bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anionic polymerization of N‐substituted maleimide. VI. Effects of counter cation on the anionic polymerization of N‐phenylmaleimide with alkali metal tert‐butoxides
Authors: Hagiwara Tokio , Shimizu Takamasa , Hamana Hiroshi , Narita Tadashi 
Published: April 2003

AbstractEffects of counter cation on the anionic polymerization of N‐phenylmaleimide (N‐PMI) were investigated with alkali metal tert‐butoxides. N‐PMI was more rapidly polymerized in the polymerization system with a larger size of counter cation (K+ > Na+ > Li+, e.g., 100% for K+, 20 min, and 2.7% for Li+, 90 min, in THF at −72°C). A significant temperature effect was observed for lithium tert‐butoxide as at 0°C the polymer yield was increased to 89% in THF. On the solvent effect, the overall polymerization rates for the every system initiated with alkali tert‐butoxide were lowered in toluene compared to those in THF. The polymerization system with sodium as counter cation showed the unique solvent effect that the fairly high polymerization rate in THF comparable to that observed in the system with potassium cation was drastically reduced in toluene to the almost same rate as that with lithium cation. The influences of crown ethers and common salt were also investigated. The molecular weight distribution of the poly(N‐PMI) was also influenced by the counter cation size. The polymerization system with lithium cation gave the narrowest molecular weight distribution and it became broader as the size of counter cation was increased.
Ethynyl‐terminated polyethers from new end‐capping agents: Synthesis and characterization
Authors: Delfort B. , Lucotte G. , Cormier L. 
Published: April 2003

AbstractDifferent main chain acetylene terminated polyethers with various molecular weights were prepared in a one‐step polyetherification reaction. This process requires the synthesis of new acetylene end‐capping agents, 4‐ethynyl‐4′‐fluorobenzophenone and 4‐ethynyl‐4′‐fluorodiphenyl sulfone. These reagents were prepared with good yields in a three‐step route. The thermally induced reaction of the ethynyl groups in an easy process leads to materials with improved solvent resistance and good thermostability. The fracture toughness was evaluated and was found to increase with the molecular weight of the precursor oligomers. High values were obtained, especially when 4,4′‐benzophenone and 4,4′‐diphenyl sulfone units are present in the polymer main chain.
Polymers containing cyanoimidazole pendant groups
Authors: Allan David S. , Thurber Ernest L. , Rasmussen Paul G. 
Published: April 2003

AbstractDicyanoimidazole (I) was attached to a polystyrene backbone in order to prepare polymers containing electron‐accepting pendant groups to complement the existing body of electron‐donating polymers. The preparation of poly[4,5‐dicyano‐1‐(vinylbenzyl)imidazole] (III), poly[4,5‐dicyano‐1‐(vinylbenzyl)imidazole‐co‐9‐(vinylbenzyl) carbazole] and attempted polymerization of 4,5‐dicyano‐1‐vinylimidazole are described. Cyclic voltammetry and charge transfer studies are used to characterize the electron‐accepting strength of the cyanoimidazole model compounds. These studies show that while cyanoimidazoles are moderate electron acceptors, they do not form charge transfer complexes with the donor molecules investigated.
Polyimides synthesized from 4,4′‐(1,2‐ethynediyl) bis (phthalic anhydride)
Authors: Nye S. A. 
Published: April 2003

AbstractA novel substituted acetylene monomer, 4,4′‐(1,2‐ethynediyl) bis (phthalic anhydride) (EBPA) was made in six steps from 4‐nitro‐N‐methylphthalimide (4‐NPI) including two palladium‐catalyzed acetylene coupling steps. Several new polyimides were prepared from this monomer and six aromatic diamines. In addition, copolymers were made with EBPA and BPADA with meta‐phenylene diamine. All of the polymers had high glass transition temperatures, high thermal stability and good solvent resistance. The copolymer containing twenty % EBPA had a glass transition temperature 33°C higher than Ultem® (a registered trademark of GE) and improved solvent resistance.
Synthesis and characterization of some halogen‐containing poly(esterurethane)s
Authors: Tamareselvy K. , Venkatarao K. , Kothandaraman H. 
Published: April 2003

