bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photogenerated hydroperoxides of EPDM rubbers and their characterization
Authors: Chmela S. , Teissèdre G. , Lacoste J. 
Published: April 2003

AbstractThree different ethylene/propylene/diene (EPDM) rubbers were allowed to react with singlet oxygen. This reaction leads to the production of polymeric pendant hydroperoxides only in one case. Terpolymer ethylene/propylene/5‐ethylidene‐2‐norbornene reacts with singlet oxygen and isolated and associated secondary hydroperoxides are formed. Anthracene was used as a sensitizer for production of singlet oxygen under 365‐nm irradiation. The course of hydroperoxide formation was similar in the solid state as well as in the toluene solution. Reactivity of hydroperoxides prepared was tested in their reaction with gaseous dimethyl sulfide (DMS). Both the isolated and associated hydroperoxides react with DMS by dual fast and slow process. Fast process is more significant in the case of the isolated hydroperoxides. © 1995 John Wiley & Sons, Inc.
Esterification reactions on syndiotactic poly(2‐methallyl alcohol). V. Homopolymers of 2‐methallyl‐(L)‐dipeptidates and dipeptides cleaved from them
Authors: Grosse Ophoff M. , Dernst C. , Dederichs B. , Klesper E. 
Published: April 2003

AbstractSyndiotactic poly(2‐methallyl alcohol) (sPMA) is esterified withNα‐protected (L)‐α‐amino acids by the DCC/HOBT method. The resulting polymer is deprotected by HBr/glacial acetic acid. A secondNα‐protected (L)‐α‐amino acid is condensed to the free α‐NH2of the amino acid already bound to the sPMA by a water‐soluble carbodiimide in mixed aqueous/organic solution. The formedNα‐protected dipeptide polymers were hydrazinolized to yield theNα‐protected dipeptide hydrazides. Alternatively, the dipeptidate polymers wereNα‐deprotected and then hydrolyzed by aqueous KOH at pH = 11.0 to yield the deprotected dipeptides. All polymers and the dipeptides were characterized by1H‐ and13C‐NMR and the water‐solubleNα‐deprotected polymers in addition by potentiometry. The synthetic procedures open a path to defined tactic polymers with chiral oligopeptide side chains and, after their cleavage, also to oligopeptides. During synthesis, the oligopeptide is bound to a dissolved polymer chain of relatively extended macroconformation which facilitates both the accessibility and reactivity of the reaction centers as well as the precipitation and filtration after each synthesis step. © 1995 John Wiley & Sons, Inc.
Selective oxidation of poly(4‐methylstyrene)
Authors: Shaver Robert T. , Vlaovic Djordje , Reviakine Ilya , Wittaker Rhonda , Ferrari Lorenzo P. , Stöver Harald D. H. 
Published: April 2003

AbstractA range of new functional copolymers bearing aldehyde and carboxylic acid groups have been prepared by functionalization of poly(4‐methylstyrene). These polymers have molecular weights from 2,000 to 16,500 and contain up to 20% aldehyde and up to 90% carboxylic acid groups. The reaction proceeds by selective catalytic oxidations with molecular oxygen or air in acetic acid/organic cosolvent mixtures in presence of cobalt acetate and sodium bromide or hydrogen bromide. The effects of reaction temperature, catalyst, co‐solvents and oxygen partial pressure on the reaction are described. © 1995 John Wiley & Sons, Inc.
Graft copolymerization of methacrylic acid and acrylamide onto acrylonitrile‐butadiene‐styrene terpolymer by photoinduced hydroperoxide
Authors: Suzuki Masanori , Wilkie Charles A. 
Published: April 2003

