bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of functional substituted polycarbosilanes based on silyltriflate derivatives
Authors: Uhlig Wolfram
Published: April 2003

Polycarbosilanes obtained by the Wurtz method or Grignard synthesis were converted by protodesilylation with trifluoromethanesulfonic acid to triflate‐substituted derivatives. Reactions of these polymers with nucleophiles led to novel functionally substituted polycarbosilanes. Polycarbosilanes with a regular alternating arrangement of silicon and carbon atoms, however, could not be obtained by this procedure. Such polymers were prepared by reactions of bis(trifluoromethylsulfonyioxysilyl)methanes with dinucleophiles. All syntheses are characterized by a high regioselectivity and high yields at low temperatures in short reaction times. The structures of the polymers were proven by NMR spectroscopy (29Si, 13C, 1H). © 1995 John Wiley & Sons, Inc.
Synthesis of stereoregular polygluconamides from D‐glucose and D‐glucosamine
Authors: Bueno M. , Galbis J. A. , García‐Martín M. G. , De Paz M. V. , Zamora F. , Muñoz‐Guerra S.
Published: April 2003

Two stereoregular polygluconamides, one (3) of polypeptide‐type and the other (16) being a polycaproamide containing four stereocenters in the main chain of the repeating unit, have been prepared from D‐glucosamine and D‐glucose, respectively. The new polyamides were characterized by elemental analysis, and IR, 1H‐ and 13C‐NMR spectroscopies. The molecular weights for 3 and 16 were estimated as 25,000 and 67,000, respectively, on the basis of viscosimetric measurements. Both polyamides display high optical activity; they are highly hydrophilic and readily soluble in water as well as in a variety of organic solvents including chloroform. Polyamide 16 is highly crystalline and yields resistant films with spherulitic texture. © 1995 John Wiley & Sons, Inc.
Synthesis of 1,1,9,9‐tetrafluoro[2.2]paracyclophane and its polymerization by vapor deposition method
Authors: Itoh Takahito , Okuoka Siro , Kubo Masataka , Iwatsuki Shouji
Published: April 2003

1,1,9,9‐Tetrafluoro[2.2]paracyclophane (1) was prepared successfully as white crystals in 72% yield via two‐step reactions from 1,9‐diketo[2.2]‐paracyclophane. The polymerization of 1 by the vapor deposition method was carried out at pyrolysis temperature range of 400 to 800°C and deposition temperature range of −20 to 20°C, and a tough, transparent poly(α,α‐difluoro‐p‐xylylene) film was obtained in 72% yield at the pyrolysis temperature of 750°C and the deposition temperature of −20°C. It was found that the pyrolysis of 1 gave a reactive α,α‐difluoro‐p‐xylylene, which polymerized on the head‐to‐tail addition to give poly(α,α‐difluoro‐p‐xylylene). Some properties such as solubility, thermal stability, glass transition temperature, and density for poly(α,α‐difluoro‐p‐xylylene) were studied. © 1995 John Wiley & Sons, Inc.
Detection of nanoscale events in dispersed polymer particles containing a charge‐transfer fluorescence probe
Authors: Verhey Herman J. , Gebben Bert , Hofstraat Johannes W. , Verhoeven Jan W.
Published: April 2003

A probe molecule, which shows an unusually large change in fluorescent properties in response to changes in its environment, was introduced into a monodisperse polystyrene latex. Upon addition of low‐molecular‐weight compounds, the ensuing swelling process of the latex could be followed via the changes in the fluorescence spectrum of the probe molecule. Polymerization reactions of monomers, introduced into the particles, could also be monitored by means of this approach. Using glycidylmethacrylate as the monomer led to the formation of particles in which two distinctly different surroundings could be detected after such a polymerization. © 1995 John Wiley & Sons, Inc.
Formation and characterization of simple and mixed vesicles based on monomeric and oligomeric phosphate bipolar amphiphiles
Authors: Kokkinia A. , Keramaris K. E. , Margaritis L. , Malliaris A. , Paleos C. M.
Published: April 2003