AbstractA series of halogen‐containing poly (esterurethane)s was synthesized from the prepolymers, i.e., hydroxy‐terminated polyesters containing chlorine and fluorine and the diisocyanates such as toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). Polyesterification of halogenated phthalic anhydride with an excess of diols such as ethylene glycol, 1,2‐propanediol, and 1,4‐butanediol in the presence of trifluoroacetic anhydride (TFAA) was carried out to prepare prepolymers. The prepolymers and the poly (esterurethane)s were characterized by infrared (IR), 1H nuclear magnetic resonance (NMR), viscosity, end‐group analysis, solubility and thermal analysis namely thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Kinetics of thermal degradation was also studied. Resistance of the polymers to alkaline agents and combustion was also tested.
Mathematical models of the initial stage of the thermal degradation of poly(vinyl chloride). I. The thermal degradation of the low molecular weight models of macromolecules of poly(vinyl chloride) having no abnormal fragments
Authors: Troitskii B. B. , Troitskaya L. S. 
Published: April 2003

AbstractSome mathematical models of the initial stage of the thermal degradation of the low molecular weight models for the normal units of PVC have been considered. The equations have been deduced. If the values of the average length of kinetic chain of dehydrochlorination of the polymer and the model compound are equal to each other, these equations may be used for the thermal degradation of idealized PVC.
Thermal properties ofN‐substituted 4‐vinylpyridinium ions and their polymers
Authors: Ranganathan Prema , Fife Wilmer K. , Zeldin Martel 
Published: April 2003

Abstract4‐Vinylpyridinium trifluoromethanesulfonate monomers substituted at nitrogen with H, O, CH3, C2H5, C6H13, and C12H25were synthesized and characterized spectroscopically. Thermal analyses (DSC and TGA) were carried out on all the compounds. The solid monomers (NH, NCH3, NC6H13, and NC12H25) exhibited endothermic melting followed by exothermic polymerization and exothermic decomposition (>400°C). Liquid NC2H5monomer revealed only exothermic polymerization and decomposition. The NO polymer underwent thermal decomposition below 300°C. The N–C12H25homopolymer, prepared from monomer in the DSC or in bulk, displayed an unusual thermal transition at 250°C, which has been attributed to a polymer backbone reorientation leading to side‐chain ordering of the dodecyl groups.
Synthesis and characterization of poly[(3,4‐dihydro‐2h‐pyran)‐alt‐(maleic anhydride)] and its derivatives: Biologically active polymers
Authors: Han Man Jung , Kim Ki Ho , Cho Tae Joon , Choi Keun Bae 
Published: April 2003

AbstractThe syntheses of several monomers, bioactive poly[(3, 4‐dihydro‐2H‐pyran)‐alt‐(maleic anhydride)] and its derivatives, which have different substituents (e.g., acetoxy, methoxy, ethoxy, methoxycarbonyl, formyl, acetoxymethyl, and tosyloxymethyl groups) in the 2‐position of the tetrahydropyran ring of the copolymer backbone, are described. The alternating sequences in copolymers of the dihydropyran derivatives and maleic anhydride were obtained from the equimolar and larger ratios of maleic anhydride to dihydropyran derivative at the onset of the copolymerization. The molecular weights of the copolymers were found to be low (Mn = 1000–7500) due to a transfer reaction of the dihydropyran derivatives. Hydrolyses of the anhydride groups in the copolymers without catalyst afforded poly[(dihydropyran)‐alt‐(maleic acid)] and its derivatives, whereas an additional three copolymers having substituents, e.g., hydroxy, hydroxymethyl, and carboxyl groups were obtained by hydrolyses of the pendent groups (acetoxy, acetoxymethyl, and methoxycarbonyl) with the aid of a hydroxide catalyst. Carbamoyl groups on the polymers were obtained from ammonolysis of methoxycarbonyl groups. The polymers having mercaptomethyl or aminomethyl groups were obtained by substitution of hydrogen sulfide or ammonia for tosyloxylmethyl groups.
The effect of the t‐butyl substituent on polymer properties in homopolymer systems
Authors: Fenoglio D. J. , Foster J. J. 
Published: April 2003

AbstractThe effect of a bulky substituent on properties of different homopolymers has been examined. The substituent is the t‐butyl moiety attached to a benzene ring found in the repeat units of the homopolymers of polyesters, polyarylates, polyamides, and polyaramides. These polymers have been prepared by melt, solution, or interfacial techniques. The source of the t‐butyl group is mainly from 5‐t‐butylisophthalic acid (5TBIA) and comparisons are generally made with corresponding homopolymers based on isophthalic acid. The effect of the t‐butyl group is shown by comparison of the properties of these homopolymers. Thermal and mechanical (tensile and impact) properties, density, water absorption, solubility, and processability are discussed. Differences in these properties are attributed to the t‐butyl group and are based on intermolecular and intramolecular interactions that include increased free volume, chain stiffening, and conformational changes.
XPS analysis of the poly(ethylene terephthalate) film grafted with acrylamide
Authors: Uchida Emiko , Uyama Yoshikimi , Iwata Hiroo , Ikada Yoshito 
Published: April 2003

