bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid‐crystalline copolyesters based on poly(p‐oxybenzoate) and poly(p,p‐biphenylene terephthalate)
Authors: Volksen W. , Lyerla J. R. , Economy J. , Dawson B.
Published: April 2003

Two copolymers composed of p‐hydroxybenzoate (PHB) and biphenylene terephthalate (BPT) with PHB/BPT ratios of 1/2 and 2/1 were characterized with respect to their tendency to exhibit liquid‐crystalline behavior in the melt phase. The BPT ‐rich copolyester, PHB/BPT = 1/2, displayed a birefringent melt phase of very high viscosity and no tendency to crystallize on cooling. The resulting fused material exhibited what apeared to be a second‐order transition at 170°C. The PHB‐rich composition, PHB/BPT = 2/1, also exhibited a highly birefringent melt phase of high viscosity which was quite shear sensitive. This polymer melt had little tendency to crystallize on cooling; however, on reheating no apparent second‐order transition could be detected. The observed phase changes were characterized by differential scanning calorimetry, hot‐stage microscopy, and wide‐angle x‐ray diffraction techniques. Additional data, pertaining to the compositional nature and apparent sequence distribution, were obtained by 13C‐NMR spectroscopy of the solid materials through magic‐angle spinning, dipolar decoupling, and cross‐polarization techniques.
Copolymerization of acrylonitrile with 3‐chloro, 2‐hydroxy‐propyl acrylate and methacrylate
Authors: Bajaj P. , Padmanaban M.
Published: April 2003

Acrylonitrile (AN) was copolymerized with 3‐chloro, 2‐hydroxy propyl acrylate (CHPA) and 3‐chloro, 2‐hydroxy‐propyl methacrylate (CHPMA) in water and water‐acetone medium at 40°C with potassium persulfate and sodium metabisulfite as redox initiators. Copolymer composition was determined from the nitrogen content. The reactivity ratios for the AN‐CHPMA system were also calculated by the Kelen–Tudos method. The reactivity ratio r2 (CHPMA) was higher for the AN‐CHPMA system in both media, which indicated higher reactivity of CHPMA toward the propagation species. Addition of acetone decreases r2 and increases r1. It was found that the copolymers prepared in water medium were not completely soluble in dimethylformamide (DMF); the insoluble fraction was rich in CHPA/CHPMA and increased with increasing comonomer composition. The influence of the acrylate comonomer on properties such as solubility and intrinsic viscosity was also studied.
Synthesis and characterization of polyesters derived from aromatic 1,4‐dimethoxylated diacids
Authors: Diaz F. R. , Tagle L. H. , Olivares J. P.
Published: April 2003

Polyesters were synthesized from the dichlorides of 2,5‐dimethoxyterephthalic and 2,5‐dimethoxy‐1,4‐benzenediacetic with dialcohols. The polymers were characterized by elemental analysis and infrared (IR) spectroscopy. Their intrinsic viscosity, glass transition temperature, and thermal decomposition were determined.
Synthesis and characterization of certain aromatic polyfumaramides
Authors: Sachindrapal P. , Nanjan M. J.
Published: April 2003

Ten polyfumaramides based on p,p′‐aromatic diamines and fumaric acid were synthesized by the phosphorylation method. The polymers were characterized by viscosity, solubility, infrared and UV‐visible spectroscopy, and thermogravimetry. The fluorescence spectra of one of the polymers were studied. A model compound, fumaroyldianilide, was synthesized and characterized.
Comparisons of glow discharge polymerization between hexamethyldisilazane and trimethylsilyldimethylamine
Authors: Inagaki N. , Kishi A.
Published: April 2003

Glow discharge polymerization between hexamethyldisilazane (HMDSZ) and trimethylsilyldimethylamine (TMSDMA) was compared by means of infrared spectroscopy and ESCA analysis. Infrared spectra pointed out differences in chemical structure between the polymers prepared from the two monomers, although the two polymers were mainly composed of resembling units such as SiCH3, SiCH2, SiH, SiOSi, and SiOC groups: (i) The polymers prepared from TMSDMA contained N → O group, but the polymers from HMDSZ did not contain this group. (ii) Influences of the W/FM parameter (W is the input energy of rf power, F the flow rate of the monomer, and M the molecular weight of the monomer) appeared on decreasing the CN group and increasing the CO group in the TMSDMA system, but little influence appeared in the HMDSZ system. ESCA spectra (C1s, Si2p, and N1s core levels) supported the differences between the two polymers elucidated by infrared spectroscopy, and pointed out differences in susceptibility of the SiN bond to plasma: The NSi sequence of TMSDMA was completely ruptured in discharge to yield polymers, and the SiNHSi sequence of HMDSZ remained in considerable amount.
Unique hydrophobic interactions of pyrene in aqueous solution as effected by polyelectrolytes and surfactants
Authors: Herkstroeter W. G. , Martic P. A. , Hartman S. E. , Williams J. L. R. , Farid S.
Published: April 2003

Pyrene substituents covalently bounded to polyelectrolytes show not only excited‐state interactions but also unique ground‐state interactions in aqueous solution. The pyrene moieties in pyrenesubstituted ionic molecules also show these interactions when aqueous solutions of these molecules are treated with polyelectrolytes or surfactants well below their critical micelle concentrations. These hydrophobic interactions are revealed by changes in absorption, fluorescence, and excitation spectra. The well‐resolved vibrational bands in the absorption and excitation spectra of pyrene become somewhat diffuse, whereas monomer fluorescence is reduced and replaced by excimer fluorescence. The rationale for these results is that the pyrene moieties in these ionic solutions seek out hydrophobic locations on the polyelectrolytes or surfactants, where pyrene aggregation is responsible for these interactions and the corresponding changes in spectra.
Interpenetrating polymer networks from polyurethanes and methacrylate polymers. I. Effect of molecular weight of polyols and NCO/OH ratio of urethane prepolymers on properties and morphology of IPNs
Authors: Xiao H. X. , Frisch K. C. , Frisch H. L.
Published: April 2003

