bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of the t‐butyl substituent on polymer properties in homopolymer systems
Authors: Fenoglio D. J. , Foster J. J.
Published: April 2003

The 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

Graft 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

Poly(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

In 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

The 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

Living 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
\documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{{\overline {M_w } } \mathord{\left/ {\vphantom {{\overline {M_w } } {\overline {M_n } }}} \right. \kern-\nulldelimiterspace} {\overline {M_n } }} = 1.1 - 1.3} \right) $\end{document}
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

Unambiguous 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

A 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

We 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

Ultra‐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

The 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

Amidoalkylation 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

A 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.
Rigid rod molecules as liquid crystal thermosets. I. Rigid rod amides
Authors: Hoyt Andrea E. , Benicewicz Brian C.
Published: April 2003

A series of rigid rod amide monomers based on 2,2′‐disubstituted‐4,4′‐diaminobiphenyl were prepared and characterized by DSC and hot stage polarized light microscopy. The monomers were endcapped with maleimide, nadimide, and methylnadimide functionalities. With one exception, all of the materials could be thermally polymerized. Nematic liquid crystalline behavior was observed in three of the new materials which could be crosslinked in either the nematic or isotropic phase. Fast heating rates with hot stage polarized light microscopy were necessary to determine the melting and phase behavior before substantial crosslinking occurred during the heating process. One of the methylnadimide endcapped monomers also showed lyotropic liquid crystalline behavior.
Phenylquinoxaline–Aryl ester block copolymers
Authors: Labadie Jeff W. , Hedrick James L.
Published: April 2003

Phenylquinoxaline–aryl ester block copolymers were synthesized using well‐defined phenolic hydroxyl terminated oligomers via a monomers/oligomer approach. Phenylquinoxaline oligomers with molecular weights of 5600 and 12,900 g/mol were prepared from the condensation of 1,4‐bis(phenylglyoxalyl)benzene and 3,3′‐diaminobenzidine in the presence of 4‐hydroxylbenzil. The oligomers were copolymerized with isophthaloyl chloride and bisphenol A in tetrachloroethane to afford the desired phenylquinoxaline–aryl ester block copolymers. Copolymers with polyester compositions ranging from 15–50 wt % were prepared by controlling the monomers/oligomer stoichiometry. The majority of the materials displayed single phase morphologies with Tgs intermediate to the Tgs for the poly (phenylquinoxaline) and polyester homopolymers. Plots of the reciprocal of the Tg of the copolymers versus composition agreed well with values predicted by the Fox equation. A multiphase morphology was obtained for the copolymer with the highest polyester block length (⋍ 13,000 g/mol), which displayed a Tg at 190 and 300°C indicative of a glassy–glassy system. Significant improvement in the elongations were observed for the copolymers relative to the poly(phenylquinoxaline) homopolymer. The improved elongations were obtained with minimal sacrifice to the modulus. These materials represent the first example of poly(phenylquinoxaline) block copolymers from well‐defined phenylquinoxaline oligomers.
Evidence for long chain branching in polyethyloxazoline
Authors: Warakomski John M. , Thill Bruce P.
Published: April 2003

It has been reported that in the polymerization of 2‐alkyl‐2‐oxazolines extensive chain transfer to monomer occurs with subsequent repolymerization and the formation of branched polymer. We undertook a study to determine if polyethyloxazoline is branched. The approach was hydrolysis of the polymer followed by reacylation; characterization at each step was by size exclusion chromatography, viscometry, and NMR spectroscopy. In addition, ethyl oxazoline was polymerized to low and high conversion and characterized. We conclude that polyethyloxazoline does contain hydrolytically unstable linkages which are probably branches formed late in the polymerization.
Molecular location in a nonaqueous lyotropic liquid crystal polymer
Authors: Friberg Stig E. , Yu Bing , Campbell Gregory A.
Published: April 2003

