bluuebunny/crossref_metadata_2025_split huggingface dataset:
The cationic polymerization of N‐vinyl‐2‐pyrrolidone initiated electrochemically by anodic polarization on a Pt surface
Authors: Léonard‐Stibbe E. , Lécayon G. , Deniau G. , Viel P. , Defranceschi M. , Legeay G. , Delhalle J. 
Published: April 2003

AbstractThe electroinitiated polymerization of N‐vinyl‐2‐pyrrolidone has been investigated. After electrolysis at controlled potential, a thin, covering, and homogeneous film of poly(N‐vinyl‐2‐pyrrolidone) appears on the electrode. The insolubility of the polymer in its classical solvents implies the existence of a true chemical grafting of macromolecules on the platinum surface. Chain propagation occurs by a cationic mechanism initiated by a direct electron transfer leading to grafted cations on the surface, followed by the nucleophilic attack of neutral molecules. The molecular weight of the polymer was estimated by gel permeation chromatography after having mechanically removed the film from the electrode. A molecular weight distribution curve showing an average value of 16,000 was observed. © 1994 John Wiley & Sons, Inc.
Rigid‐rod polymers with polysiloxane side chains. I. Synthesis and characterization of rigid‐rod polyimides with polysiloxane side chains and their compatibility with linear polysiloxanes
Authors: Itoh Maki , Mita Itaru 
Published: April 2003

AbstractRigid‐rod aromatic polyimdies having polydimethylsiloxane side chains were prepared for the purpose of dispersing rigid‐rod molecules in silicone matrices for molecular reinforcement. The polyimides were obtained by imidizing the polyamide‐acids bearing the side chains either thermally or chemically, which were synthesized by reacting 4,4′‐diaminobiphenyl‐terminated polysiloxane macromonomers with pyromellitic dianhydride in THF. The polyamide‐acid films obtained by removing the solvent were soluble in THF, but the polyimides were insoluble in any common solvent. The polyimides showed no melting transition below 350°C on DSC analysis, at which temperature the side chain started decomposing. Although all the polyimides were anisotropic as observed by a polarizing microscope, x‐ray diffraction analysis suggested the presence of only limited chain organization. Blends with linear polydimethylsiloxanes were prepared by casting the THF solution containing the polyamide‐acid and the polydimethylsiloxane, followed by solvent evaporation and thermal imidization. With relatively longer side chains, the polyimides were proved to be compatibilized with polydimethylsiloxanes. © 1994 John Wiley & Sons, Inc.
Whiskers. VIII. A convenient synthesis of poly(4‐hydroxybenzoate) whiskers and their application in composites of nylon‐6
Authors: Kricheldorf Hans R. , Adebahr Thorsten , Wahlen Lars 
Published: April 2003

AbstractWhiskers of poly(4‐hydroxybenzoate) [poly(4‐HBA)] were prepared by polycondensation of free 4‐hydroxybenzoic acid with acetic anhydride and pyridine in a high boiling inert solvent. The purity of the monomer is decisive for the success of the synthesis. For a less pure 4‐hydroxybenzoic acid, the preparation of acetylated oligomers with acetylchloride, followed by polycondensation of the isolated oligomers is a suitable alternative. Whiskers, with a solid‐solid phase transition at 364°C were obtained, which is the highest temperature reported for this transition so far. Two batches of composites were prepared from nylon‐6 using polyester whiskers with an alkaline or an acidic surface treatment. A third batch was prepared using poly(ester‐amide) whiskers. The mechanical properties of these composites indicate that the surface treatment does not play any role, and that the poly(esteramide)s are inferior to the polyester whiskers, because they are not single crystals. © 1994 John Wiley & Sons, Inc.
Synthesis of novel polymer containing selenium by radical addition polymerization of 1,4‐benzenediselenol to 1,4‐divinylbenzene
Authors: Kobayashi Eiichi , Akiba Yasuhide , Aoshima Sadahito 
Published: April 2003

