bluuebunny/crossref_metadata_2025 huggingface dataset:
Homopolymerization of methyl methacrylate by novel salicylaldiminate‐nickel/methylaluminoxane catalysts obtained by oxidative addition of the chelate ligand to a nickel(0) precursor
Authors: Carlini Carlo , Martinelli Marco , Raspolli Galletti Anna Maria , Sbrana Glauco
Published: April 2003

Salicylaldimine ligands, such as 5‐nitro‐N(2,6‐diisopropylphenyl)salicylaldimine, 3,5‐dinitro‐N(2,6‐diisopropylphenyl)salicylaldimine, and 3‐phenyl‐N(2,6‐diisopropylphenyl) salicylaldimine were checked in the oxidative addition to bis(1,5‐cyclooctadiene)nickel(0) to prepare, after activation by methylaluminoxane (MAO), novel nickel‐based catalytic systems active in the polymerization of methyl methacrylate. The catalytic behavior of the aforementioned systems, in terms of activity, molecular weight, and polydispersity of the resulting poly(methyl methacrylate) as well as its stereoregularity degree, was investigated as a function of the Al/Ni molar ratio, reaction temperature, and nature of the salicylaldimine ligand. The effect of ethylene atmosphere present during the preparation of the catalyst precursors was also investigated. The results are discussed and compared with those previously obtained by bis(salicylaldiminate)nickel(II)/MAO catalytic systems. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1716–1724, 2003
Synthesis of transition‐metal‐ion‐selective poly(N‐isopropylacrylamide) hydrogels by the incorporation of an Aza crown ether
Authors: Kuckling Dirk , Pareek Pradeep
Published: April 2003

A functionalized cyclam was synthesized by the attachment of a polymerizable acryloyl group to one of the four nitrogens on the cyclam molecule. The polymerization of the functionalized cyclam was performed with N‐isopropylacrylamide and N,N′‐methylene bisacrylamide, and the gels obtained were studied in the presence of different transition‐metal‐ion solutions. There was a drastic difference in the phase‐transition temperature (Tc) of the poly(N‐isopropylacrylamide) (PNIPAAm)/cyclam gel in comparison with the pure PNIPAAm gel. For the described system, a Tc shift of 15 °C was obtained. The presence of functionalized cyclam increased the hydrophilicity and Tc of the aforementioned polymer gels in deionized water (at pH 6) because of the presence of protonated amino moieties. The PNIPAAm/cyclam gels showed a dependence of the swelling behavior on pH. Tc of the pure PNIPAAm gel was weakly influenced by the presence of any transition‐metal ions, such as Cu2+, Ni2+, Zn2+, and Mn2+. The addition of Cu2+ or Ni2+ to the PNIPAAm/cyclam gel reduced Tc of the polymer gel, and a shift of approximately 12 °C was observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1594–1602, 2003
Novel acrylic macromonomer with amphiphilic character derived from Triton X‐100: Radical copolymerization with methyl methacrylate and thermal properties
Authors: Larraz Elena , Elvira Carlos , San Román Julio
Published: April 2003

This article explores the synthesis of a novel methacrylic macromonomer with an amphiphilic character derived from poly(ethylene glycol) tert‐octylphenyl ether (MT) and its respective homopolymer. To know their reactivity in radical copolymerization reactions with methyl methacrylate (MMA), a model monomer (MTm) was synthesized to determine the reactivity ratios and compare them with the low molar fractions of copolymers of MT with MMA because they were difficult to isolate. They were rMTm = 0.97 and rMMA = 0.95. The compositional diagrams when representing the weight fraction of MT and MTm in the feed and the copolymer suggested that a clear correlation exists between the experimental points of the model monomer MTm and the macromonomer MT ones, suggesting that the length of the side poly(ethylene oxide) chain does not affect the reactivity of the methacrylic double bond in the prepared monomers for this type of polymerization reaction. The reactivity ratios of the copolymers have a tendency for the formation of random or Bernoullian copolymers. The glass‐transition temperatures (Tg's) of the prepared copolymers were determined by differential scanning calorimetry, deviated from the Fox equation, and discussed on the basis of treatments that consider the influence of the monomeric units along the copolymer chains, determining the Tg of the corresponding alternating dyads. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1641–1649, 2003
Conformational analysis of dipeptide‐derived polyisocyanides
Authors: Cornelissen Jeroen J. L. M. , Graswinckel W. Sander , Rowan Alan E. , Sommerdijk Nico A. J. M. , Nolte Roeland J. M.
Published: April 2003

The conformational properties of polymers derived from isocyanodipeptides have been investigated with a combination of model calculations, X‐ray diffraction, and circular dichroism spectroscopy. Depending on the configuration of the side chains, defined arrays of hydrogen bonds along the polymeric backbone are formed. This leads to a well‐defined conformation as, for example, expressed in the formation of lyotropic liquid‐crystalline phases and increased helical stability. Upon the disruption of the hydrogen bonds by a strong acid, a less well‐defined macromolecular conformation is observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1725–1736, 2003
Roles of rhenium diimine complexes as metal‐ion probes and photosensitizers in functional polyurethanes
Authors: Hui Ching Sum , Lam Lillian Sze Man , Yin Chun , Chan Wai Kin , Djurišić Aleksandra B.
Published: April 2003

Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10−3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003
Synthesis and self‐assembly of a chiral alternating sexithiophene–undeca(ethyleneoxy) block copolymer
Authors: Henze Oliver , Fransen Michel , Jonkheijm Pascal , Meijer E. W. , Feast W. James , Schenning Albertus P. H. J.
Published: April 2003