A surfactant bis[2‐(10‐undecenoyloxycarbonyl)ethyl] (p‐vinylbenzoyl) methylammonium chloride formed a lamellar liquid crystal in native form and retained the structure after polymerization. Addition of heptadiene, of glycerylmonomethacrylate, and of both to the surfactant monomer gave an isotropic solution, which was transformed to a lamellar liquid crystal after polymerization. Low angle X‐ray diffractometry was used to determine the interlayer spacing and to estimate the location of the added molecules. 1.6‐Heptadiene was located between methyl group layers of the surfactant chains with 46 vol % of the molecules penetrating between the hydrocarbon chains of the surfactant. Addition of both the polar and the nonpolar monomer followed by polymerization caused the latter to be expelled from the space in between the chains.
Studies on the thermotropic liquid crystalline polymer. I. Synthesis and properties of polyamide‐azomethine‐ether
Authors: Li Chien‐Hui , Chang Teh‐Chou
Published: April 2003

A series of polyamide‐azomethine‐ethers was prepared by condensation of 4,4′‐diaminoanilide with 4,4′‐diformyl‐α,ω‐diphenoxyalkane, 4,4′‐diformyl‐3,3′‐methoxy‐α,ω‐diphenoxyalkane, and 4,4′‐diformyl‐3,3′‐ethoxy‐α,ω‐diphenoxyalkane, respectively. The inherent viscosities of polymers were obviously increased when the polymers were treated by heat under nitrogen at 220°C. The thermotropic liquid crystalline properties were examined by DSC, microscope observations, and TGA. All of the polymers, except polymer A‐1, exhibit thermotropic liquid crystalline properties. They also exhibit threaded and/or Schlieren textures examined by the polarizing microscope which indicate a nematic phase. In most cases, the mesophase exists up to ca. 400‐460°C shown by TGA study. The mesophase cannot exist above 400‐460°C because of the thermal decomposition.
Polyurethane elastomers with hydrolytic and thermooxidative stability. II. Polyurethanes with n‐alkylated polyurethane soft blocks
Authors: Chapman Toby M. , Benrashid Ramazan
Published: April 2003

Block copolyurethanes with N‐alkylated polyurethanes as nonself‐associating soft segments are prepared. The polymers compare well in hydrolytic stability with block copoly(N‐alkylamide urethane)s prepared in an earlier study but have better dimensional stability on exposure to moist heat. They show comparable hydrolytic stability and better oxidative stability than a poly(ether urethane) from the earlier study. The effect of different alkyl substituents on tensile properties and thermostability is studied. The tensile properties are also examined as a function of soft‐segment molecular weight at constant weight‐percent of hard‐block. It is shown that yield stress and ultimate stress increase and elongations decrease as the soft‐block M̄n increases. DSC measurements do not generally show well defined endotherms with few exceptions but dynamic mechanical testing of some samples does show transitions between 14 and 23°C.
Studies of alkylthio‐substituted aromatic diamines as curatives for polyurethane cast elastomers
Authors: Davis Robert L. , Nalepa Christopher J.
Published: April 2003

A series of alkylthio‐substituted aromatic diamines was synthesized using a convenient high yield procedure. The method consisted of heating a mixture of dialkyl disulfide and aromatic diamine in the presence of cuprous iodide or other Lewis acid catalyst. Dialkyl disulfide was continually replenished as consumed, throughout the reaction, to maintain the desired reaction temperature. Compounds so prepared were isolated by first precipitating the catalyst with solid caustic and then vacuum flashing the crude products. When desired, the final product purity could be increased by washing with acid to remove starting material or reaction intermediates. The final products were often liquids or low melting solids and showed utility as curatives for polyurethane cast elastomers. Alkylthio substitution of the aromatic diamines lowered reactivity toward isocyanates and generally provided for facile processing during molding. The series of derivatives allowed for great flexibility in controlling both diamine reactivity and the physical properties of the final elastomers. These benefits arose from the diverse electronic, steric and isomeric properties of the derivatives. Polymers were prepared from the alkylthio‐substituted compounds and commercially available TDI‐based prepolymers using conventional cast elastomer techniques. The physical properties of the polymers were determined and their relation to alkylthiodiamine structure examined.
Living carbocationic polymerization of p‐halostyrenes. III. Syntheses and characterization of novel thermoplastic elastomers of isobutylene and p‐chlorostyrene
Authors: Kennedy J. P. , Kurian Joseph
Published: April 2003

