bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and characterization of poly(cyclohexane 2,2‐dipropargyl‐1,3‐propylene ketal) containing double spiro structure
Authors: Kwon Soon‐Ki , Kim Yun‐Hi , Choi Sam‐Kwon
Published: April 2003

The Polymerization was carried out by MoCl5 and WCl6 associated with various organo‐metallic cocatalysts. MoCl5‐based catalysts were found to be more effective. Polymerization of monomer containing a spiro structure proceeded rapidly to reach 80% yield within 2 h at 30°C. Polymerization of monomer led to a soluble, purple colored polymer with number average molecular weight (Mn) of 50000. Elemental analysis, 1H‐NMR, 13C‐NMR, IR, and UV‐visible spectra of the resulting polymer indicated that the polymer contains alternating double and single bonds along the polymer backbone and a cyclic recurring unit with a double spiro structure. In addition, the polymer had good oxidative and thermal stability and good solubility in common organic solvents. © 1995 John wiley & Sons, Inc.
Synthesis of aromatic polyesters having pendant carboxyl groups in the side chains and conversion of the carboxyl groups to other reactive groups
Authors: Wang Chonghui , Nakamura Shigeo
Published: April 2003

Aromatic polyester, copolyester, and poly(ester‐amide‐thioester) having pendant carboxyl groups are directly synthesized by the organic phase/water phase interfacial polyconden‐sation using low‐molecular and polymeric phase transfer catalysts. Spectral analysis of the resulting polymers indicates that the nucleophilicity of salts of phenols to diacid chloride is far higher than that of salts of carboxylic acids and chemoselective esterification occurs in a 100% yield. Even if the polymeric catalyst having amino acid moiety as a nucleophilic group is used in the polycondensation, the polymers do not contain anhydride groups. The polyester can be almost quantitatively converted to polymers with different reactive groups by reacting the pendant carboxyl groups with alkyl halides in a DMAc‐H2O mixture con‐taining K2CO3. A bifunctional catalytic mechanism is proposed for the chemical modification of the polyesters. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of polyyne polymer containing nickel in the main chain
Authors: Yang Mujie , Zhang Lingjun , Cai Zhigang , Yang Peiqing , Xu Zhiling
Published: April 2003

The synthesis of the nickel dialkynyl complex Ni(CCC6H4CCH)2(PPh3)2 and of the corresponding polyyne polymer containing nickel in the main chain [Ni(PPh3)2CCC6H4CC]n are described and discussed. A new mixed solvent system DMSO/HNEt2 and homogeneous step‐wise condensation method used for their synthesis are presented for the first time. The Ni‐polyyne polymer obtained is dark yellow powder and soluble in THF or CH2Cl2. Its M̄w is about 104, and the MWD is less than 2. Both the prepared complex and polymer have been characterized by IR, UV, 1H‐NMR, and DTA. Preliminary results on photoluminesence of nickel polyyne polymers are present. © 1995 John Wiley & Sons, Inc.
LC polyimides. XXI. Thermotropic poly(amide‐imide)s based on trimellitimides
Authors: Kricheldorf Hans R. , Gurau Mihai
Published: April 2003

Polycondensation of α, ω‐bis(‐4‐aminophenoxy) alkanes with trimellitic anhydride chloride (TMA‐Cl) in m‐cresol yielded a new class of poly(amideimide)s. Starting from the same diamine spacers poly(amideimides) with a more regular sequence of amide and imide groups were prepared by another synthetic method. All these poly(amide‐imide)s are semi‐crystalline and melt in the range of 250–300°C. They form a smectic‐A phase over a narrow temperature range and suffer thermal degradation at the isotropization temperature (330–350°C). The smectic‐A phase was characterized by optical microscopy (“batonnet texture”) and by synchrotron radiation measurements conducted at a heating rate of 20°C. Furthermore, it is demonstrated that slight variation of the chemical structure, such as methyl substituents or meta positions in the spacer prevent the formation of a LC phase. © 1995 John Wiley & Sons, Inc.
A mass spectrometric investigation of the water‐soluble oligomers remaining after the emulsion polymerization of methyl methacrylate
Authors: Thomson Barry , Wang Zhiyu , Paine Anthony , Lajoie Gilles , Rudin Alfred
Published: April 2003

A “surfactant‐free” emulsion polymerization of methyl methacrylate was conducted at 80°C with ammonium persulfate initiator. The water‐soluble MMA‐based oligomers re‐maining were isolated and analyzed both as‐produced and after hydrolysis. NMR analysis revealed that the mole ratio of MMA repeat units to sulfate end groups in the former is 6.5. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and gel permeation chromatography both showed that the mean number of MMA repeat units comprising the extracted material is 8–9. The hydrolysis procedure rids the oligomers of their terminal groups and converts some of the methyl ester groups to acid, greatly sim‐plifying the mass spectrum. This appears to be the first direct measurement of “surfactants” produced in situ from monomer and persulfate initiator. © 1995 John Wiley & Sons, Inc.
Kinetics of competitive polymerization in bidisperse seed systems using oil‐soluble initiators: Calculation of effect of various dimensionless parameters
Authors: Mørk P. C.
Published: April 2003

Expressions for calculating the stationary state distribution of radicals in a bidisperse seed system initiated by oil‐soluble initiators were developed. Dimensionless parameters were used throughout, thus making it possible to obtain general trends without introducing specific numerical values. Desorption and reabsorption of radicals, aqueous phase termi‐nation, partition of the initiator into the aqueous phase, and a possible generation of single radicals are taken into account. The radical entry and exit rate coefficients are formulated in terms of power laws with respect to particle diameter. No discrimination of the various radical species and their origin is made. The derivation is based on a probabilistic stationary state analysis leading to third‐order recurrence relations that are solved using confluent, hypergeometric Kummer functions. A selection of curves illustrating the effect of various dimensionless parameters on the calculated average number of radicals per particle, the order of volume growth with respect to the particle diameter, and relative rates are given. © 1995 John Wiley & Sons, Inc.
Aliphatic‐aromatic copolycarbonates derived from 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol
Authors: Geiger Carey Cecil , Davies Jack D. , Daly William H.
Published: April 2003

