bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical modification of the reducing chain end in dextrans and trimethylsilylation of its hydroxyl groups
Authors: Hashimoto Kazuhiko , Imanishi Shin‐Ichiro , Okada Masahiko , Sumitomo Hiroshi
Published: April 2003

The reducing ends of dextrans, of which number‐average molecular weights were 3600 and 16000, were almost quantitatively converted to lactone, amine, and acyllactam groups, successively, by iodine oxidation followed by lactonization, aminolysis with 1,4‐diaminobutane, and finally reaction with terephthaloylbis (ϵ‐caprolactam). Hydroxyl groups in dextrans were also trimethylsilylated for protection with a mixture of 1,1,1,3,3,3‐hexamethyldisilazane and trimethylchlorosilane. In advance of every run, the adequate reaction conditions were search by using D‐maltose as a low molecular weight model compound for dextrans.
Synthesis and polymerization of racemic and optically active substituted β‐propiolactones. VI. α‐Phenyl β‐propiolactone
Authors: Hmamouchi Mohammed , Prud'Homme Robert E.
Published: April 2003

The synthesis and optical resolution of α‐phenyl β‐amino‐ethylpropionate led to the preparation of optically active α‐phenyl β‐propiolactones (PhPL) of different optical purities. The enantiomeric excess of PhPL was determined using 200 MHz 1H‐NMR spectroscopy, after complexation with tris[3‐(trifluoromethyl hydroxymethylene)‐d‐camphorato]europium III. It was then polymerized, in bulk and in solution, using a potassium acetate/crown ether complex as initiator. The optically active poly(PhPL)s thus obtained are insoluble in most organic solvents, whereas atactic poly(PhPL)s are soluble in CCl4, CHCl3, and dichloroethane. Several differences are observed between the physical properties of optically active and atactic poly(PhPL)s. However, atactic poly(PhPL)s are semi‐crystalline polymers, similar to poly(α‐disubstituted β‐propiolactone)s, but in contrast with poly(α‐methyl β‐propiolactone). Melting (Tf) and glass transition temperatures, as well as enthalpy of fusion (ΔH), vary with the optical purity of the polymers. For example, atactic poly(PhPL) exhibits a Tf = 94°C and ΔH = 9 J/g as compared to Tf = 119°C and ΔH = 37 J/g for a poly(PhPL) having an enatiomeric excess of 50%.
Synthesis and characterization of novel polyarylates from 2,5‐bis(4‐hydroxyphenyl)‐3,4‐diphenylfuran and aromatic diacid chlorides
Authors: Jeong Hwa‐Jin , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

New tetraphenylated heterocyclic diol, 2,5‐bis(4‐hydroxyphenyl)‐3,4‐diphenylfuran, was synthesized by the oxidative coupling of 4‐methoxydeoxybenzoin as a starting material, followed by simultaneous cyclodehydration and demethylation. Tetraphenylfuran‐containing polyarylates with inherent viscosities of 0.2–0.7 dL/g were prepared from various diacid chlorides by both solution polycondensation and phase transfer catalyzed two‐phase polymerization methods. All the polymers were easily soluble in dichloromethane, o‐chlorophenol, 1,4‐dioxane, pyridine, and N‐methyl‐2‐pyrrolidone and showed semicrystalline patterns as evidenced by the X‐ray diffraction studies. These polyarylates have glass transition temperatures in the range of 222–236°C and 10% weight loss was observed above 430°C in both air and nitrogen.
Terminal anhydride functionalization of polystyrene
Authors: Park Inha , Barlow J. W. , Paul D. R.
Published: April 2003

Polystyrene chains with terminal anhydride groups were synthesized by direct chain transfer reaction between poly(styryl) lithium and trimellitic anhydride chloride (TMAC) and by the alkoxy‐de‐halogenation reaction between TMAC and hydroxy terminated polystyrene. Pyridine was used as a catalyst for these nucleophilic substitution reactions. For the direct reaction a poly(styryl) lithium with M̄n ∼ 1000 (a low MW was used for characterization purposes) was prepared in an argon purged reactor and then introduced into an excess of trimellitic anhydride chloride. Due to the nature of our reaction system, the molecular weight distributions obtained were broader than those possible using more stringent high vacuum techniques. Hydroxy terminated polystyrenes with M̄n = 3,000 and 13,000 obtained elsewhere were used for the indirect addition of terminal anhydride groups. 1H‐NMR spectroscopy, gel permeation chromatography (GPC), and FTIR spectroscopy were used to characterize the reaction products. A maximum yield of 61% for the direct functionalization route and 85% for the indirect functionalization route using hydroxyl terminated polystyrene were achieved. The higher yield of the indirect method seems to be the result of the relatively mild reactivity of the hydroxyl group.
Preparation and photochemistry of macromolecular bound ruthenium(II) complexes in aqueous solutions
Authors: Ramaraj R. , Natarajan P.
Published: April 2003

Ruthenium(II) polypyridyl complexes with macromolecular ligands poly(methylolacrylamide‐co‐vinylpyridine) and poly (acrylamide‐co‐vinylpyridine) have been synthesized. The macromolecular ruthenium (II) complexes which are soluble in water have been characterized and their absorption and emission properties have been studied in aqueous solution. Photolysis of the complex in aqueous solution leads to photoaquation reactions with release of coordinated pyridines of the polymer. In the case of monomeric complex, cis‐[Ru(bpy)2(py)2]Cl2, photolysis in water in presence of Cl− ions produces only the substitution of the pyridine by water whereas in the polymeric complexes, [Ru(bpy)2(MAAM‐co‐VP)2]Cl2 photolysis in the presence of chloride produces [Ru(bpy)2(MAAM‐co‐VP)Cl]Cl and [Ru(bpy)2(AM‐co‐VP)Cl]Cl, respectively. Quantum yields for the photosubstitution reactions have been determined and mechanistic details are outlined.
Synthesis and characterization of phosphorylated polystyrene derivatives for use in chromatography: DNA‐like and phospholipid‐like behavior
Authors: Letourneur D. , Douzon C. , Jozefowicz M.
Published: April 2003