Two types of reinforced elastomeric interpentrating polymer network (IPN) were prepared by simultaneous polymerization and crosslinking in solution. The first type consisted of polyurethane‐poly(methyl methacrylate) (PU/PMMA), and the second, of polyurethane‐poly(methyl methacrylate‐methacrylic acid) PU/P(MMA–MAA) of constant composition (90/10) and (80/20) by weight, respectively. The members of each type differed in the NCO/OH ratio of the PU prepolymer and the molecular weight (MW) of the polyol in the PU component because we wished to investigate systematically the effect of changing the NCO/OH ratio and MW of the polyol on the mechanical properties and morphology of the resulting IPNs. The mechanical properties, particularly the modulus of both tyes of IPN, increased with increasing NCO/OH ratio and decreased with increasing MW of the polyol in the PU. The morphology of the IPNs was studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Improved phase compatibility and decreasing extent of phase separation was observed in both types of IPN with increasing NCO/OH ratio and decreasing MW of the polyol used in the PU. These results may imply that improved interpenetration results from increasing the NCO/OH ratio and decreasing the MW of the polyol in the PU component. The fact that the effect is more pronounced with the type of PU‐P(MMA–MAA) IPN can be rationalized as due to the additional hydrogen bonding between the carbonyl in the carboxyl groups and the urethane or urea groups in the PU component.
Graft polymerization of acrylic monomers onto starch fractions. I. Effect of reaction time on grafting methyl methacrylate onto amylose
Authors: Goñi I. , Gurruchaga M. , Valero M. , Guzman G. M.
Published: April 2003

A study was made of the ceric‐ammonium‐nitrate‐initiated graft polymerization of methyl methacrylate (MMA) onto a lineal fraction of starch (amylose). Grafting yields were determined by extraction with appropriate solvents: 1,2‐dichloroethane for homo‐PMM, and 0.5N NaOH for ungrafted amylose. Percent grafting was calculated by acid hydrolysis with 1N HCl. Molecular weights of PMMA side chains were determined by gel permeation‐chromatography. Grafting efficiencies ranged from 72 to 83%, grafting, from 190 to 271%, and frequency of attachment of side chains, from 900–1250 glucose units per chain. The results observed are discussed.
Hydrogels préparés par le greffage radiochimique pour l'immobilisation des enzymes
Authors: Jendrychowska‐Bonamour A.‐M.
Published: April 2003

The direct method of radiation grafting was used to cover poly(methyl methacrylate) tubes and rings with a thin layer of poly(acrylic acid) hydrogel. The copolymer formed is used as a support for covalent immobilization of enzymes. The enzyme support coupling was realized with carbodimide or glutaraldehyde. The activity of the immobilized chymotrypsin and peroxidase was determined and the stability of the enzyme‐linked copolymers was tested.
Anionic polymerization and copolymerization of p‐bromostyrene
Authors: Königsberg Itzhak , Jagur‐Grodzinski Joseph
Published: April 2003

Monodispersed poly(4‐bromostyrenes) (PBs) and their block copolymers with styrene, isoprene, and 3‐methylbutene were prepared and characterized by GPC and NMR. Polystyryl and α‐methylstyryl carbanions act as effective initiators of the anionic polymerization of Bs in THF. The undersirable side reactions, due to thermally or photochemically induced decomposition of the bromostyryl carbanions, PBs−, may be eliminated by conducting the reaction at −78°C and in the dark. Under such conditions, the rate constant of propagation, kp (−78°), is 1.5 × 103 M−1 s−1. Radical anions, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Bs}^{\mathop - \limits_ \cdot} $\end{document}, formed as result of electron transfer from sodium naphthalenide to Bs, may eject spontaneously bromine ions. This step and reactions involving the respective phenyl radicals compete at −78°C with the addition steps leading to polymer formation. Electron affinity of Bs seems to be much higher than that of styrene or isoprene, and PBs− carbanions do not add to the latter monomers. Addition of Bs to polyisoprenyl carbanions leads to formation of the BsIBs block copolymers. BsIBs, prepared in THF, may be converted by preferential hydrogenation of the 1–2 adducts into block copolymers of Bs with poly(2‐methylbutene) and isoprenyl segments. The effectiveness of Bs as a flame retarding constituent of polymeric systems seems to be much more pronounced when it is incorporated in a “block” than in a random fashion. A considerably larger fraction of PBs is required to achieve the same LOI value when the respective homopolymers are blended. Spatial distribution of the easily charred microdomains in the block copolymers is believed to be responsible for this phenomenon.
The effect of the radical structure in trialkylaluminums on cis polymerization of dienes on titanium catalyst systems
Authors: Rafikov S. R. , Monakov Yu. B. , Tolstikov G. A. , Marina N. G. , Minchenkova N. Kh. , Savelieva I. G.
Published: April 2003