AbstractA novel addition polymerization of 1,4‐benzenediselenol (BDSe) to 1,4‐divinylbenzene (DVB) was carried out with various azo radical initiators [dimethyl 2,2′‐azobisisobutyrate (DAIB), 1,1′‐azobis(1‐acetoxy‐1‐phenylethane) (AAPE), and AIBN] in toluene at 65 and 75°C under a nitrogen atmosphere. The polymerization proceded without an induction period, and pale‐yellowish powder polymers were obtained in 89% yields for 75 h (DAIB), 89% yields for 24 h (AAPE), and 60% yields for 8 h (AIBN). The molecular weight (Mw) of the insoluble polymers in toluene was about 4000 (IBN) to 14,000 (DAIB or AAPE) by GPC. The polymer had an alternating structure of BDSe to DVB units by 1H‐NMR, IR analyses, and selenium contents, but the polymer contained the diselenide linkage by Raman spectroscopy. By AIBN initiator, the yield of the polymers did not increase over 60% and higher molecular weight polymer was hardly obtained. According to the model addition reaction of benzeneselenol to styrene by AIBN, it was found that AIBN was consumed by the side reaction between dimethyl‐N‐(2‐cyano‐2‐propyl)ketenimine derivedAppl 11 from AIBN and benzeneselenol to give the adduct C, MH+ 295 by DCI MS. On the other hand, DAIB and AAPE initiators, which do not form a ketenimine intermediate, gave the polymers of higher molecular weight in a higher yield. The polymer film exhibited high refractive index (n25D = 1.81) and a reversible phase transition between a transparency and an opaque by thermal mode. © 1994 John Wiley & Sons, Inc.
Synthesis and photopolymerization of 1‐propenyl glycidyl ether
Authors: Crivello J. V. , Kim Whan‐Gi 
Published: April 2003

AbstractThe ambifunctional monomer, 1‐propenyl glycidyl ether, was prepared from allyl glycidyl ether, by a ruthenium‐catalyzed isomerization reaction in high yield. 1‐Propenyl glycidyl ether undergoes facile photoinduced cationic polymerization to yield a crosslinked polymer. The structure of this polymer was studied using 1H‐ and, 13C‐NMR spectroscopies and employing well‐characterized related polymers as models. The model polymers were prepared by the cationic polymerization of allyl glycidyl ether with BF3OEt2 followed by isomerization of the pendant allyl groups by a ruthenium catalyst. Subsequently, the resulting polyether‐bearing pendant 1‐propenyl ether groups was subjected to a diaryliodonium salt‐photoinitiated polymerization. A comparison of the spectra of the polymers indicated the presence of cyclic acetal units in the polymer backbone. © 1994 John Wiley & Sons, Inc.
Photomodification of a poly(acrylonitrile‐co‐butadiene‐co‐styrene) containing diaryltetrazolyl groups
Authors: Darkow Rita , Yoshikawa Masakazu , Kitao Toshio , Tomaschewski Georg , Schellenberg Jürgen 
Published: April 2003

AbstractA new type of membrane polymer, containing a photosensitive moiety, was synthesized. The photochemically induced functionalization and crosslinking of poly [acrylonitrile‐co‐butadiene‐co‐styrene‐co‐2‐(4‐ethenyl) phenyl‐5‐phenyl‐2H‐tetrazole], ABSV, has been studied. A variety of dipolarophiles and phenolic compounds were applied to alter the polarity of the membrane surface. The functionalization and crosslinking were initiated by photoirradiation. DSC and contact angle measurements were used to characterize the modified polymer. Pervaporation experiments with a cyclohexane/benzene mixture (5 wt% benzene) were carried out, with the results showing, that the photochemical treatment significantly effects both permselectivity and flux. Solubility parameters were found to be useful to interpret the pervaporation data. In general, the selectivity towards benzene increases with the polarity of the membrane surface, i.e., with increasing polarity of the modifier. A mechanism to explain the influence of both functionalization and crosslinking on the membrane performance, is proposed. © 1994 John Wiley & Sons, Inc.
Cationic polymerization of vinyl monomers initiated by 10‐methylphenothiazine cation radicals
Authors: Nomura Shigeki , Morishima Yotaro , Koremoto Toshihiro , Kamachi Mikiharu 
Published: April 2003