The synthesis of copolycarbonates with high aliphatic contents for possible applications as optical plastics is described. Copolymers of 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol (TMCBD) with a series of 14 bisphenol derivatives were prepared and characterized. The refractive index of these materials varies from 1.49 for the 2,2‐hexafluoropropane substituted copolymer to 1.57 for the 9,9‐fluorene substituted copolymer; thus, all of the copolymers exhibit lower refractive indices than the bisphenol A homopolycarbonate. The glass tran‐sition temperatures of the copolymers vary from 110 to 210°C; the beta transition tem‐peratures vary from ‐70 to 0°C when measured at 10 Hz by dynamic mechanical analysis. The copolymers exhibited good thermal stability (0–3% weight loss) when heated above the glass transition temperature, and only undergo extensive decomposition (80–90%) at 300–360°C. © 1995 John Wiley & Sons, Inc.
Effect of aggregation of p‐phenylphenol on enzymatic polymer synthesis in dioxane/water mixture
Authors: Liu W. , Ma L. , Wang J. D. , Jiang S. M. , Cheng Y. H. , Li T. J.
Published: April 2003

The state of p‐phenylphenol molecules in dioxane/water mixture, a commonly used reaction system for enzymatic polymerization of phenols and aromatic amines, was investigated by difference UV absorption spectroscopy and Fourier transform (FT) Raman spectroscopy. The aggregate of p‐phenylphenols is found on the basis of the exciton peaks observed in difference UV absorption spectra. FT Raman spectroscopy demonstrates further that p‐phenylphenol molecules aggregate together in “face to face” fashion. A simplified model is proposed for aggregation of p‐phenylphenol molecules in dioxane/water mixture, which can elucidate the variation of the molecular weight of poly (p‐phenylphenol) coupled in the reaction system. © 1995 John Wiley & Sons, Inc.
Synthesis and crosslinking of poly (aryl ether)s containing 1,1‐diphenylethylene moieties
Authors: Gao Chunping , Hay Allan S.
Published: April 2003

Poly (aryl ether)s containing the diphenylethylene moiety, synthesized from 1,1‐bis(4‐fluo‐rophenyl)ethylene or 1,1‐bis(4‐hydroxyphenyl)ethylene, are thermally crosslinkable. Char‐acterization and crosslinking studies of these polymers were carried out by GPC, DSC, TGA, and NMR. The solvent resistance and Tg's of the resulting crosslinked networks increase after crosslinking. Thermogravimetric analysis shows that no significant mass loss accompanies the crosslinking reaction. © 1995 John Wiley & Sons, Inc.
Synthesis of new ethynylene‐containing aromatic polyamides by palladium‐catalyzed polycondensation of aromatic diiodides with aromatic diethynyl compounds having amide units
Authors: Watanabe Shinji , Tanabe Masaru , Jikei Mitsutoshi , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

New ethynylene‐containing aromatic polymides were synthesized by the carbon–carbon crosscoupling polycondensation of aromatic diiodides with aromatic amide‐bearing diethynyl compounds in the presence of a palladium catalyst, cuprous iodide, and an organic base. The polymers having sulfone linkages were soluble in various organic solvents and their weight average molecular weights were in the range of 12,500 and 26,500. The polymers with the highest inherent viscosity were obtained, when the monomer ratio of a diethynyl compound to a diiodide was 1.01. The polymers showed no detectable glass transition temperature and no weight loss up to around 300° C in nitrogen. The thermal crosslinking of the polymers occurred at 280°C through the existing internal ethynylene group. © 1995 John Wiley & Sons, Inc.
Addition polymerization of 2‐cyano‐1, 4‐benzenedithiol to 1,4‐diethynylbenzene and properties of polymers
Authors: Kobayashi Eiichi , Yoshino Toshizumi , Aoshima Sadahito , Furukawa Junji
Published: April 2003

A novel addition polymerization of 2‐cyano‐1,4‐benzenedithiol to 1,4‐diethynylbenzene was carried out by UV irradiation in toluene at 50°C under nitrogen atmosphere. The polymerization proceeded readily, and a pale‐yellowish conjugated polymer contain‐ing sulfur atoms and cyano groups (M̄n = 20,400–80,800) was obtained in a 60–80% yield for 120–250 min. The polymer was found to be 1 : 1 alternating structure of anti‐Markownikoff's type and was insolu‐ble in conventional organic solvents. Since the polymer having molecular weight of the order of 104 had a softening point at 115°C, a thin polymer film was obtained by heat press. TG analysis of the polymer indicated its decomposition point at about 620°C under argon atmosphere. The electrical conductivity of the polymer pellet was 10−10 S/cm at 300 K without doping and on the order of 10−5 S/cm on I2 doping. Fur‐thermore, the electrical conductivity of the undoped polymer pellet reversibly changed from the order of 10−10 S/cm at 300 K to 10−7 S/cm at 435 K with temperature variation, accompanying with increasing carrier density and mobility. The polymer pellet (M̄n = 80,800) aged at 250°C for 5 min under nitrogen atmosphere exhibited the order of 10−7 S/cm at 300 K. Thermal treatment of the polymers was thought to cause spreading of conjugated system through molecular rearrangement supported by x‐ray diagrams. An absorption edge of diffuse reflectance spectra of the polymer (M̄n = 80,800) was 635 nm and shifted to 880 nm by heat treatment of the polymer. © 1995 John Wiley & Sons, Inc.
New poly(amide‐lmide)s syntheses. XV. Preparation and properties of poly(amide‐imide)s derived from 9, 9‐bis[4‐(4‐aminophenoxy) phenyl]fluorene and various bis(trimellitimide)s
Authors: Yang Chin‐Ping , Lin Jiun‐Hung
Published: April 2003