1,4‐cis‐polymerizations of 1,3‐dienes of TiCl4‐AIR3 catalyst systems for isoprene and on TiI2Cl2‐AIR3 caltalyst systems for butadiene have been investigated. AIR3 denotes herein an organoaluminum compound (OAC) containing hydrocarbon radicals, linear of different lengths or cyclic, both saturated and unsaturated, as well as those containing O, N, or Si atoms. Neither the OAC radical structure nor the Al/Ti ratios in the range investigated have been found to influence the stereospecificities and reactivities (chain propagation constant) of the active centers. Differing activities of the catalyst systems have been established to result from the variations in the concentrations of the active centers involving <1–5% of all the Ti species. The nature of the OAC radical does not change the mode of the molecular weight distribution in the polymers obtained. An increase in the molecular weight (MW) of the polydienes produced with the use of higher‐MW trialkylaluminums was provoked by an increase in the macromolecules propagation period owing to the lower constant of chain transfer to the higher‐MW OAC.
Terpolymerization of acrylonitrile, styrene, and 2,4,6‐tribromophenyl acrylate
Authors: Janović Zvonimir , Sarić Karla , Vogl Otto
Published: April 2003

Acrylonitrile was terpolymerized with styrene and 2,4,6‐tribromophenyl acrylate in aqueous emulsion and dimethylformamide solution. Experimental terpolymerization data agreed well with calculations based on the Alfrey–Goldfinger equation. Triangular coordinate graphs show the feed/terpolymer relationships; the lines of unique and binary azeotropic compositions were identified. No points of true azeotropic composition were found but a “pseudo‐azeotropic” region was recognized. The experimental data of the emulsion terpolymerization experiment agreed well with the theoretical curves over a wide range of monomer compositions up to high conversions. Incorporation of 2,4,6‐tribromophenyl acrylate in the terpolymer decreased the thermal stability but improved the flame retardancy of the terpolymers.
Characterization of polyacetylene/low density polyethylene composites prepared by in‐situ polymerization
Authors: Galvin Mary E. , Wnek Gary E.
Published: April 2003

The results of thermal, mechanical, and conductivity studies of polymer composites prepared by polymerization of acetylene in low‐density polyethylene (LDPE) films impregnated with a Ziegler–Natta catalyst are presented and discussed. The enthalpy of melting of the LDPE component decreases as the amount of polyacetylene (CH)x grown in the matrix increases and is rationalized as being due to entanglement effects, although grafting cannot be unequivocally ruled out. Composites prepared well below the melting point of the LDPE matrix possess enhanced tensile moduli and tensile strengths at break, compared with pristine LDPE; this suggests reinforcement of the LDPE amorphous regions by the (CH)x chains. Measurements of electrical conductivity as a function of (CH)x content for a series of iodine‐doped composites reveal an apparent percolation threshold at ca. 3 wt % (CH)x.
Synthesis of poly(vinyl alcohol)‐based poly(crown ether)s and permeability of their polymeric membranes
Authors: Kimura Keiichi , Yoshinaga Masanobu , Kitazawa Sadaya , Shono Toshiyuki
Published: April 2003

Polymers that contain crown ether moieties at the side chain and are capable of forming rather tough film were synthesized by the polymer reaction of poly(vinyl alcohol) with formyl derivatives of aliphatic crown ethers such as 12‐crown‐4, 15‐crown‐5, and 18‐crown‐6. In the passive transport of alkali metal picrates across the poly(crown ether) membranes the permeation, particularly of alkali metals which tend to form intramolecular sandwich‐type complexes with the crown ether rings, was retarded, compared with a poly(vinyl alcohol) membrane. The cation selectivities in the permeation of poly(crown ether) membranes differed significantly from those of poly(vinyl alcohol).
Glow discharge polymerization of tetramethylgermanium
Authors: Inagaki N. , Mitsuuchi M.
Published: April 2003

A glow discharge polymerization technique was applied in the preparation of germanium‐containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by the rupture of bonds between Ge and CH3 groups which led to mixtures of polymers that consisted of CH3, CH2, GeCH3, GeOC, and GeOGe groups and germanium metal. Most Ge species present at the outermost layers of the films were oxidized subsequently by air, whereas the Ge species at the inner layers still existed as Ge metal. This film‐forming process can be explained by the concept of atomic polymerization proposed by Yasuda.

See H. Yasuda, J. Polym. Sci. Macromol. Rev., 16, 199 (1981).
Preparation of monodisperse reactive styrene‐glycidyl methacrylate latexes by the emulsifier‐free dispersion copolymerization technique
Authors: Z̆ůrková E. , Bouchal K. , Zden̆ková D. , Pelzbauer Z. , S̆vec F. , Kálal J. , Batz H. G.
Published: April 2003

Latexes based on styrene‐glycidyl methacrylate copolymers were prepared by the emulsifier‐free dispersion copolymerization technique. The main factors affecting the size and morphology of the latex particles and their distribution are the initiator concentration (K2S2O8), the total ionic strength of the aqueous phase, and the total monomer concentration. The existence of critical values for these variables was demonstrated. In the range in which these factors had values below the critical, the synthesized latex particles were spherical, homogeneous, and in varied sizes, depending on the abovementioned parameters in the range of 220–500 nm. Above the critical values of these variables the latex particles consisted of spherical aggregates of smaller particles. The reactive oxirane groups of the latex particles were modified later by hydrolysis, ammonolysis, reaction with Na2S, or periodic acid oxidation of the hydrolyzed or ammonolyzed forms of the latex particles.
Linear polythioesters. VI. Products of interfacial polycondensation of bis/4‐mercaptophenyl/ether with some aliphatic acid dichlorides
Authors: Podkościelny Wawrzyniec , Wdowicka Danuta
Published: April 2003