Certain phosphate bipolar amphiphiles, both monomeric (I and II) and polymeric or rather oligomeric (poly‐I and poly‐II), were used as basic materials for the preparation of simple and mixed vesicles. Specifically, it was found that oligomeric phosphate bipolar amphiphiles form stable vesicles in aqueous media. The same oligomeric bolaamphiphiles in mixture with their monomeric counterparts also form stable mixed vesicles with sonication; they are relatively less stable with the “thin film method.” Furthermore, it was shown that the method of spanning the membrane of didodecylphosphate vesicels with the dipolar amphiphile II is not effective for enhancing stability. © 1995 John Wiley & Sons, Inc.
Curing of diglycidylamine‐based epoxides with amines: Kinetic model and simulation of structure development
Authors: Matêjka Libor , Duŝek Karel
Published: April 2003

A complex mechanism of the reaction of diglycidylamine (DGA)‐based epoxides with primary amines is described and the kinetic model is developed. The reaction mechanism involves the addition of amine, etherification, and also formation of small cycles and anionic homopolymerization of the epoxide compound including transfer and termination. The polymer structure was theoretically described by distribution of structural fragments determined using the kinetic model. Simulation of the structure evolution during the DGA‐aniline reaction at varying molar ratios of reagents and dilution of the system was performed. The effect of the reaction conditions on the distribution of structural fragments, such as branching units and cyclic structures, was determined. © 1995 John Wiley & Sons, Inc.
Cationic polymerization of glycidyl phenyl ether by benzylammonium salts
Authors: Nakano S. , Endo T.
Published: April 2003

Novel cationic initiators, p‐substituted benzylanilinium SbF–6 salts (1), were synthesized from the corresponding benzylchloride and N,N‐dimethylaniline, where Cl– was exchanged with SbF–6. Their catalytic activities in the cationic polymerization of glycidyl phenyl ether (GPE) were examined and compared to that of benzylpyridinium SbF–6 salts (2), latent thermal initiators previously reported by Endo et al. It was found that 1 acted as a latent thermal initiator in the cationic polymerization of glycidyl phenyl ether (GPE) above 80°C for 10 min. Furthermore, 1 showed higher activity than 2 having the same p‐substituents, except for a p‐Cl group in the cationic polymerization of GPE. Both the GPE polymer structure and the benzyl group reactivity in 1 or 2 indicate that 1 generates benzyl cations that are active species for the cationic polymerization of GPE, and that in cationic polymerization using 2, side reactions generating active species other than benzyl cations occur. magnified image © 1995 John Wiley & Sons, Inc.
Investigation of polyimides containing naphthalene units. II. Model compounds synthesis
Authors: Sek Danuta , Wanic Andrzej , Schab‐Balcerzak Ewa
Published: April 2003

A series of model compounds from 4‐benzoyl‐1,8‐naphthalene anhydride and aromatic amines and diamines has been synthesized. The influence of the reaction conditions on the structure of the compounds obtained has been investigated to explain the high‐temperature polycondensation reaction mechanism. It was found that at high‐temperature polycondensation of 1,8‐naphthalene‐type anhydrides with aromatic amines, isoimides with cis and and trans structures are formed instead of amic acids. The only trans isoimides may isomerize to imide structure. © 1995 John Wiley & Sons, Inc.
Grafting of maleic anhydride to hydrocarbons below the ceiling temperature
Authors: Russell K. E.
Published: April 2003

Maleic anhydride has been grafted to eicosane and squalane at 60–80°C using 1,2‐dichlorobenzene as solvent and benzoyl peroxide as initiator. These hydrocarbons are low molecular weight models for hydrocarbon polymers containing secondary and tertiary hydrogen atoms. In the absence of the hydrocarbon and with monomer concentrations of the order of 1M, low molecular weight poly(maleic anhydride) is formed. On addition of the hydrocarbon, the main product is grafted material and very little homopolymer is formed. The grafts consist primarily of single succinic anhydride units but some of them are short poly(maleic anhydride) chains. Ceiling temperature considerations control the formation of homopolymer in the absence of hydrocarbon substrate. In the presence of eicosane or squalane, initiation of grafting proceeds by hydrogen abstraction from the hydrocarbon. The main factor controlling graft length is then the ratio of the rates of intramolecular hydrogen abstraction and of monomer addition to succinic anhydride radicals © 1995 John Wiley & Sons, Inc.
Grafting of polymers with controlled molecular weight onto ultrafine silica surface
Authors: Tsubokawa Norio , Yoshikawa Sachio
Published: April 2003