Fifteen bis(phenoxy) fluorene‐containing poly(amide‐imide)s III were synthesized by the direct polycondensation of 9,9‐bis[4‐(4‐aminophenoxy)phenyl]fluorene (BAPPF) with var‐ious aromatic bis(trimellitimide)s II in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Poly(amide‐imide)s III having inherent vis‐cosities up to 1.45 dL/g were obtained in quantitative yields. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP and N,N‐dimethylacetamide. All the soluble poly(amide‐imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 263–315°C and the 10% weight loss temperatures were above 510°C in nitrogen. Some properties of poly(amide‐imide)s III were compared with those of the corresponding isomeric poly(amide‐imide)s III′ prepared from 9,9‐[4‐(4‐trimellitimidophenoxy)phenyl]fluorene and various aromatic diamines. © 1995 John Wiley & Sons, Inc.
Spectral and thermal characterization of polyaniline–oxalic acid salt
Authors: Palaniappan S.
Published: April 2003

Polyaniline–oxalic acid salts were prepared at 5 and 30°C by chemical polymerization of aniline using different concentration of oxalic acid. Polyaniline base was obtained from the corresponding polyaniline salt by dedoping using aqueous ammonium hydroxide solution. Conductivity measurements, elemental analysis, Infrared, electronic absorption, electron paramagnetic resonance spectral, and thermogravimetric analysis were performed on the polyaniline salts and bases. Composition and the extent of dopant in polyaniline salt systems where determined. The value of composition of polyaniline: oxalic acid is 4: 1.6 and the polymer yield is around 66%. The value of conductivity, polymer yield and composition of polyaniline–oxalic acid salt is independent of concentration of oxalic acid used and also the synthesis temperature. The results are compared with polyaniline–hydrochloride salt prepared by chemical polymerization. The conductivity of polyaniline–oxalic acid salt is three orders of magnitude lower than that of polyaniline‐hydrocholoride salt. © 1995 John Wiley & Sons, Inc.
Solution viscosity behavior of polystyrene‐based cationic ionomers: Effects of quaternary‐group structure and counter ion
Authors: Ohtani Noritaka , Inoue Yukihiko , Kaneko Yasumasa , Okumura Shinsuke
Published: April 2003

The dilute solution viscosity was investigated for several polystyrene‐based cationic io‐nomers. It was found that intramolecular aggregation among the ionic groups was strongly dependent on the sizes of quaternary onium groups and counter anions. The extent of the aggregation was controled by the solvent polarity and the solvation to the ionic groups. When there was a strong selective soivation to small counter ions, the structure of onium groups shows a minor effect on the viscosity behavior, indicating little aggregation among the ionic groups. A strong solvation to small quaternary cations also eliminates the intra‐molecular aggregation and the influence of counter ions was barely observable. When the selective solvation to counter ions was disabled by the enlarged size of the counter ions, however, the viscosity depended on onium group structure or spacer chain length. If the solvent solvates neither counter ions nor quaternary groups, the smaller the sizes of onium cation and counter anion, the lower the reduced viscosity due to an enhancement of the ionic aggregate formation. © 1995 John Wiley & Sons, Inc.
Polymerization and characterization of polyfunctional amphiphilic diacetylenes
Authors: Nezu S. , Lando J. B.
Published: April 2003

Amphiphilic diacetylenes of the type HCC(CH2)nCCCC(CH2)8COOH (n=6 and 12) were synthesized. The solid‐state polymerization of the bulk crystals, mono‐layers on the gas‐water interface, and multilayers were investigated. The diacetylene moieties underwent polymerization upon irradiation by UV or γ‐rays, showing different polymerizability depending on the material form. The polymerization of the terminal acetylene groups was not observed. Enhanced polymerizability and stability of the monolayers on subphases containing LiOH are explained by a proposed model of the monolayers. © 1995 John Wiley & Sons, Inc.
Synthesis and cationic photopolymerization of alkoxyallene monomers
Authors: Crivello J. V. , Yoo T. , Dougherty J. A.
Published: April 2003

A series of cationically polymerizable mono‐and difunctional alkoxyallene monomers have been prepared via the straight forward base catalyzed isomerization of the corresponding propargyl ethers. Rate studies conducted using real‐time infrared spectroscopy showed that these monomers exhibit high reactivity in photoinitiated cationic polymerization. Monomers bearing a single alkoxyallene group undergo rapid polymerization to yield crosslinked polymers indicating that both double bonds react during polymerization. A mechanism has been proposed that explains this observation. © 1995 John Wiley & Sons, Inc.
A Nd‐carboxylate catalyst for the polymerization of 1,3‐butadiene: The effect of alkylaluminums and alkylaluminum chlorides
Authors: Wilson David J.
Published: April 2003