New functional crosslinked polystyrene derivatives have been synthesized. These polymers are substituted with chemical groups such as phosphate, purine, and pyrimidine bases, choline, serine, and nucleotides in order to mimic DNA and phospholipids. For this purpose, hydroxylated polystyrene beads were prepared, where monomer units were substituted via spacers. Then, phosphomonoester groups at various substitution ratios were grafted onto hydroxylated resins by using a phosphorus oxychloride method. Nucleosides and nucleic acid bases derivatives were coupled with dicyclohexylcarbodiimide on phosphorylated polymers whereas nucleotides, phosphorylcholine, and phosphorylserine were grafted on to hydroxylated polystyrene. The synthesis and characterization of these DNA‐like and phospholipid‐like polystyrene resins are described here extensively.
Substituted rod‐like aromatic polyamides: Synthesis and structure‐property relations
Authors: Hatke Wilfried , Schmidt Hans‐Werner , Heitz Walter
Published: April 2003

The synthesis and structure‐property relations of a number of novel substituted paralinked aromatic homopolyamides and copolyamides are described. The synthesis of the polyamides was carried out by polycondensation of activated N,N'‐bis‐(trimethylsilyl) substitued aromatic diamines and aromatic diacid chlorides. In order to improve the solubility and to lower melting temperatures, novel arylsubstituted terephthalic acids moieties, such as p‐terphenyl‐2,5‐dicarboxylic acid and o‐terphenyl‐2,5‐dicarboxylic acid, were used in combination with substituted and noncoplanar diamines. Depending on the chemical structure, polyamides with very high solubility (up to 40% w/w) in polar aprotic solvents such as N,N‐dimethylacetamide without the addition of inorganic salts were obtained. Lyotropic liquid crystalline behavior was observed for the first time in polyamides which contain noncoplanar biphenylene units.
Side‐chain liquid crystalline polymers with silphenylene‐siloxane main chains. I. Synthesis of silphenylene‐siloxane polymers containing hydrosilane units
Authors: Itoh Maki , Lenz Robert W.
Published: April 2003

Siophenylene‐siloxane polymers with repeating units containing hydrosilane, SiH, groups were synthesized for use as backbone polymers in side‐chain liquid crystalline polymers. The polymerization of 1,4‐bis (hydroxydimethylsilyl) benzene with a bis (Pyrrolidinyl) silane monomer formed a crosslinked polymer during the course of the reaction, while the use of a bis (ureido) silane monomer gave a polymer which crosslinked on storage after preparation. However, a soluble polymer could be prepared successfully by using a dichlorosilane as the comonomer. Polymers containing two and three SiH groups in each unit were prepared by the last method. All Soluble polymers were characterized by gel permeation chromatography (GPC), infrared spectroscopy (IR) multinuclear NMR spectroscopy, and differential scanning calorimetry (DSC).
Side‐chain liquid crystalline polymers with silphenylene‐siloxane main chains. II. Preparation and characterization of polymers containing biphenyl mesogens
Authors: Itoh Maki , Lenz Robert W.
Published: April 2003

Side‐chain liquid crystalline polymers with poly(silphenylene‐siloxane) backbones and 4,4′‐biphenyl‐containing pendant mesogenic groups have been prepared and characterized. Polymers with spacers having only three methylene groups were not liquid crystalline, LC, but those with spacers having eight methylene groups or more and a long terminal substituent were LC as indicated by an isotropization peak on the shoulder of the melting peak in the DSC thermogram and the appearance of a Schlieren texture on examination by polarized light microscopy. However, the LC behavior could not be confirmed by wide‐angle X‐ray diffraction, WAXD, because the crystalline pattern apparently remained up to the isotropization temperature, presumably because the melting transition and isotropization are too close. In contrast, polymethylsiloxanes with the same mesogenic side‐chains revealed the presence of well‐defined smectic phases by WAXD as well as by polarized light microscopy.
Coordination copolymerization of tetrahydrofuran and oxepane with oxetanes and epoxides
Authors: Vandenberg E. J. , Mullis J. C.
Published: April 2003

The chelate catalyst, as typified by the Et3Al‐0.5 H2O‐0.5 acetylacetone product, usually prepared with Et2O or tetrahydrofuran (THF) present, has all the known characteristics of a coordination catalyst for polymerizing epoxides and uniquely for oxetanes. We have found that the chelate catalyst gives fairly good copolymerization of THF (54% in monomer charge) with 3‐(trimethylsilyloxy) oxetane which, after hydrolysis, is a water‐soluble, moderate molecular weight copolymer of THF (36%) with 3‐hydroxyoxetane (HO). This apparent coordination copolymerization of THF has been extended to trimethylene oxide (TMO), 3,3‐bis(trimethylsilyoxymethyl) oxetane, 3,3‐bis(chloromethyl)oxetane (BCMO),trans‐2,3‐epoxybutane (TBO), and propylene oxide, listed in order of decreasing copolymerizability with THF. Presumably, this is the first known coordination copolymerization of THF which hitherto has only been polymerized with cationic catalysts. Oxepane also copolymerizes coordinately with TMO and BCMO, but less readily than THF, with the chelate catalyst. TBO polymerizes slowly with the chelate catalyst to form stereoregular polymer which can be separated into an acetone‐insoluble, highly stereoregular fraction and an acetone‐soluble, somewhat less stereoregular fraction. The soluble fraction can be eliminated by using 1.0 acetyl acetone per Al in the catalyst or by adding a small amount of a very strong base (0.09 quinuclidine per Al). The copolymerization of TBO with THF (39%) gives insoluble stereoregular homopolymer and soluble copolymer containing about 23% THF, reflecting the varied steric hindrance of the sites.