AbstractGraft copolymerization of methacrylic acid (MAA) or acrylamide (AM) from an aqueous solution onto acrylonitrile‐butadiene‐styrene terpolymer (ABS) was initiated by the thermal decomposition of polymeric hydroperoxides, which are formed upon UV irradiationof ABS, which contains anthracene. Diffusion of anthracene at room temperature from a methanolic solution into ABS was affected by the acrylonitrile content ofABS.The graft yield was independent on the concentration of anthracene in the wide range of 0.03 X 10‐3 to 14.29 X 10−3 mol/L in ABS. The graft polymerization reaction does not occur below 100°C.The effect of other variables, such as time of irradiation, intensity of UV, reaction time, and concentration of monomer in aqueous solution, on the amount of monomer grafted to ABS were also investigated.The contact angle significantly decreases upon grafting, indicating that the graft layer is on the surface of the polymer. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of soluble aromatic polyurea‐amides from new N,N′‐‐dimethyl‐N,N′‐bis(aminophenyl)ureas and aromatic dicarboxylic acid chlorides
Authors: Park Ki Hong , Tani Takashi , Kakimoto Masa‐aki , Imai Yoshio 
Published: April 2003

AbstractAromatic polyurea‐amides having inherent viscosities of 0.36–0.67 dL/g were synthesized by the low temperature solution polycondensation of new N,N′‐dimethyl‐N,N′‐bis(aminophenyl)ureas with various aromatic dicarboxylic acid chlorides. All the polymers were amorphous, and most of them were soluble in a variety of organic solvents such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide (DMAc), m‐cresol, and pyridine. Some of the polymers could be cast from the DMAc solutions into transparent and flexible films having good tensile properties. The glass transition temperatures of the polyurea‐amides obtained from the bis(4‐aminophenyl)‐substituted ureas were 244–272°C. The temperatures of 10% weight loss under nitrogen of the polymers were in the range of 430 and 480°C. © 1995 John Wiley & Sons, Inc.
Synthesis and barrier properties of poly(ε‐caprolactone)‐layered silicate nanocomposites
Authors: Messersmith Phillip B. , Giannelis Emmanuel P. 
Published: April 2003

AbstractA new polymer‐ceramic nanocomposite has been synthesized consisting of well‐dispersed, two‐dimensional layers of an organically modified mica‐type silicate (MTS) within a degradable poly(ε‐caprolactone) matrix. A protonated amino acid derivative of MTS was used to promote delamination/dispersion of the host layers and initiate ring‐opening polymerization of ε‐caprolactone monomer, resulting in poly(ε‐caprolactone) chains that are ionically bound to the silicate layers. The polymer chains can be released from the silicate surface by a reverse ion‐exchange reaction and were shown to be spectroscopically similar to pure poly(ε‐caprolactone). Thick films of the polymer nanocomposite exhibit a significant reduction in water vapor permeability that shows a linear dependence on silicate content. The permeability of nanocomposite containing as low as 4.8% silicate by volume was reduced by nearly an order of magnitude compared to pure poly(ε‐caprolactone). © 1995 John Wiley & Sons, Inc.
Radical polymerization of methyl trans‐β‐vinylacrylate
Authors: Ueda Mitsuru , Shimada Shinichi , Ogata Tateaki , Oikawa Kazuo , Ito Hiroshi , Yamada Bunichiro 
Published: April 2003

AbstractMethyl trans‐β‐vinylacrylate (MVA) undergoes radical polymerization with α,α′‐azobis(isobutyronitrile) (AIBN) in bulk and solution. The polymer obtained consists of 85% trans‐1,4 and 15% trans‐3,4 units. Poly(MVA) (PMVA) is readily soluble in common organic solvents, but insoluble in n‐hexane and petroleum ether. PMVA exhibits a glass transition at 60°C, and loses no weight up to 300°C in nitrogen. The kinetics of MVA homopolymerization with AIBN was investigated in benzene. The rate of polymerization (Rp) can be expressed by Rp = k[AIBN]0.5[MVA]1.0, and the overall activation energy has been calculated to be 94 kJ/mol. The propagation radical of MVA at 80°C was detected by ESR spectroscopy, which indicated that the unpaired electron of the propagating radical was completely delocalized over the three allyl carbons. Furthermore, the steady‐state concentration of the propagating radical of MVA at 60°C was determined by ESR spectroscopy, and the propagation rate constant (kp) was calculated to be 1.25 X 102 L/mol ·s. Monomer reactivity ratios in copolymerization of MVA (M2) with styrene (M1) are r1 = 0.16 and r2 = 4.9, from which Q and e values of MVA are calculated as 4.2 and ‐0.32, respectively. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of epoxy‐functional polystyrene particles
Authors: Kling Janet A. , Ploehn Harry J. 
Published: April 2003