The ternary neodymium‐based catalyst for the polymerization of 1,3‐butadiene, Nd(versatate)3/Ali‐Bu2H/tert‐butyl chloride, has been examined with respect to the effects of a range of alkylaluminums and alkylaluminum chlorides. Using either pre‐formed or in situ catalysts, observations pertaining to catalyst activity and physical state and the characteristics of the final polymer are discussed. The catalyst activity series with the type of alkylaluminum was found to be: Aln‐Pr3 ≫ Aln‐Dodec3 = Aln‐Oct3 = Aln‐Hex3 > Ali‐Bu2H > Ali‐Bu3 > AlEt3 ≫ AIMe3. Polybutadiene cis content was found to vary with the type of alkylaluminum used. Pre‐formed catalysts using methylaluminum chlorides as chloride source were found to be the most active; AlMe2Cl chloride gave the highest activity. The activity of in situ catalysts prepared using alkylaluminum chlorides was found to be independent of alkylaluminum chloride structure. Polybutadiene prepared using catalysts based on different alkylaluminums and alkylaluminum chlorides was found to decrease in cis content with conversion. © 1995 John Wiley & Sons, Inc.
Fundamental studies of grafting reactions in free radical copolymerization. III. Grafting of styrene, acrylate, and methacrylate monomers onto cis‐polybutadiene using benzoyl peroxide initiator in solution polymerization
Authors: Huang Nai‐Jen , Sundberg Donald C.
Published: April 2003

Benzoyl peroxide (BPO), due to its higher radical reactivity as compared to AIBN, is known to promote grafting onto cis‐polybutadiene. Switching from AIBN to BPO initiator made a dramatic difference in the extent of grafting for styrene and methacrylate monomers, but only a modest difference for acrylate monomer. For styrene and methacrylate monomers, graft site formation is due to BPO initiator radical attack onto the backbone via allylic hydrogen abstraction. Significant levels of grafting are achieved and depend upon the relative concentrations of monomer and backbone polymer but not upon the level of initiator. For acrylic monomer, graft site formation was found to be due to polymer radical attack at the double bond in the backbone. Abstraction of allylic hydrogen also occurs but results in retardation of the overall reaction rate. Graft level was dependent upon initiator and back‐bone polymer concentrations but not upon monomer concentration. The effective role of the initiator is only to produce polymer radicals; the BPO has no direct role in the formation of effective graft sites. © 1995 John Wiley & Sons, Inc.
The association of aqueous phenolic resin with polyethylene oxide and poly(acrylamide‐co‐ethylene glycol)
Authors: Xiao Huining , Pelton Robert , Hamielec Archie
Published: April 2003

Comb copolymers formed from acrylamide and poly(ethylene‐glycol) methacrylate macro‐monomer (PAM‐co‐PEG) were compared to poly(ethylene oxide) (PEO) with respect to hydrogen bond complex formation with water‐borne phenolic resins. The behaviors of the two types of high molecular weight polyethers were similar. Complex formation gave a transient increase in viscosity followed by precipitation. Copolymers with pendant PEG chain lengths ≥ 9 formed complexes with phenolic resin whereas PEG homopolymer with a molecular weight of 2000 did not form a complex. For both copolymer and high molecular weight PEO, the tendency of the complex to precipitate increased when the pH was decreased from 7 to 4. Acridine orange, a cationic dye, bound to the phenolic resin and, after the addition of PEO, yielded visible complex gels with diameters about 20 μm. © 1995 John Wiley & Sons, Inc.
The conformation and dynamics study of amphoteric copolymers, P(sodium 2‐methacryloyloxyethanesulfonate‐co‐2‐methacryloyloxyethyltrimethylammonium iodide), using viscometry, 14N‐, and 23Na‐NMR
Authors: Yang Jung Hwan , John Mu Shik
Published: April 2003

Solution conformations and dynamic mobilities of novel amphoteric copolymers were studied for aqueous solutions of p(sodium 2‐methacryloxyethanesulfonate‐co‐2‐methacryloy‐loxyethyltrimethylammonium iodide) [P(NaMES‐co‐METMAI)] as a function of com‐position, concentration, and addition of HCI or KCI. As HCI or KCI was added successively to 5 w/v% copolymer solutions, the reduced viscosities of the solutions were reduced except the 1:1 copolymer solution. The dynamic mobility of the cationic side chain was estimated with the quadrupolar 14N‐NMR relaxation technique. The motion of the interacting coun‐terion, Na+, was studied by Poisson‐Boltzmann electrostatic theories and the quadrupolar 23Na‐NMR. Since the intramolecular 1:1 ion pair between MES‐ and METMA+ acts as an effective charge‐screening factor, the copolymers P(NaMES‐co‐METMAI) behave as ordinary polyelectrolytes with the exception of the 1 : 1 copolymer. © 1995 John Wiley & Sons, Inc.
Crosslinked poly(ethylene oxide) modified with tetraalkylammonium salts as phase transfer catalyst
Authors: Tsanov T. , Vassilev K. , Stamenova R. , Tsvetanov C.
Published: April 2003

Radiation crosslinked poly(ethylene oxide)s (PEO) modified with two tetraalkylammonium salts: allyldimethyldodecylammonium bromide and ethylmethacrylate dimethyldodecylammonium bromide were prepared. They have been characterized by elemental analysis, IR, 1H‐NMR spectra, and DSC measurements. Their activity as phase transfer catalysts (PTC) in the model displacement reaction of 1‐bromooctane with aqueous sodium cyanide were studied. The reaction kinetics were followed under pseudo‐first‐order conditions. Small amounts of onium salt inserted into the PEO network gave rise to a five time increase in the rate constant. The recovered catalysts could be re‐used without loss of activity. © 1995 John Wiley & Sons, Inc.
Surface graft polymerization of glycidyl methacrylate onto polyethylene and the adhesion with epoxy resin
Authors: Zhang Junfeng , Kato Koichi , Uyama Yoshikimi , Ikada Yoshito
Published: April 2003