Some anomalous results appear to be related to the mechanism: (1) steric and electronic factors of the monomers and of the polymerization site. For example, the fourth coordination position of Al is needed to achieve homopolymerization of BCMO and TMO‐THF copolymerization. (2) The aggregation state of the catalyst, since a nonpolar diluent as toluene is unfavorable for coordination copolymerization of THF. (3) The greater ring strain of epoxides causes a greater ease of polymerization, compared to oxetanes. Thus, Et2O often present in the chelate catalyst lowers the molecular weight of the polymer considerably with oxetanes compared to epoxides where Et2O has little or no effect.
Cationic polymerization of styrenes by activated covalent species. Direct 1H‐NMR observation of complexes of 1‐phenylethyl acetates with lewis acids
Authors: Matyjaszewski Krzysztof , Lin Chih‐Hwa
Published: April 2003

Complexes of boron trichloride, boron tribromide, and ethylaluminumdichloride with various acetates were directly observed by 1H‐NMR. Complexes of secondary and tertiary acetates which model macromolecular active species in polymerization of styrene and isobutene are stable at −75°C, but decompose at temperatures above −30°C to yield corresponding chlorides or bromides. The stability of complexes depends on the Lewis acid, the alkyl group in the ester, and the structure of acetate. Rates of the bimolecular exchange of complexes with excess acetate were calculated from dynamic NMR to be kex = 2 × 101 L mol−1 s−1 (−65°C) and kex = 5 × 104 L mol−1 s−1 (−75°C) for 1‐phenylethyl acetate with BCl3 and EtAlCl2, respectively.
Studies on the thermotropic liquid crystalline polymer. VI. Synthesis and properties of homo‐ and co‐poly(amide‐azomethine‐ether)
Authors: Li Chien‐Hui , Hsu Keh‐Ying , Chang Teh‐Chou
Published: April 2003

Two series of poly(amide‐azomethine‐ether)s and poly(ester‐azomethine‐ether)s were prepared by the condensation of dialdehydes with N,N'‐bis(aminobenzamide)s and 4,4′‐bis(p‐aminophenyl)terephthalester, respectively. The thermotropic liquid crystalline properties were examined by DSC microscopic observations. Almost half of the synthesized polymers exhibit thermotropic liquid crystalline properties which are in the nematic phase since threaded and/or Schlieren textures are observed under polarizing microscope. The effects of the number of amide group and the nature of the nonlinear bibenzamide moiety, which link in the rigid segment, on the thermotropic liquid crystalline properties of the homo‐ and co‐poly(amide‐azomethine‐ether)s were also investigated.
Solvent effects, species and extraction method effects, and coinitiator effects in the grafting of lignin
Authors: Meister John J. , Lathia Amit , Chang Fu‐Fong
Published: April 2003

A general method of grafting lignin has been developed which allows solvent extracted lignin, steam exploded lignin, and kraft lignin to be converted to complex polymers. The lignins grafted have been obtained from aspen, poplar, oak, grasses, and pine. The lignins are research samples, pilot plant products, and commerical products from paper production. Nonionic copolymers of virtually any composition and molecular weight can be made from lignin and 2‐propenamide by free radical reaction of 2‐propenamide in the presence of the lignin. The water soluble product is a thickening agent and has limiting viscosity number in water at 30°C that vary from 0.1 to 2.0 dL/g. The grafting reaction is rapid and yields of 80 wt % or more can be obtained in as little as 30 min from reactions run in 1,4‐dioxacyclohexane or dimethylsulfoxide. The reaction is initiated by a hydroperoxide, chloride ion, and lignin.
Polymerization of coordinated monomers. XX. Ab initio molecular orbital study on the binary molecular complex composed of methyl methacrylate and boron trichloride
Authors: Sato Kota , Hirai Hidefumi
Published: April 2003

The stereo and the electronic structures of methyl methacrylate and the binary molecular complex composed of methyl methacrylate and boron trichloride are determined by quantum chemical calculations based on ab initio molecular orbital methods with the STO‐3G basis set. The Stable structures of methyl methacrylate in the free state are a transoid from and a cisoid form. The transoid form is slightly (0.5 kcal/mol) more stable than the cisoid form. The total energy change accompanying binary molecular complex formation is calculated to be −43 kcal/mol. The most stable structure of the binary molecular complex composed of methyl methacrylate and boron trichloride is a twisted form in which the dihedral angle between the vinyl group and the ester group is 19.7°. A large amount of electron transfer from methyl methacrylate to boron trichloride is calculated to occur on binary molecular complex formation. Mulliken's population analysis shows the electron transfer to be the origin of the twist of the binary molecular complex. The energy level of the lowest unoccupied molecular orbital is substantially lowered by the coordination of boron trichloride.
On amide exchange reaction of polymide precursor
Authors: Hasegawa Masatoshi , Shindo Yoichi , Sugimura Tokuko , Horie Kazuyuki , Yokota Rikio , Mita Itaru
Published: April 2003

The reaction of poly(amic acid) (PAA) derived from pyromellitic dianhydride (PMDA) and oxydianiline (ODA) with 1‐aminopyrene (APy) in solution as a model of amide exchange reaction between PAAs was studied in the temperature range of 0–60°C using viscometry and light‐scattering (LS) measurements. The decrease in the weight‐average molecular weight (M̄w) of PAA in N,N‐dimethylacetamide (DMAc) solution with time and the acceleration of M̄w drop due to the increase in storage temperature or the addition of APy into PAA solution were observed. Apparent activation energies (Ea) for scission of PAA chains were similar: about 13 kcal/mol in PAA/DMAc and PAA/APy/DMAc, respectively. When stored at 60°C for a week, the number of scissions per polymer chain in PAA/DMAc is about 2, but is about 5 in PAA/DMAc with a large amount of APy. The result indicates that the M̄w drop accelerated by the addition of APy is attributed to amide exchange reaction between PAA Chains and monofunctional APy. It was concluded from the dependence of M̄w drop on Apy concentration that the exchange reaction between different PAA molecules during storage of PAA/PAA solution may scarcely occur under the conditions (storage time and temperature) used for preparation of PAA/PAA blends.
Photo‐redox induced cationic polymerization of divinyl ethers
Authors: Sundell Per‐Erik , Jösson Sonny , Hult Anders
Published: April 2003