New polythioesters by interfacial polycondensation of bis/4‐mercaptophenyl/ether with oxalyl, succinyl, adipoyl, suberoyl, or sebacoyl chlorides were obtained. To define the optimal conditions of the process, the polythioesters of dithiol and adipoyl or sebacoyl chlorides were chosen as a model system. Yield for all reaction products and reduced viscosity were found. The following factors were studied: organic phase, contribution of catalyst, concentration and molar ratio of reagents, rate of addition of acid chloride, temperature of reaction, contribution of emulsifier, and concentration of hydrochloride acceptor. The structure of all polythioesters was determined by elementary analysis, infrared spectra, and x‐ray. Initial decomposition and initial intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Some mechanical and electrical properties of polythioesters from dithiol and adipoyl or sebacoyl chlorides were studied. The molecular weights for these polymers were also determined by gel‐chromatography.
Synthesis, characterization, and Diels–Alder extension of cyclopentadiene telechelic polyisobutylene. III. Silylcyclopentadiene‐telechelic polyisobutylene
Authors: Kennedy J. P. , Carlson G. M.
Published: April 2003

Telechelic polyisobutylenes with silylcyclopentadiene termini (CpSi‐PIB‐SiCp) were prepared, starting with α,ω‐di(t‐chloro)polyisobutylene and followed by dehydrochlorination, hydrosilylation, and cyclopentadienylation. The prepolymer was characterized and found to have a terminal functionality close to 2.0. Thermal chain extension by Diels–Alder addition of the end groups did not occur, most likely because of fluxional isomerization of the silylcyclopentadiene end groups, confirmed by model studies. Chain coupling of CpSi‐PIB‐SiCp prepolymers with stoichiometric amounts of bismaleimide gave rise to degrees of extension of more than 11.
Structure and sorption properties of the polyion complex between poly(acrylic acid) and poly(4‐vinylpyridine)
Authors: Oyama Hideko Tamaru , Nakajima Toshinari
Published: April 2003

A polyion complex was formed from poly(acrylic acid) (PAA) and poly(4‐vinylpyridine) (PVP). Its structure and composition were examined by means of infrared spectroscopy (IR), x‐ray photoelectron spectroscopy (XPS), and elemental analysis. The polyion complex was obtained by dissolving PAA and PVP together in methanol. The composition of the polyion complex was independent of stirring speed, mixing sequence, and standing time after mixing. However, the composition depended on the concentrations and the ratio of the components in the reaction mixture. Excess of PAA in the product was observed when concentrated solutions (2.0 × 10−1M) were used for the preparation or when an excess of PAA was added to PVP. The sorption of water vapor by an equimolar PAA/PVP complex at 293 and 303 K was higher than that by the pure components, especially in the low‐ and middle‐pressure regions. In the high‐pressure region, however, the uptake was not affected by the complex formation. While hydrogen bond interactions in general decrease sorption, Coulombic interactions between polymer chains increased the sorption capacity.
Ethynylated N‐phenylbenzimidazoles: Synthesis and thermal properties
Authors: Lau K. S. Y. , Kelleghan W. J. , Boschan R. H. , Bilow N.
Published: April 2003

Three diethynylated bisbenzimidazole prepolymers were synthesized and their polymerization characteristics examined. N‐phenyl‐substituted diethynylated bisbenzimidazoles melted between 250 and 265°C and had gel times of several seconds to several minutes. In contrast, an N‐phenoxyphenyl diethynylated bisbenzimidazole melted at a temperature sufficiently low (ca. 150°C) to provide a 5‐min gel time at 170°C and a 4‐min gel time at 210°C. This material showed promise as a potential laminating resin and a brief screening of the prepolymer for this application was carried out. The polymers of both N‐phenyl‐ and N‐phenoxyphenyl‐substituted diethynylated bisbenzimidazoles showed apparent degradation temperatures of 500°C or greater when examined by thermogravimetric analysis.
Properties of polyphenylene films deposited electrochemically in an HF‐benzene system
Authors: Rubinstein Israel
Published: April 2003

Free‐standing polyphenylene films, prepared by the electrochemical oxidation of benzene in an HF‐benzene, two‐phase system, were investigated. From electron microscope pictures, x‐ray diffraction patterns, and infrared (IR) spectra of polyphenylene films and commercial polyphenylene powder it is concluded that the films, which are largely para linked, contain in addition a substantial amount of meta and possibly ortho linkages and are amorphous in nature. Doping with AsF5 increases the electrical conductivity of the otherwise insulating films to 10−4−10−2ohm−1cm−1; doped films are relatively stable in air. The lower conductivity of doped films with respect to reported values for chemically synthesized poly‐p‐phenylene appears to be the result of the amorphous nature of the films.
Synthesis of casein‐G‐poly(vinyl acetate). II
Authors: Mohan D. , Radhakrishnan Ganga , Rajadurai S.
Published: April 2003

Poly(vinyl acetate) was graft‐copolymerized onto casein in the presence of potassium peroxydisulfate‐ascorbic acid. The effect of synthetic variables on the rates of conversion of monomer (Rp), graft copolymerization (Rg), and homopolymerization (Rh), percent grafting, and grafting efficiency were investigated and the results, compared with the system initiated by peroxydisulfate alone.
Preparation of silicon‐containing polymers. I. Polyimides from dianhydrides and organosilicon diisocyanates
Authors: Ghatge N. D. , Jadhav J. Y.
Published: April 2003

New silicon‐containing polyimides have been prepared by the reaction of pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) with organosilicon diisocyanates having the following general structure:
magnified image
where R1 = R2 = CH3 and C6H5. Thermal properties of these polyimides were studied were by TG, DTA, and DTG.
Studies on the role of peroxy and hydroperoxy groups in polymer photodegradation
Authors: Wismontski‐Knittel T. , Kilp T.
Published: April 2003