AbstractColloidal polystyrene particles with surface epoxy groups have been synthesized through surfactant‐free emulsion copolymerization of styrene with glycidyl methacrylate; and through copolymerization of glycidyl methacrylate (GMA) and methyl methacrylate as shells around existing polystyrene seed particles. We developed two titration methods to quantify the number of epoxy groups that survived the polymerization processes. The styrene‐GMA copolymer particles were judged to be unsatisfactory as model colloidal materials due to their size polydispersity and unknown internal distribution of epoxy groups. The core‐shell particles had high epoxy surface densities with at least 60% of the initial epoxy groups surviving the synthesis process. Transmission electron microscopy shows that the thickness of the epoxy‐rich shell is less than expected based on the volume of monomers added, suggesting that some of the monomer forms water‐soluble oligomers. Photon correlation spectroscopy measurements imply that the shell is swollen with water and consists of polymer configurations which extend out into solution. The morphological details vary consistently with the GMA content, and hence the hydrophilicity, of the shell polymer. © 1995 John Wiley & Sons, Inc.
Silylation of poly(vinyl alcohol) with hexamethyldisilazane in liquid ammonia
Authors: Mormann Werner , Wagner Thomas 
Published: April 2003

AbstractSilylation of poly(vinyl alcohol) has been performed with hexamethyldisilazane in liquid ammonia in an autoclave. This novel procedure has the advantage that the educt, the reagent, and the product are soluble in ammonia, which works under homogeneous conditions. No salt like by‐products are formed and no tedious purification of the product is necessary. The degree of silylation has been adjusted through the ratio of silylating agent to hydroxy groups. Random incorporation of trimethylsilyl groups was proven by the linear dependence of the glass transition temperature from the degree of silylation and the solubility of the partially silylated material. Quantitative investigation of the silylation reaction showed first‐order kinetics for the initial and final stages of the reaction indicative of a reaction where k1 > k2 > k3. © 1995 John Wiley & Sons, Inc.
Novel fluorinated poly(aryl ether ketone)s
Authors: Elce Edmund , Hay Allan S. 
Published: April 2003

AbstractTwo novel fluorinated monomers were prepared and polymerized with biphenols to produce amorphous, thermally stable poly(aryl ether ketone)s. The properties of the fluorinated polymers are compared to those of unfluorinated, amorphous poly(aryl ether ketone)s. The presence of fluorine in the polymers was found to cause a decrease in glass transition temperature and Young's moduli, however, no increase in thermal stability was observed. The fluorinated polymers are soluble in common organic solvents such as chloroform and methylene chloride at room temperature, and also show solubility in solvents containing a ketonic moiety, such as acetone. Evidence of polymer branching through fluorines considered to be unreactive under the polymerization conditions was found. Efforts were made to evaluate the reactivity of fluorine atoms under the polymerization conditions using both molecular modeling and 19F‐NMR to ascertain if such branching could be avoided. © 1995 John Wiley & Sons, Inc.
Ring‐opening polymerization of cyclobutane adducts of tetracyanoethylene and vinyl ethers with tertiary amines
Authors: Yokozawa Tsutomu , Fukata Hideaki 
Published: April 2003