The cationic polymerization of diethyleneglycoldivinyl ether was initiated by cationic species originating from the redox reaction between photochemically generated free radicals or excited state photosensitizers and various onium salts. For the oxidation of free radicals, the efficiency of the initiation process depended primarily on the redox potential of the redox couple and hence the reactivity could be altered by choosing an appropriate combination of free radical photoinitiator and onium salt. The electron transfer from excited state photosensitizers to the phenacyletramethylenesulfonium salt showed no correlation between the free energy of the process and the initiation efficiency.
Cyclotrimerization of aryl isocyanates catalyzed by alkoxyallenes through zwitterionic mechanism
Authors: Mizuya Jiro , Yokozawa Tsutomu , Endo Takeshi
Published: April 2003

Alkoxyallenes (1) are found to catalyze cyclotrimerization of aryl isocyanates (2) in dimethylformamide (DMF) to afford 1,3,5‐triaryl‐s‐triazine‐2,4,6‐trione (3: cyclic trimer of 2), although the reaction of 1 with 2 in bulk gave the corresponding copolymer. In order to speculate about the mechanism of the cyclotrimerization, macrozwitterion 4, was prepared by copolymerization of 1 and 2 in bulk, and the catalytic activity of 4 was further studied. Cyclotrimerization of 2 was promoted by 4 and quenching of 4 with methanol completely destroyed the catalytic activity. Consequently, the alkoxyallene‐catalyzed cyclotrimerization of 2 is assumed to take place through a zwitterion generated from 1 and 2.
Synthesis and characterization of polymers produced by horseradish peroxidase in dioxane
Authors: Akkara Joseph A. , Senecal Kris J. , Kaplan David L.
Published: April 2003

Polymers were synthesized from substituted phenolic and aromatic amine compounds with hydrogen peroxide as the source of an oxidizing agent and horseradish peroxidase enzyme as the catalyst. The polymerization reaction was carried out in a monophasic organic solvent with small amounts of water at room temperature. Conditions for the synthesis of polymers with respect to reaction time and yield were studied with a number of monomers at different concentrations and in solvents with different buffers with pH range of 5.0–7.5. Physical and chemical properties of these homo‐and copolymers were determined with respect to melting point, solubility, elemental analysis, molecular weight distribution, infrared absorption (including FTIR), solid‐state 13C nuclear magnetic resonance, thermal gravimetric analysis, and differential scanning calorimetry. The enzyme catalyzed reactions produced polymers of molecular weight greater than 400,000 which were further fractionated by differential solubility in solvent mixtures and the molecular weight distribution of the polymer fractions were determined. In general, the polymers synthesized have low solubilities, high melting points, and some degree of branching.
Poly[(4‐N‐ethylene‐N‐ethylamino)‐α‐cyanocinnamate]: A nonlinear optical polymer with a chromophoric mainchain. I. Synthesis and spectral characterization
Authors: Stenger‐Smith J. D. , Fischer J. W. , Henry R. A. , Hoover J. M. , Nadler M. P. , Nissan R. A. , Lindsay G. A.
Published: April 2003

Poly[(4‐N‐ethylene‐N‐ethylamino)‐α‐cyanocinnamate] was prepared by solution esterification of (4‐N‐ethyl‐N‐(2‐hydroxyethyl) amino)‐α‐Cyanocinnamic acid and by melt transesterification of ethyl (4‐N‐ethyl‐N‐(2‐hydroxyethyl) amino)‐α‐cyanocinnamate. The melt transesterification generally yielded polymer with a number‐average molecular weight of about 10,200 by gel permeation chromatography (GPC) versus polystyrene standards. The polymer was found to be amorphous with a glass transition temperature of about 103°C by differential scanning calorimetry (DSC). The solution esterification generally gave a polymer with a number‐average molecular weight of about 2200 by GPC versus polystyrene standards. This polymer was found to have a glass transition temperature varying between 60 and 90°C by DSC. The infrared (IR) spectrum of the polymer made from both methods were analyzed in detail. The1H‐ and13C‐NMR spectra of the meltsynthesized ethyl cinnamate derivative polymer are consistent with the reported structure.
2,5,‐Dimethoxy‐ and 2,5‐di‐n‐butoxy‐1,4‐benzoquinone reactions and polymerization with 1,6‐hexanediamine
Authors: Colletti Ronald F. , Stewart Michael J. , Taylor Amelia E. , MacNeill Nancy J. , Mathias Lon J.
Published: April 2003

The serendipitous formation of 2,5‐dimethoxy‐ 1,4‐benzoquinone is reported from the reaction of 1,4‐benzoquinone with methanol, DABCO, and paraformaldehyde. This monomer, and its di‐n‐butoxy analog, are also available from 2,5‐dihydroxy‐1,4‐benzoquinone. These materials are capable of novel polycondensation reactions with diamines such as 1,6‐hex‐anediamine. Use of m‐crexsol as polymerization solvent gave a dark, insoluble product while various amide solvents lead to orange or pink polymers that had average degrees of polymerization from 5 up to >30. These polymers, Plus model compounds obtained from 1‐aminopropane and N,N'‐ dimethyl‐1,6‐hexanediamine, were characterized by FTIR, solution, and solid‐state NMR.
Influence of allyl ethers in coating resins
Authors: Johansson Mats , Hult Anders
Published: April 2003

The effects of allyl ethers in coating resins have been studied in relations to different systems. The details that have been investigated are: the reactions between allyl ethers‐styrene‐cobalt salt in air, the influence of cobalt salt on oxidized allyl ethers, and the interaction between allyl ethers and maleic esters with respect to copolymerization. The curing rates of allyl functional oligomers as coatings have also been studied. The results are summarized together with the results from a previous article by the same authors to give an overall view of the curing mechanism in allyl ether functional unsaturated polyester resins dissolved in styrene.
Seperation of metal alginate ionotropic gels to polymembranes with special evidence on the position of chelation in copper alginate complex
Authors: Hassan R. M. , Awad A. , Hassan Ahmed
Published: April 2003