Interactions of carbonyl singlet and triplet excited states with peroxides and hydroperoxides were examined in order to ascertain the reasons why the latter two compounds act as nearly diffusion controlled quenchers of ketone‐containing polymer photodegradation. From singlet state fluorescence quenching and laser flash photolysis measurements of triplet decays, direct interaction with the carbonyl excited states was ruled out. These processes occurred with rate constants at least one to two orders of magnitude below the diffusion controlled limit. Trapping of the 1,4‐biradical precursor to chain scission, thereby preventing its disproportionation was also tentatively eliminated. Results obtained using benzoyl peroxide suggest that quencher photodissociation into alkoxy radicals might represent the key step in the quenching of ketone‐containing polymer photodegradation.
Preparation of polyaryl esters by a new direct polycondensation reaction with arylsulfonyl chlorides in pyridine
Authors: Higashi Fukuji , Akiyama Naoki , Koyama Tsugio
Published: April 2003

Arylsulfonyl chlorides were successfully used as a new condensing agent for the synthesis of polyaryl esters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols. High‐molecular‐weight polymers (Mw = 84,000) were prepared by reacting dicarboxylic acids with the sulfonyl chlorides in pyridine in the presence of LiCI, followed by treating with a pyridine solution of bisphenols. The polycondensation was significantly affected by factors, such as, the kind of arylsulfonyl chlorides, its amount, the conditions of initial reaction of the acids with the sulfonyl chlorides, the amounts of LiCI added, and dropwise addition of bisphenols.
Head‐to‐head vinyl polymers. XI. Preparation and characterization of poly(methyl acrylate) and poly(methyl methacrylate) consisting of head‐to‐head and head‐to‐tail units through cyclopolymerization of acrylic and methacrylic anhydrides
Authors: Ohya Takahiro , Otsu Takayuki
Published: April 2003

Acrylic anhydride (AAn) and methacrylic anhydride (MAAn) were polymerized with radical initiator in polar solvents at high temperatures. The polymers obtained were found to consist of five‐and six‐membered ring structures by comparing IR spectra of the polymers with those of model compounds, succinic anhydride, and glutaric anhydride. Hydrolysis and methylation of the polymers gave new polymers composed of head‐to‐head (HH) and head‐to‐tail (HT) methyl acrylate (MA) or methyl methacrylate (MMA) units. The content of HH unit of these HH/HT polymers was determined by 1H‐NMR and 13C‐NMR spectra. The softening, glass transition, and thermal degradation temperatures of the poly(MA) with HH and HT units were found to somewhat increase with increasing of the content of the HH units. On the other hand, the glass transition and thermal degradation temperatures of the poly(MMA) with HH and HT units increased similarly, but the softening temperature decreased as the content of the HH units increased.
Photoresponsive crown ethers. 10. Metal complexation by light‐switched crown ethers immobilized in polymer matrices
Authors: Shinkai Seiji , Kinda Hidefumi , Ishihara Midori , Manabe Osamu
Published: April 2003

The crosslinked polystyrene beads which immobilized two terminal azophenoxide groups of an azobenzene‐crown(24‐crown‐8)‐azobenzene unit were synthesized. The polymer beads adsorbed Cs+ in the dark while they rapidly released Cs+ into the solution under UV‐light irradiation, and the photoresponsive complexation occurred reversibly. On the other hand, the crosslinked polystyrene beads which immobilized one terminal azophenoxide group of an azobenzene‐crown (24‐crown‐8) unit scarcely (or only to a smaller extent) exhibited such a photoresponsive behavior. Similarly, the polymer beads which immobilized two terminal azophenoxide groups of an azobenzene‐crown (18‐crown‐6) azobenzene unit reversibly adsorbed and desorbed K+ in response to UV‐light irradiation. The novel photoresponsive behavior is ascribed to a conformational distortion of the crown rings which induced by the photoisomerization of the azobenzene moiety, although the photoinduced polarity change of the polymer beads is not completely ruled out. The results suggest that the polymer support is useful as a “fixed point” to enforce the conformational changes of immobilized functional molecules.
Water‐soluble copolymers. VII. Cerium (IV) induced graft copolymerization of acrylamide and sodium‐2‐acrylamido‐2‐methylpropane sulfonate onto dextran
Authors: McCormick Charles L. , Park Lee S.
Published: April 2003

Studies were conducted on grafting of acrylamide (AM) and sodium‐2‐acrylamido‐2‐methylpropane sulfonate (NaAMPS) comonomers onto dextran utilizing Ce(IV) induced initiation. The effects of reaction temperature, the Ce(IV)/dextran ratio, and the AM/NaAMPS ratio on grafting yield were investigated. The graft copolymerization behavior can be explained by exchange of the AMPS anion with one of the ligands on the Ce(IV) initiator. Oxidative modification of the dextran substrate improved the yield of graft copolymer. The dextran‐g‐poly(acrylamido‐co‐sodium‐2‐acrylamido‐2‐methylpropane sulfonate) samples prepared by this method were characterized as to copolymer composition and molecular weight utilizing elemental analysis, dilute solution viscometry, and aqueous size exclusion chromatography. Relationships of molecular weight and charge density to kinematic viscosity and salt sensitivity are discussed.
Synthesis and attempted polymerization of N‐arylmaleimides substituted with allylamino or cyclopropylamino groups at 2‐position
Authors: Pyriadi Thanun M. , Kaleefa H.
Published: April 2003