AbstractRing‐opening polymerizations of cyclobutane adducts of tetracyanoethylene (TCNE) and vinyl ethers (VE) or p‐methoxystyrene with tertiary amines are described. The polymerization of the cyclobutane adduct 1a of TCNE and ethyl vinyl ether (EVE) was carried out with 10 mol % of triethylamine in acetonitrile at ambient temperature to afford the alternating copolymer of TCNE and EVE with high molecular weight in good yield under various conditions. Under the optimum condition, the cyclobutane adducts of TCNE and a variety of VEs such as n‐butyl vinyl ether, isobutyl vinyl ether, 2,3‐dihydrofuran, and 3,4‐dihydro‐2H‐pyran were polymerized to yield similar polymers. Although the cyclobutane adduct 4 of TCNE and p‐methoxystyrene did not polymerize under these conditions, the treatment of 4 with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in acetonitrile at 60°C gave the polymer. On the basis of the fact that the polymer molecular weight increased rapidly at the initial stage and slowly even after the consumption of all of monomers, we propose that the tertiary amine initiates the chain anionic polymerization of the cyclobutane adduct to afford an ammonium macrozwitterion 3, which is subjected to the intermolecular nucleophilic substitution with each other in a step polymerization manner. © 1995 John Wiley & Sons, Inc.
Liquid crystalline epoxy resins by polyaddition of aliphatic diepoxides with 4,4′‐dihydroxybiphenyl
Authors: Szczepaniak Barbara , Frisch Kurt C. , Penczek Piotr , Leszczyńska Irena , Cholińska Mariola , Rudnik Ewa 
Published: April 2003

AbstractLiquid crystalline epoxy resins were synthesized from 4,4′‐dihydroxybiphenyl (DHB), which was used as a mesogenic component, and diglycidyl ethers of aliphatic glycols (ethylene glycol and 1,6‐hexanediol) which were used as flexible spacers. The synthesis was carried out by the catalytic polyaddition in the melt. Triphenylphosphine was used as the catalyst. The course of the polyaddition was investigated at various molecular ratios of the reactants. It was found that both linear and branched structures were formed in the course of the synthesis. The rates of the formation of the structures were calculated. The epoxy oligomers were investigated by DSC, polarizing microscope, and x‐ray and IR spectroscopy. The molecular weight distribution was determined by GPC. The dependence of liquid crystalline properties of the obtained epoxy resins on the molecular weight and on the chain length of the flexible spacer was investigated. The molecular weight of the epoxy oligomers and the length of flexible spacer influence the phase transition temperatures. © 1995 John Wiley & Sons, Inc.
Thermal degradation of poly(methyl‐n‐hexylsilylene)
Authors: Jambe Baudouin , Marchand‐Brynaert Jacqueline , Devaux Jacques 
Published: April 2003

AbstractThermal degradation of poly(methyl‐n‐hexylsilane) in the solid state in absence of oxygen reveals formation of a cyclic pentamer between 150 and 250°C. Polymer is gradually degraded to an intermediate molecular weight distribution. The weight average of this new distribution is not only temperature‐dependent, but is also a function of viscosity of the polymer and nature of chain ends. As no insolubles or SiH groups are formed, the degradation mechanism is most likely a back‐biting mechanism induced by active chain ends such as silyl anions or SiCl rather than a homolytic cleavage of the main chain. A concurrent intramolecular rearrangement reaction is also proposed. Moreover, this study proposes an explanation to the trimodal molecular weight distribution obtained by the Wurtz coupling of dichlorosilanes with molten sodium in refluxing toluene. © 1995 John Wiley & Sons, Inc.
Miniemulsion polymerization of styrene: Evolution of the particle size distribution
Authors: Miller C. M. , Sudol E. D. , Silebi C. A. , El‐Aasser M. S. 
Published: April 2003