To graft polymers with controlled molecular weight and narrow molecular weight distribution, the grafting of polymers onto ultrafine silica surface by the termination of living polymer cation with amino groups introduced onto the surface was investigated. The introduction of amino or N‐phenylamino groups onto the silica surface was achieved by the treatment of silica with γ‐aminopropyltriethxysilane or N‐phenyl‐γ‐aminopropyltrimethoxysilane. It was found that these amino groups on silica are readily reacted with living poly(isobutyl vinyl ether) (polyIBVE), which was generated with CF3COOH/ZnCl2 initiating system, and polyIBVE with controlled molecular weight and narrow molecular weight distribution is grafted onto the surface. By the termination of living poly(2‐methyl‐2‐oxazoline), which was generated with methyl p‐toluenesulfonate initiator, with amino groups on silica, polyMeOZO was also grafted onto the surface. The percentage of grafting of polymer onto the silica surface decreased with increasing molecular weight of the living polymer, because the steric hindrance of silica surface increases with increasing molecular weight of living polymer. Polymer‐grafted silica gave a stable dispersion in a good solvent for grafted chains. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of sulfone‐containing polyesters derived from 4,4′‐dicarboxydiphenyl sulfone by direct polycondensation
Authors: Liaw Der‐Jang
Published: April 2003

Several sulfone‐containing polyesters having inherent viscosities 0.43‐0.19 dL g−1 were prepared by direct polycondensation of 4,4′‐dicarboxydiphenyl sulfone (DCDPS) with various aromatic and aliphatic diols, by p‐toluenesulfonyl chloride and N,N′‐dimethylformamide in pyridine solution. The polyesters were examined by elementary analysis, IR spectra, inherent viscosity, x‐ray diffraction, solubility, DSC, and TGA. The diffraction diagram showed that all polyesters were crystalline except that obtained from bisphenol‐A. All polymers were soluble in sulfonic acid (18M), phenol and p‐chlorophenol, but not in acetone and toluene. These polymers obtained from aromatic bisphenols lost no mass below 325°C, but 10% loss of mass was recorded above 396°C in nitrogen. DCDPS copolymerized with isophthalic acid (IPA) and bisphenol‐A had inherent viscosity up to 0.49 dL g−1,

with relatively narrow distribution of molar mass

. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of poly(4‐vinyl,2′‐carboxybensophenone)
Authors: Kamble K. J. , Patkar D. N.
Published: April 2003

The synthesis and characterization of poly(4‐vinyl,2′‐carboxybenzophenone) ion exchange resin is described. This resin displays a remarkably high capacity for Cu2+. Control of pH permits selective adsorption and estimation of Fe3+. This ion‐exchanger is quite stable to loading acid washing cycles. © 1995 John Wiley & Sons, Inc.
Kinetics and mechanism of the grafting of 2‐(dimethylamino)ethyl methacrylate onto hydrocarbon substrates
Authors: Shing J. B. Wong , Baker W. E. , Russell K. E.
Published: April 2003

The kinetics of grafting a basic monomer, 2‐(dimethylamino)‐ethyl methacrylate (DMAEMA) to hydrocarbon substrates have been investigated. These systems were chosen as models for the grafting of a homopolymerizable monomer to polyolefins such as polyethylene. The reactions with squalane and n‐eicosane were initiated by an organic peroxide, 2,5‐dimethyl 2,5 dit‐butylperoxy)‐3‐hexyne; grafting yields become significant at high reaction temperatures and low monomer concentrations. In squalane, the order of reaction with respect to monomer increased from about 1.1 for 0.22−0.44M DMAEMA to almost 2 at 0.69M DMAEMA; the order with respect to initiator was 0.56. The overall activation energy in the 130−160°C temperature range was, however, surprisingly low, 42±5 kJ mol−1. When analytical data were used to separate the overall rate into those for grafting and homopolymerization, different kinetic paths were observed for the competing reactions. These results are interpreted in terms of two different mechanisms; intramolecular chain transfer plays an important role in grafting, while depropagation becomes a major factor in homopolymerization at temperatures above 150°C. © 1995 John Wiley & Sons, Inc.
Photogenerated hydroperoxides of EPDM rubbers and their characterization
Authors: Chmela S. , Teissèdre G. , Lacoste J.
Published: April 2003