An oligothiophene/chiral oligo(ethyleneoxy) block copolymer (PolyT6) has been synthesized in which a sexithiophene block alternates with a well‐defined chiral undeca(ethyleneoxy) block. The polymer shows good solubility in chloroform, and ultraviolet–visible studies in this solvent reveal a spectrum similar to that of the chirally substituted monomeric sexithiophene (T6) analogue. The aggregation of PolyT6 occurs in dioxane; however, no helicity is present in this aggregate, in contrast to aggregated T6. This behavior illustrates that although the processability and mechanical robustness of block copolymers may be superior to those of analogous oligomers, the degree of self‐assembled order found in oligomer‐based systems may be lost in the polymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1737–1743, 2003
Copolymerization of cationic monomers with acrylamide in an aqueous solution
Authors: Tanaka Hiroo
Published: April 2003

The radical copolymerizations of commercially available cationic monomers (M1) with acrylamide (M2) have been investigated at pH 6.1 in aqueous solutions. The cationic groups in copolymers were analyzed by a colloid titration method and the reactivity ratios were determined by the Fineman–Ross method. The values of r1 and r2 were 1.71 and 0.25 for methacryloyloxyethyltrimethylammonium chlorideM2, 1.68 and 1.26 for N,N‐dimethylaminoethylmethacrylateM2, 1.13 and 0.57 for methacrylamidopropyltrimethylammonium chlorideM2, 1.10 and 0.47 for N,N‐dimethylaminopropylmethacrylateM2, 0.47 and 0.95 for N,N‐dimethylaminopropylacrylamideM2, 0.48 and 0.64 for acryloyloxyethyltrimethylammonium chloride‐M2, and 0.58 and 6.7 for dimethyldiallylammonium chloride‐M2 systems. The Alfrey‐Price Q and e values were calculated and the linear relationship between log Q and ultraviolet absorption maxima of cationic monomers was found.
Carbazole substituted N‐acylated linear polyethylenimines (PEI). synthesis and characterization of poly[N‐(9‐carbazolyl)acetylethylenimine] and poly[N‐(2‐(9‐carbazolyl))propanoylethylenimine]
Authors: Arora Kartar S. , Overberger C. G.
Published: April 2003

The synthesis of carbazola substituted N‐acylated polyethylenimines, namely, poly[N‐(9‐carbazolyl)acetylethylenimine] 20 and poly[N‐(2‐(9‐carbazolyl))propanoylethylenimine] 21 by a grafting reaction onto PEI and isomerization polymerization of the carbazole substituted 2‐oxazolines is reported. A complete acylation of amino groups in PEI by the 9‐carbazolylacetyl groups was achieved by the p‐nitrophenyl active ester method but PEI was only partially N‐acylated by the 2‐(9‐carbazolyl)propanoyl groups under similar reaction conditions. The carbazole substituted 2‐oxazolines, namely, 2‐(9‐carbazolyl)methyl‐2‐oxazoline 18 and (R,S)‐2‐[1‐(9‐carbazolyl)]ethyl‐2‐oxazoline 19, were prepared by a base induced cyclization of ß‐chloroamides. The ring‐opening isomerization polymerization of 18 and 19 in the molten state with a cationic initiator (dimethyl sulfate, methyl triflate, or ethylene glycol ditosylate) gave 20 and 21. Gel permeation chromatography of 20 and 21 obtained with different monomerto‐initiator ratios gave evidence of a chain transfer reaction with the monomer. The polymers were characterized by elemental analyses, IR, and 1H‐NMR spectroscopy.
Permeation control of ionic fluorescent probes by ambient pH changes from nylon capsule membranes depending on their microstructures
Authors: Seki Takahiro , Okahata Yoshio
Published: April 2003

Permeations of water‐soluble, ionic fluorescent probes from a large, ultrathin nylon‐2,12 capsule membrane were largely affected by the ambient pH of the outer medium; permeations of cationic and anionic probes were accelerated by a factor of 50–100 in the basic and acidic medium, respectively, relative to that in the neutral‐pH region. The permeation of NaCl and nonionic fluorescent probes was hardly affected by the ambient pH. The nylon capsule membrane was elucidated to have an asymmetrical structure: the dense‐thin inner layer and the porous‐thick outer part. The pH‐sensitive permeation could be explained due to the ionization of a small amount of residual end‐groups (COOH and NH2) existing in the dense‐thin inner layer of the nylon capsule membrane.
Cationic polymerization of p‐methylstyrene initiated by acetyl perchlorate: An approach to living polymerization
Authors: Tanizaki Akio , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

The cationic polymerization of p‐methylstyrene initiated by acetyl perchlorate at −78°C led to long‐lived (living‐like) polymers with a narrow molecular weight distribution (M̄w/M̄n = 1.1–1.4) in methylene chloride containing a common ion salt (n‐Bu4NClO4) or in a less polar solvent (CH2Cl2/toluene, 1/4v/v). Under these conditions, the number‐average molecular weight (M̄n) of the polymers increased in proportion to monomer conversion and was regulated by the monomer‐to‐initiator ratio. When fresh feeds of the monomer were repeatedly added to a completely polymerized solution, the polymerization ensued at the same rate as before and the linear increase in M̄n with monomer conversion continued. The effects of solvent polarity and the common ion salt on the polymerization showed the suppression of the ionic dissociation of the propagating species, resulting in a “nondissociated species,” to be the key factor for the formation of the long‐lived polymers.
Preparation of silicon‐containing polymers IV. Thermally stable organosilicon poly‐1,2,4‐triazoles
Authors: Ghatge N. D. , Jadhav J. Y. , Shinde B. M. , Misra B. M.
Published: April 2003

Novel silicon‐containing poly‐1,2,4‐triazoles have been synthesized by the reaction of polyhydrazide precursors and aniline in polyphosphoric acid (PPA) at 260°C. The polyhydrazide intermediates were prepared from aromatic dihydrazides and silicon‐containing acid dichlorides via interfacial polycondensation. These polymers and their intermediates were characterized by infrared spectroscopy (IR), solubility, and by solution viscosity. The thermal behavior of these polytriazoles has been studied by dynamic thermogravimetry.
Determination of molecular weight distribution of nylon 12 by gel permeation chromatography
Authors: Ogawa Toshio , Sakai Masakazu , Ishitobi Wataru
Published: April 2003