AbstractGraft polymerization of acrylamide (AAm) was performed onto the surface of a poly(ethylene terephthalate) (PET) film with the simultaneous UV irradiation method but using no photosensitizer and without degassing. To examine whether polyacrylamide (PAAm) was introduced into the bulk place of PET film by the surface graft polymerization, an x‐ray photoelectron spectroscopic (XPS) study was performed on the PAAm‐grafted PET films. The distribution of grafted PAAm chains on and in the PET films was estimated from the PAAm/PET ratio calculated from the XPS spectra of PET films with different amounts of grafted PAAm. The results clearly demonstrate that graft polymerization has actually occurred not merely on the outermost surface but also within the thin surface region of the PET film. In addition, the XPS analysis revealed that the PET component was always present in the grafted surface region by a mole fraction of 0.1 to 0.05 even when the amount of PAAm grafted was larger than 10 μg/cm2.
Poly(2‐methoxyphenylene vinylene): Synthesis, electrical conductivity, and control of electronic properties
Authors: Liang W. B. , Lenz R. W. , Karasz F. E. 
Published: April 2003

AbstractPoly(2‐methoxyphenylene vinylene) has been synthesized by a four step reaction sequence beginning with the bromination of 2,5‐dimethylanisole and proceeding to the formation of an intermediate sulfonium salt precursor polymer. The infrared and UV‐visible spectra of the PPV derivative asymmetrically substituted on the phenyl ring are presented. Films of poly(2‐methoxyphenylene vinylene) can be doped with iodine to give a conductivity of 1 S cm−1. Films doped with AsF5 exhibited activated charge transport behavior with room temperature conductivities of about 100 S cm−1.
Lifetime of living polymers in cationic polymerization. II. Living polymerization of isobutyl vinyl ether initiated by the hydrogen iodide/zinc halide systems
Authors: Choi Won Ok , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractIn the living cationic polymerization of isobutyl vinyl ether (IBVE) initiated by the hydrogen iodide/zinc halide (HI/ZnX2; X = I, Br, Cl) systems, the concentration ([P*]) of the living propagating species was determined by quenching with sodiomalonic ester (1). The quenching reaction was shown to be clean, instantaneous, and quantitative to give poly (IBVE) with a terminal malonate group from which [P*] was obtained by 1H‐NMR spectroscopy. In the polymerizations in toluene below +25°C, [P*] was constant and equal to the initial concentration ([HI]0) of hydrogen iodide, independent of the type and concentrations of ZnX2 as well as monomer conversion. At 0 and +25°C, however, the living species started decaying immediately after the complete consumption of monomer. In contrast, such a decay process was absent at −15°C even in the absence of monomer until about an hour (depending on the conditions) after the end of polymerization. The deactivation reaction was first order in [P*], and the lifetime (half‐life) of the living species was longer at lower temperature and at lower ZnX2 concentration. On the basis of these [P*] and lifetime measurements, the HI/ZnX2 systems were also compared with the HI/I2 counterpart.
Water‐Soluble imide‐amide copolymers. II. Preparation and characterization of poly (acrylamide‐co‐p‐maleimidobenzoic acid)
Authors: Hocking Martin B. , Syme David T. , Axelson David E. , Michaelian Kirk H. 
Published: April 2003