Novel linear and three‐arm star radial thermoplastic elastomers (TPE) comprising rubbery polyisobutylene (PIB) center blocks connected to glassy poly(p‐chlorostyrene) (PpClSt) outer blocks have been synthesized by sequential monomer addition. For triblock polymer synthesis isobutylene (IB) was added continuously to a bifunctional initiating system (dicumylmethyl ether/TiCl4) dissolved in CH3Cl/methylcyclohexane solvent mixture at –80°C. After the living PIB sequence has reached the desired molecular weight p‐chlorostyrene (pClSt) was added to produce the PpClSt end blocks. The synthesis conditions for the TPEs were developed with the help of model experiments using the 2‐chloro‐2,4,4‐trimethylpentane (TMPCl)/TiCl4 initiating system and subsequent PIB‐PpClSt diblock syntheses. The triblock and radiol block polymers after solvent extraction exhibited excellent TPE characteristics. Copolymer compositions were determined by 1H‐NMR and UV spectroscopy and further characterization was carried out by GPC, DSC, DMTA, and selective solvent extraction techniques. The TPEs exhibit two Tg's characteristic of glassy PpClSt (129°C) and rubbery PIB (−70°C) segments. Cast TPE films were clear and gave tensile strengths of 1.2‐21 MPa with elongations of 460–1500%. Transmission electron microscopy (TEM) of a triblock polymer containing ca. 38 wt % PpClSt suggests cylindrical PpClSt domains of 40–70 nm length and 25–35 nm diam embedded in a PIB matrix.
Polyurethane‐polyacrylamide IPNs. I. Synthesis and characterization
Authors: Nair Prabha D. , Jayabalan M. , Krishnamurthy V. N.
Published: April 2003

Hydrophobic‐hydrophilic interpenetrating polymer networks (IPNs) of polyurethane and polyacrylamide have been synthesized. The IPNs have been characterized by IR, thermal, and mechanical studies. SEM studies indicate phase mixing of some IPNs. Solvent resistance and surface hydrophilicity as evidenced by contact angle measurements suggest that these IPNs could be used for biomedical applications.
Liquid crystal polymers containing macroheterocyclic ligands. III. Side chain liquid crystalline polymethacrylates containing mesogenic units based on diarylacetylenes and benzo‐15‐crown‐5
Authors: Percec V. , Rodenhouse R.
Published: April 2003

The synthesis and polymerization of 4′‐[4‐ethynyl‐1‐(11‐methacryloylundecan‐1‐yloxy) benzene] benzo‐15‐crown‐5 (8), 4′‐[4‐ethynyl‐4′‐(11‐methacryloylundecan‐1‐yloxy) biphenyl] benzo‐15‐crown‐5 (15), 4′‐[2‐ethynyl‐6‐(11‐methacryloylundecan‐1‐yloxy) naphthalene] benzo‐15‐crown‐5 (24), and 4′‐[2‐ethynyl‐6‐(11‐methacryloylundecan‐1‐yloxy)naphthalene]‐5′‐ethylbenzo‐15‐crown‐5 (35) is described. The synthesis and characterization of 4′‐[4‐(4‐ethynyl‐1‐(2‐ethynyl‐6‐(6‐hydroxyhexan‐1‐yloxy)naphthathalene)benzene]) benzo‐15‐crown‐5 (29) is also presented. Both monomers and polymers were characterized for their mesomorphic behavior. 8, poly(8), and 15 are crystalline. Due to the insolubility of 15, poly(15) could not be synthesized. 24 is crystalline, while poly(24) displays a monotropic nematic mesophase. 29 exhibits also a monotropic nematic mesophase. 35 is crystalline, while poly(35) displays an enantiotropic nematic mesophase which is kinetically controlled due to its close proximity to the glass transition temperature.
Copolymers of 2‐vinyl‐4,4‐dimethylazlactone with styrene and ethyl α‐hydroxymethylacrylate
Authors: Muthiah Jeno , Mathias Lon J.
Published: April 2003

