bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grafting of polyesters from carbon whisker surface: Copolymerization of epoxides with cyclic acid anhydrides initiated by COOK groups introduced onto the surface
Authors: Tsubokawa Norio , Yoshihara Toshio 
Published: April 2003

AbstractTo modify the surface of carbon whisker (vapor‐grown carbon fiber) the grafting of polyesters by use of potassium carboxylate (COOK) groups introduced onto the surface was investigated. The introduction of COOK groups onto the carbon whisker was achieved by the treatment of surface carboxyl groups with KOH aqueous solution. Untreated carbon whisker has no ability to initiate the polymerization. It was found that the anionic ring‐opening alternating copolymerization of epoxides with cyclic acid anhydrides is successfully initiated by COOK groups on the carbon whisker surface. The corresponding polyester was grafted onto the surface based on the propagation of polymer from COOK groups introduced on the surface. The percentage of grafting of the polyester from styrene oxide and phthalic anhydride was determined to be 91.0%. The polymerization rate and percentage of grafting increased upon addition of crown ether. Furthermore, the rate of polymerization increased with increasing the dielectric constant of the solvent, but the percentage of grafting decreased. Polyester‐grafted carbon whisker was found to give a stable colloidal dispersion in a good solvent for the grafted polymer. © 1993 John Wiley & Sons, Inc.
Highly crosslinked micron‐range polymer microspheres by dispersion polymerization of divinylbenzene
Authors: Li Kai , Stöver Harald D. H. 
Published: April 2003

AbstractNarrow disperse microparticles are formed by dispersion polymerization of commercial divinylbenzene in acetonitrile or ethanol solution in the presence of 2,2′‐azobis(2‐methylpropionitrile) initiator and polyvinylpyrrolidone stabilizer. The particles have average diameters between 1 and 9 μm depending on monomer concentration, solvent, and temperature. While the smaller particles are relatively smooth, surface texture increases with diameter to give popcorn shapes at 9 μm diameter. High crosslinker concentration is shown to be essential for particle formation. © 1993 John Wiley & Sons, Inc.
Interpenetrating polymer networks of poly(dimethyl siloxane–urethane) and poly(methyl methacrylate)
Authors: Zhou Peiguang , Frisch H. L. , Rogovina L. , Makarova L. , Zhdanov A. , Sergeienko N. 
Published: April 2003

AbstractSimultaneous IPNs of poly(dimethyl siloxane‐urethane) (PDMSU)/poly(methyl methacrylate) (PMMA) and related isomers have been prepared by using new oligomers of bis(β‐hydroxyethoxymethyl)poly(dimethyl siloxane)s (PDMS diols) and new crosslinkers biuret triisocyanate (BTI) and tris(β‐hydroxylethoxymethyl dimethylsiloxy) phenylsilane (Si‐triol). Their phase morphology have been characterized by DSC and SEM. The SEM phase domain size is decreased by increasing crosslink density of the PDMSU network. A single phase IPN of PDMSU/PMMA can be made at an Mc = 1000 and 80 wt % of PDMSU. All of the pseudo‐ or semi‐IPNs and blends of PDMSU and PMMA were phase separated with phase domain sizes ranging from 0.2 to several micrometers. The full IPNs of PDMSU/PMMA have better thermal resistance compared to the blends of linear PDMSU and linear PMMA. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of polyimide–clay hybrid
Authors: Yano Kazuhisa , Usuki Arimitsu , Okada Akane , Kurauchi Toshio , Kamigaito Osami 
Published: April 2003