Molecular weight distribution of Nylon 12 was determined with hexafluoroisopropanol/toluene mixture as eluent by gel permeation chromatography. Calibration curve for Nylon 12 was easily obtained from that of polystyrene because the method of universal calibration was applicable among these polymers. The molecular weight distributions of Nylon 12 were always broader than expected by the theory of polymerization, i.e., most probable distribution. This result was not caused by broadening effect in gel permeation chromatography, but by polymerization itself.
Polymers of ortho‐vinylbenzaldehyde
Authors: Roth Robert J. G. , Rudin Alfred , Tchir Morris F.
Published: April 2003

Ortho‐vinylbenzaldehyde has been prepared in a three‐step synthesis. Vacuum‐degassed monomer was polymerized with azodiisobutyronitrile initiator in bulk and in solution in 2‐butanone. The kp/kt1/2 value at 60°C is 4.7 × 10−2 L1/2 mol−1/2s−1/2. This is about twice the ratio for styrene. Chain transfer to monomer appears to be significant. Insoluble, crosslinked products were produced at high conversions, because of chain transfer to polymer. Tg of poly(ortho‐vinylbenzaldehyde) was found to be 142°C.

Polymers made under N2 atmosphere often contained acetal groups. These can be produced by acid catalysis in the presence of small concentrations of ortho‐vinylbenzyl alcohol. A laddertype structure is produced.

The monomer is capable of photoinitiation. Insoluble gels were produced in bulk monomer at all conversions. The initiation rate was very high and crosslinking resulted from combination of radicals produced from photolysis of the pendant 0‐benzaldehyde groups in the macromolecules.
Cationic polymerization initiated by intercalation compounds of lewis acids. II. Initiating ability and mechanism of action of the initiators
Authors: Rashkov Iliya Bl. , Gitsov Ivan
Published: April 2003

The initiating ability of the graphite intercalation compounds (GICs) of SbCl5, FeCl3, and AlBr3 was investigated. It was found that GICs were able to initiate the polymerization of monomers of different types–cyclosiloxanes, 1,2‐epoxides, vinyl ethers, lactones, and vinyl monomers. GICs of SbCl5 initiated also the polymerization of tetrahydrofuran. The interaction of the monomers (with the exception of the lactones) caused a size increase of the GICs and deformations in their lamellar structure. Relatively high‐molecular poly(vinyl ethers) and polydimethylcyclosiloxanes were obtained. The mechanism of action of GICs was discussed.
Radical copolymerization of γ‐methylene‐Δα,β‐butenolide derivative: ethyl(E)‐5‐OXO‐2,5‐dihydrofuran‐2‐ylidene‐acetate
Authors: Nagai Katsutoshi , Akiyama Kazuhiko , Kuramoto Noriyuki
Published: April 2003

Radical polymerications including co‐ and terpolymerizations of a γ‐methylene‐Δα,β‐butenolide derivative, ethyl (E)‐5‐oxo‐2,5‐dihydrofuran‐2‐ylideneacetate(EODY) was investigated. The monomer had no homopolymerizability but copolymerized with styrene (ST) and 1,3‐cyclohexadiene to yield alternating copolymers. From IR and 1H‐NMR spectra of the copolymers, the 1,4‐addition was confirmed to exclusively occur for the conjugated double bond of EODY. Terpolymerization for the system involving an acceptor monomer such as maleic anhydride, α‐chloromaleic anhydride, or 7,7,8,8‐tetracyanoquinodimethane in addition to ST and EODY gave the terpolymer containing about 50 mol% of ST, in spite of a high fraction of ST in the feed. It was inferred that such an apparent behavior of EODY as an acceptor monomer could be due to a resonance‐stabilization of the propagating radical having EODY as a terminal unit, which is also responsible for the poor yields of the copolymers and terpolymers.
Synthesis and characteristics of microspheres of polystyrene derivatives
Authors: Shahar Michal , Meshulam Haim , Margel Shlomo
Published: April 2003

Two sytrene derivatives formylstyrene and styrene sulfonylcholoride, were synthesized. Polymeric microspheres in diameters ranging from 0.1 to 2 μm were synthesized by polymerization of chlormoethylstyrene, formylstyrene, and styrene sulfonylcholoride in organic solvents, in the presence of appropriate surfactants. The kinetics of microsphere formation were studied. The molecular weight distribution of the products was determined by gel permeation chromatography. Conditions for binding various amino ligands to the microspheres were also established.
Photolabeling studies of polymer–cell surface interaction. Evaluation of 3‐[(4‐azidophenyl)dithio]propionic acid as a polymer‐bound photolabel
Authors: Ramaswami V. , Tirrell D. A.
Published: April 2003

3‐[(4‐Azidophenyl)dithio]propionic acid (1a) was prepared in four steps from 4,4′‐diamino‐diphenyldisulfide. Attachment of 1a to poly[(3‐hydroxypropyl)oxirane] was accomplished under very mild conditions via an acid‐catalyzed caarbodiimide coupling. Photolysis of polymer‐bound 1a with an electronic flash unit proceeded without detectable disulfide bond cleavage. Mild reduction of the disulfide bond of an analogue of 1a which carried no azido group confirmed that 1a should be useful in photolabeling studies of polymer–cell surface interaction.
Radiation resistant amorphous–all aromatic polyarylene ether sulfones: Synthesis, characterization, and mechanical properties
Authors: Hedrick J. L. , Mohanty D. K. , Johnson B. C. , Viswanathan R. , Hinkley J. A. , McGrath J. E.
Published: April 2003