Several N‐substituted chloromaleimides were prepared by dehydrating the corresponding chloromaleamic acids. Treatment of chloromaleimides with allylamine or cyclopropylamine produced N‐aryl‐2‐(allylamino)maleimides and N‐aryl‐2‐(cyclopropylamino)maleimides, respectively. Neither the N‐substituted chloromaleimides nor the N‐aryl‐2‐(allylamino) or N‐aryl‐2‐(cyclopropylamino)maleimides polymerized free radically or anionically. The difficulty of achieving good pi‐pi overlap and stiric effects at the propagation step prevented the cyclopolymerization of the prepared 1,5‐dienes.
Radiolysis of resist polymers. IV. Poly(p‐substituted‐α‐methylstyrene)s
Authors: Babu G. N. , Lu P. H. , Hsu S. L. , Chien James C. W.
Published: April 2003

The effect of parasubstituents on the radiation chemistry of poly(α‐methylstyrene) (PMS) was compared for the fluoro (PFMS), chloro (PCMS), bromo (PBMS), isopropyl (PiPMS), and methoxy (PMeOM) derivatives. Radiolysis yields, ESR spectra, and GCMS analysis of products were obtained. PMS and PFMS have similar low radiolysis yields, products, and product distributions. Only main‐chain radicals which persist to 200° were observed. PCMS has increased values of Gs, Gx, and Gr. The product analysis results suggest that the presence of chlorine contributes to the primary process by dissociative electron capture and enhances the cleavage of α‐methyl group. Irradiation of PBMS caused crosslinking and yielded few volatile products. PMeOMS and PiPMS gel readily by γ‐irradiation and may be useful as negative radiation resists.
The role of oxygen in the ignition of polystyrene by a small flame
Authors: Clark Ferrers R. S.
Published: April 2003

The ignition of slabs of high‐impact polystyrene by a lean hydrogen–oxygen flat flame was studied. The ignition delays and inital rates of flame development after ignition are reported as functions of gas temperature and the separation between flame and polymer surface. The delays follow an Arrhenius‐type expression with an activation energy of 98 ± 18 kJ mol−1. The rates of flame development drop as the gas temperature increases. During long ignition delays the apparent heat transfer coefficient at the sample surface dropped from about 100 W m−2 K−1 to values close to that expected for a hot gas impinging at right angles on a cold surface. For short delays it was higher and more constant at about 100 W m−2 K−1. Although the surface temperature reached before ignition exceeded that required for nonoxidative pyrolysis, the polymer surface charred only when oxygen was present. It is concluded that both oxidative and nonoxidative pyrolysis contribute to the ignition of polystyrene.
System development for aqueous gel permeation chromatography
Authors: Callec G. , Anderson A. W. , Tsao G. T. , Rollings J. E.
Published: April 2003

To devise an improved gel permeation chromatography system for the analysis of macromolecules, with a strongly alkaline solution as eluent, three Fractogel TSK gels were investigated. Because primary standards are usually unavailable, calibration was achieved by using Benoit's universal procedure and polystyrene sulfonates, polyethylene glycols, and dextrans as secondary calibrants. Continuous monitoring of intrinsic viscosity resulted from coupling a viscodetector with a classical differential refractometer. It was found that column efficiency and fractionation range could be extended well beyond those of previously studied systems on a reasonably short period of analysis.
A comparison of theoretically determined and experimentally measured velocity distributions of poly(ethylene terephthalate) flow in a capillary
Authors: Crater Davis H. , Cuculo John A.
Published: April 2003

A streak photographic technique was used to determine the velocity distribution in a capillary produced by the flow of poly(ethylene terephthalate) (PET). This uniquely designed quartz die assembly, which was fitted onto a melt extruder, permitted visualization of polymer flow behavior during melt spinning. Aluminum tracer particles were mixed with polymer chips prior to extrusion. A laser beam was directed through a lens system that illuminated the tracer particles in the melt only in a thin, vertical cross section of the transparent quartz die. A pressure‐drop analysis was also performed on PET, under the same experimental conditions, to determine rheological properties of the polymer. By using these rheological properties theoretical velocity distributions were calculated for PET and then compared with the profiles obtained by the streak photographic technique.
Copolymerization of ethylene with higher linear α‐olefins—reactivity ratios
Authors: Kissin Y. V. , Beach D. L.
Published: April 2003

Copolymerization of ethylene with mixtures of linear α‐olefins C6–C36 in the presence of two heterogeneous Ziegler–Natta catalysts, δ‐TiCl3–AlEt3 and TiCl4/MgCl2–AlEt3, at 90°C was studied by the GC method, and reactivity ratios for all paris ethylene–α‐olefin were estimated from the data on olefin consumption in the reactions. In the case of the δ‐TiCl3–AlEt3 system, the r2 value decreases from ca. 0.05 for 1‐decene to ca. 0.02 for α‐C22H44 and then remains approximately constant. This change is similar to the dependence of the modified steric parameter ESC of the olefin alkyl group on the size of the alkyl group. In the case of the supported TiCl4/MgCl2–AlEt3 system a similar variation of r2 with the length of the alkyl group were observed but the absolute values of r2 were six to ten times lower than those for the first catalytic system.
Catalysis of enantiomeric ester hydrolysis in polymer domains: Catalytic effects of N‐decanoyl‐histidine and of dipeptide derivatives containing a histidyl residue
Authors: Kimura Yoshiharu , Tanaka Akihiro , Nango Mamoru , Kuroki Nobuhiko , Ihara Yasuji
Published: April 2003