AbstractThe comonomer required, p‐maleimidobenzoic acid (MBA) was first prepared in good yield by refinements of published methods. p‐Carboxysuccinanilic acid (CSA), and p‐succinimidobenzoic acid (SBA), were also prepared to provide models useful for IR and NMR for spectroscopic assignments of the new copolymers. Polymerization of MBA with acrylamide in glacial acetic acid at 60°C gave copolymers with estimated viscosity average molecular weights of 60,000 to 90,000. Yields and viscosity average molecular weights decreased as the MBA to acrylamide monomer feed ratio was increased. The rate of incorporation of MBA into the copolymer rose from 7 to 23% when the mole ratio in the feed was raised from 5 to 20%. Decreasing the initiator concentration increased molecular weights by less than predicted and reduced the yield of copolymer for any given feed ratio of MBA to acrylamide. In all cases about 30–40% of the MBA units in the purified copolymers were hydrolyzed. A change to dimethyl sulfoxide solvent gave good, and poor yields of copolymer at 5 and 10 mol % MBA, respectively, and no copolymer at 20 mol % MBA. Viscosity average molecular weights of the copolymer products prepared in DMSO were somewhat lower than obtained for the copolymers prepared in acetic acid. Polymerization in a DMSO‐water mixture gave a negligible yield of polymeric product. Instead, only hydrolysates of MBA precipitated when the coloured polymerization solutions were added to methanol.
Living cationic polymerization of p‐methylstyrene by hydrogen iodide/zinc halide initiating systems
Authors: Kojima Kazushige , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractLiving cationic polymerization of p‐methylstyrene has been investigated with use of hydrogen iodide/zinc halide initiating systems (HI/ZnX2; X = Cl, I) in toluene and methylene chloride solvents. The best results were obtained with HI/ZnCl2 below 0°C where the zinc salt was employed in excess over hydrogen iodide (HI/ZnCl2 = 1/5 molar ratio). Under these conditions, the number‐average molecular weights
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of the produced polymers increased proportionally to monomer conversion, further increased upon addition of fresh feeds of p‐methylstyrene into completely polymerized reaction mixtures, and were in good agreement with the calculated values assuming that one living polymer chain forms per molecule of hydrogen iodide; the molecular weight distributions (MWDs) of the polymers were fairly narrow
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throughout these processes. In contrast, when equimolar mixtures of hydrogen iodide and zinc chloride or iodide were employed, the polymerizations were rather slow even in methylene chloride at +25°C, and the product polymers exhibited bimodal MWDs, the lower‐molecular weight fraction of which was mediated by long‐lived growing species. Addition of tetra‐n‐butylammonium iodide as a common ion salt (nBu4NI/HI = 1/200 molar ratio) led to unimodal MWDs consisting of the long‐lived lower polymer fraction alone.
Unambiguous 13C‐NMR assignments for isocyanate carbons of isophorone diisocyanate and reactivity of isocyanate groups in Z ‐ and E‐stereoisomers
Authors: Hatada Koichi , Ute Koichi , Oka Ken‐Ichi , Pappas S. Peter 
Published: April 2003

AbstractUnambiguous 13C‐NMR assignments for the primary (prim‐) and secondary (sec‐) isocyanate carbons of isophorone diisocyanate (IPDI) have been made by using two‐dimensional NMR measurements. On the basis of the assignments, relative reactivity of the prim‐ and sec‐isocyanate groups with n‐butanol was studied by quantitative 13C‐NMR analysis. The individual stereoisomers of IPDI (Z‐IPDI and E‐IPDI) and their equimolar mixture were reacted with n‐butanol (IPDI/n‐butanol = 2/1 molar ratio) at 50°C for 3 days. It was found that the sec‐NCO is about 1.6 times more reactive than the prim‐NCO in both Z‐ and E‐isomers. Reactivity of the E‐isomer was found to be slightly higher than that of the Z‐isomer. When di‐n‐butyltin dilaurate (DBTDL) was used as a catalyst, the reactivity of the sec‐NCO became about 12 times higher than that of the prim‐NCO with both isomers. In the case of 1,4‐diazabicyclo [2.2.2] octane (DABCO) catalyst, the prim‐NCO was 1.2 times more reactive than the sec‐NCO with both isomers.
Selective single ring‐opening polymerization of spiroorthoesters with aluminium (III) acetylacetonate
Authors: Chikaoka Satoyuki , Takata Toshikazu , Endo Takeshi 
Published: April 2003

AbstractA spiroorthoester, 2‐methyl‐1,4,6‐trioxaspiro[4.6]undecane (1), was polymerized with aluminium (III) acetylacetonate as a catalyst. The resulting polymer structure was analyzed in detail by FT‐IR and 270 MHz 1H NMR, and consisted of poly(orthoester) which was obtained by selective ring‐opening of the seven‐membered ring. In contrast, 2‐methyl‐1,4,6‐trioxaspiro[4.5]decane (2) and 2‐methyl‐1,4,6‐trioxaspiro[4.4]nonane (3) did not afford any polymers. The reactivity difference of these monomers was discussed in terms of their strain energies on the basis of MM2 calculations.
A molecular orbital study of the interactions of acrylic polymers with aluminum: Implications for adhesion
Authors: Chakraborty Arup K. , Davis H. Ted , Tirrell Matthew 
Published: April 2003

AbstractWe present results of molecular orbital thory calculations of the interactions of acrylic polymers with aluminum, with a view toward understanding the nature of chemical bonding at the corresponding polymer‐metal interfaces. The reported results are for the interactions of polymer model compounds with metal atoms (as opposed to our ongoing studies with metal surfaces). As such, the results relate to experimental studies where small dosages of metal atoms are evaporated onto polymer surfaces in pristine high vacuum environments. Our studies have been conducted within the theoretical framework of Hartree‐Fock molecular orbital theory. We find that aluminum atoms interact primarily with the carbonyl group of acrylic polymers. The reaction proceeds by the metal atoms interacting with both the carbon and the oxygen atoms of the carbonyl functionality. This weakens the CO bond. Finally, the carbonyl bond loses double bond character, and strong AL—O bonds are formed. Our results are compared to experimental data, and the implications of the detailed nature of bonding for adhesion applications are discussed.
Synthesis of ultra‐thin films of aromatic polymers at air/water interface
Authors: Ueda Tomoko , Yokoyama Shiyoshi , Watanabe Masayoshi , Sanui Kohei , Ogat Naoya 
Published: April 2003