Three 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

Syndiotactic 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

A 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

Graft 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

Aromatic 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

A 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

Methyl 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

Colloidal 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

Silylation 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

Two 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

Ring‐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

Liquid 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

Thermal 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

The 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

The 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

Synthesis 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

The 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

Polyurethanes 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

The 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

Upon 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.
Synthesis and free radical polymerization of 2‐methylene‐7‐oxabicyclo[2.2.1]heptane
Authors: Bai Ru‐Ke , Li Shi‐Hua , Wu Cheng‐Pei , Zou Ying‐Fang , Pan Cai‐Yuan , Uryu Toshiyuki
Published: April 2003

A new monomer, 2‐methylene‐7‐oxabicyclo[2.2.1]heptane (IV) was synthesized via four steps. Its structure was confirmed by IR, 1H‐NMR, and 13C‐NMR spectra as well as elementary analysis. Free radical polymerization and copolymerization of IV were investigated. No homopolymer was obtained due to the effect of allyl inhibition. When IV copolymerized with electron‐donor monomers, such as vinyl acetate and stvrene, IV acted as inhibitor for the polymerization of vinyl acetate, but could not inhibit the polymerization of styrene. However, the copolymers of IV with electron‐accepting monomers, such as methyl methacrylate, acrylonitrile, or maleic anhydride (MA) were obtained. The contents of IV in the copolymers increased as e values of electron‐accepting monomers increased. Strictly alternating copolymer was obtained only in the case of MA and IV. The thermal properties of copolymers were investigated. © 1995 John Wiley & Sons, Inc.
Copolymerization of ethylene/carbon monoxide by a cationic hydridoaquopalladium complex
Authors: Valli V. L. K. , Alper H.
Published: April 2003

The cationic hydridoaquopalladium (II) complex, trans‐[(PCy3)2Pd(H)(H2O)]+BF−4, is an excellent catalyst for the ethylene/carbon monoxide alternating copolymerization in the presence of a bidentate phosphorus ligand and p‐toluenesulphonic acid. © 1995 John Wiley & Sons, Inc.
Control of hard segment size in polyurethane formation
Authors: Lai Yu‐Chin , Quinn Edmond T. , Valint Paul L.
Published: April 2003

In general, segmented polyurethane elastomers are prepared by reacting an isocyanate‐capped polyol prepolymer with a short‐chain diol chain extender, yielding an elastomer with hard segments of uniform size. However, the hard segment size will not be uniform if the polyurethane polymer is prepared by forming the hard segment first, followed by soft segment formation. Because the mechanical properties of polyurethane elastomers depend on the relative ratio of the hard to soft segments as well as the effectiveness of the hard segment as a physical crosslinker, the control of the size distribution of the hard segment is a key factor in designing polyurethane elastomers. It was found that reaction conditions can affect the size distribution of hard segments derived from an aliphatic diisocyanate with differential reactivity between the two isocyanate groups. Lower reaction temperatures and simultaneous mixing of all reactants gave the preferred size distribution of hard segments. © 1995 John Wiley & Sons, Inc.
Ring‐opening metathesis polymerization of 9‐phenyl‐1,5‐cyclododecadiene
Authors: Cho Iwhan , Moon Gyeong Sik
Published: April 2003

Synthesis of butadiene‐based sequence‐controlled copolymers that are composed of commercial monomers such as styrene, butadiene, and ethylene was investigated. New substituted cyclododecadiene derivatives, 9‐phenyl‐1,5‐cyclododecadiene was synthesized by reductive‐phenylation method from 1,5‐cyclododecadiene‐9‐one and was polymerized with tungsten‐based catalyst systems to obtain a microstructure‐controlled terpolymer. A sequence‐controlled 2 : 1 : 1 terpolymer of butadiene, styrene and ethylene was successfully synthesized. The glass transition of the terpolymer occurred at −33.6°C. © 1995 John Wiley & Sons, Inc.
Perfluorocyclobutane aromatic ether polymers. II. Thermal/ oxidative stability and decomposition of a thermoset polymer
Authors: Kennedy Alvin P. , Babb David A. , Bremmer Jeffrey N. , Pasztor Andrew J.
Published: April 2003