The catalytic activities of N‐decanoyl‐L‐histidine and its methyl ester and of dipeptide derivatives containing an L‐histidine residue toward the stereoselective hydrolysis of enantiomeric substrates have been studied at pH 7.30 (in 0.01M Bis‐tris buffer) and 25°C in the presence of poly(ethyleneimine) derivatives. The dipeptide catalyst revealed greatest stereoselectivity in a quaternized poly(ethyleneimine) derivative. A comparison of catalytic effects on both the rate constants and stereoselectivities of N‐decanoyl‐L‐histidine and its methyl ester elucidates the cooperative effects of carboxyl groups in the polymer domains. The structure of the substrates influenced both the rate constants and stereoselectivities in polymer domains.
Preirradiation grafting of N‐vinyl‐2‐pyrrolidone onto poly(tetrafluoroethylene) and poly(tetrafluoroethylene‐hexafluoropropylene) films
Authors: Hegazy El‐Sayed A.
Published: April 2003

Preirradiation grafting of N‐vinylpyrrolidone (NVP) onto poly(tetrafluoroethylene) (PTFE) and poly(tetrafluoroethylene‐hexafluoropropylene) (FEP) films was investigated. The influence of grafting parameters such as preirradiation dose, monomer concentration, and grafting temperature on the rate and grafting yield was studied. Different solvents were used for diluting the monomer and it was found that the aqueous monomer solution at a concentration of 80 wt% was suitable for this grafting system. However, the graft polymerization of NVP in benzene terminated within a short time without significant grafting yield. The dependence of the grafting rate on preirradiation dose and monomer concentration was 1.2 and 1.07 order, respectively, for grafting onto PTFE films and 1.1 and 1.2 order, respectively, for grafting onto FEP films. Arrhenius plots for grafting onto PTFE films showed a breaking point at ca. 35°C and the overall activation energies were calculated as 23.6 and 9.0 Kcal/mol below and above 35°C, respectively. For grafting onto FEP films, however, no break was observed in the Arrhenius plots; the overall activation energy was 11.9 Kcal/mol. The swelling behavior and electric resistance of the grafted materials were investigated.
Adsorption of methylmethacrylate‐vinylferrocene copolymers at the solution/solid interface
Authors: Diaz‐Barrios Antonio , Rengel Aristides
Published: April 2003

A series of methylmethacrylate–vinylferrocene random copolymers was synthesized and characterized. Their adsorption from toluene and chloroform was measured onto pyrogenic silicas. The level of adsorption depended on the solvent, the surface area of the adsorbent, and the copolymer composition. Thus, an inverse adsorption‐solubility relationship for toluene and chloroform was observed. However, in solvents such as tetrahydrofuran, 2‐butanone, and cyclobutanone, which have strong interaction with silica, this trend was not evident. The compositional dependence of the adsorption of these copolymers in toluene and chloroform is similar. Initially, adsorption tends to increase with the vinylferrocene content in the polymer, and at equimolar copolymer compositions the adsorption reaches a maximum which is followed by a decrease in the adsorption values at high vinylferrocene contents. Gel permeation chromatography(GPC) measurements allowed us to conclude that high molecular weight polymer was preferentially adsorbed.
Synthesis and properties of some new polyimidosulfides with highly mobile backbones
Authors: White Jerry E. , Snider Deborah A. , Scaia Mark D.
Published: April 2003

Various alkanedithiols [HSRSH; R = (CH2)3–6 orCH2CH2OCH2CH2] add to the carbon‐carbon double bonds of N,N′‐bismaleimido‐1,8‐octane (1) at room temperature in m‐cresol that contains triethylamine as a catalyst to produce the corresponding polyimidosulfides (3) in yields of 75–86% and with inherent viscosities (ηinh) of 0.30–1.05 dL/g. In general (3) are amorphous, elastomeric materials that undergo glass transitions (Tg) within the range of 6.5–13°C but product (3a) [R = (CH2)6] is a tough, leatherlike polymer that exhibits Tg = 35°C and a melting transition at 77°C. X‐ray analysis indicates that (3a) is ca. 37% crystalline. In addition to further details of the synthesis and properties of polyimidosulfides (3), comparisons are made between crystalline (3a) and a structurally analogous but morphologically dissimilar, elastomeric polyaspartimide synthesized earlier

J. E. White, M. D. Scaia, and D. A. Snider, J. Appl. Polym. Sci., in press.

from (1) and N,N′‐dimethyl‐1,6‐hexanediamine.
The photoelectrochemical initiation of polymerization of styrene
Authors: Funt B. Lionel , Tan Shu‐Rong
Published: April 2003

A TiO2 semiconductor was immersed in a solution that contained styrene monomer and a supporting electrolyte. Polymer was formed when light was focused on the semiconductor. The yield was a function of the bias level maintained at the semiconductor elecotrode. With methylmethacrylate monomer direct photoinitiation of the monomer occurred, but the polymer yield could be reduced by varying the electrode potential.
Modification of an epichlorohydrin polymerization
Authors: Morse S. D. , Wilson T. D. , Merrill C. I.
Published: April 2003

The acid‐catalyzed polymerization of epichlorohydrin was modified by the addition of 1,4‐butanediol diglycidyl ether to the reaction. The amount of diepoxide added and the method of addition were varied to produce a series of polymers with increased molecular weight, broad molecular weight distributions, and variations in hydroxyl functionality. Polyurethane networks were prepared from these polyols for the evaluation of elastomeric properties. The most obvious result was the lack of elastomeric network formation in the unmodified material when modified polyols produced elastomeric properties under the same conditions. Differences in properties between samples with more diepoxide added in the original polymerization generally showed trends to lower elongation and higher modulus. Changes in the method of addition of the diepoxide produced great differences in the toughness of the elastomers formed in the cure process.
Synthesis of high molecular weight polyester carbonates via interfacial phosgenation of aromatic dicarboxylic acids and bisphenols
Authors: Keohan F. L. , Freelin R. G. , Riffle J. S. , Yilgör İ. , McGrath J. E.
Published: April 2003