AbstractUltra‐thin films of and precursor polymers for polybenzimidazole (PBI), polybenzoxazole (PBO), or polybenzothiazole (PBT) were formed at air/water interface by spreading monomers and then polymerizing on the water surface. These thin films could be deposited onto appropriate substrates by using the LB method of horizontal lifting. Moreover, the heat‐treatment of the built‐up films of the precursor polymers of PBI, PBO, and PBT formed the ultra‐thin films of high temperature polymers. The resulting ultra‐thin films had uniform and controllable thickness, but remained fairly stable when subjected to temperature up to 300°C. They also had good solvent resistance.
Homogeneous rare earth coordination catalysts for copolymerization of styrene with acrylonitrile
Authors: Yang Mujie , Xu Jinlong , Shen Zhiquan 
Published: April 2003

AbstractThe study on homogeneous rare earth coordination catalysts, LnL3‐Al(i‐Bu)3‐CCl4, for the copolymerization of styrene with acrylonitrile has been successfully carried out for the first time. Some features and kinetic behavior of copolymerization of styrene with acrylonitrile by Nd(P204)3‐Al(i‐Bu)3‐CCl4 system are described. The catalyst sites appear to possess both coordinate anionic and free radical characteristics. The catalytic activity of various rare earth elements in Ln(P204)3 and ligands in NdL3 for the copolymerization have the following order, respectively: Yb > Er > Tb ∼ Tm > Ho > Ce > Lu ∼ Sm ∼ La > Pr > Nd, and Nd(naph)3 > Nd(P204)3 ∼ Nd(P507)3 > Nd(acac)3·3H2O. An alternating‐rich copolymer of styrene‐acrylonitrile with a high softening point (195–230°C) was obtained by the LnL3‐Al(i‐Bu)3‐CCl4 systems in toluene at 80°C.
Functional macrocyclic polysulfones via aminomethylpolysulfone
Authors: Kahana N. , Arad‐Yellin R. , Deshe A. , Warshawsky A. 
Published: April 2003

AbstractAmidoalkylation of polysulfone (PS) with N‐chloromethylphthalimide (CMPi) to polymer 2/2a (PiPs), followed by hydrazinolysis of PiPs in CHCl3 with neat N2H4 + H2O (RT 3 days) to aminomethylpolysulfone (3, AMPS). Condensation of AMPS with 4‐chlorosulfonylbenzo‐18‐crown‐6 produced B18C6AMPS. Okawara‐type condensations with diglycydyl glycols (5) led to azacrown polysulfone polymers 6d, and polystyrene azacrown polymers 6a–6c. Products were characterized by 270 MHz 1H‐NMR, thermogravimetric (TGA) and DSC analysis. Insoluble aminomethylpolystyrene beads were used as model supports to study the Okawara‐type reaction with diglycydyl ethers and the products showed thermoregulated complexation of alkali salts on polymers 6b and 6c. Polysulfone membranes were prepared from B18C6AMPS and transport of K+ in a liquid membrane‐type experiment was demonstrated.
Blend of polyimide having internal acetylene units and oligoimide end‐capped with biphenylenes
Authors: Takeichi Tsutomu , Date Hideo , Takayama Yuzi 
Published: April 2003

AbstractA N‐Methylpyrrolidone (NMP) solution of polymic acid having internal acetylene units in the backbone was mixed with a NMP solution of oligomeric amic acid end‐capped with biphenylenes to afford a miscible solution. The viscosity of polymic acid solution lowered considerably by the addition of oligomers, which could lead to improved processability. The amic acid mixture was thermally or chemically cyclized to give a blend of internal‐reactive polymide and end‐reactive oligoimide. Films of imide blends were easily prepared by casting solutions of the amic acid blends followed by imidization. The imide blends were thermally cured at 400°C for 10 min to give cross‐linked polyimides that showed excellent thermal stability as confirmed by DSC, TGA, TMA, and viscoelastic analyses of the cured films. A selective co‐crosslinking reaction between biphenylene in the oligomide and acetylene in the polyimide to give phenanthrene linkage is supposed to be the cause of the high thermal stability.