AbstractThe mechanism of the miniemulsion polymerization of styrene was investiaged through a combination of calorimetry to monitor the polymerization rate and transmission electron microscopy (TEM) to follow the evolution of the particle size distribution. These techniques proved to be a powerful combination for gaining detailed mechanistic information regarding these polymerizations. Particle size analysis of the latexes withdrawn during the course of the reaction revealed that most of the polymer particles were formed by a relatively low conversion (i.e., 10% conversion). However, nucleation continued well past this point (to 40‐60% conversion). In fact, it was observed that nucleation in miniemulsion polymerizations using cetyl alcohol continued past the maximum in the rate of polymerization. As a result of these long nucleation periods, the latex particle size distributions produced from these miniemulsion polymerizations were broader than their conventional emulsion polymerization counterparts, and were negatively skewed with a tail of small particles. The amount of negative skewing of the particle size distributions was found to decrease with increasing initiator (potassium persulfate) concentration. Finally, a correlation was observed between the length of time to the maximum polymerization rate and the breadth of the particle size distribution as reflected in the standard deviation. © 1995 John Wiley & Sons, Inc.
Photoinitiated cationic polymerization using o‐phthaldehyde and pyridinium salt
Authors: Yagci Yusuf , Denizligil Selcuk 
Published: April 2003

AbstractThe cationic polymerization of cyclohexene oxide (CHO), n‐butyl vinylether (BVE), N‐vinylcarbazole (NVC), and 4‐vinyl cyclohexenedioxide (4‐VCHD) is initiated upon UV irradiation (Λinc. = 350 nm) of dichloromethane solution containing N‐ethoxy‐2‐methyl‐pyridinium hexafluorophosphate (EMP+PF6) and o‐phthaldehyde. A feasible initiation mechanism involves formation of biradical by intramolecular hydrogen abstraction of triplet o‐phthaldehyde. Oxidation of these radicals by EMP+ ions yields protons capable of initiating the cationic polymerization. © 1995 John Wiley & Sons, Inc.
Kinetic study of polyesterification: Unsaturated polyesters
Authors: Beigzadeh D. , Sajjadi S. , Taromi F. Afshar 
Published: April 2003

AbstractSynthesis of unsaturated polyesters using adipic acid, ethylene glycol, and fumaric acid in the absence and presence of a foreign acid (phosphoric acid) as catalyst was carried out by a two‐stage method under constant reaction temperatures of 160–180°C and at different ratios of diol to diacid. The experimental data fit the Chen–Wu rate equations for self‐catalyzed and acid‐catalyzed reactions. The reaction rate constants and activation energies for both systems were calculated. The rate constants of fumaric acid–ethylene glycol systems were found to be nearly constant and had negligible variations with increasing chain length of polymer. © 1995 John Wiley & Sons, Inc.
Dispersion polymerization in polar solvents
Authors: Sáenz José M. , Asua José M. 
Published: April 2003

AbstractThe effect of the nitrogen purge, monomer purification, type of agitation, and presence of costabilizer on the particle size distribution (PSD) was investigated in the dispersion po‐lymerization of styrene in ethanol and in the dispersion copolymerization of styrene and butyl acrylate in a water–ethanol mixture. Purging with nitrogen and, to a lesser extent, monomer purification, were of paramount importance to achieve monodispersity. The type of agitation had a week effect on the PSD, whereas the presence of costabilizer had no effect on the PSD. © 1995 John Wiley & Sons, Inc.
Segmented polyurethanes with 4,4′‐bis‐(6‐hydroxyhexoxy) biphenyl as chain extender. I. Synthesis and characterization of 2,4‐tdi‐polyurethanes
Authors: Mix R. , Goering H. , Schulz G. , Gründemann E. , Gähde J. 
Published: April 2003