AbstractA small quantity of 10‐methylphenothiazine cation radical (MPT.+), electrochemically prepared and stocked in acetonitrile solution, initiated cationic polymerizations of n‐butyl, t‐butyl, and 2‐methoxyethyl vinyl ethers and p‐methoxystyrene, while no initiation occurred for phenyl vinyl ether, styrene, methyl methacrylate, and phenyl glycidyl ether. 1H‐NMR studies of oligomers and low molecular weight compounds isolated from the reaction mixture for the polymerization of t‐butyl vinyl ether in the presence of a small amount of D2O indicated that electron transfer from the monomer to MPT.+ was involved in the initiation step. 1H‐ and 13C‐NMR and MO calculation implied that monomers with higher electron densities on the vinyl groups and with lower ionization potentials were more susceptible to the initiation of MPT.+. © 1994 John Wiley & Sons, Inc.
Thermogravimetric analysis of poly(alkyl methacrylates) and poly(methylmethacrylate‐g‐dimethyl siloxane) graft copolymers
Authors: Smith S. D. , Long T. E. , Mcgrath J. E. 
Published: April 2003

AbstractThe thermal stabilities of various poly(alkyl methacrylate) homopolymers and poly(methyl methacrylate‐g‐dimethyl siloxane) (PMMA‐g‐PSX) graft copolymers have been determined by thermogravimetric analysis (TGA). As expected, the thermal stabilities of poly(alkyl methacrylates) were a function of the ester alkyl group, and polymerization mechanism. In particular, thermally labile linkages, which result from termination during free radical or nonliving polymerization mechanisms, decrease the ultimate thermal stabilities of the polymers. However, graft copolymers, which were prepared by the macromonomer technique with free radical initiators, exhibited enhanced thermal stability compared to homopolymer controls. A more complex free radical polymerization mechanism for the macromonomer modified polymerization may account for this result. © 1994 John Wiley & Sons, Inc.
Synthesis and polymerization of cyano‐substituted monomers derived from 4‐amino‐α‐methyl‐β,β′‐dicyanostyrene
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractA novel class of polymer precursors of the general formula, magnified image where A is an aromatic structure bearing amide or imide linkages, were synthesized. More particularly, 4‐aminoacetophenone was condensed with malononitrile to afford 4‐amino‐α‐methyl‐β,β′‐dicyanostyrene (1). The condensation of the latter with half molar amount of terephthaloyl dichloride, pyromellitic dianhydride, or benzophenone tetracarboxylic dianhydride yielded the polymer precursors. In addition, compound 1 was condensed with an equimolar amount of maleic anhydride to afford the corresponding maleimide. The monomers were characterized by elemental analyses, FT‐IR, 1H‐NMR, and DTA. Crosslinked resins were obtained upon curing the monomers at 300°C for 72 h. They were stable up to 381‐422°C in N2 or air and afforded anaerobic char yields of 64‐68% at 800°C. © 1994 John Wiley & Sons, Inc.
Hexafluoro‐2‐hydroxy‐2‐propyl‐modified polyisoprene blends
Authors: Coleman Michael M. , Yang Xiaoming , Painter Paul C. , Kim Young H. 
Published: April 2003

AbstractDimensionless equilibrium constants describing the self‐association of the hexafluoro‐2‐alkyl‐2‐propanol group have been determined from infrared spectroscopic data. Corresponding values of these equilibrium constants for a fully modified polyisoprene containing the hexafluoroisopropanol group (PHFPI) were calculated by taking into account differences in the molar volume of the model and the specific repeat unit of the polymer. Equilibrium constants describing the inter‐association of PHFPI with methacrylate, acrylate, and acetoxy type carbonyl groups were obtained from spectroscopic studies of miscible PHFPI blends with poly(n‐butyl methacrylate), poly(methyl acrylate), and an ethylene‐co‐vinyl acetate copolymer containing 70 wt% vinyl acetate. The set of equilibrium constant values were then used to calculate theoretical miscibility windows for the complete range of PHFPI blends with poly(n‐alkyl methacrylate)s and four copolymers, ethylene‐co‐methyl methacrylate, styrene‐co‐methyl acrylate, ethylene‐co‐methyl acrylate, and ethylene‐co‐vinyl acetate. Experimental infrared studies confirm the general validity of the predicted miscibility windows. © 1994 John Wiley & Sons, Inc.
Synthesis of new siloxane urethane block copolymers and their properties
Authors: Benrashid Ramazan , Nelson Gordon L. 
Published: April 2003