The results of thermal and oxidative stability studies are reported for one perfluorocyclo‐butane aromatic ether thermoset polymer. The polymer was prepared from 1,1,1‐tris (4‐trifluorovinyloxyphenyl)ethane by the thermal cyclodimerization of the trifluorovinyl either functionality, resulting in a network polymer comprising alternating perfluorocy‐clobutane and aromatic either groups. The results of isothermal and dynamic thermal gravimetric analysis (TGA) studies are reported with kinetic approximations for de‐composition in nitrogen, along with FTIR studies of the oxidative process in air and TGA/mass spec determination of the gasses evolved from decomposition in air. Based on these results, thermal and oxidative decomposition mechanisms are proposed. © 1995 John Wiley & Sons, Inc.
Polymerization of [o‐n‐(perfluorohexyl)phenyl]acetylene and polymer properties
Authors: Seki Hiroyuki , Masuda Toshio
Published: April 2003

Synthesis, properties, and membrane‐separation functions of a novel fluorine‐containing poly(phenylacetylene) were examined. The monomer used was [o‐n‐(perfluorohexyl)phe‐nyl]acetylene, which has a rigid rod‐like ortho‐substituent. Polymers, whose intrinsic vis‐cosities ([η]) were ca. 0.4–2.2 dL/g, were obtained in high yields with various W and Mo catalysts. The MoCl5–Ph3Sb catalyst achieved the highest [η] of 2.25 dL/g corresponding to an Mw over one million. The polymer was a brown solid soluble only in F ‐containing solvents such as m‐(CF3)2C6H4. The oxygen permeability coefficient of the polymer mem‐brane was 90 barrers, which is the second highest among those of ortho‐substituted poly(phenylacetylenes). In the pervaporation of an ethanol–water mixture, the poly‐mer membrane showed ethanol permselectivity [α(EtOH/H2O) = 1.7]. © 1995 John Wiley & Sons, Inc.
Tandem GC/MS: A useful tool for studying end‐capping reactions of oligo(styryl)lithium anions
Authors: Brestensky Donna M. , Hoye Thomas R. , Macosko Christopher W.
Published: April 2003

Anionic living polymerization methods, using organometallic initiators such as butyllithium reagents, have proven useful for, inter alia, styrene polymerization and are amenable to subsequent functionalization of poly(styryl)lithium in the termination step. In this study, general methods for the selective preparation of small styrene oligomers and termination of the intermediate oligo(styryl)lithium anions were investigated. The crude reaction mixtures were analyzed directly by tandem gas chromatography/mass spectrometry (GC/MS). Of the carbon‐ and silicon‐based electrophiles tested, chloro(chloroalkyl)silanes, Cl‐SiR2(CH2)nCl in particular, were shown by GC/MS to be regioselective end‐capping reagents, thus allowing subsequent transformation to the primary amine. The combined GC/MS data allow not only an estimate of the degree of functionalization, but also the identification of by‐products, thus providing insight into the end‐capping process that otherwise might be difficult to access. © 1995 John Wiley & Sons, Inc.
Main chain scission reaction of poly(methyl methacrylate) caused by two‐photon ionization of dopant
Authors: Sakai Wataru , Tsuchida Akira , Yamamoto Masahide , Yamauchi Jun
Published: April 2003

The main chain scission reaction of poly(methyl methacrylate) (PMMA) doped with N,N,N,′,N′‐tetramethyl‐p‐phenylenediamine (TMPD) was examined by ESR spectroscopy and GPC measurement, and the scission mechanism was analyzed. The two‐photon ionization of TMPD with excimer laser excitation at 77 K produced an ester radical anion of PMMA (PMMA·m̌), which becomes the main chain tertiary radical CH2C˙(CH3)CH2after the detachment of the ester side group by annealing of the sample at room temperature. The main chain scission radical ˙C(CH3)(COOCH3)(PMMA˙) which was produced by the β‐scission fromCH2˙C(CH3)CH2showed the 13‐line ESR spectrum instead of the ordinary 9‐line, due to the fast quenching of the sample to 77 K. The change of the molecular weight distribution was measured by GPC after several irradiation‐and‐annealing operations. The simulation of the GPC curve confirmed that the scission re‐action occurs at random in the PMMA chain in the solid and the main chain scission yield from the ester radical anion, [PMMA˙]/[PMMA·m̌], is 0.30. © 1995 John Wiley & Sons, Inc.
Synthesis of monodisperse polyamides by living anionic polymerization of β‐lactams in the mixture of N,N‐dimethylacetamide and lithium chloride
Authors: Hashimoto Kazuhiko , Hotta Koji , Okada Masahiko , Nagata Shiro
Published: April 2003