AbstractPolyurethanes composed of 2,4‐toluene diisocyanate (TDI), poly (butylene adipate) diols (PBA) of different molecular weights, and 4,4′‐bis‐(6‐hydroxyhexoxy) biphenyl (BHHBP) were prepared by a two‐step solution polymerization process. The polyurethanes were char‐acterized by elemental analysis, NMR, and SEC. The thermal properties were investigated by DSC, DMA, and optical polarizing microscopy. Dependent on the molecular weight of the PBA, a shift in the glass transition temperature Tg of the polyurethanes has been observed by DSC and DMA. Polyurethanes based on poly (butylene adipate)s of Mn ∼ 2000 exhibited a Tg nearly independent on the hard‐segment content up to 50% LC hard segments, indicating the existence of mainly phase separated soft and hard segments. By shortening the PBA chain length up to 1,000 and further to 600, the Tg of the polyester soft‐segment phase increases with growing hard‐segment content, a consequence of enhanced interaction between the hard and soft segments. This tendency is observed to the greatest extent at polyurethanes with the shortest, polyester diol and can be interpreted as a partial miscibility or compatibility of hard and soft segments. Although in polyurethanes with PBA 2000 the mesophase can be proven at a hard‐segment content of ∼ 40%, its appearance in polyure‐thances prepared with PBA 1000 or PBA 600 requires a hard‐segment content > 60%. © 1995 John Wiley & Sons, Inc.
Oxidative polymerization of pyrrole in polymer matrix
Authors: Saraç A. Sezai , Ustamehmetoǧlu Belkis , Mustafaev Mamed I. , Erbil Candan , Uzelli Gülay 
Published: April 2003

AbstractThe oxidative matrix polymerization of pyrrole (Py) by Ce(IV) in the presence of Polyacrylic acid (PAA) has been studied to obtain water‐soluble and insoluble products. The role of the PAA, Pyrrole, and Ce(IV) concentration, order of component addition, the structure of polymer matrix (PAA, Hydroxy Ethyl Cellulose (HES), Poly‐N‐vinylpyrrolidone (PVP)], and model unit of PAA (propionic acid), on the polymerization system were investigated.Interaction of PAA with insoluble polypyrrole (PPy) and the interpolymer complex formation were investigated along with the aggregation of PPy onto the matrix polymer followed by spectral shifts. FTIR results of insoluble products obtained from the PAA–Py–Ce(IV) system and solubility of the system is explained in light of the mechanism of the polymerization of pyrrole on the polymer matrix. © 1995 John Wiley & Sons, Inc.
Photoinduced ring opening metathesis polymerization (PROMP) of strained bicyclic olefins with ruthenium complexes of the type [(η6‐arene1)Ru(η6‐arene2)]2+ and [Ru(Nc‐R)6]2+
Authors: Karlen T. , Ludi A. , Mühlebach A. , Bernhard P. , Pharisa C. 
Published: April 2003

AbstractUpon UV irradiation, the complexes [(η6‐arene1)Ru(η6‐arene2)]2+ (toluene‐4‐sulfonate or trifluormethane‐sulfonate as counter ion; examples for arene: benzene, toluene, mesitylene, hexamethylbenzene, anisole, biphenyl, naphthalene) and [Ru(NC‐R)6]2+ (tosylate or triflate as counter iron; R = methyl, ethyl, phenyl) are transformed into active catalysts for ring opening metathesis polymerization (ROMP) of strained bicyclic olefins. The photoinduced ring opening metathesis polymerization (PROMP) is most efficient with sandwich complexes having high quantum yields for the photochemically induced solvation of [(η6‐arene1)Ru(η6‐arene2)]2+ to [Ru(solvent)6]2+. With most of the complexes no (or only low) catalytic activity is observed in the absence of light. After the photolysis step, the mechanism of the polymerzation is identical to ROMP reactions with thermally activated ruthenium catalysts. Good yields and high molecular weights are obtained with a catalyst concentration of 0.1–1%. A mechanistic model for the initiation is presented. © 1995 John Wiley & Sons, Inc.