu Shik
Published: April 2003

The conformational stability of tactic poly(2‐hydroxyethyl methacrylate) (PHEMA) in aqueous salt solutions was investigated by measurements of swelling, surface‐free energy, and differential scanning calorimetry, as this polymer in water is sensitive in various electrolytes. In the case of inorganic salts, the major role for the salt effect is played by the anions, and the exposure of hydrophobic components at the PHEMA surface can be correlated with the increase of the degree of swelling. The influence of cations is considerably weaker. In the case of organic salts, tetraalkylammonium halides cause the chain extension more effectively with the increase of alkyl chain length in the cations. This result indicates that the breakdown of the hydrophobic parts in PHEMA provides an important clue on conformational stability. The amount of water molecules bound with the hydrophilic sites of tactic‐PHEMA mainly depends on the chain extension and the hydration of cations. Since the sites in tactic‐PHEMA influenced by the cation and the anion are different, their effects cause the conformational transition at a specific range of salt concentration. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of polysiloxane–polyamide block and graft copolymers
Authors: Mougin N. , Rempp P. , Gnanou Y.
Published: April 2003

The synthesis of copolymers constituted of a central polydimethylsiloxane (PDMS) block flanked by two polyamide (PA) sequences is described. α, ω‐diacyllactam PDMS, when used as macroinitiator of lactam polymerization, gives rise to the expected triblock copolymer. Likewise, PDMS‐g‐PA graft copolymers are obtained from acyllactam containing polysiloxanes. NaAlH2(OCH2CH2OMe)2 turns out to be the best suited activating agent for the polymerization of ϵ‐caprolactam, in the experimental conditions required for the synthesis of polysiloxane–polyamide copolymers. The nucleophilic species formed by reaction of NaAlH2(OCH2CH2OMe)2 with ϵ‐caprolactam—2‐[bis(methoxyethoxy) aluminumoxy]‐1‐azacycloheptane sodium—is indeed nucleophilic enough to bring about the growth of PA chains and mild enough to stay inert towards PDMS. © 1993 John Wiley & Sons, Inc.
Bond interchange reactions in functionalized triglyceride oil/poly(ethylene terephthalate) compositions
Authors: Barrett L. W. , Ferguson G. S. , Sperling L. H.
Published: April 2003

Naturally functionalized triglyceride oils are renewable resources which contain reactive chemical groups, hydroxyl in the case of castor oil, and epoxide in the case of vernonia oil. In this article, the reaction of these groups, and the ester linkages between the glycerol and acid residue portions of the oil molecule with poly(ethylene terephthalate) (PET) is investigated through a variety of means. Multiple reactions are possible in the triglyceride–PET system, some of which form a copolymer that increases miscibility, and if allowed to continue, forms a completely random copolymer mixture. Among the numerous reactions possible, PET–ester exchange with the hydroxyl or epoxide functionality of the triglyceride oils is found to be the most significant, and the effects of these and other reactions are observed and structural implications discussed. © 1993 John Wiley & Sons, Inc.
A new class of aromatic polyetheraroylhydrazides. I. Synthesis and chemical–physical characterization
Authors: Lanzetta N. , Malinconico M. , Martuscelli E. , Volpe M. G.
Published: April 2003

A series of new aromatic polyetheraroylhydrazides incorporating 4‐oxybenzoyl units has been synthesized, whose general formula was [CONHNHCOOO–(CH2)xOphenyl O‐CONHNHCOO]n with x values in the range of 2 to 12. The increasing number of methylene units in the backbone gave rise to polymers which melted before the hydrazidic linkage underwent thermal cyclation to oxadiazole. Moreover, many polymers showed multiple endotherms on melting. X‐ray diffraction studies confirmed a crystalline organization of polyhydrazides for methylene units above 4. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of terminally carboxyl ethylene glycol monomethyl ethers‐substituted side‐chain liquid‐crystalline polysiloxanes
Authors: Chien Guo‐Ping Chang , Kuo Jen‐Feng , Chen Chuh‐Yung
Published: April 2003

Alkene monomers containing phenyl or biphenyl carboxylate benzoate ester based on a mesogenic group of varied lengths of carboxyl oligo (ethanediol) monomethyl ethers as the terminal were synthesized. They were grafted onto poly(methyl‐hydrosiloxane) by the platinum‐catalyzed hydrosilylation process. The thermal transition temperatures and mesophase textures of monomers and of polymers were characterized by using differential scanning calorimetry (DSC), x‐ray diffraction, and polarized optical microscopy with a hot stage. The factors governing mesophase textures and thermal transition temperatures are discussed. © 1993 John Wiley & Sons, Inc.
The influence of microstructure and monomer properties on the erosion mechanism of a class of polyanhydrides
Authors: Göpferich Achim , Langer Robert
Published: April 2003