The synthesis and characterization of amorphous, aromatic, polyaryl ethers has been investigated. Detailed synthesis procedures are provided. The main thrust of these activities was to synthesize polymers which could serve as castable amorphous matrix resins for carbonfiber composites and which would be highly resistant to radiation degradation. It was important that these polymers not contain any aliphatic groups in order to contrast their behavior with the commercially available Bisphenol‐A polysulfones. The approach taken was to synthesize a series of statistical or random copolymers derived from hydroquinone and biphenol together with 4,4′‐dichlorodiphenyl sulfone. In order to produce copolymers of high molecular weight, modified techniques were developed which utilized potassium carbonate as a weak base and N‐methyl‐2‐pyrrolidone as the aprotic dipolar solvent. Detailed procedures are provided in this paper for the synthesis of high molecular weight copolymers of this type. In addition, stress‐strain, dynamic mechanical properties and preliminary electron beam (e‐beam) degradation studies are reported significantly. Improved mechanical property retention after e‐beam exposure was observed with the all aromatic polyether sulfones.
Correlation of thermal degradation mechanisms: Polyacetylene and vinyl and vinylidene polymers
Authors: Montaudo Giorgio , Puglisi Concetto , Scamporrino Emilio , Vitalini Daniele
Published: April 2003

The thermal degradation of poly(vinyl bromide) (PVB), poly(vinyl chloride) (PVC), poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), poly(vinyl fluoride) (PVF), poly(vinylidene chloride) (PVC2), and poly(vinylidene fluoride) (PVF2) has been studied by direct pyrolysis–mass spectrometry (DP‐MS) and flash pyrolysis–gas chromatography–mass spectrometry techniques. Vinyl and vinylidene polymers exhibit two competitive thermal degradation processes: (1) HX elimination with formation of polyene sequences which undergo further moleculaar rearrangements, and (2) main‐chain cleavage with formation of halogenated or oxigenated compounds. The overall thermal degradation process depends on the prevailing decomposition reaction in each polymer; therefore, different behaviors are observed. The thermal degradation of polyacetylene (PA) has also been studied and found important for the elucidation of the thermal decomposition mechanism of the title polymers.
Photodegradation of O‐methacryloyl ketone oxime‐methyl mechacrylate copolymers in the solid phase
Authors: Tsunooka Masahiro , Imono Syozo , Nakayama Kazuo , Kuwabara Hideaki , Tanaka Makoto
Published: April 2003

Several kinds of copolymers bearing O‐acyloxyimino groups were prepared and their photodegradabilities were examined. Copolymers of O‐methacryloyl ketone (acetophenone, benzophenone, or 2‐acetonaphthone) oxime and methyl methacrylate (or styrene) were photodegradable even in the solid phase but in the case of copolymers of O‐acryloyl acetophenone oxime and methyl methacrylate (or styrene) both photodegradation and photocrosslinking were observed. From these results it was found that the photodegradability of the copolymers was not dependent on the comonomer (methyl methacrylate or styrene) but dependent on the structure of the monomer bearing O‐acyloxyimino groups. From detailed analysis of photodegradation of the copolymer of O‐methacyloyl acetophenone oxime and methyl methacrylate in the presence of benzophenone it was found that the benzophenone worked not only as a sensitizer for the decomposition of O‐acyloxyimino groups but also as a plasticizer to assist segment motions of polymer chains and the diffusion of oxygen in the film.
Evolution of H2O and CO2 during the copper‐catalyzed oxidation of isotactic polypropylene
Authors: Jellinek H. H. G. , Wei You Ching
Published: April 2003

The kinetics and mechanism of H2O and CO2 evolution during uncatalyzed and copper(oxide)‐catalyzed (Cu, CuO, CuO0.67) oxidation of isotactic polypropylene have been investigated in detail for various catalysts over a range of temperatures (90–150°C). These volatiles were determined chromatographically; H2O and CO2 represent the main volatiles of the oxidation, comprising about 80 mol % of all volatiles. Uncatalyzed oxidation evolves ca. 1 mol of H2O and 1 mol of CO2 for each unit mole of polymer oxidized, while catalyzed oxidation produces 2 mol of H2O and ca. 1.2 mol of CO2 for each unit mole of polymer. These results indicate that secondary as well as tertiary H atoms on the polymer chains are involved in hydroperoxide formation and decay. The oxidation mechanism has been formulated and evaluated on this basis. It consists essentially of two parallel oxidation reactions involving tertiary and secondary groups (H atoms and hydroperoxides), respectively. The mechanism can be represented by first‐ and pseudo‐first‐order reactions in series: (1) oxygen absorption showing induction periods; (2) hydroperoxide formation and decay (plateaus are reached); (3) H2O evolution from the decay of hydroperoxides; and (4) subsequent CO2 production involving chain scission. Arrhenius parameters for all oxidation reactions (uncatalyzed and catalyzed) are also presented. It appears that CuO0.67 is the most efficient catalyst of those investigated.
Block copolymers derived from azobiscyanopentanoic acid. VI. Synthesis of a polyethyleneglycol–polystyrene block copolymer
Authors: Ueda Akira , Nagai Susumu
Published: April 2003

Polycondensations were carried out between azobiscyanopentanoly chloride (ACPC) and polyethyleneglycols (PEG) having average molecular weight of 600, 2000, 8400, and 21,500, resulting in the chain extended PEG of several times the original polymer chain length and containing scissile NN units of azobiscyanopentanoic acid (ACPA). The poly(polyethyleneglycol‐azobiscyanopentanoate), designated as \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} (PEG\rlap{--} )_n^*$\end{document} were thermally decomposed in the presence of styrene (St) to obtain PEG–PSt block copolymers. The amount of St consumed was proportional to [NN]0.5 and [St]1.2, whereas the chain length of the PSt segment was proportional to [NN]−0.5 and [St]0.8.
Preparation and properties of the polyester made from 2.2‐bis(4‐hydroxycyclohexyl)propane and adipic acid
Authors: Gaughan R. G. , Hill H. W. , Inda J. E.
Published: April 2003

Poly[2,2‐bis(4‐oxycyclohexyl)propane adipate] was formed by melt polymerizing adipic acid and 2,2‐bis(4‐hydroxycyclohexyl)propane in the presence of n‐butylhydroxyoxostannane. This polyester possessed a melting temperature (Tm) of 200°C and a glass transition temperature (Tg) of 75°C. An excellent notched impact strength of 22 ft. lbs./in. was its best physical property.
Functional polymers and sequential copolymers by phase transfer catalysis. XIX. Thermotropic polythioethers and copolythioethers based on 4,4′‐dithiolbiphenyl
Authors: Shaffer Timothy D. , Percec Virgil
Published: April 2003