AbstractSiloxane urethane block copolymers were prepared with siloxanes as the soft segment. Films were cast from a variety of solvents. Solvent has an effect on the segregation of soft and hard segments. Surface studies, including ESCA, EDS, and FT‐IR, show well segregated block copolymers with enhanced siloxane on the surface. DSC studies show a low mp (‐44°C) for the soft segment and a Tg for the hard segment above room temperature. These materials show higher thermal stability compared to polyether urethane block copolymers. These copolymers also show relatively good resistance to exposure to oxygen plasma and show improved flame retardancy compared to nonsiliconated, polyether polyurethane block copolymers. © 1994 John Wiley & Sons, Inc.
Effects of chain end group composition and concentration on the properties of bisphenol A–tetrabromobisphenol A copolycarbonates
Authors: Marks M. J. , Sekinger J. K. 
Published: April 2003

AbstractThe types and concentrations of end groups present in bisphenol A‐tetrabromobisphenol A copolycarbonates (BA‐TBBA coPCs) have major effects on the copolymer solution washability and thermal stability. Six types of coPC end groups are possible: two by monophenol capping of each comonomer, two phenolics (BA‐OH and TBBA‐OH), and two carbamates (one from each comonomer). BA‐TBBA coPCs were prepared by typical solution and interfacial methods and their phenolic and carbamate end group concentrations were correlated with their solution washability and thermal discoloration. Both phenolic and carbamate end groups proved deleterious to these two copolymer properties. An improved interfacial process that employs 4‐N,N‐dimethylaminopyridine as the coupling catalyst provides coPCs having low concentrations of phenolic and carbamate end groups and that, therefore, wash without emulsification and are thermally stable. © 1994 John Wiley & Sons, Inc.
Laser‐Induced generation of thin silicone layers with high chemical and spectral purity
Authors: Roth Wolfgang , Hoffmann Klaus W. , Kurz Wolfgang 
Published: April 2003

AbstractExcimer lasers (ArF, λ = 193 nm, and KrF, λ = 248 nm) were used to generate polymers free of additives such as catalysts, initiators, or sensitizers. The layers obtained are of potential interest for medical applications and future molecular electronics. Dimethylpolysiloxanes and dimethylsiloxane copolymers that contain phenyl‐, n‐hexyl‐ or 3.3.3‐trifluoropropyl groups or silicon‐bound hydrogen atoms were crosslinked in the liquid phase, whereby layer thicknesses in the range from 1–300 μm were obtained. Disiloxanes and alkoxysilanes were deposited from the gas phase (LCVD, laser chemical vapor deposition) resulting in layer thicknesses below 1 μm. In almost all cases, organic layers with a smooth surface, transparency, and good adhesion were obtained on silicon as well as quartz substrates. © 1994 John Wiley & Sons, Inc.
Poly(terephthalic acid anhydride) as a latent monomer in polybenzoxazole synthesis
Authors: So Ying‐Hung 
Published: April 2003

AbstractHigh molecular weight poly(p‐phenylenebenzobisoxazole) (PBO) was prepared from poly(terephthalic acid anhydride) (PTAA) and 1,3‐diamino‐4,6‐dihydroxybenzene dihydrogenchloride in polyphosphoric acid (PPA). PTAA may react directly with the o‐aminophenol groups to form benzoxazoles or react with PPA to generate terephthalic acid (TA) of very small particle size, which dissolves readily in PPA. PTAA provides the advantages of bypassing the requirement of small particle size TA, reducing the amount of water liberated by half, and possibly providing faster kinetics in PBO synthesis. © 1994 John Wiley & Sons, Inc.
Synthesis and thermal stability of the resins prepared from the reactions of 1,4‐bis(2,2‐dicyanovinyl)benzene with aromatic diamines and electrical conductivity of the resulting materials following pyrolysis
Authors: Diakoumakos Constantinos D. , Mikroyannidis John A. , Krontiras Christoforos A. , Pisanias Michael N. 
Published: April 2003