The monomer reactivity ratios for copolymerization of 2‐vinyl‐4,4‐dimethylazlactone (VA) and ethyl α‐hydroxymethylacrylate (EHMA) were 0.20–0.24 and 0.53–0.74, respectively, which show that EHMA is slightly more reactive with VA than with itself and should lead to random copolymers favoring alternation. The VA–styrene (VA–St) system also has a tendency to form random copolymers but with increased tendency for alternation with both r1 and r2 between 0.18–0.22. Tg's of VA–EHMA and VA–St copolymers varied between 100 and 136°C, and 96 and 117°C, respectively. Thermolysis of VA–EHMA copolymers resulted in crosslinking via the ring‐opening reaction of VA groups by EHMA alcohols, followed by transesterification involving EHMA units at higher temperatures leading to highly crosslinked structures. The performed dimer of EHMA and VA was also synthesized and found to be an effective crosslinking agent in free radical vinyl polymerizations.
Synthesis and characterization of new soluble aromatic polyimides from 3,4‐bis (4‐aminophenyl)‐2,5‐diphenylfuran and aromatic tetracarboxylic dianhydrides
Authors: Jeong Hwa‐Jin , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

New soluble polyimides with inherent viscosities of 0.2–0.6 dL/g were synthesized from 3,4‐bis (4‐aminophenyl)‐2,5‐diphenylfuran and various aromatic tetracarboxylic dianhydrides by the conventional two‐step method which involved ring‐opening polyaddition and subsequent cyclodehydration. Almost all of the polymides were generally soluble in a wide range of organic solvents such as N,N‐dimethylacetamide, 1,3‐dimethyl‐2‐imidazolidone, m‐cresol, o‐chlorophenol, and pyridine. The polyimide prepared from pyromellitic dianhydride was crystalline, whereas the other polyimides were amorphous. All the polyimides have glass transition temperatures in the range of 281–344°C and showed no appreciable weight loss up to 410°C in both air and nitrogen atmospheres.
Infrared spectral study of noncrystalline rodlike polymers
Authors: Gaudiana R. A. , Sinta R. F.
Published: April 2003

Oriented and unoriented films of noncrystalline, wholly‐aromatic, rodlike polyamides, and polyesteramides were examined by infrared spectroscopy. The results indicate that orientation, accomplished by means of mechanical stretching, approaches 80% in both polymer classes. Examination of the NH and the CO stretching region revealed an increase in the population of nonhydrogen bonded species (plateauing at ∼ 85%) as orientation increases. This unusual result may be caused by interchain steric interactions which may also be responsible for both the noncrystalline morphology and the non‐lyotropic behavior exhibited by these polymers.
Synthesis and electroconductivities of poly(2‐methoxy‐5‐methythio‐1,4‐phenylene vinylene) and copolymers
Authors: Jin Jung‐Il , Park Chi‐Kyun , Shim Hong‐Ku
Published: April 2003

Poly(2‐methoxy‐5‐methylthio‐1,4‐phenylene vinylene), PMTPV, and copolymers containing both unsubstituted or 2,5‐dimethoxy‐substituted and 2‐methoxy‐5‐methylthio‐1,4‐phenylene vinylene units were prepared in thin films from their water‐soluble, sulfonium salt precursor polymers. Doping of drawn and undrawn films of PMTPV with I2 vapor led to conductivities of 10−4–10−3 S cm−1, which is significantly lower than those reported for poly(2,5‐dimethoxy‐1,4‐phenylene vinylene). Conductivity of I2‐doped copolymer films ranges from 10−3–100 S cm−1 depending on composition.
A model of the kinetics of macrocyclic BPA carbonate formation
Authors: Kosky P. G.
Published: April 2003