Thermotropic liquid crystalline (LC) polythioethers and copolythioethers have been synthesized from 4,4′‐dithiolbiphenyl (TB) and α,ω‐dibromoalkanes having between two and twelve methylene units. Copolythioethers were prepared from TB and a 1:1 mol/mol ratio of 1,5‐dibromopentane and α,ω‐dibromoalkanes having nine to twelve methylene units. Peculiarities of the phase‐transfer catalyzed (PTC) polyetherification reaction in the preparation of these polymers have led to aliphatic‐ether structural units. This side reaction has been explained by a possible neighboring group effect with sulfur, through sulfonium formation, and is consistent with a mechanism previously proposed in PTC polyetherifications. While not significantly enhancing solubility, the copolymeric nature of these polymers have led to lower melting and isotropization temperatures with broad mesophase thermal stability ranges. Lastly, unique spherulitic textures resembling higher‐ordered smectic mesophases have been observed in all the prepared polymers.
Kinetics of reaction of methyl α‐eleostearate with phenol
Authors: Yoshimura Yukio
Published: April 2003

The kinetics of addition reactions between methyl α‐eleostearate which forms the main chain of tung oil and phenol when catalyzed by an acid, p‐toluene sulfonic acid, have been studied. The addition reactions, carried out with phenol was shown to be second order with regard to methyl α‐eleostearate concentration and first order with regard to phenol concentration. The reactions were additions of two phenol molecules to one methyl α‐eleostearate molecule, and it was presumed that they proceed in the two steps given below in which the first step is rate determining:

The apparent reaction rate constant (l/mol min) was found to be 0.036 and its value was nearly equal to that in the case of m‐cresol. The apparent activation energie (kcal/mol) was found to be 4.76 and its value was larger than that in the case of m‐cresol.
Polymerization by phase‐transfer catalysis 3: Poly(1,4‐oxylylene thioethers) synthesis
Authors: Tagle L. H. , Diaz F. R. , De La Maza M. P. , Vega J. C.
Published: April 2003

Poly(1,4‐oxylylenethioethers) were synthesized from 2,5‐disubstituted‐1,4‐bis(chloromethyl)‐benzenes and sodium sulfide under phase‐transfer conditions. The polythioethers were characterized by elemental analysis and infrared spectroscopy. The effect of the catalyst, solvent, and temperature were studied. Their glass transition temperature and thermal decomposition were determined.
Synthesis and characterization of model compounds for carbazole‐substituted N‐acylated linear polyethylenimine (PEI). Synthesis and 1H‐NMR spectra of N‐acylated diethylamine and N,N′‐dimethyl‐1,2‐ethanediamine containing 9‐carbazolylacetyl, (R,S)‐ or (R)‐2‐(9‐carbazolyl)propanoyl groups
Authors: Arora Kartar S. , Overberger C. G.
Published: April 2003

The synthesis of N,N‐diethyl‐9‐carbazolylacetamide (6), (R,S)‐ and (R)‐N,N‐diethyl‐2‐(9‐carbazolyl)propanamide (7), N,N′‐dimethyl‐N,N′‐di‐(9‐carbazolylacetyl)‐1,2‐ethanediamine (11), and (R)‐N,N′‐dimethyl‐N,N′‐di[2‐(9‐carbazolyl)propanoyl]‐1,2‐ethanediamine (13) is reported. The racemic compound, (R,S)‐2‐(9‐carbazolyl)propanoic acid (2), was resolved by partial crystallization of the diastereomeric salts formed between 2 and (+)‐α‐methylbenzylamine. The 1H‐NMR spectra of 6 and 7 showed magnetic nonequivalence of the chemically equivalent protons of the methyl and methylene groups in 6 and 7 due to partial double bond character of the amide bond. The upfield resonances corresponding to the two sets of methyl and methylene protons were assigned by the aromatic solvent‐induced shift (ASIS) method to the protons anti to the carbonyl oxygen in the conformation of amide bond in 6 and 7. The 1H‐NMR spectra of 11 and (R)‐13 were used to determine the population of anti‐anti, anti‐syn (syn‐anti) and syn‐syn conformers in the structures of these dimer model compounds; the relative conformer populations were 0.45:0.47:0.08 and 0.28±0.02:0.29±0.01:0.43±0.01 in 11 and (R)‐13.
Synthesis of polyesters containing nucleic acid base derivatives as pending side chains
Authors: Lu C. X. , Li Qiang , Zhang Dehong , Ji Aixue
Published: April 2003

Preparations of four diol monomers containing nucleic acid bases and the corresponding model polymers of polynucleotides with linear polyester backbone and nucleic acid base derivative as pending side chains are described. N‐(1′,3′‐Dihydroxy‐2′‐methyl‐2′‐propyl)‐2‐(thymin‐l‐yl)propionamide (Ia, HMPTPA), N‐(1′,3′‐dihydroxy‐2‐methyl‐2′‐propyl)‐2‐(uracil‐l‐yl)propionamide (Ib, HMPUPA), and their isomers, N‐(β,β′‐dihydroxyethyl)‐2‐(thynin‐1‐yl)propionamide (IIa, HETPA) and N‐(β,β′‐dihydroxyethyl)‐2‐(uracil‐1‐yl)propionamide (IIb, HEUPA) were synthesized through the selective N‐acylation of 2‐methyl‐2‐amino‐1,3‐propanediol and diethanolamine with 2‐(thymin‐1‐yl)propionic acid (TPA) and 2‐(uracil‐1‐yl)propionic acid (UPA), respectively, by the active amide‐benzotriazole method. Diol monomers I and II were polycondenzed with active amide of benzotriazole such as 1,1′‐(isophthaloyl)bisbenzotriazole (IPBBT) in the presence of triethylamine and in DMF at 60°C, giving polyesters containing thymine and uracil derivatives as the side group. Prior to polymer synthesis, an O‐acylation of Ia using the active monoamide l‐benzoylbenzotriazole was carried out as a model compound study.
Precipitation polymerization of acrylamide using vazo‐33 as an initiator and acetonitrile/water mixtures as the solvent
Authors: Tai Eva F. , Caskey Jerry A. , Allison Bruce D.
Published: April 2003