A descending technique has been used to make multilayer ionotropic membranes within capillary structure from the gelation of macromolecular chains of alginate sol and electrolytes of divalent metal ions. A successful method was introduced to separate these polymembranes into layers. The electron‐microscopical investigation confirms that the chelation in such gel membrane complexes occurred between the divalent metal ion, and two carboxylate and two hydroxyl groups of two neighboring units of the same macromolecular chain.
Mechanism and kinetics of the polymerization of thermoplastic polyimides. I. Study of the pyromellitic anhydride/aromatic amine system
Authors: Grenier‐Loustalot Marie‐Florence , Joubert Frédéric , Grenier Philippe
Published: April 2003

We have synthesized model compounds representing the repeating units of a polyamic acid prepared from pyromellitic anhydride and an aromatic amine. They were characterized with HPLC, 1H and 13C liquid and solid NMR and FTIR. The Kinetic study of the ring dehydration reaction of model compounds showed that the reaction paths were very different, depending on the experimental conditions (isotherms, liquid, or solid states). They could lead to a deterioration of the polyamic of the polyamic acid by the formation of side reactions. These reactions could predominate as a result of the existence of an equilibrium between the amic acid group and starting monomers.
Synthesis and characterization of poly(arylene ether imidazole)s
Authors: Connell J. W. , Hergenrother P. M.
Published: April 2003

Poly(arylene ether imidazole)s were prepared by the aromatic nucleophilic displacement reaction of a bisphenol imidazole with activated aromatic dihalides. The polymers had glass transition temperatures ranging from 230 to 318°C and number‐average molecular weights as high as 82,000 g/mol. Thermogravimetric analysis showed a 5% weight loss occurring ∼ 400°C in air and ∼ 500°C in nitrogen. Typical neat resin mechanical properties obtained at room temperature included tensile strength and tensile modulus of 14.2 and 407 ksi and fracture energy (Glc) of 23 in. lb/in.2 Titanium‐to‐titanium tensile shear strengths measured at 23 and 200°C were 4800 and 3000 psi, respectively. In addition, preliminary data were obtained on carbon fiber laminates. The chemistry, physical, and mechanical properties of these polymers are discussed.
Synthesis and characterization of new soluble aromatic polyimides from 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole and aromatic tetracarboxylic dianhydrides
Authors: Jeong Hwa‐Jin , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Novel aromatic polyimides containing tetraphenylpyrrole unit were synthesized from 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole and various aromatic tetracarboxylic dianhydrides by the usual two‐step procedure that included ring‐opening polyaddition and subsequent thermal cyclodehydration. These polymers had inherent viscosities in the 0.20–0.65 dL/g range and were practically amorphous as shown by the X‐ray diffraction studies. All the polyimides except for polypyromellitimide were easily soluble in a wide range of organic solvents such as o‐chlorophenol, pyridine, 1,3‐dimethyl‐2‐imidazolidone, N,N‐dimethylacetamide, and N‐methyl‐2‐pyrrolidone at room temperature. These polyimides had high glass transition temperatures of 302–359°C and exhibited 10% weight loss at temperatures above 510°C in nitrogen.
Synthesis of substituted polymethylenes by radical polymerization of alkyl N,N‐dialkylfumaramates and maleamates: Relative reactivity of the isomers
Authors: Matsumoto Akikazu , Kotaki Ryuji , Otsu Takayuki
Published: April 2003

Bulk polymerization of alkyl N,N‐dialkylfumaramates (FAE) and maleamates (MAE) was performed in the presence of a radical initiator. It has been found that FAE is more reactive than MAE when the reactivity of the two geometrical isomers was compared for their homo‐ and copolymerizations. From investigation on the effect of ester and N‐substituents of these monomers, it has been found that the isopropyl ester shows a higher reactivity than the methyl ester and that N‐ethyl and n‐butyl substitution gives polymers with high molecular weight of more than several thousands. The resulting substituted polymethylenes from FAE and MAE were characterized and compared with each other. The isomerization of MAE to FAE with morpholine as an isomerization catalyst and monomer‐isomerization radical polymerization were also investigated.
Photochemistry of macromolecular metal complexes. II. Synthesis, thermal, and photochemistry of some polypyridyl complexes of chromium (III) bound to macromolecules
Authors: Anbalagan K. , Natarajan P.
Published: April 2003

Polymer coordinated chromium(III) complexes [Cr(bpy)2(PAA)2]+, 1, [Cr(bpy)2‐(PMA)2]+, 2, [Cr(phen)2(PAA)2]+, 3, and [Cr(phen)2(PMA)2]+, 4, [where bpy, phen, PAA and PMA are, respectively, 2,2′‐bipyridine, 1,10‐phenanthroline, poly(acrylic acid), and poly(methacrylic acid)] were synthesized. The polymer–chromium(III) complexes were characterized by elemental and spectroscopic analyses. Thermal substitution reactions of these macromolecular chromium(III) complexes in basic solutions lead to the replacement of the polypyridyl ligand by hydroxide ion while in strong acidic solutions the polymer complexes precipitate out. The photochemical reactions are qualitatively similar to that of the thermal reactions and the quantum yields are dependant on the pH of the medium. Further, lower quantum yields were observed for the aquation of the polymer complexes in comparison with the monomeric chromium(III) complexes and the results are discussed in terms of the effect of the polymer environment. Flash photolysis of 1 and 3 results in the formation of transients with maxima at 480 nm for 1 and 470 nm, 580 nm for 3. The decay of the transients were found to obey first order kinetics and the rate constants were determined. The transients were suggested to be the alkyl‐chromium complexes. Flash photolysis of 2 and 4 does not produce transients which is interpreted to be due to the presence of a methyl group in the ligand which hinders the formation of the carbonchromium bond.
New polymer syntheses. 60. Thermostable polymers of 2‐(hydroxyaryl)benzoxazole‐5‐carboxylic acids
Authors: Kricheldorf H. R. , Thomsen Sven A.
Published: April 2003