AbstractA polyimide hybrid with montmorillonite clay mineral has been synthesized from a dimethylacetamide (DMAC) solution of poly(amic acid) and a DMAC dispersion of montmorillonite intercalated with an ammonium salt of dodecylamine. Montmorillonite consists of stacked silicate sheets about 2000 Å in length, 10 Å in thickness. In this hybrid, montmorillonite is dispersed homogeneously into the polyimide matrix and oriented parallel to the film surface. Thanks to this special structure, this hybrid showed excellent gas barrier properties. Only 2 wt % addition of montmorillonite brought permeability coefficients of various gases to values less than half of those of ordinary polyimide. Furthermore, this hybrid had low thermal expansion coefficient. © 1993 John Wiley & Sons, Inc.
Preparation and properties of aromatic polyamides from 2,2′‐bis(p‐aminophenoxy) biphenyl or 2,2′‐bis(p‐aminophenoxy)‐1,1′‐binaphthyl and aromatic dicarboxylic acids
Authors: Liou Guey‐Sheng , Maruyama Masaki , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew aromatic diamines having kink and crank structures, 2,2′‐bis(p‐aminophenoxy)biphenyl and 2,2′‐bis(p‐aminophenoxy)‐1,1′‐binaphthyl, were synthesized by the reaction of p‐fluoronitrobenzene with biphenyl‐2,2′‐diol and 2,2′‐dihydroxy‐1,1′‐binaphthyl, respectively, followed by catalytic reduction. Biphenyl‐2,2′‐diyl‐ and 1,1′‐binaphthyl‐2,2′‐diyl‐containing aromatic polyamides having inherent viscosities of 0.44–1.18 and 0.26–0.88 dL/g, respectively, were obtained either by the direct polycondensation or low‐temperature solution polycondensation of the diamines with aromatic dicarboxylic acids (or diacid chlorides). These polymers were readily soluble in a variety of organic solvents including N,N‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), dimethyl sulfoxide, m‐cresol, and pyridine. Transparent, pale yellow, and flexible films of these polymers could be cast from the DMAc or NMP solutions. These aromatic polyamides containing biphenyl and binaphthyl units had glass transition temperatures in the range of 215–255 and 266–303°C, respectively. They began to lose weight at ca. 380°C, with 10% weight loss being recorded at about 470°C in air. © 1993 John Wiley & Sons, Inc.
Synthesis and thermal properties of poly(cycloalkyl methacrylate)s bearing bridged‐ and fused‐ring structures
Authors: Matsumoto Akikazu , Mizuta Keiichiro , Otsu Takayuki 
Published: April 2003

AbstractRadical polymerizations of some cycloalkyl methacrylates bearing bridged‐ and fused‐ring structures, i.e., bornyl methacrylate (BoMA), isobornyl methacrylate (IBoMA), 2‐decahydronaphthyl methacrylate (DNMA), and 3‐tetracyclo [4.4.02,5.17,10] dodecyl methacrylate (TCDMA), were carried out. The radical polymerization reactivities of these monomers depended on the structure of the cycloalkyl ester groups in the following order: TCDMA > BoMA > DNMA > CHMA > IBoMA > MMA, where CHMA and MMA are cyclohexyl and methyl methacrylates, respectively. The propagation and termination rate constants of these monomers were evaluated from the polymer radical concentration determined by electron spin resonance spectroscopy. The solubilities and microstructures of the resulting polymers were examined. Thermal properties, i.e., glass transition temperatures and decomposition behaviors, of the polymers were also investigated and related to the structures of the polymer side chain. © 1993 John Wiley & Sons, Inc.
Regioselective hydrosilations. I. The hydrosilation of α,ω‐dihydrogen functional oligopolydimethylsiloxanes with 3‐vinyl‐7‐oxabicyclo[4.1.0]heptane
Authors: Crivello J. V. , Bi Daoshen 
Published: April 2003

AbstractThe hydrosilation of α,ω‐dihydrogen functional oligopolydimethylsiloxanes with epoxy compounds containing vinyl groups has been found to take place regioselectively in such a manner that compounds can be isolated in high yields in which only one SiH group has been reacted. Three different α,ω‐dihydrogen functional oligopolydimethysiloxanes with different chain lengths were monohydrosilated and the resulting epoxide monomers characterized. The rate of hydrosilation at the first SiH functional group has been shown to be considerably faster than at the second site and from these kinetic studies, activation energies for each hydrosilation step were calculated. Mechanisms are considered which offer an explantion for these observations. © 1993 John Wiley & Sons, Inc.
Design of alkaline metal ion conducting polymer electrolytes
Authors: Okamoto Y. , Yeh T. F. , Lee H. S. , Skotheim T. A. 
Published: April 2003

AbstractPolysiloxanes with covalently attached oligo ethylene oxide and di‐t‐butylphenol (I), naphthol (II), and hexafluoropropanol (III) were synthesized. The crosslinked polymers with a hexamethylene spacer were also prepared. The ion conductivities of the Li, Na, and K salts were measured as a function of temperature. The highest conductivities for K and Na of I at 30°C were 5.5 × 10−5 and 5.0 × 10−5 S/cm, respectively, when the ratio of the ion to ethylene oxide unit was 0.014. On the other hand, Li conductivity was 8.0 × 10−6 S/cm when the ratio between Li and ethylene oxide unit was 0.019. The maximum conductivities of Li ions of II and III were in the order of 10−6 and 10−7 S/cm at 30°C, respectively. When the polymers were crosslinked by a hexamethylene residue, the ion conductivities decreased while the degree of crosslinking increased. The temperature dependence of the cation conductivities of these systems could be described by the Williams‐Landel‐Ferry (WLF) and the Vogel‐Tammann‐Fulcher (VTF) equation. The results demonstrate that ion movement in these polymers is correlated with the polymer segmental motion. The order of ionic conductivity was K+ > Na+ ≫ Li+. This suggests that steric hindrance and π‐electron delocalization of the anions attached to polymer backbone have a large effect on ion‐pair separation and their ionic conductivities. Thermogravimetric analysis of the polymers indicated that the degradation temperature for I and II were about 100°C higher than for poly(siloxane‐g‐ethylene oxide). This is due to the antioxidant properties of sterically hindered phenols and naphthols. © 1993 John Wiley & Sons, Inc.
Synthesis and physical properties of N‐substituted polyimides based on imidazole
Authors: Kim Yang‐Kook , Rasmussen Paul G. 
Published: April 2003