Precipitation polymerization of acrylamide initiated by a thermal initiator, Vazo‐33 (DuPont Vazo Initiator), was achieved at a solvent composition of acetonitrile/water = 4/6 (vol/vol). The polymerization kinetics were investigated in the acrylamide [M] concentration range 0.86–2.27M, Vazo‐33 [I] concentration range 1.4–11.0 × 10−4M, and temperature range 30–40°C. Polymerization was carried out in reaction ampules and the rate was determined gravimetrically. Number‐average molecular weight was obtained from intrinsic viscosity. The precipitation polymerization rate varied as [M]2.16 and [I]0.44. Number‐average molecular weight was proportional to [M]1.22 and inversely proportional to [I]0.31. The overall reaction activation energy was calculated as 17.3 kcal/mol in the temperature range studied. The optimal reaction conditions studied were: acetonitrile/water = 4/6, temperature = 40°C, [M] = 1.95M and [I] = 2.8 × 10−4M. One hundred percent conversion was achieved in 90 min and a polymer with a number‐average molecular weight of 1,200,000 was obtained.
Direct polyesterification promoted by a complex of phosphorus oxychloride with LiCl monohydrate
Authors: Higashi Fukuji , Fujiwara Yō‐Ichi , Yamada Yukiharu
Published: April 2003

The reaction of benzoic acid and p‐chlorophenol with phosphorus oxychloride (POC) was significantly affected by the presence of metal salt hydrates or a mixture of metal salts and water sufficiently aged. Among metal salts examined, LiCl was most effective for the reaction to give quantitative yield of the benzoate. The reaction was assumed to proceed via a complexation of POC with LiCl monohydrate followed by selective hydrolysis of POC by water bound to LiCl. The reaction promoted by a complex derived from POC and LiCl monohydrate in pyridine was successfully used as a new condensing agent for the synthesis of aromatic polyesters by the direct polycondensation or aromatic dicarboxylic acids and bisphenols. Under favorable conditions for aging of POC with LiCl monohydrate and for addition of bisphenols, polymers of moderate to high molecular weights were obtained in quantitative yield. The reaction was applied with limited success to the preparation of a copolymer of high molecular weight from hydroxybenzoic acids.
Synthesis of soluble aromatic polyesteramides by stepwise copolycondensation of bisphenols and aromatic diamines with diphenyl chlorophosphate in pyridine
Authors: Higashi Fukuji , Ozawa Michihide , Mochizuki Akihiko
Published: April 2003

The reaction promoted by diphenyl chlorophosphate (DPCP) in pyridine was successfully applied to the preparation of soluble aromatic copolyesteramides of high molecular weights directly from aromatic dicarboxylic acids, bisphenols, and a wide range of mol % aromatic diamines. Dropwise addition of a mixture of bisphenols and diamines (more favorably of bisphenols and then diamines) to the mixture of dicarboxylic acids activated by DPCP led the reactions homogeneously even with high mol % of diamines to produce copolymers of good solubility. This improved copolymer solubility was roughly estimated by sequence distribution of polyamide and polyester units in the copolymers, which was studied in a model reaction and in the copolycondensations by simultaneous and stepwise addition of bisphenols and diamines.
The effects of oxidative reaction on ionic permeabilities through polypeptide membranes containing –SH groups in the side chains
Authors: Takizawa A. , Kinoshita T. , Ohtani A. , Tsujita Y.
Published: April 2003

The effects of the oxidative reaction on the ionic permeabilities through polypeptide membranes containing thiol groups in the side chains were investigated. Membranes were derived from poly(glutamyl‐cysteine) (PGC) containing 12% (in mol %) of SH groups in the side chains, and from poly(L‐cysteine) (PlCys) containing 26% of thiol groups in the side chains, respectively. On the basis of the polarographic analysis, it can be estimated that more than 80% of SH groups in the membranes could be oxidized by using 10 mM solution of iodine. The membrane potentials across the PGC membrane were increased by the iodine oxidation, indicating that SH groups of PGC were converted to highly dissociable groups, i.e., sulfonic acid derivatives. The decrease in the ionic permeabilities through the PGC membrane by the oxidation, therefore, was attributed to the decrease in ionic solubility into the membrane owing to the increase in fixed charge density of the membrane (Donnan exclusion effect). On the other hand, no influence of the oxidation on the membrane potentials of the PCys membrane suggests the possibility of oxidative S‐S cross linking in the membrane. The oxidation‐induced permeability decrease of the PCys membrane could be explained in terms of the decrease in ionic diffusibility associated with the formation of the side chain cross linkings between SH groups in the membrane.
Photoinduced membrane potential changes. Bi‐ionic potential across poly(vinyl chloride) membranes entrapping a photoresponsive bis(15‐crown‐5) derivative and the effects of photoirradiation
Authors: Anzai Jun‐Ichi , Sasaki Hiroshi , Ueno Akihiko , Osa Tetsuo
Published: April 2003

Bi‐ionic potential (BIP) across poly(vinyl chloride) membranes containing azobenzene‐modified bis(15‐crown‐5) was measured in the presence of alkali‐metal chlorides. The BIP measurements revealed the cation selectivity sequence of the membranes (K+ > Rb+ > Cs+ ≫ Na+ > Li+), which agreed well with the potentiometric selectivity order of 15‐crown‐5–based ion‐selective electrodes developed so far. UV‐light irradiation induced the positive or negative shift of BIP. The magnitude and sign of the photoinduced potential shift depended considerably upon the kind and concentration of electrolytes and, as well, the direction from which the membrane was irradiated. The results were explained in terms of the surface‐potential changes induced by light irradiation.
Rigorous approach to kinetic parameters: polymerization of styrene with benzoyl peroxide in carbon tetrachloride
Authors: Ng S. C. , Chee K. K.
Published: April 2003