Tristrimethylsilyl‐3‐amino‐4‐hydroxybenzoic acid was condensed with various aromatic acetoxy carboxylic acid chlorides in Marlotherms‐S® at 20–350°C. Under these conditions formation of an amide group, ring closure to benzoxazole groups and polycondensation occur step by step in a “one‐pot procedure”. The crude polyesters were hydrolyzed to yield pure 2‐(hydroxyaryl) benzoxazole‐5‐carboxylic acids which were acetylated and polycondensed. The pure polyesters obtained in this way were characterized by viscosity and DSC measurements, WAXS‐powder patterns, and thermogravimetric analyses. The polyester of 2‐(4‐hydrophenyl) benzoxazole‐5‐carboxylic acid has a degree of crystallinity > 90% and a short term in thermostability in air up to 500°C.
Polymerization of α‐methyleneindane: A cyclic analog of α‐methylstyrene
Authors: Ueda Mitsuru , Mano Motokazu , Mori Hideharu , Ito Hiroshi
Published: April 2003

α‐Methyleniedane (MI), a cyclic analog of α‐methylstyrene which does not undergo radical homopolymerization under standard conditions, was synthesized and subjected to radical, cationic, and anionic polymerizations. MI undergoes radical polymerization with α,α′‐azobis(isobutyronitrile) in contrast to α‐methylstyrene, owing to its reduced steric hindrance, though the polymerization is slow even in bulk. Cationic and anionic polymerization of MI with BF3OEt2 and n‐butyllithium, respectively, proceed rapidly. The thermal degradation behavior of the polymer depends on the polymerization conditions. The anionic and radical polymers are heteortactic‐rich. Reactivity ratios in bulk radical copolymerization on MI (M2) with methacrylate (MMA, M1) were determined at 60°C (r1 = 0.129 and r2 = 1.07). In order to clarify the copolymerization mechanism, radical copolymerization of MI with MMA was investigated in bulk at temperatures ranging from 50 to 80°C. The Mayo–Lewis equation has been found to be inadequate to describe the result due to depolymerization of MI sequences above 70°C.
Synthesis of aromatic polyethers by Scholl reaction. V. Synthesis and polymerization of 1,3‐bis[4‐(1‐naphthoxy) benzoyl]benzene, 1,4‐bis[4‐(1‐naphthoxy)benzoyl]benzene, bis[4‐(1‐naphthoxy)phenyl]methane, 1,3‐bis[4‐(1‐naphthoxy) phenylmethyl]benzene, and 1,4‐bis‐[4‐(1‐naphthoxy)phenylmethyl]benzene
Authors: Percec Vergil , Wang James H. , Okita Shigeru
Published: April 2003

This article describes the synthesis and the cation‐radical polymerization (Scholl reaction) of 1,3‐bis[4‐(1‐naphthoxy) benzoyl] benzene (6) and 1,4‐bis[4‐(1‐naphthoxy) benzoyl]‐ benzene (7) initiated by FeCI3. This polymerization produced poly(ether ether ketone ketone)s (PEEKK) of number average molecular weight (M̄n) up to 5400 g/mol. The synthesis of bis[4‐(1‐naphthoxy) phenyl] methane (8), 1,3‐bis[4‐(1‐napthoxy) phenylmethyl] benzene (9), and 1,4‐bis[4‐(1‐naphthoxy) phenylmethyl] benzene (10) are also described. Polyethers of M̄n up to 15400 g/mol at a FeCl3/monomer molar ratio of 2/1 were obtained. An increased polymerizability of the monomers 9 and 10 containing two CH2 groups versus that of the corresponding monomers containing two carbonyl groups (6 and 7) was observed. This enhanced polymerizability was explained based on the increased nucleophilicity of monomers 9 and 10.
Solvay type VCl3 isospecific catalysts
Authors: Nozaki Takashi , Chien James C. W.
Published: April 2003

Solvay type S–VCl3 catalyst has 7% of catalytically active vanadium sites ([C*]) with kp (rate constant of propagation) = 31 (M s)−1 for ethylene polymerization. Addition of a comonomer, propylene of 4‐methylpentene‐1 (4‐MP) significantly raised the ethylene polymerization activity. S–VCI3 catalyst has very small amounts of catalytically active vanadium for propylene polymerizations: [C] = 0.19% with kp,i = 857 (M s)−1 and [C] = 0.45% with kp,a = 23 (M s)−1 for isospecific and nonspecific sites, respectively. Addition of a conomer, ethylene or 4‐MP. lowered the propylene polymerization activity. S–VCI3 is more easily reduced to the divalent ion by AIR3 than S–TiCl3. Methyl‐p‐toluate moderates the reducting power of AIR3; it increase the productivity and stereoselectivity of the S–YiCl3 catalyst, VCI3 supported on MgCl2 (CW–V catalyst) has enhanced rate constant of propylene polymerization but has the opposite effects on the S–TiCl3 Catalyst. VCI3 supported on MgCl2 (CW–V catalyst) has enhances rate constant of propylene polymerization but only a minute fraction of the supported vanadiums are catalytically active: [C] = 0.019% and kp,i = 1580 (Ms)−1, [C] = 0.057% and kp,i = 58 (M s)−1. This is compared with far greater number of catalytically active titanium sites in the TiCl3 supported on MgCl2 catalyst: [C] = 6% and kp,i = 200 (M s)−1, [C] = 6% and kp,a = 16(M s)−1. Therefore, both the S–VCI3 and CW–V catalysts are highly stereoselective but low in efficiency with respect to the utilization of the vanadium ion in the catalysis.
Polymerization and copolymerization of α‐alkylacrylic acids and characterization of their polymers
Authors: Cheng Jin‐Shun , Yamada Bunichiro , Otsu Takayuki
Published: April 2003