Cyclic oligocarbonates are synthesized by two‐phase interfacial reactions of aryl bischloroformates in the presence of an amine phase transfer catalyst and an alkali: nClOCOArOCOCl + 4nNaOH → (OArOCO)n + 2nNaCl + nNa2CO3 + 2nH2O. The organocarbonate product may be a macrocyclic oligomer or a linear chain polymer. A qualitative mechanism for this behavior has been proposed by Brunelle, Boden, and co‐workers. Four steps are identifiable: activation of the aryl bischloroformate by the amine catalyst, hydrolysis of a portion of this intermediate at the aqueous/organic phase interface, oligomerization between activated and hydrolyzed moieties also at the interface, and chain terminating carbamate formation that leads to polymer. An important modification is made within the framework of the Brunelle and Boden mechanism. While the intramolecular cyclization reaction is formally second‐order overall, it behaves as a first‐order process. The kinetic constants for both this pseudo‐first‐order cyclization step and the corresponding second‐order linearization step are simply related. It is speculated that the above relationship can be generalized for a whole class of pseudo‐first‐ and second‐order rate constants for similar macrocyclic reactions.
Amorphous celluloses stable in aqueous media: Regeneration from SO2–amine solvent systems
Authors: Isogai A. , Atalla R. H.
Published: April 2003

Amorphous celluloses were prepared by regeneration of cellulose from its solutions in the SO2–diethylamine–dimethylsulfoxide (SO2–DEA–DMSO) solvent system, and other selected SO2–amine–organic solvents. The celluloses were amorphous whether regenerated in water or in alcohols or other organic solvents; in this respect the observations differ from all prior experience in the regeneration of cellulose. These celluloses retain their amorphous character even after extended soaking in water at room temperature. Viscosity measurements have shown that little or no depolymerization occurs during the dissolution, regeneration, and drying processes. Thus the procedures allow the preparation of amorphous celluloses of a wide range of molecular weights for use to model the behavior of amorphous domains in fibrous celluloses. The unusual stability of the amorphous cellulose structures prepared by these procedures is attributed to very rapid decomposition of the SO2–amine complex with the cellulosic hydroxyl groups which is believed to occur in the solvated state. The rate of decomposition of this complex appears to be sufficiently high so that the cellulose chains aggregate in an amorphous state before they have any opportunity to realign into crystalline domains.
Synthesis and characterization of silicon‐containing polyamides from aromatic sulfone ether diamines and aromatic organosilicon diacid chlorides
Authors: Jadhav A. S. , Maldar N. N. , Shinde B. M. , Vernekar S. P.
Published: April 2003

New polymides and copolyamides containing silicon and sulfone ether linkages, soluble in common aprotic solvents and having inherent viscosities of 0.3–0.6 dL/g have been synthesized by solution condensation of bis‐(4‐chlorocarbonyl phenyl) dimethylsilance (DMSC) and/or bis‐(4‐chlorocarbonyl phenyl) diphenylsilance (DPSC) with 4,4′‐[sulfonylbis‐(4,1‐phenylenoxy)] bisbenzenamine, 3,3′‐[sulfonylbis (4,1‐phenyleneoxy)] bisbenzenamine, and bis (4‐aminophenyl) ether. These polymers were characterized by infrared spectra, solution viscosity, thermooxidative degradation, differential scanning calorimetry, and x‐ray diffraction. These polymers show good thermal stability.
Cinnamate ester containing liquid crystalline side chain polymers
Authors: Whitcombe M. J. , Gilbert A. , Hirai A. , Mitchell G. R.
Published: April 2003

The synthesis of methacrylate esters of 4‐cyanophenyl‐(4‐(ω‐hydroxyalkyloxy)) cinnamates, with spacer lengths of 2 and 6 methylene units and the synthesis of the corresponding acrylate ester with a spacer of 2 methylene units are described. The methacrylate monomers were polymerized by free radical polymerization, both as homopolymers and as copolymers with the analogous benzoate monomer of spacer length 6. The acrylate ester could not be polymerized successfully under the same reaction conditions. Polymers were characterized by NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermo‐optic observations. Of the monomers prepared, only the cinnamate with a hexamethylene spacer shows a mesophase, seen on supercooling of the melt. All of the polymers prepared were liquid crystalline, with smectic behavior predominating in the polymethacrylates with the longer spacer group. A narrow nematic region is seen just below the clearing temperature with a range of 3–9°C, nematic character is increased in the copolymer series with the degree of incorporation of the cinnamate monomer with the spacer group of length 2.
Polymerization of vinyl monomers initiated by KO2–charge transfer agent systems. II
Authors: Han Yang‐Kyoo , Kim Ji‐Heung , Choi Sam‐Kwon
Published: April 2003