The erosion of three different polyanhydrides consisting of sebacic acid (SA) and 1,3‐bis(p‐carboxyphenoxy)propane (CPP) was investigated. Melt cast polymer matrices were prepared from the homopolymer p(SA) and two copolymers, p(CPP‐SA) 20 : 80 and p(CPP‐SA) 50 : 50. Particular attention was paid to the influence of the polymer matrix microstructure and of the monomers on erosion. Using polarized light microscopy we found that p(SA) and p(CPP‐SA) 20 : 80 matrices consist of spherulites. SEM investigations showed that their crystalline parts are more resistant to erosion than their amorphous areas. The matrices erode into highly porous devices, whose porosity is detectable by mercury porosimetry. Using wide‐angle x‐ray diffractometry we found that monomers crystallize inside the pores. DSC investigations showed a maximum of crystallized SA after 2–6 days and a continuous increase of CPP, which stays in the devices for weeks. We conclude that the microstructure and the monomer properties are the two main factors which determine the erosion of these polymers. The obtained data on changes in porosity, crystallinity, polymer matrix thickness, erosion front velocities, crystalline monomer content, and monomer release provides the basis for quantitatively describing the erosion process. © 1993 John Wiley & Sons, Inc.
Grafting of polyesters from carbon whisker surface: Copolymerization of epoxides with cyclic acid anhydrides initiated by COOK groups introduced onto the surface
Authors: Tsubokawa Norio , Yoshihara Toshio
Published: April 2003

To modify the surface of carbon whisker (vapor‐grown carbon fiber) the grafting of polyesters by use of potassium carboxylate (COOK) groups introduced onto the surface was investigated. The introduction of COOK groups onto the carbon whisker was achieved by the treatment of surface carboxyl groups with KOH aqueous solution. Untreated carbon whisker has no ability to initiate the polymerization. It was found that the anionic ring‐opening alternating copolymerization of epoxides with cyclic acid anhydrides is successfully initiated by COOK groups on the carbon whisker surface. The corresponding polyester was grafted onto the surface based on the propagation of polymer from COOK groups introduced on the surface. The percentage of grafting of the polyester from styrene oxide and phthalic anhydride was determined to be 91.0%. The polymerization rate and percentage of grafting increased upon addition of crown ether. Furthermore, the rate of polymerization increased with increasing the dielectric constant of the solvent, but the percentage of grafting decreased. Polyester‐grafted carbon whisker was found to give a stable colloidal dispersion in a good solvent for the grafted polymer. © 1993 John Wiley & Sons, Inc.
Highly crosslinked micron‐range polymer microspheres by dispersion polymerization of divinylbenzene
Authors: Li Kai , Stöver Harald D. H.
Published: April 2003

Narrow disperse microparticles are formed by dispersion polymerization of commercial divinylbenzene in acetonitrile or ethanol solution in the presence of 2,2′‐azobis(2‐methylpropionitrile) initiator and polyvinylpyrrolidone stabilizer. The particles have average diameters between 1 and 9 μm depending on monomer concentration, solvent, and temperature. While the smaller particles are relatively smooth, surface texture increases with diameter to give popcorn shapes at 9 μm diameter. High crosslinker concentration is shown to be essential for particle formation. © 1993 John Wiley & Sons, Inc.
Interpenetrating polymer networks of poly(dimethyl siloxane–urethane) and poly(methyl methacrylate)
Authors: Zhou Peiguang , Frisch H. L. , Rogovina L. , Makarova L. , Zhdanov A. , Sergeienko N.
Published: April 2003

Simultaneous IPNs of poly(dimethyl siloxane‐urethane) (PDMSU)/poly(methyl methacrylate) (PMMA) and related isomers have been prepared by using new oligomers of bis(β‐hydroxyethoxymethyl)poly(dimethyl siloxane)s (PDMS diols) and new crosslinkers biuret triisocyanate (BTI) and tris(β‐hydroxylethoxymethyl dimethylsiloxy) phenylsilane (Si‐triol). Their phase morphology have been characterized by DSC and SEM. The SEM phase domain size is decreased by increasing crosslink density of the PDMSU network. A single phase IPN of PDMSU/PMMA can be made at an Mc = 1000 and 80 wt % of PDMSU. All of the pseudo‐ or semi‐IPNs and blends of PDMSU and PMMA were phase separated with phase domain sizes ranging from 0.2 to several micrometers. The full IPNs of PDMSU/PMMA have better thermal resistance compared to the blends of linear PDMSU and linear PMMA. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of polyimide–clay hybrid
Authors: Yano Kazuhisa , Usuki Arimitsu , Okada Akane , Kurauchi Toshio , Kamigaito Osami
Published: April 2003

A polyimide hybrid with montmorillonite clay mineral has been synthesized from a dimethylacetamide (DMAC) solution of poly(amic acid) and a DMAC dispersion of montmorillonite intercalated with an ammonium salt of dodecylamine. Montmorillonite consists of stacked silicate sheets about 2000 Å in length, 10 Å in thickness. In this hybrid, montmorillonite is dispersed homogeneously into the polyimide matrix and oriented parallel to the film surface. Thanks to this special structure, this hybrid showed excellent gas barrier properties. Only 2 wt % addition of montmorillonite brought permeability coefficients of various gases to values less than half of those of ordinary polyimide. Furthermore, this hybrid had low thermal expansion coefficient. © 1993 John Wiley & Sons, Inc.