Both the rate constant of initiator dissociation, kd, and the chain transfer constant, Cx, are determined by monitoring the rates of monomer and transfer agent conversions in a chain polymerization. Statistical analysis that takes into account the errors of experimental variables has been used to treat the kinetic data for the polymerization of styrene initiated by benzoyl peroxide (Bz2O2) in carbon tetrachloride at 60°C. Values of kd and Cx produced by this error‐in‐variable method (EVM) are in accordance with those reported in literature. More important, the EVM algorithm always results in the smallest standard deviations of estimates, and hence, it is superior to the usual least‐squares calculations. Other distinct features of the method are outlined. The initiator efficiency for Bz2O2 is estimated to be 0.72 under the present conditions.
Direct polyamidation with thionyl chloride in N‐methyl‐pyrrolidone
Authors: Higashi Fukuji , Nishi Toshiharu
Published: April 2003

Mechanistic features of the reaction promoted by thionyl chloride and amides such as N‐methylpyrrolidone (NMP) were studied. The reaction was effective in the amidation of carboxylic acids, but not effective in the esterification. The amidation was affected by the kind and the amount of amides used, most favorably by two equivalents of NMP with respect to the acid. These amides were assumed to be involved in the intermediate formation, and the reaction was proposed to proceed via Vilsmeier adducts derived from thionyl chloride and the amides, and through activation of a carboxylic acid different from an acyl chloride. The reaction was successfully applied to the direct polycondensation of aromatic dicarboxylic acids and diamines in NMP at 70°C to produce polyamides with high molecular weights. Initial reaction of dicarboxylic acids with the adducts, additive effect of tertiary amines, and polycondensation temperatures were studied in terms of the inherent viscosity of the polymers produced.
Solution copolymerization of styrene and 2‐hydroxyethyl mechacrylate.
Authors: Lebduška Jan , Šnupárek Jaromîr , Kašpar Karel , Čermák Vladimír
Published: April 2003

The rate of solution copolymerization of styrene (M1) and 2‐hydroxyethyl methacrylate (M2) was investigated by dilatometry. N,N‐dimethyl formamide, toluene, isopropyl alcohol, and butyl alcohol were used as solvents. Polymerization was initiated by α,α′‐azobisisobutyronitrile at 60°C. The initial copolymerization rate increased nonlinearly with increasing 2‐hydroxyethyl methacrylate (HEMA)/styrene ratio. The copolymerization rate was promoted by solvents containing hydroxyl groups. Two different approaches were used for the prediction of copolymerization rates. The relationships proposed for the copolymerization rates calculation involve the effects of the total monomer concentration, mole fraction of HEMA, and of the solvent type. Different reactivity ratios were found in polar and nonpolar solvents: r1 = 0.53, r2 = 0.59 in N,N‐dimethyl formamide, isopropyl alcohol and n‐butyl alcohol; r1 = 0.50, r2 = 1.65 in toluene. The usability of these reactivity ratios was confirmed by batch experiments.
Inclusion polymerization in perhydrotriphenylene studied by ESR spectroscopy: Growing chain structure and conformation of methylsubstituted polybutadienes
Authors: Sozzani P. , di Silvestro G. , Gervasini A.
Published: April 2003

Inclusion polymerization of diene monomers promoted by γ rays and performed in perhydrotriphenylene was studied by ESR techniques. During polymerization of butadiene, 1,3‐pentadiene, isoprene, 2,3‐dimethylbutadiene, 2‐methylpentadiene, and 2,4‐hexadiene, spectra attributable to allyl‐type radicals were collected. It was demonstrated they actually represent the propagating radicals and they do not vary over a long period of time. They are not temperature dependent in the range −150°/ +60°C, apart from the radical of polybutadiene, suggesting that the included methyl‐substituted polybutadienes are conformationally fixed. When the two opposite insertions of monomers 1,4 and 4,1 are distinguishable, the radicals bearing the higher number of methyl groups at the ends of allyl system prevail.
Solvation of polymeric organolithium compounds. Heats of interaction of tetrahydrofurans and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) with poly(butadienyl)lithium
Authors: Quirk Roderic P. , McFay Dennis
Published: April 2003

The enthalpies of interaction of tetrahydrofuran, 2,5‐dimethyltetrahydrofuran and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) with 0.02M benzene solutions of poly(butadienyl)lithium (MN∼4,000) were measured as a function of R([base]/[Li]) using highdilution, solution calorimetry at 25°C. At low R values (ca. 0.2) the enthalpy of interaction of THF ( — 6.1 kcal/mol) is only 1.5 kcal/mol more exothermic than with 2,5‐dimethyltetrahydrofuran and both decrease rapidly with increasing R value. These results indicate that this coordination process is much less sensitive to the steric requirements of the base than analogous processes for poly(isoprenyl)lithium and poly(styryl)lithium. The concentration dependence for the enthalpy of interaction with TMEDA falls off precipitously with increasing R values from an initial value of −12.4 kcal/mol at R = 0.14. These results suggest either a higher degree of association or a less favorable dissociation equilibrium constant for poly(butadienyl)lithium versus poly(isoprenyl)lithium.
Stereochemistry and dynamic behavior of some synthetic “angular” profisetinidin tetraflavanoid derivatives
Authors: Young Desmond A. , Ferreira Daneel , Roux David G.
Published: April 2003

The structure and stereochemistry of four synthetic “angular” tetraflavanoid‐condensed tannin derivatives are examined by high‐resolution variable temperature 1H NMR. spectroscopy, and hence correlated with their dynamic behavior. Three “angular” oligomers exist as stable rotational isomers at ambient temperatures, thus contrasting with the mobility about their interflavanoid bonds of most natural profisetinidin “trimeric” and “tetrameric” homologs. A “linear” tetraflavanoid analog results from one of these regioselectively controlled condensations.
On the copolymerization model and microstructure of methyl acrylate ‐ styrene radical copolymer. Influence of ZnCl2
Authors: Simionescu Cristofor I. , Bǎrboiu Virgil , Simionescu Bogdan C. , Talmaciu Viorica , Sava Corina
Published: April 2003