Vinyl monomers having electron acceptor groups such as nitroethylene, acrylonitrile, and acrolein were polymerized by KO2–charge transfer agent initiator systems in dimethylsulfoxide (DMSO) at 25°C. The new initiator systems were found to be stable for almost 1 month under nitrogen atmosphere. The initial rate of polymerization was so fast that both conversion and molecular weight of the polymers obtained were high. Especially their molecular weight distribution was observed to be very narrow by means of gel permeation chromatography (GPC). The anion radicals generated by one electron transfer from potassium superoxide (KO2) to charge transfer agents such as naphthalene, benzoquinone, azobenzene, etc., were suitable as initiator for the anionic polymerization of electron acceptor monomers. Study on block copolymerization of nitroethylene with acrylonitrile or acrolein was also attempted.
Selective degradation of silicone copolymers and networks
Authors: Keohan F. L. , Swint S. A. , Buese M. A.
Published: April 2003

An exhaustive end‐capping method for the analysis of silicone copolymers and networks using hexamethyldisiloxane in the presence of trifluoromethanesulfonic acid was demonstrated. The hard block of a polymide‐co‐polysiloxane was isolated by the equilibration of the copolymer with a large excess of hexamethyldisiloxane and subsequently examined by size exclusion chromatography. Addition cured polyimidesiloxane networks were also equilibrated with an excess of the disiloxane and the resulting oligmoers characterized by gas chromatography of the end‐capped fragments.
Molecular engineering of liquid crystal polymers by living polymerization. II. Living cationic polymerization of 11‐[(4‐cyano‐4′‐biphenyl) oxy] undecanyl vinyl ether and the mesomorphic behavior of the resulting polymers
Authors: Percec V. , Lee M. , Jonsson H.
Published: April 2003

The synthesis and living cationic polymerization of 11‐[(4‐cyano‐4′‐biphenyl)oxy]‐undecanyl vinyl ether (6–11) are described. The mesomorphic phase behavior of poly(6–11) with different degrees of polymerization was compared to that of 6–11 and of 11‐[(4‐cyano‐4′‐biphenyl) oxy] undecanyl ethyl ether (8–11) which is the model compound of the monomeric structural unit of poly(6–11). 6–11 displays a monotropic SA and a monotropic nematic mesophase while 8–11 an enantiotropic SA mesophase. Poly(6–11) with low degrees of polymerization exhibits an enantiotropic SA mesophase. Poly(6–8) with high degrees of polymerization displays an enantiotropic SX (i. e., an unidentified smectic phase) and an enantiotropic SC mesophase. These results demonstrate that the transformation of the nematic mesophase of the monomer into a smectic mesophase after polymerization, occurs at the level of monomeric structural unit.
Polychloromethylstyrene microspheres: Synthesis and characterization
Authors: Margel Shlomo , Nov Eliahu , Fisher Inna
Published: April 2003

The synthesis and characterization of polychloromethylstyrene microspheres are described. The effect of various factors, e.g., monomer concentration, surfactant concentration, solvents, crosslinker, etc., on the yield, diameter, and size distribution of these microspheres was elucidated. Conditions to covalently bind various primary amino ligands to these microspheres in aqueous solution were also established. The possible routes to modify the surface of these microspheres to obtain functional groups other than chloromethyl are discussed.
Thermotropic liquid crystalline polymer. III. Synthesis and properties of poly(amide‐azomethine‐ester)
Authors: Li Chien‐Hui , Chang Teh‐Chou
Published: April 2003

A series of novel dialdehydes as new monomers, 4,4′‐diformyl‐α,ω‐diphencarbonylalkane, 4,4′‐diformyl‐3,3′‐methoxy‐α,ω‐diphencarbonylalkane, and 4,4′‐diformyl‐3,3′‐ethoxy‐α,ω‐diphencarbonylalkane, was prepared from aliphatic diacid chloride with p‐hydroxybenzaldehyde, vanillin, and 3‐ethoxy‐4‐hydroxybenzaldehyde, respectively. A series of poly(amide‐azomethine‐ester)s was prepared by condensation of 4,4′‐diaminoanilide with 4,4′‐diformyl‐α,ω‐α,ω‐diphencarbonylalkane, 4,4′‐diformyl‐3,3′‐methoxy‐α,ω‐diphencarbonylalkane, and 4,4′‐diformyl‐3,3′‐ethoxy‐α,ω‐diphencarbonylalkane, respectively. Their thermotropic liquid crystalline properties were examined by DSC microscope observations. In most cases, the mesophase extends up to ca. 288–380°C, where thermal decomposition prevents further observation.
Investigation of the formation of poly(ethylene terephthalate) with model molecules. IV. Catalysis of the esterification of ethylene glycol with benzoic acid and of the condensation of ethylene glycol monobenzoate
Authors: Otton Jean , Ratton Serge
Published: April 2003