AbstractAB‐type monomers based on imidazole for the preparation of polyimides were synthesized by carrying out a substitution at the 1‐position of 2‐amino‐4,5‐dicyanoimidazole, followed by hydrolysis. Thus, pendant groups such as hexyl and 2,4‐dinitrophenyl as an aliphatic long chain and an electron‐withdrawing group, respectively, were introduced at the 1‐position of the imidazole monomer. A solid‐state polymerization was employed to prepare the poly(imidazoleimide)s in the form of a film from poly(imidazoleamic acid chloride)s by heating up to 180–200°C. The carbonyl stretching peaks of the imide ring appear at 1808 (sym) cm−1 and 1756 (antisym) cm−1. The effects of monomer structure on reactivity and the degree of imidization were investigated by comparing the viscosity of the resultant polymers and intensity of carbonyl peak at 1808 cm−1. The difference in the hydrolysis rate between polyimides having short or long aliphatic pendant groups at the 1‐position was observed using FT‐IR. The inherent viscosity of the N‐hexyl polyimide was 1.26 dL/g in N‐methyl pyrrolidinone (NMP) and 0.22 dL/g in the case of N‐2,4‐dinitrophenyl poly(amic acid) in methanesulfonic acid at 30°C. The structural, physical, and material properties of the polyimides were characterized by infrared, nuclear magnetic resonance, luminescence, viscosimetric methods, differential scanning calorimetry, thermogravimetric analysis, optical microscopy, and wide angle x‐ray scattering. Solution properties were also investigated by monitoring the viscosity as a function of time at 30°C. Luminescence spectroscopy of the poly(1‐methyl imidazole imide) and poly(1‐methyl imidazoleamic acid) films shows an emission band centered at 535 and 505 nm, respectively. Thermal properties are described comparing the weight loss and decomposition temperature as a function of the polymer structure and the degree of imidization. © 1993 John Wiley & Sons, Inc.
Paracyanogen reexamined
Authors: Maya Leon 
Published: April 2003

AbstractSamples of paracyanogen were prepared by the pyrolysis of silver cyanide, the photolysis of cyanogen, and by sputtering a carbon electrode in a nitrogen plasma. This work was undertaken to establish whether these materials are alike and to derive structural information on the basis of FT‐IR, 13C‐MAS—NMR, and through temperature‐programmed thermal decomposition. Paracyanogen derived from the above sources is indeed alike spectrally and thermally. Paracyanogen is a polymer that incorporates carbon, mostly sp2, and nitrogen in a disordered structure. Cyanogen is the main volatile component released in the thermal decomposition of paracyanogen. The cyanogen released was identified by FT‐IR and MS. The rate of release reaches a maximum at ca. 700°C. Paracyanogen is not an appropriate carbon nitride precursor because of its limited thermal stability. © 1993 John Wiley & Sons, Inc.
Immobilization of poly(ethylene oxide) on polyethylene using a plasma‐induced graft copolymerization process
Authors: Wang Chee‐Chan , Hsiue Ging‐Ho 
Published: April 2003

AbstractA radio‐frequency glow discharge induced graft copolymerization process has prepared a PAAc‐grafted PE film in this present study. Poly(ethylene oxide) (PEO) was then covalently immobilized onto PAAc‐grafted PE film by a chemical coupling reaction. Carboxylic groups were introduced onto the surface of PE film by exposing the film to an Ar plasma, and the plasma‐treated film was then next reacted with a 50% acrylic acid aqueous solution. These functional groups were reacted with bisamino PEO by a coupling agent CMC. ESCA, IR, and water contact angle studies were conducted for characterizing the surfaces of these films during the varied stages of the reaction. Increasing the molecular weight of the PEO attached to the PAAc‐grafted PE resulted in an increased wettability of the films. © 1993 John Wiley & Sons, Inc.
Soluble polymers with pendant thionine groups: Synthesis and evaluation as singlet oxygen photosensitizers
Authors: Amat‐Guerri F. , Botija J. M. , Sastre R. 
Published: April 2003