Surface graft polymerization of glycidyl methacrylate (GMA) was carried out onto a high‐ density polyethylene (PE) sheet pretreated with corona to introduce peroxides onto the PE surface. Graft polymerization of GMA was effected by UV irradiation of the coronatreated PE in the presence of monomer solution without the use of any photosensitizer. The graft layer was found by staining the PE cross section to localize in the surface region of PE. The physical change in the PE surface was characterized by scanning electron microscopy, while the chemical changes due to the GMA graft polymerization were assessed by the dynamic contact angle, FT‐IR, and x‐ray photoelectron spectroscopy (XPS) measurement. The peroxide formation by corona exposure was confirmed by the XPS measurement after derivatization with SO2. The epoxy groups introduced onto the PE surface by the GMA graft polymerization were reactive with water (in the presence of HCI) and amines. The adhesion between the GMA‐grafted PE and an epoxy resin was studied by means of a shear strength test method. The GMA‐grafted PE exhibited strong interfacial adhesion with the epoxy resin, compared to the original and corona‐treated PE. The adhesion strength of the GMA‐grafted PE was nearly two times higher than that of the corona‐treated PE. This strongly suggests that the enhanced adhesion between the surface‐grafted PE and the epoxy resin is ascribed to covalent bonding of the epoxy groups on the GMA‐grafted surface to the amines in the epoxy resin. © 1995 John Wiley & Sons, Inc.
Monodisperse polymer beads as packing material for high‐performance liquid chromatography. Preparation of macroporous poly(2,3‐epoxypropyl vinylbenzyl ether‐co‐divinylbenzene) beads, their properties, and application to HPLC separations
Authors: Liang Yi‐Chun , Svec Frantisek , Fréchet Jean M. J.
Published: April 2003

In search for HPLC separation media with new surface chemistries, a styrene‐based monomer, 2,3‐epoxypropyl vinylbenzyl ether, containing reactive epoxide groups has been syn‐thesized and copolymerized with divinylbenzene in a suspension polymerization. The process involves the use of size monodisperse particles that are swollen with monomer and then polymerized in the presence of a porogenic diluent consisting of a mixture of 4‐methyl‐2‐pentanol and octane. The effect of concentration of divinylbenzene on the pore size dis‐tribution and the specific surface area of the resulting uniformly sized porous poly(2,3‐epoxypropyl vinylbenzyl ether‐co‐divinylbenzene) beads has been studied. The epoxide groups of the copolymer have been hydrolyzed and the beads used for reversed‐phase chro‐matography of both small molecules and proteins to show the effect of hydrophobicity of the matrix on the separation properties. Reversed‐phase chromatography of alkylbenzenes follows the expected pattern while for proteins the hydrolyzed beads with the highest content of the crosslinking monomer exhibit a remarkable deviation from the predicted retention characteristics. © 1995 John Wiley & Sons, Inc.
New polymer syntheses. LXXXII. Syntheses of poly(ether‐sulfone)s from silylated aliphatic diols including chiral monomers
Authors: Kricheldorf Hans R. , Masri Majdi Al
Published: April 2003

Attempts were made to synthesize poly(ether‐sulfone)s from aliphatic diols or bissilylated diols on the one hand, and 4,4′‐dichlorodiphenylsulfone or 4,4′‐difluorodiphenylsulfone on the other hand. The reaction conditions and the catalyst were varied. Polycondensations of silylated diols with 4,4′‐difluorodiphenylsulfone and powdered K2CO3inN‐methylpyr‐rolidone proved to give the best results. Using silylated isosorbide and isomannide as mono‐mers chiral poly(ether‐sulfone)s were prepared. GPC measurements indicate weight‐average molecular weights in the range of 27×103–200×103. © 1995 John Wiley & Sons, Inc.
Ring‐substituted polyaniline copolymers combining high solubility with high conductivity
Authors: Liao Yun‐Hsin , Angelopoulos Marie , Levon Kalle
Published: April 2003

Poly(aniline‐co‐phenetidine)s were synthesized by the copolymerization of aniline and o‐phenetidine (o‐ethoxyaniline). The molar feed ratio of the starting aniline monomers was varied to result in copolymers with different compositions. The actual composition was deduced by integrated proton NMR spectroscopy. The copolymers exhibit excellent solubility characteristics. It was particularly interesting to find that the 20% ethoxyaniline containing copolymer exhibits excellent solubility and yet retains the high conductivity characteristic of the unsubstituted homopolymer. The conductivity of the hydrochloride salt of this par‐ticular copolymer is identical to that of the unsubstituted derivative. However, the copolymer solubility greatly exceeds that of the unsubstituted homopolymer. The copolymer in the base form exhibits very high solubility in NMP and the resulting solutions are exceedingly more stable than those of the unsubstituted derivative. A 10% by weight solution of the 20% ethoxy copolymer in NMP is stable for ⋍ 50 days at room temperature afterwhich a gel is formed as compared to previous reports of ⋍ 3–10 h stability for corresponding solutions of the unsubstituted derivative. © 1995 John Wiley & Sons, Inc.
The interaction of vinyl monomers and poly (ethylene terephthalate) in the presence of various initiators produces a physical mixture, not a graft copolymer
Authors: Xue Thomas J. , Wilkie Charles A.
Published: April 2003

The interaction between poly(ethylene terephthalate) and four vinyl monomers, methacrylic acid, methyl methacrylate, styrene, and vinyl acetate, has been studied using hydrogen peroxide, benzoyl peroxide, azobisisobutyronitrile, and cobalt acetylacetonate as initiators. The ease of addition of the monomer to the polymer follows the solubility of the monomer in the polymer film. No chemical interaction occurs between the PET film and the monomer; rather, the monomer is homopolymerized within the film and forms a semi‐interpenetrating network so that the two homopolymers cannot be separated unless the PET matrix is destroyed. © 1995 John Wiley & Sons, Inc.
Redox polymerization of 2‐hydroxyethyl methacrylate (HEMA). I. Influence of surfactants on polymerization kinetics
Authors: Mathew Jainamma , Mahadevan Venkatanarayana
Published: April 2003