AbstractNew thermosetting resins were prepared from the reaction of 1,4‐bis(2,2‐dicyanovinyl)benzene with aromatic diamines in varying molar ratios. The thermal stability of these resins was correlated with their composition and the curing conditions. They were stable in N2 up to 370–448°C and afforded anaerobic char yields of 73–84% at 800°C after curing at 300°C for 20–60 h. The temperature dependence of the electrical resistivity of all resins pyrolyzed at 700°C for 15 h was studied in the temperature range from −173–327°C (100–600 K). The results showed that at room temperature the unpyrolyzed polymers have insulating properties, whereas a dramatic decrease in the electrical resistivity is observed following pyrolysis. The temperature dependence of the electrical resistivity suggests that all of the materials studied have semiconducting properties. The observed electrical conductivity is thermally activated with activation energies ranging from 0.03–0.06 eV. © 1994 John Wiley & Sons, Inc.
Synthesis of poly(γ‐methoxypropylmethylsilylene) and poly(γ‐methoxypropylmethylsilylene‐co‐di‐n‐hexylsilylene)
Authors: Hrkach Jeffrey S. , Matyjaszewski Krzysztof 
Published: April 2003

AbstractThe synthesis of γ;‐methoxypropylmethyldichlorosilane, and its subsequent polymerization and copolymerization with di;‐n;‐hexyldichlorosilane through the reductive coupling with sodium has been accomplished. The resulting polymers contain methyl ether side groups that allow further synthetic transformations on the polysilane backbone. For poly (γ;‐methoxypropylmethylsilylene) these groups impart solubility characteristics different than typical alkyl and aryl substituted polysilanes. These new polymers and copolymers have been characterized by GPC and 1H‐, 13C‐, and 29Si‐NMR. © 1994 John Wiley & Sons, Inc.
Radical polymerization of alkyl crotonates as 1,2‐disubstituted ethylenes leading to thermally stable substituted polymethylene
Authors: Matsumoto Akikazu , Shimizu Keiichi , Mizuta Keiichiro , Otsu Takayuki 
Published: April 2003

AbstractRadical polymerization of several alkyl crotonates (RCr) was carried out in bulk or in benzene in the presence of radical initiators. Homopolymerization of RCr bearing bulky ester alkyl groups, e.g. tert‐butyl (tBCr), 1‐adamantyl (AdCr), and 3,5‐dimethyl‐1‐adamantyl crotonate (DMAdCr) proceeded to give a polymer with molecular weight of several thousands despite of the steric hindrance and chain transfer by the presence of the β‐methyl group, while the methyl and ethyl esters gave no polymer. The kinetics of the polymerization was examined in detail and absolute rate constants were evaluated by means of electron spin resonance spectroscopy. The propagation rate constants of RCr were 0.41–1.0 L/mol s, being much smaller than those of the corresponding methacrylates (530–570 L/mol s). The termination rate constants were also determined from the analyses of steady state and non‐steady state polymerizations. Radical copolymerizations of AdCr (M2) with several vinyl monomers (M1) were carried out in bulk at 60°C and the rate constants for cross propagations were calculated to examine reactivities of the monomer and its polymer radical. The structure and thermal properties of the resulting poly (AdCr) were also investigated. Onset temperature of decomposition and glass transition temperature of poly(AdCr) were revealed to be much high as 302 and 234°C, respectively. © 1994 John Wiley & Sons, Inc.
Synthesis and properties of poly(arylene ether imide ketone)s
Authors: Matsuo Shigeru , Mitsuhashi Ken‐Ichi 
Published: April 2003