The synthesis of bisphenol A poly(carbonate–ester) copolymers was studied by phase‐transfer catalysis and modified interfacial polymerization. Only low molecular weight copolymers were prepared directly from dicarboxylic acids, phosgene, and bisphenol A by an interfacial process that involves the use of pyridine as catalyst, HCl acceptor, and weak base. To avoid the use of tertiary amines, which can be difficult to remove from the polymer products, and to produce higher molecular weight copolymers from the same dicarboxylic acid precursors another synthetic method was developed. This more effective method required careful pH control that was achieved by the selective use of the weak‐base potassium carbonate in the first stage of the process. Moreover, elevated reaction temperatures (∼65–70°C) and phase‐transfer catalysis were used. The carbonate–ester copolymers prepared by this technique had consistently high intrinisic viscosities, little or no anyhydride microstructure, and higher degrees of ester unit incorporation than those produced by the pyridine‐catalyzed method. These copolymers also had glass transition temperatures (Tg) 20–30°C higher than bisphenol A polycarbonate homopolymer. An analytical method for determining quantitatively the amount of ester units in the bisphenol A poly(carbonate‐esters) was developed by using Fourier transform infrared spectroscopy (FT‐IR). Agreement between this FT‐IR method and a quantitative nuclear magnetic resonance (NMR) method was found to be reasonable, especially for copolymers with ester unit percentages lower than 40%.
Synthesis and characterization of sulfonated poly(acrylene ether sulfones)
Authors: Johnson B. C. , Yilgör İ. , Tran C. , Iqbal M. , Wightman J. P. , Lloyd D. R. , McGrath J. E.
Published: April 2003

Ionic groups incorporated into a polymer have a decided effect on its physical properties. A number of ionomers and polyelectrolytes have been widely applied. In particular, sulfonated bisphenol‐A polysulfone (SPSF) has been used as a composite or single‐component membrane for the desalination of water. In this article, the synthesis and physical characteristics of sulfonated polysulfone are addressed. A detailed synthesis route is provided and methods that yield determinable levels of sulfonation are described. These ion‐containing polymers retain an excessive amount of residual salts, which, of course, are impurities to the system. Therefore, before any analyses were made the polymers were subjected to a thorough soxhlet extraction process with boiling water, which appeared to be quite effective. The degree of sulfonation was assessed by several methods such as 1H NMR and FT‐IR. A new 1H NMR method was derived because the method cited in the literature proved to be too inconsistent for our work. The new 1H NMR method used a quaternary ammonium counterion [N(CH3)4]. These methyl protons are easily measured and may be ratioed against the isopropylidene protons in the polymer backbone that act as an internal standard. Characterization of the physical properties of SPSF consisted of water uptake, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and solubility studies. Its physical appearance and mechanical behavior were improved by the solution procedure. Also addressed were the effects of different counterions (Na+ & Mg++) with SPSFs of low levels of sulfonation. The variation in physical properties between the divalent and monovalent counterions is dramatic, especially when observed by TMA in the rubber plateau above the apparent glass temperature.
Photochemical reactions of polymers containing thiocyanatoacetyl groups and dyeing the resulting polymer films
Authors: Tsunooka Masahiro , Cha Younsik , Tanaka Makoto , Konishi Fumiya
Published: April 2003

Poly(styrene‐co‐4‐thiocyanatoacetylstyrene) and poly(4‐acetylstyrene‐co‐4‐thiocyanatoacetyl‐styrene) were prepared and their photochemical reactions were studied in the solid state. It was found that the thiocyanatoacetyl groups were easily rearranged with the corresponding isothiocyanatoacetyl groups by ultraviolet (UV) irradiation and that the resulting isothiocyanatoacetyl groups underwent intramolecular cyclization when treated with triethylamine or ammonia to yield oxazole‐2‐thione moieties. The irradiated polymer films could be dyed selectively with cationic dyes in an appropriate dye bath because of the formation of anionic species by keto‐enol tautomerization of oxazole‐2‐thione moieties in an alkaline state.
Gamma‐radiolysis of polysalicylide
Authors: Gupta Mool C. , Deshmukh Vilas G.
Published: April 2003

Polysalicylide, a condensation product of acetylsalicylic acid, was irradiated with 60Co‐γ‐rays. Viscosity, end‐group analysis, and ultraviolet (UV) spectral measurement technique, and electrical conductivity were used to study the changes that occurred during γ‐radiolysis. It was observed that polysalicylide undergoes chain scission caused by weak links. The enthalpy of fusion is 16.0 and 13.4KJ/mol−1 repeat units of polysalicylide in air and N2, respectively. The indirect effective band gap decreased and electrical conductivity increased after irradiation.
Diffusion‐controlled reaction. VI. Radiation graft polymerization of styrene to polyethylene
Authors: Odian George , Lee Dong‐Ho , Patel Vishnu , Rabje Abdelgewad , Zahran A. H.
Published: April 2003

The radiation graft polymerization of styrene to polyethylene was studied under diffusion‐controlled conditions of radiation intensity I, monomer concentration M1, and polymer sample thickness L. The results of the present study together with previous work under diffusion‐free conditions verify our theoretical model for the diffusion‐controlled reaction. The grafting rate is inverse first order in L for diffusion‐controlled reaction and independent of L for diffusion‐free reaction. The order of dependence of grafting rate on radiation intensity for diffusion‐controlled reaction is one‐half that for diffusion‐free reaction. Diffusion control leads to a decrease in the order of dependence of grafting rate on monomer concentration. The decrease is greater than theoretically predicted; possible reasons for this effect are described.