AbstractThionine (1) has been covalently bound to linear copoly(styrene‐p‐vinylbenzyl chloride) and to linear copoly(acrylic acid‐2‐ethylhexyl acrylate). The resulting polymeric dyes, purified by ultrafiltration, present quantum yields of singlet oxygen generation in dimethylformamide solution lower than their corresponding low‐molecular‐weight models thionine hydrochloride (1.HCl) and N(3)‐acetylthionine (Ac‐1), the decrease being more pronounced in the case of the polystyrene‐dye photosensitizer. High chromophore concentrations within the volume encompassed by each macromolecule in the solution can explain this fall in efficiency. The free dyes thionine hydrochloride and its hydrolysis products thionoline (2) and thionol (3) behave as good singlet oxygen generators, with quantum yields of 0.71, 0.62, and 0.63, respectively. © 1993 John Wiley & Sons, Inc.
Semi‐interpenetrating polymer networks synthesis by photocrosslinking of acrylic monomers in a polymer matrix
Authors: Moussa K. , Decker C. 
Published: April 2003

AbstractSemi‐interpenetrating polymer networks have been obtained by UV‐radiation curing of acrylate monomers dispersed in a polymer matrix, using an arylketone as photoinitiator. The polymerization kinetics was studied quantitatively by infrared spectroscopy for the various polymers examined: polyurethane, poly(vinyl chloride), poly(methyl methacrylate). The fastest reaction occurs in PVC films, where UV‐curing develops extensively within a fraction of a second, leading to an insoluble and highly resistant material. The functionality of the acrylic monomer has a strong influence on the formulation reactivity, as well as on the mechanical and chemical properties of the final product. In PMMA, the polymerization was shown to continue to proceed efficiently for a few seconds after the UV exposure, even in the presence of air, due to both the high concentration of initiating radicals generated by the intense irradiation and the slow termination processes in solid media. © 1993 John Wiley & Sons, Inc.
Study of polymer treatment with tetrafluoromethane plasma: Reactivity of fluorinated species on model surfaces
Authors: Poncin‐Epaillard Fabienne , Pomepui Barbara , Brosse Jean‐Claude 
Published: April 2003

AbstractPolyolefins and their model molecules, some n‐alcanes, have been modified by a tetrafluoromethane microwave plasma. The chosen molecules are high‐density polyethylene (HDPE) and hexatriacontane (HTC), low‐density polyethylene (LDPE) and paraffin, and polycaprolactone (PCL) and octadecyl octadecanoate (ODO). It has been found, except for paraffin, that the model surfaces have the same behavior as the corresponding polymers. Plasma modification is described as the sum of two mechanisms: degradation and fluorination. These reactions seem to be competitive and parallel. Degradation and fluorination rates are dependent on treatment time and are practically independent on substrate position. A domain of fluorination exists near the edge of plasma, whatever the substrate in or outside plasma. © 1993 John Wiley & Sons, Inc.
Synthesis and propeller–propeller transition of optically active poly(diphenyl‐o‐tolylmethyl methacrylate)
Authors: Yu Bin , Ding Mengxian , Wang Yuechuan , Wang Fosong 
Published: April 2003

AbstractDiphenyl‐o‐tolymethyl methacrylate (DPTMA) was synthesized and polymerized using initiators of organolithium complexes with (+)‐(2S,3S)‐dimethoxy‐1,4‐bis(dimethylamino) butane (DDB) and (−)‐sparteine (Sp) as the chiral ligands. DDB was suitable for its complex effective to prepare optically active poly(diphenyl‐o‐tolylmethyl methacrylate) (PDPTMA) with one‐handed helical conformation, whereas only low‐molecular weight polymer was formed when Sp was used as ligand due to the repulsive hindrance between the triarylmethyl group and the ligand. A new mutarotation propeller–propeller transition, was observed for PDPTMA from the optical rotation curves and CD spectra in THF solution. The equivalent period of PDPTMA was estimated to be 14 Å based on the x‐ray diffraction. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of monodisperse polydimethylsiloxane networks
Authors: Bontems Susan L. , Stein Judith , Zumbrum Michael A. 
Published: April 2003