The esterfication of ethylene glycol (EG) with benzoic acid (BA) is an acid‐catalyzed reaction which leads, as a first intermediate, to ethylene glycol monobenzoate (EGMB). This compound has an OH group which is more active towards carboxylic groups than the first OH group of EG. Moreover, it is a key intermediate in the formation of sideproducts containing diethylene glycol (DEG) moieties. The condensation reaction of EGMB was particularly studied in the presence of carboxylic acids or metal derivatives as catalysts. Titanium is the most active. Sb, which is widely used in the industrial synthesis of PET, needs to be present at a high level of concentration to show an activity. The presence of carboxylic groups in the reaction medium does not affect its activity, but it is necessary to remove the ethylene glycol as soon as it is formed in order to keep it active during the condensation reaction.
Polyisobutylene‐containing block polymers by sequential monomer addition. II. Polystyrene–polyisobutylene–polystyrene triblock polymers: Synthesis, characterization, and physical properties
Authors: Kaszas G. , Puskas J. E. , Kennedy J. P. , Hager W. G.
Published: April 2003

New linear and three‐arm star thermoplastic elastomers (TPEs) comprising a rubbery polysobutylene (PIB) midblock flanked by glass polystyrene (PSt) blocks have been synthesized by living carbocationic polymerization in the presence of select additives by sequential monomer addition. First, isobutylene (IB) was polymerized by bi‐ and trifunctional tert‐ether (dicumyl‐ and tricumyl methoxy) initiators in conjunction with TiCl4 conintiator in CH3Cl/methylcyclohexane (MeCHx) (40/60 v/v) solvent mixtures at −80°C. After the living, narrow molecular weight, distribution PIB (M̄w/M̄n = 1.1‐1.2) has reached the desired molecular weight, styrene (St) together with an electron pair donor (ED) and a proton trap (di‐tert‐butylpyridine, DtBP) were added to block PSt from the living chain ends. Uncontrolled initiation by protic impurities that produces PSt contamination is prevented by the use of DtBP. PSt‐PIB‐PSt blocks obtained in the absence of additives are contaminated by homopolymer and /or diblocks due to inefficient blocking and initiation by protic impurities, and exhibit poor physical properties. In contrast in the presence of the strong ED N,N‐dimethylacetamide (DMA) and DtBP the blocking of St from living PIB chain occurs efficiently and block copolymers exhibiting good mechanical properties can be prepared. Virgin TPEs can be repeatedly compression molded without deterioration of physical properties. The products exhibit a low and a high temperature Tg characteristic of phase separated PIB and PSt domains. Transmission electron microscopy of linear triblocks containing ∼ 34 wt % PSt also indicates microphase separation and suggests PSt rods dispersed in a PIB matrix.
Preparation of polymide‐imides by direct polycondensation with triphenyl phosphite. V. Aliphatic‐aromatic polyamide‐imides based on N,N′‐bis(ω‐carboxyalkyl) benzophenone‐3,3′,4,4′‐tetracarboxylic diimides
Authors: Hsiao Sheng‐Huel , Yang Chin‐Ping
Published: April 2003