Living anionic polymerization of two kinds of methyl‐substituted β‐lactams, 3,3‐dimethyl‐, and 4,4‐dimethyl‐2‐azetidinones, was attained at 25°C in N,N‐dimethylacetamide containing 5 wt % of lithium chloride and proceeded in a homogeneous phase quantitatively. The resulting polyamides were found to have a narrow molecular weight distribution from the gel permeation chromatography. The number average molecular weights estimated from the peak intensities in the 1H‐NMR spectra were almost equal to those calculated from the mol ratio of the consumed lactam to the corresponding N‐benzoyl derivative used as an activator. In addition, the acyllactam‐type growing chain ends were modified quantitatively by the reaction with benzylamine after the polymerization. © 1995 John Wiley & Sons, Inc.
Surface modification of aromatic polyamide film by oxygen plasma
Authors: Inagaki N. , Tasaka S. , Kawai H.
Published: April 2003

The surface of poly(p‐phenylene terephthalamide) (PPTA) films was modified by oxygen plasma, and the modified film surface was analyzed by an advancing contact meter and X‐ray photoelectron spectroscopy (XPS). The advancing contact measurement showed that the oxygen plasma treatment made the surface of the PPTA film hydrophilic. The XPS analyses also showed the increase in the O/C and N/C atom ratio, especially the O/C atom ratio, at the PPTA film surface by the oxygen plasma treatment. A main oxygen functionality formed by the oxygen plasma treatment is a carboxylic acid group, and a main nitrogen functionality formed is a protonated amino group. The formation of the oxygen and nitrogen functionalities formed by the oxygen plasma treatment is not restricted to the surface of the PPTA film, but penetrates at least 35 Å deep from the film surface. The formation of these carboxylic acid and protonated amino groups is a result of the bond scission of the amide linkages in the PPTA film. Interactions of photons in the oxygen plasma rather than interactions of electrons and activated oxygen atoms contribute greatly to the bond scission. © 1995 John Wiley & Sons, Inc.
Graft polymerization of acrylamide onto LLDPE film by electron beam pre‐irradiation in air and argon. II. Influence of mohr's salt
Authors: Wirsén A. , Albertsson A.‐C.
Published: April 2003

LLDPE film pre‐irradiated by electron beam (EB) in air and argon was grafted in an aqueous acrylamide solution containing Mohr's salt in the concentration range 0.0025–2% The grafting rate and yield were strongly dependent on the Mohr's salt concentration, mainly as a result of chain termination. The exponential grafting rate dependence on the pre‐irradiation dose was quite insensitive to a hundred‐fold variation in Mohr's salt concentration. © 1995 John Wiley & Sons, Inc.
Studies on thermotropic liquid crystalline elastomers. II. Synthesis and properties of liquid crystalline polyester elastomers
Authors: Sun Shih‐Jieh , Chang Teh‐Chou
Published: April 2003

Three series of novel thermotropic liquid crystalline polyester elastomers (TLCPEEs) were prepared by direct polycondensation from terephthalic acid, polyols (Mn = 1000 or 2000), and various diols. The structures and thermal properties of the synthesized TLCPEEs were examined by FTIR spectroscopy, differential scanning calorimetry, thermal optical polarized microscopy, thermogravimetric analysis, and wide‐angle x‐ray diffraction. The effects of kinds and amount of diols and the molecular weight of polyols on the thermal properties of TLCPEEs were studied. By introducing long flexible spacers (PE‐1000 or PE‐2000) into the polymer main chain, all polymers showed two‐phase morphology under the thermal optical microscopic observation. All of the synthesized polymers, except polymer P1‐BPA60 and P2‐BPA60, which were prepared from BPA, exhibited thermotropic liquid crystalline properties that were in the smectic phase. © 1995 John Wiley & Sons, Inc.