α‐Alkylacrylic acids (RAA's) bearing n‐alkyl groups were found to homopolymerize with slower rates than acrylic and methacrylic acids to number‐average molecular, weight (M̄n) of 104 or above. When the α‐substituent was a branched alkyl group, the polymerization rate and M̄n decreased further. Reactivities of RAA's in copolymerization were interpreted by steric and resonance effects of the alkyl group using Hancock's steric substituent constant. Comparison of the reactivities of RAA's with those of methyl α‐alkylacrylates revealed that replacement with the smaller carboxyl group facilitates polymerization and copolymerization. Preference of co‐syndiotactic propagation in the copolymerization of methacrylic acid with styrene changed to random fashion in the copolymerization of the α‐higher alkyl derivatives. After methylation with diazomethane, the homopolymers were shown to be thermally less stable than poly(methyl methacrylate). Tg's of poly(methyl α‐ethylacrylate) and poly(methyl α‐n‐propylacrylate) were 57 and 25°C, respectively.
Synthesis of polymer containing o‐nitrobenzyl ether structure in the main chain
Authors: Iizawa Takashi , Kudou Hiroshi , Nishikubo Tadatomi
Published: April 2003

The polycondensation of nitrated xylenedihalides with diphenols was carried out under various conditions. The polycondensation of 2‐nitro‐1, 3‐xylylenedibromide (NXDB) with 4,4′‐isopropylidenediphenol proceeded in competition with the decomposition of polymer in the mixed solvent of tetrahydrofuran (THF) and dimethylsulfoxide (DMSO). The viscosity of the resulting polymer was markedly affected by the concentration of aqueous sodium hydroxide, reaction time, and reaction temperature. When dibromomethane was used as a solvent, the polycondensation proceeded very smoothly without the decomposition to give a higher reduced viscosity polymer than that in THF‐DMSO at 60°C. The polymer obtained in dibromomethane contained a very small amount of formal bonds determined from the 1H‐NMR spectrum. The formation of formal bonds seems to cause the molecular weight in increase. Furthemore, the polycondensation of NXDB with 2,2‐bis (4‐hydroxyphenyl) hexafluoropropane afforded high molecular‐weight polyether in dibromomethane. However, either high reaction temperatures or the high concentrations of aqueous potassium hydroxide solution casused the viscosity of the resulting polymer to decrease during the polycondensation in dibromomethane. The obtained polyethers with o‐nitrobenzyl groups showed relatively good solubility, and decomposed smoothly upon the irradiation with UV light. Therefore, these polymers might be useful for positive type photoresists.
Synthesis of aromatic polyamide‐imides from N,N′‐bis(trimethylsilyl)‐substituted aromatic diamines and 4‐chloroformylphthalic anhydride
Authors: Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

The polymerization of N,N′‐bis(trimethylsilyl)‐substituted aromatic diamines with 4‐chloroformylphthalic anhydride in various solvents at a temperature range between 10 and 70°C afforded polyamide‐amic acid trimethylsilyl esters having inherent viscosities of 0.8–1.4 dL/g. Transparent and flexible films of the silylated precursor polymers were obtained by casting directly from the polymer solutions. Desilylation of the silylated polymers with methanol resulted in the formation of the corresponding polyamide‐amic acids. Subsequent thermal imidization of the silylated precursor polymers with the elimination of trimethylsilanol afforded yellow, transparent, and tough films of the aromatic polyamide‐imides. The thermal conversion of the silylated precursor polymer to polyamide‐imide proceeded almost as rapidly as that of the corresponding polyamide‐amic acid prepared by a conventional method from the parent aromatic diamine and 4‐chloroformylphthalic anhydride.
Novel synthesis of aromatic polysulfides from S,S′‐bis(trimethylsilyl)‐substituted aromatic dithiols and activated aromatic dihalides
Authors: Hara Atsushi , Oishi Yoshiyuki , Kakikoto Masa‐Aki , Imai Yoshio
Published: April 2003

A new method for the synthesis of aromatic polysulfides has been developed by the polycondensation of S,S′‐bis(trimethylsilyl)‐substituted aromatic dithiols with activated aromatic dihalides. The solution polycondensation of three S‐silylated aromatic dithiols with bis(4‐chloro‐3‐nitrophenyl) sulfone afforded readily aromatic polysulfides having inherent viscosities of 0.7 dL/g, and the polymerization with bis(4‐fluorophenyl) sulfone gave the polymers with viscosity values of 0.3 dL/g. The silylation method was compared advantageously with a conventional route using parent dithiols and activated aromatic dihalides.
The active species of the chromium (phillips type) catalysts for the polymerization of ethylene: A unifying approach
Authors: Rebenstorf Bernd
Published: April 2003

From literature data it is concluded that the rate of the reduction, alkylation, polymer chain growth, and chain transfer reactions of three chromium(II) and one chromium(III) surface species all increase with decreasing electron density at the chromium ion. This electron density has previously been measured by the IR shift of the stretching vibration of one CO molecule terminally adsorbed on these chromium ions. It is observed that the reduction half time decreases proportional to the increasing Lewis acidity and that the rate of the polymer chain growth reaction increases exponentially for three chromium surface species with increasing CO stretching vibration. Due to the large difference of the polymer chain growth rates for the two chromium (II) species (Ad and Cd), common in the normal Phillips catalyst, both contribute almost equally to the polymer product, although the Ad species outnumbers the Cd one by more than 3 to 1.
Novel dialkylaminoalkyl‐ and dialkylaminoalcoxi‐benzophenones as photoinitiators of polymerization. I. Photochemical characteristics and radical efficiencies
Authors: Mateo J. L. , Bosch P. , Catalina F. , Sastre R.
Published: April 2003