Oxidation of ferrous orthophenanthroline (FeP) by peroxydiphosphate (PP) in aqueous medium at pH 1 was followed spectrophotometrically. Kinetic analysis has shown that oxidation occurs via the formation of an intermediate complex between FeP and PP. Equi‐librium and rate constants were calculated. Influence of surfactants on the oxidation of FeP by PP was also Investigated. The equilibrium constant for complex formation was found to be higher in the presence of surfactants. The enhanced complex formation has been attributed to the ionic interactions between the charged surfactant and the ionic species in the reaction medium. Polymerization of HEMA initiated by the redox system,FeP/PP, was carried out in aqueous medium, under the conditions of excess reductant over oxidant and excess oxidant over reductant. The polymerization followed different mech‐anisms under these conditions; with excess oxidant, the growing polymer radicals underwent oxidative termination, while with excess reductant, primary radical termination was pre‐ferred. The effect of surfactants on the aqueous polymerization of HEMA using the redox system FeP/PP was also investigated. In addition to the decrease in rate, the polymerization followed a different mechanism in the presence of surfactants, the growing radicals ter‐minated by mutual interaction. © 1995 John Wiley & Sons, Inc.
Penetration of plasma surface modification into porous media. III. Multiple samples exposed to CF4 and C2F4 low temperature cascade arc torch
Authors: Krentsel E. , Yasuda H. , Miyama M. , Yasuda T.
Published: April 2003

The depth and possible mechanisms of the penetration of surface modification into porous media by a low temperature cascade are torch are investigated. Two different modes of such penetration (“flow controlled” and “diffusion controlled”) are evaluated. Three porous samples [stacks of 10 sheets of nonwoven fabrics of poly(ethylene terephthalate)each], placed at an axial distance of 24, 28, and 32 cm from the cascade are anode, are exposed to a low temperature cascade arc torch containing argon and CF4 or C2F4, and surface properties of each of the sheets within treated porous samples are examined by ESCA. It is shown that interaction of chemically reactive species, created in the low temperature cascade arc torch, with the surface is not limited to the surface directly contacted by the torch. The flow controlled penetration is more pronounced for the outer layers, while diffusion controlled penetration is within the inner layers of the porous structure. Substantial differences in the fluorination effect of CF4 (nonpolymer forming gas) and C2F4 (polymer forming gas) discharges for the second and third stacks are observed, that can be explained by the fact that the major effect of the CF4 cascade arc torch treatment is based on the reaction of reactive species with the surface polymer molecules. The effect of C2F4 cascade arc torch treatment is based on the reactions of reactive species with polymers as well as reactions of reactive species themselves at the surface (plasma polymerization). Reactivity of the species created in C2F4 discharge is much higher compared to that created in CF4 discharge, which is one of the major factors influencing penetration trends of low temperature cascade arc treatment into porous media. © 1995 John Wiley & Sons, Inc.
Molecular composite fibers from rigid rod polymers and thermoset resin matrixes
Authors: So Ying‐Hung , Sen Ashish , Kim Peter , Jeor Var St.
Published: April 2003

Fibers consisting of a rigid rod polymer and thermoset resin matrices were prepared. Poly(benzo‐[1,2‐d : 5,4‐d′]bisoxazole‐2,6‐diyl)‐1,4‐phenylene} (PBO) in polyphosphoric acid (PPA) was blended with isophthaloyl bis‐4‐benzocyclobutene (1) or 2,6‐bis‐4‐benzocyclobutene benzo[1,2‐d: 5,4‐d′]bisoxazole (2), and fibers were spun from these dopes. As‐spun fibers that did not show phase segregation between the two components as examined with an optical microscope, were soluble in methanesulfonic acid (MSA). After heat treat‐ment, the fibers swelled but did not dissolve in MSA. A fiber cross section of heat‐treated PBO‐1 fiber showed well‐dispersed benzocyclobutene polymer domains of 200–500 Å by transmission electron microscopy (TEM). Films cast from MSA solutions of PBO and 2 were homogeneous, and TEM of heat‐treated fiber showed only one phase. A molecular composite fiber was made. Some of these fibers showed 20–30% improvement in compressive strength over unmodified PBO fiber. © 1995 John Wiley & Sons, Inc.
Effect of reaction medium on the ionizing radiation‐initiated cationic copolymerization of styrene derivatives
Authors: Wood Kenneth B. , Stannett Vivian T. , Sigwalt Pierre
Published: April 2003

The influence of reaction medium polarity on the ionizing radiation‐initiated copolymer‐ization of styrene derivatives involving unpaired carbocations is examined. In the copo‐lymerization of nonpolar monomers such as p‐CH3styrene/styrene, a small effect consistent with that predicted by Laidler‐Eyring theory is found. In the copolymerization of nonpolar/polar monomer pairs such as p‐CH3styrene/p‐Clstyrene and styrene/p‐Clstyrene, any such effect is masked by specific solvation phenomena. A competition between such phenomena appears to exist, in which the different cations are dominated by different interactions. The p‐Clstyryl cation appears to undergo strong intramolecular complexation with the penultimate aromatic ring in nonpolar conditions; thus, this cation displays increased se‐lectivity toward monomers best able to disrupt the complex. The p‐CH3styryl and styryl cations do not appear to be subject to such strong complexation; thus, in nonpolar solvent, their selectivity tends towards monomers with the highest cation‐solvating ability. The differing copolymerization behavior of the p‐Clstyryl cation is consistent with the findings of previous investigations of the effect of reaction medium on chain transfer with these monomers. © 1995 John Wiley & Sons, Inc.
c‐Jun NH2‐terminal kinase‐dependent fas activation contributes to etoposide‐induced apoptosis in p53‐mutated prostate cancer cells
Authors: Shimada Keiji , Nakamura Mitsutoshi , Ishida Eiwa , Kishi Munehiro , Yonehara Shin , Konishi Noboru
Published: April 2003

Background

The death receptor, Fas, has recently been demonstrated to contribute the chemotherapeutic agents‐induced apoptosis, however, the detail mechanisms have yet to be fully understood, especially in prostate cancer cells.

