bluuebunny/crossref_metadata_2025_split huggingface dataset:
Terminal anhydride functionalization of polystyrene
Authors: Park Inha , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractPolystyrene 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

AbstractRuthenium(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

AbstractNew 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

AbstractThe 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

AbstractSiophenylene‐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

AbstractSide‐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

AbstractThe 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

AbstractComplexes 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

AbstractTwo 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractAlkoxyallenes (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

AbstractPolymers 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

AbstractPoly[(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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractWe 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

AbstractPoly(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.