Bulk radical copolymerization of methyl acrylate (MeA, M1) with styrene (St, M2) in presence and absence of ZnCl2 as complexing agent was studied. 1H‐NMR spectra were used to establish copolymer composition and sequence distribution. The methoxy group signal was observed to be split due to pentads, but the analysis of sequence distribution is possible only at triad level. Both composition and sequence distribution data confirmed that bulk radical copolymerization respects quite well the terminal addition model; the values of r1 = 0.14 ± 0.02 (from composition data) and r1 = 0.25 ± 0.03 (from sequence distribution data) and r2 = 0.83 ± 0.10 (from composition data) were found. The presence of ZnCl2 increases the probability of alternating addition, e.g., for [ZnCl2]/[MeA] = 0.2, r1 = 0.03 ± 0.02 and r2 = 0.17 ± 0.03. The radical copolymer obtained in bulk in the absence of ZnCl2 presents a coisotactic configuration with σ = 0.75 ± 0.03, but the presence of the complexing agent reduces the probability of coisotactic addition, e.g., for [ZnCl2]/[MeA] = 0.2, σ = 0.52 ± 0.03.
Methylene‐bridged aromatic polyesters. Synthesis, characterization, and radiation‐induced crosslinking
Authors: Havens Stephen J. , Bell Vernon L.
Published: April 2003

Aromatic polyesters connected by methylene groups were synthesized. Two pairs of aromatic diacid chlorides, 3,3′‐methylenedibenzoyl chloride and 4,4′‐methylenedibenzoyl chloride were each polymerized via interfacial polycondensation with 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol A), 3,3′‐methylenediphenol, and 4,4′‐methylenediphenol. For comparison, 3,3′‐carbonyldibenzoyl chloride and 4,4′‐carbonyldibenzoyl chloride were similarly polymerized with bisphenol A. Substitution of meta,meta' oriented phenylene groups for para,para' oriented phenylene groups had a significant and cumulative effect in reducing the glass transition temperatures of the polymers, thereby enhancing their processability. In air the methylene groups of the polyesters undergo oxidation and crosslinking at elevated temperatures. Electron beam irradiation of thin films of the methylene‐linked polyesters at room temperature resulted in some chain extension and crosslinking, as evidenced by increased solution viscosity and gel formation. Irradiation at a temperature near or above the glass transition temperatures of the polymers greatly enhanced the tendency for the polymers to crosslink.
Amino acid end‐group in commercial heparin. I. Determination of the number of amino and hydroxyl end groups in heparin
Authors: Arai Kozo , Nakamura Yoshio , Edwards H. E. , Phillips G. O.
Published: April 2003

Three commercial heparins of different molecular weights and anticoagulant activities were dinitrophenylated (DNP) with 2,4‐dinitrofluorobenzene under aqueous conditions. The absorption spectra observed for DNP heparins in a 1% NaHCO3 solution consisted of the two absorption spectra characteristic of DNP—amino (N—DNP) and DNP—hydroxyl (O—DNP) groups. The number of N—DNP, O—DNP, and (N + O)—DNP groups were determined as well as the number of N—DNP groups per heparin chain; different values (i.e., 0.16, 0.17, and 0.55) for the latter were obtained with the three heparins. Further calculations showed that two of the heparins had approximately two (N + O)—DNP groups per chain (i.e., 2.1 and 1.8) whilst the third sample, considered to be a “cruder” heparin, had a value of 1.4.
ESR studies on radical polymerization of vinyl ethers
Authors: Kamachi Mikiharu , Tanaka Kohji , Kuwae Yoko
Published: April 2003

ESR studies on the radical polymerization of vinyl ethers were performed from −50°C to room temperature using di‐tert‐butylperoxide as a photoinitiator. Well resolved ESR spectra were assigned to propagating radicals of vinyl ethers. Their hyperfine splitting constants due to α‐proton were about 16 G, being smaller than those of ethyl acrylate and vinyl acetate. The smaller constants is ascribed to a deviation of the propagating radicals from sp2 hybrid structure. The reason why high polymers are not obtained from vinyl ethers by radical polymerization is discussed on the basis of information from the ESR studies.
Preparation and characterization of aromatic copolyesters containing the o,o′‐biphenylene ring system
Authors: Polk Malcolm B. , Kannappan Venu , Harruna Issifu , Phingbodhipakkiya Metha
Published: April 2003

Poly[oxy‐2,2′‐diphenyleneoxyisophthaloyl‐b‐oxy(2‐methyl‐1,3‐phenylene)oxyterephthaloyl] I, poly[oxy‐2,2′‐diphenyleneoxyterephthaloyl‐b‐oxy(2‐methyl‐1,3‐phenylene)oxyterephthaloyl] II, poly(oxy‐2,2′‐diphenyleneoxyisophthaloyl‐b‐oxy‐2,2′‐diphenyleneoxyterephthaloyl) III, poly[oxy‐2,2′‐diphenyleneoxyterephthaloyl‐b‐oxy(2‐methyl‐1,4‐phenylene)oxyterephthaloyl] IV, poly[oxy2,2′‐diphenyleneoxyterephthaloyl‐b‐oxy(2‐chloro‐1,4‐phenylene)oxyterephthaloyl] V, poly[oxy‐2,2′‐diphenyleneoxyterephthaloyl‐co‐oxy(2‐chloro‐1,4‐phenylene)oxyterephthaloyl] VI, and poly[oxy‐2,2′‐diphenyleneoxyterephthaloyl‐co‐oxy(2‐methyl‐1,4‐phenylene)oxyterephthaloyl] VII have been synthesized and characterized. Random copolyester VI appears to form a birefringent fluid phase above the melting temperature.