Methods

PC‐3 and DU145 stably transfected with dominant negative form of Fas‐associated death domain (FADD) or specific kinase of c‐Jun NH2‐terminal kinase (JNK) (mitogen‐activated protein kinase kinase, MKK7) were selected in the presence of hygromycin B (Hyg B). Cell viability was examined by (3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulphonyl)‐2H‐tetrazolium, inner salt (MTS) assay or flowcytometric analysis using green fluorescent protein (GFP). Apoptosis was examined by DNA ladder, Western blotting analysis of cleaved caspases, or morphological analysis. The expression of Fas and JNK activation were investigated by Western blotting/flowcytometric analysis and in vitro kinase assay, respectively.

Results

Stimulation with etoposide significantly up‐regulated Fas, and the death‐inducing signaling complex (DISC) was formed in PC‐3 and DU145. Stable transfection with dominant‐negative FADD inhibited etoposide‐induced apoptosis. In addition, stable transfection with dominant‐negative MKK7, by which JNK activation was inhibited, canceled both the up‐regulation of Fas and the formation of DISC by etoposide. Re‐introduction of wild type p53 into PC‐3 and DU145 completely suppressed these inhibitory effects.

Conclusions

These results suggest that, in p53‐mutated prostate cancer, JNK‐initiated Fas‐mediated apoptotic signals may play an important role in chemosensitivity. Prostate 55: 265–280, 2003. © 2003 Wiley‐Liss, Inc.
Topological Requirements and Signaling Properties of T Cell–activating, Anti-CD28 Antibody Superagonists
Authors: Lühder Fred , Huang Yun , Dennehy Kevin M. , Guntermann Christine , Müller Ingrid , Winkler Erna , Kerkau Thomas , Ikemizu Shinji , Davis Simon J. , Hanke Thomas , Hünig Thomas
Published: April 2003

Full activation of naive T cells requires both engagement of the T cell antigen receptor (TCR; signal 1) and costimulatory signaling by CD28 (signal 2). We previously identified two types of rat CD28-specific monoclonal antibodies (mAbs): “conventional,” TCR signaling–dependent costimulatory mAbs and “superagonistic” mAbs capable of inducing the full activation of primary resting T cells in the absence of TCR ligation both in vitro and in vivo. Using chimeric rat/mouse CD28 molecules, we show that the superagonists bind exclusively to the laterally exposed C′′D loop of the immunoglobulin-like domain of CD28 whereas conventional, costimulatory mAbs recognize an epitope close to the binding site for the natural CD80/CD86 ligands. Unexpectedly, the C′′D loop reactivity of a panel of new antibodies raised against human CD28 could be predicted solely on the basis of their superagonistic properties. Moreover, mouse CD28 molecules engineered to express the rat or human C′′D loop sequences activated T cell hybridomas without TCR ligation when cross-linked by superagonistic mAbs. Finally, biochemical analysis revealed that superagonistic CD28 signaling activates the nuclear factor κB pathway without inducing phosphorylation of either TCRζ or ZAP70. Our findings indicate that the topologically constrained interactions of anti-CD28 superagonists bypass the requirement for signal 1 in T cell activation. Antibodies with this property may prove useful for the development of T cell stimulatory drugs.
Immune Enhancement of Skin Carcinogenesis by CD4+ T Cells
Authors: Daniel Dylan , Meyer-Morse Nicole , Bergsland Emily K. , Dehne Kerstin , Coussens Lisa M. , Hanahan Douglas
Published: April 2003

In a transgenic model of multi-stage squamous carcinogenesis induced by human papillomavirus (HPV) oncogenes, infiltrating CD4+ T cells can be detected in both premalignant and malignant lesions. The lymph nodes that drain sites of epidermal neoplasia contain activated CD4+ T cells predominantly reactive toward Staphylococcal bacterial antigens. HPV16 mice deficient in CD4+ T cells were found to have delayed neoplastic progression and a lower incidence of tumors. This delay in carcinogenesis is marked by decreased infiltration of neutrophils, and reduced activity of matrix metalloproteinase-9, an important cofactor for tumor progression in this model. The data reveal an unexpected capability of CD4 T cells, whereby, proinflammatory CD4+ T cells, apparently responding to bacterial infection of dysplastic skin lesions, can inadvertently enhance neoplastic progression to invasive cancer.
CD1d-restricted Help To B Cells By Human Invariant Natural Killer T Lymphocytes
Authors: Galli Grazia , Nuti Sandra , Tavarini Simona , Galli-Stampino Luisa , De Lalla Claudia , Casorati Giulia , Dellabona Paolo , Abrignani Sergio
Published: April 2003

Invariant natural killer T (NKT) cells are a highly conserved subset of T lymphocytes expressing a semi-invariant T cell receptor (TCR), which is restricted to CD1d and specific for the glycosphingolipid antigen α-galactosylceramide. Their ability to secrete a variety of cytokines, which in turn modulate the activation of cells of both innate and acquired immune responses, suggests that invariant NKT cells exert a regulatory role mainly via indirect mechanisms. A relevant question is whether invariant NKT cells can directly help B cells. We document here that human invariant NKT cells are as efficient as conventional CD4+ Th0 lymphocytes in promoting proliferation of autologous memory and naive B lymphocytes in vitro, and in inducing immunoglobulin production. Help to B cells by invariant NKT cells is CD1d-dependent and delivered also in the absence of α-galactosylceramide, suggesting that NKT cells recognize an endogenous ligand presented by CD1d on B cells. The two major subsets of invariant NKT cells, CD4+ and double negative (CD4−CD8−), express comparable levels of CD40 ligand and cytokines, but differ in helper functions. Indeed, both subsets induce similar levels of B cell proliferation, whereas CD4+ NKT cells induce higher levels of immunoglobulin production. These results suggest a direct role for invariant NKT cells in regulating B lymphocyte proliferation and effector functions.
Involvement of Avidity for Major Histocompatibility Complex in Homeostasis of Naive and Memory T Cells
Authors: Kassiotis George , Zamoyska Rose , Stockinger Brigitta
Published: April 2003