Five diimide‐dicarboxylic acids were prepared from benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride and glycine, β‐analine, 4‐aminobutyric acid, 6‐aminocaproic acid, and 11‐aminoundecanoic acid. New aromatic‐aliphatic polyamide‐imides were prepared by the direct polycondensation of these diacids with aromatic diamines using triphenyl phosphite in N‐methyl‐2‐pyrrolidone (NMP)–Pyridine solution in the presence of calcium chloride. The resulting polymers were characterized by inherent viscosity, infrared spectra, elemental analyses, solubility, differential scanning calorimetry (DSC), thermogravimetry, and wideangle x‐ray diffraction measurements.
Synthesis and characterization of random poly(amide‐sulfonamide)s. II. Polymers from unsymmetrical diamine monomers
Authors: Adduci Jerry M. , Rochanapruk Theverak
Published: April 2003

Novel poly(amide‐sulfonamide)s have been prepared by reacting terephthalic, isophthalic, and sebacic acid and their acid chlorides with variously substituted diamines containing preformed sulfonamide linkages utilizing solution polymerization techniques. Inherent viscosities of the prepared polymers varied from 0.22 to 1.21 dL/g. Those having inherent viscosities greater than 0.4 dL/g formed clear, tough, flexible films. Glass transition temperatures ranged from 87 to 273°C. Thermogravimetric analyses of the polymers showed moderate thermal stability.
Mechanistic study on mechanochemical polymerization of acrylamide
Authors: Kuzuya Masayuki , Kondo Shin‐Ichi , Noguchi Akihiro , Noda Nahoko
Published: April 2003

The ESR study of the radicals formed in mechanochemical polymerization of acrylamide (AAM) was undertaken. The nature of the radical formation was compared with the mechano‐radical formation produced by mechanical fracture of polyacrylamide (PAAM). The structure of radicals formed were all identified to be an end‐chain radical, equivalent to a polymer‐chain propagating radical. The computer simulation disclosed that the observed spectra of the propagating radical can be approximated essentially by two kinds of component spectra, a large amount of triplet, and a small amount of quarter (a triplet of doublets). Thus, the existence of two major conformers in a single end‐chain radical has been proposed. The ESR kinetics of the radical formation were further studied and its correlation with the nature of polymerization (the changes in molecular weight and polymer conversion) was discussed.
Polymer precursor synthesis of alumina fibers
Authors: Chien James C. W. , Yang Yingsong , Martinez J. R. , Dong Sizhong , Telluri Venkatesh , Jakus Karl
Published: April 2003

High strength alumina fibers were fabricated with a polymer precursor process which was monitored with 13C‐NMR, elemental analysis, gas evolution, SEM, and X‐ray diffraction. Methylaluminoxane was chain extended by reaction with H2O, the unreacted methyl groups were converted to propanoyloxyl and i‐propanoyl groups in molar ratios of 0.2 : 0.8 to 0.4 : 0.6 to afford spinning dope of adequate fluidity which can be spun into filaments with suitable stability. These precursor fibers were hydrolyzed in two stages at ambient temperatures and at 320–350°C, and then calcined at 950°C. The resulting alumina fibers have average tensile strengths up to 1.1 GPa and modulus of greater than 140 GPa.
High activity magnesium chloride supported catalysts for olefin polymerization. XXIX. Molecular basis of hydrogen activation of magnesium chloride supported Ziegler–Natta catalysts
Authors: Chien James C. W. , Nozaki Takashi
Published: April 2003

Hydrogen (pH2 = 72 torr) increases the rate of propylene polymerization by a MgCl2/ethyl benzoate/p‐cresol/AlEt3/TiCl4‐AlEt3/methyl‐p‐toluate catalyst (CW‐catalyst) by two‐to three‐fold which corresponds closely with the increase in the number of active sites as counted by radiolabeling with tritiated methanol. The oxidation states of titanium in decene polymerizations by the CW‐catalyst were determined as a function of time of polymerization (tp). In the absence of H2, all [Ti+n] for n = 2, 3, 4 remain constant during a batch polymerization. In the presence of H2 and within 5 min of tp, [Ti+2] decreases by an amount, corresponding to 15% of the total titanium and [Ti+3] increases by the same amount, while [Ti+4] is not changed. Therefore, three‐fourths of the H2 activation result from oxidative addition processes. The remaining one‐fourth of the H2 activation may be attributed to the activation of previously deactivated Ti+3 ions by hydrogenolysis. Monomer converts some of the EPR silent Ti+3 sites to EPR observable species resulting in their activation.