The behavior of the nonconjugated aminated benzophenones—4‐[2′‐N,N‐(diethylamino)ethoxy]benzophenone (E4), 2‐[2′‐N,N‐(diethylamino)ethoxy]‐4‐methoxybenzophenone (E2), and 4‐N,N‐dimethylaminomethylbenzophenone (DM)—as photoinitiators of MMA polymerization has been studied and the results compared with those obtained with the conjugated aminobenzophenone 4‐N,N‐dimethylamino‐4′‐isopropyl‐benzophenone (CU—MI). Photoreduction behavior of these compounds in various solvents in the presence and absence of MMA has been also examined. The order of the polymerization reaction with respect to monomer and initiator concentrations has been investigated; values of initiation quantum yield (Φi), Kp/K1/2t and efficiencies of the different radicals have also been determined. Similar polymerization rates (Rp) of methyl methacrylate (MMA) were found when E4 and CU‐MI were used as photoinitiators under the same range of absorbed irradiation intensity. This fact results from a compensation between the higher rate of E4 radical production (n‐π* transition type) and the greater reactivity of the radicals generated from CU‐MI.
Novel regular network polyester films from aromatic tetracarboxylic acids and ethylene glycol
Authors: Tsutsumi Naoto , Chen Ying‐Hsien , Kiyotsukuri Tsuyoshi
Published: April 2003

Novel regular network polyester films were prepared from pyromellitic (X), biphenyltetracarboxylic (U), and 3,3′,4,4′‐benzophenonetetracarboxylic (W) dianhydrides and ethylene glycol (2G). Prepolymers prepared by melt polycondensation were cast from DMF solution and successively post‐polymerized at 260°C for various times to form a network. The resultant films were transparent, flexible, and insoluble in any solvents. The structure and properties of these network polyester films were compared with those of previously reported network polyester film from trimesic acid (Y) and 2G. Two diffraction peaks appeared in X‐ray diffraction curves of 2GY, 2GX, and 2GU films. Peaks of 2GX and 2GU were broader than that of 2GY, suggesting less ordered structure of 2GX and 2GU by the less symmetric aromatic tetracarboxylic acid moieties. Densities of network films decreased with increasing the post‐polymerization time. The degree of reaction (the degree of network formation) was estimated by the change of infrared absorption of hydroxyl and methylene groups. The degree of reaction obtained was 95 and 87% for 2GY and 2GX films post‐polymerized for 12 h, respectively. Distortion temperature (Th) was measured by a penetration mode of thermomechanical analysis (TMA). Th, was 222 and 240°C for 2GY and 2GW films post‐polymerized at 260°C for 12 h, respectively, while it disappeared for 2GX and 2GU films post‐polymerized for more than 30 min and 1 h, respectively. Drastic decrease in TMA curves around 400°C corresponded to the rapid weight loss in TG curves due to the thermal decomposition. Young's modulus of network film was 2GX > 2GW = 2GU > 2GY, while the tensile strength and elongation were 2GY > 2GU > 2GW > 2GX. Water absorbing capacity was 2GX > 2GY > undrawn PET, while the alkali resistance was undrawn PET = 2GY > 2GX.
Electroinitiated polymerization of butadiene sulfone
Authors: Aybar S. P. , Hacioglu B. , Akbulut U.
Published: April 2003

Electroinitiated polymerization of butadiene sulfone was achieved by direct electron transfer in acetonitrile—tetrabutylammonium fluoroborate system by controlled potential electrolysis technique. High conversions were obtained at reasonable temperatures and polymerization times. The polymer was found to be composed of linear segments along with some cyclic units. The effect of monomer concentration, temperature, and polymerization potential on the rate of polymerization was investigated. Temperature and polymerization potential have positive effects on the rate of polymerization. The effect of ultrasonic vibration was also investigated by conducting electrolyses at different monomer concentrations in the presence and absence of ultrasonic vibration. It was observed that the rate of polymerization increases significantly in the presence of ultrasonic vibration. The inverse relationship between the rate of polymerization and monomer concentration was observed in presence and absence of ultrasonic vibration.
Control synthesis of isocyanate and alkoxy‐silane terminated macromers
Authors: Surivet Françoise , Lam Thanh My , Pascault Jean‐Pierre
Published: April 2003

The kinetics of the reactions in bulk of 4,4′‐dicyclohexyl methane diisocyanate (H12 MDI) and 5‐isocyanato‐1,3,3‐trimethylcyclohexylmethyl isocyanate or isophorone diisocyanate (IPDI) with benzylic alcohol (BZA) and α‐hydroxy‐ω‐methyl ether‐terminated polyethylene oxide PEO (M̄w = 350) were studied by size exclusion chromatography (SEC) and 13C nuclear magnetic resonance (13C‐NMR). The substitution effect is exhibited in the case of H12 MDI reactivity. The kinetic constants were calculated by a numerical method. The second‐order kinetic mechanism was shown to be valid. In the IPDI case, the cycloaliphatic isocyanate group is shown to be more reactive than the aliphatic group in our conditions, without catalysis, in agreement with previous results from the literature, in our obtained by 1H‐and 13C‐NMR without any catalyst. The reactivity ratio is found to be on the order of 3. This difference in reactivity of the two isocyanate groups is used for the control synthesis of isocyanate and alkoxy‐silane‐terminated macromers.
Regioselective rhodium‐containing catalysts for ring‐opening polymerizations and hydrosilylations
Authors: Crivello J. V. , Fan M.
Published: April 2003

Organometallic rhodium complexes are described which are highly efficient initiators for the ring‐opening polymerization of expoxides and other heterocyclic compounds. A cocatalyst, consisting of a compound or polymer containing silicon–hydrogen bonds must also be present. These same catalyst–cocatalyst mixtures are also highly active for hydrosilylation reactions. Other complexes bearing phosphine ligands have been discovered, which while active for hydrosilylation, are not catalysts for epoxide polymerizations. Polymer supported rhodium catalysts are also described which permit the synthesis of epoxy‐functional silanes in high yields without competing ring‐opening polymerization.