The requirements for survival and self-renewal of peripheral T cells and the nature of mechanisms controlling the size of the naive and memory pool are not completely understood. Here, we examine the involvement of the major histocompatibility complex (MHC) in survival and homeostatic expansion of naive and memory T cells. We show that the homeostatic behavior of naive T cell receptor (TCR)-transgenic T cells can be deduced by the expression levels of TCR and CD5, a negative regulator of TCR signaling. Both these factors determine the strength of TCR stimulation by MHC-derived signals. We further show that, similarly to naive T cells, MHC-derived signals influence the homeostatic expansion capacity of memory T cells under lymphopenic conditions. In contrast to naive T cells, however, memory T cells can reach a homeostatic equilibrium, in which survival/self-renewal of each clone is dissociated from their avidity for MHC-derived signals.
Human Dendritic Cells Activated by TSLP and CD40L Induce Proallergic Cytotoxic T Cells
Authors: Gilliet Michel , Soumelis Vassili , Watanabe Norihiko , Hanabuchi Shino , Antonenko Svetlana , de Waal-Malefyt Rene , Liu Yong-Jun
Published: April 2003

Human thymic stromal lymphopoietin (TSLP) is a novel epithelial cell–derived cytokine, which induces dendritic cell (DC)-mediated CD4+ T cell responses with a proallergic phenotype. Although the participation of CD8+ T cells in allergic inflammation is well documented, their functional properties as well as the pathways leading to their generation remain poorly understood. Here, we show that TSLP-activated CD11c+ DCs potently activate and expand naive CD8+ T cells, and induce their differentiation into interleukin (IL)-5 and IL-13–producing effectors exhibiting poor cytolytic activity. Additional CD40L triggering of TSLP-activated DCs induced CD8+ T cells with potent cytolytic activity, producing large amounts of interferon (IFN)-γ, while retaining their capacity to produce IL-5 and IL-13. These data further support the role of TSLP as initial trigger of allergic T cell responses and suggest that CD40L-expressing cells may act in combination with TSLP to amplify and sustain pro-allergic responses and cause tissue damage by promoting the generation of IFN-γ–producing cytotoxic effectors.
Comment on “Voter Turnout and the National Election Studies”
Authors: Martinez Michael D.
Published: April 2003

A recent article by Barry Burden inPolitical Analysisalerts us to a steadily increasing gap during presidential election years between self-reported turnout in the NES (National Election Studies) and “official turnout” figures based on the voting-age population (VAP), and points to declining response rates as a culprit. Changing the baseline from the VAP to the VEP (voting-eligible population) significantly changes these conclusions, and point to panel effects as a culprit. The rise in the gap was not linear, but it does emerge rather suddenly in 1996. Gaps between NES self-reported turnout and VEP estimates are higher in presidential election years than in off-years, and self-reported turnout is higher among long-term panel participants than among cross-section respondents in multielection panels.
The Doctor Is In
Authors: Chiaverina Chris
Published: April 2003

In 1999, Tung Jeong, professor emeritus at Lake Forest College, spent a week at New Trier High School as scientist-in-residence. During this time, he met with physics students and staff in both large and small groups to discuss the art and science of holography. As a result of a workshop he presented to our physics teachers, more than 700 physics students now make reflection holograms annually. In conjunction with his visit, he displayed some of his most spectacular holograms in our school's art gallery. Many visitors to the gallery were convinced that the disarmingly real-looking images were actually objects displayed behind glass. One hologram in particular fooled almost everyone.
Comparison of Different Commercial Wireless Keypad Systems
Authors: Burnstein Ray A. , Lederman Leon M.
Published: April 2003

Wireless keypad systems have been in limited use for the past 10 years in the classroom.1,2 Such systems can be used to quiz students in real time during the class, thus engaging students more directly in the lecture.3 Nonetheless, until recently widespread use of such keypad systems has been limited for several reasons. First, the original systems were relatively expensive but perhaps more important was the reluctance on the part of faculty to change the existing passive lecture format.4,5 However, problems associated with large lecture classes6 and the validation of the concept of “interactive engagement” from the high-statistics study of Hake7 has changed the opinions of many. In addition the desirability of peer learning,8 which is enhanced with a response system, has also been accepted. At the present time a number of commercial systems are available. The purpose of this paper is to present a comparison and summary of what is commercially available9 and a reminder that keypads are a dramatically effective teaching and learning tool.
Galileo's Lens
Authors: Manos Harry
Published: April 2003

Most visitors to Florence, Italy, know about the Galleria dell'Accademia, housing Michelangelo's famous statue of David, or the Galleria degli Uffizi with the famous Medici collection. Few visitors know that only two blocks from the Uffizi on the Arno River is one of the world's finest museums featuring historic scientific instruments, the Museo di Storia della Scienza. In the February issue of TPT, Nickell states that the Museo di Storia della Scienza “is perhaps the best museum on the history of science in the world.”1 This fact is likely true, and the museum is a must for physics teachers visiting Florence. It features a vast collection of authentic “cutting-edge” scientific instruments, including one of Galileo's lenses in a magnificent ebony and ivory frame. One of the tragedies is that this museum goes unmarked on many tourist maps and unmentioned in many guidebooks.