AbstractPoly(arylene ether ketone)s containing imide units were prepared by the aromatic nucleophilic displacement reaction of the potassium salts of bisphenols with bis(4‐fluorobenzoyl)phthalimides in N‐methyl‐2‐pyrrolidone at elevated temperature. The polymers having inherent viscosities of 0.34–0.77 dL/g were obtained in 2 h. The polymers exhibited glass transition temperatures ranging from 216 to 268°C and decomposition temperatures (5% weight loss under air atmosphere) ranging from 450–570°C mainly depending on the bisphenols used in the polymer synthesis. The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'‐biphenol‐ and hydroquinone‐based poly(arylene ether ketone imide)s belong to a superior class of heat resistant polymers. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc.
High‐yield synthesis and characterization of 1,2‐bis(p‐vinylphenyl)ethane
Authors: Li W.‐H. , Li K. , Stöver H. D. H. , Hamielec A. E. 
Published: April 2003

AbstractThe quantitative synthesis and complete characterization of 1,2‐bis(p‐vinylphenyl)ethane (p,p‐BVPE) and its meta‐, para‐mixed isomers are reported. These crosslinkers copolymerize randomly with p‐methylstyrene, leading to random crosslink distributions. The crosslinkers are prepared by Grignard coupling of (m,p)‐vinylbenzyl chloride in tetrahydrofuran at low temperature to give the statistical mixture of m,m‐, m,p‐, and p,p‐isomers in quantitative yield. Pure p‐vinylbenzyl chloride is converted to pure p,p‐BVPE. p,p‐BVPE has also been separated from the mixture of isomers. The isomers are characterized by elemental analysis, mass spectrometry, 1H‐NMR, and 13C‐NMR and by reversed‐phase HPLC. © 1994 John Wiley & Sons, Inc.
Novel synthesis of polymeric phase transfer catalyst containing polar unit
Authors: Iizawa Takashi , Yamada Yoichi , Ogura Yoshio , Sato Yuichiro 
Published: April 2003

AbstractSoluble polymeric phase transfer catalysts (PTCs) containing benzyltributylphosphonium chloride moieties and p‐nitrophenoxy group or N,N‐dimethylacrylamide as a polar unit were prepared via two‐step reactions from polymers with chloromethyl group and polar units. These polymers were synthesized by copolymerization of p‐chloromethylstyrene and the corresponding monomer or substitution of some parts of chloromethyl group with potassium p‐nitrophenoxide. When the obtained polymers were added, the phase transfer catalyzed reaction of benzylchloride with solid potassium acetate to proceed smoothly. The catalytic activity was strongly affected by the content of phosphonium chloride and the varieties of comonomer unit in the polymeric PTC. The polymeric PTC containing N,N‐dimethylacrylamide unit showed much higher catalytic activity than the corresponding low molecular weight PTC when the phase transfer catalyzed reaction was carried out in low polar solvent. © 1994 John Wiley & Sons, Inc.
Synthesis of poly(ether‐ketone‐amide)s by palladium‐catalyzed polycondensation of aromatic dibromides containing ether ketone structure, aromatic diamines, and carbon monoxide
Authors: Ueda Mitsuru , Yokoo Takayoshi 
Published: April 2003

AbstractAromatic poly(ether‐ketone‐amide)s were prepared by the palladium‐catalyzed polycondensation of aromatic dibromides containing ether ketone units, aromatic diamines, and carbon monoxide. Polymerizations were carried out in N,N‐dimethylacetamide (DMAc) in the presence of palladium catalyst, triphenylphosphine, and 1,8‐diazabicyclo [5,4,0]‐7‐undecene (DBU), and resulted in poly(ether‐ketone‐amide)s with inherent viscosities up to 0.82 dL/g under mild conditions. The polymers were quite soluble in strong acid, dipolar aprotic solvents, and pyridine. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 400°C in nitrogen atmosphere. The glass transition temperatures of the polymers were about 200°C, which are higher than those of poly(ether‐ketone) analogues. These polymers also showed good tensile strength and tensile modulus. © 1994 John Wiley & Sons, Inc.