Abstractα,ω‐Divinyl‐terminated polydimethylsiloxane polymers with low polydispersivity were synthesized via anionic polymerization of hexamethylcyclotrisiloxane (D3). Five “monodisperse” polymers with different molecular weights were hydrosilylated with tetrakisdimethylsiloxysilane in the presence of platinum catalysts and inhibitors to form crosslinked networks. Control studies to determine the effect of platinum, silicon hydride, and heat were performed to verify that no redistribution occurred during hydrosilylation. The properties of these cured samples were characterized chemically by degradation with trifluoromethanesulfonic acid in the presence of hexamethyldisiloxane, infrared spectroscopy, and nuclear magnetic spectroscopy. Mechanical properties were studied by measurements of Shore A hardness, dynamic shear modulus, and tensile modulus. The relationship between the molecular weight of the vinyl polymer and the final properties of the cured networks was measured. © 1993 John Wiley & Sons, Inc.
Helix‐sense‐selective polymerization of phenyl[bis(2‐pyridyl)]methyl methacrylate and chiral recognition ability of the polymer
Authors: Ren Changyu , Chen Chuanfu , Xi Fu , Nakano Tamaki , Okamoto Yoshio 
Published: April 2003

AbstractA novel monomer, phenyl[bis(2‐pyridyl)]methyl methacrylate (PB2PyMA), was synthesized. The solvolysis rate of PB2PyMA measured in CDCl3–CD3 OD [1/1 (v/v)] by 1H‐NMR spectroscopy at 35°C was much smaller than those of triphenylmethyl methacrylate (TrMA) and diphenyl‐2‐pyridylmethyl methacrylate (D2PyMA). PB2PyMA was anionically polymerized with the complexes of organolithiums with (−)‐sparteine (Sp), (S,S)‐(+)‐and (R,R)−(‐)‐2,3‐dimethoxy‐1,4‐bis(dimethylamino)butanes[(+)‐and (−) ‐DDB], and (S)‐(+)‐1‐(2‐pyrrolidinylmethyl) pyrrolidine (PMP) in toluene at low temperature. The polymers obtained with Sp and DDB complexes showed low optical activity. PMP complexes, particularly that with N,N′‐diphenylethylenediamine monolithium amide, were effective in synthesizing a polymer of high optical rotation ([α]25365 ∼ +1350°) which was comparable to those of poly(TrMA) and poly(D2PyMA) with one‐handed helical structure. The optical rotation of poly(PB2PyMA) in a mixture of CHCl3 and 2,2,2‐trifluoroethanol (9/1, v/v) slowly decreased with time. Optically active poly(PB2PyMA) coated on macroporous silica gel was able to resolve racemic compounds as a chiral stationary phase for high‐performance liquid chromatography. © 1993 John Wiley & Sons, Inc.
Heat‐resistant thermosetting polymers based on a novel tetrakisaminophenoxycyclotriphosphazene
Authors: Kumar Devendra , Gupta Alka D. , Khullar Mrignaini 
Published: April 2003

AbstractTwo heat‐resistant thermosetting polymers (IX and X) have been developed based on a new cyclotriphosphazene containing tetrakisamine. These polymers were synthesized by the reaction of tetrakisamine (IV) with maleic anhydride followed by in situ cyclodehydration and polymerization of the maleimides (VII and VIII) at 235–240°C for 1.5 h and 290°C for 0.5 h. The thermogravimetric analyses (TGA) of the developed cyclotriphosphazene containing cyclomatrix polymers showed their thermal stability up to 350°C and char yield of 71% in nitrogen at 800°C and 65% in air at 700°C. The monomer, 2,2,4,4‐tetrakis(4′‐aminophenoxy) ‐6,6‐diphenylcyclotriphosphazene (IV), useful for producing a variety of heat‐ and fire‐resistant polymers, has been synthesized in good yield. Its syntheses involve Friedel‐Crafts reaction of hexachlorocyclotriphosphazene (I) with benzene followed by the reaction of 2,2,4,4‐tetrachloro‐6,6‐diphenylcyclotriphosphazene (II) with potassium 4‐nitrophenoxide. The reduction of the obtained 2,2,4,4‐tetrakis(4′‐nitrophenoxy)‐6,6‐diphenylcyclotriphosphazene (III) with molecular hydrogen in presence of PtO2 gave the tetrakisamine (IV). The structure of the synthesized monomer and intermediates were characterized by FT‐IR, 1H‐NMR, 31P‐NMR, mass spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. These resins are potential candidates for the development of heat‐ and fire‐resistant composites, laminates, and adhesives, useful for space, aerospace, and electronic application. © 1993 John Wiley & Sons, Inc.
Molecular composite. I. Novel block copolymers of liquid‐crystalline polyamide and amorphous polyimide: Synthesis and characterization
Authors: Chang Ken‐Yuan , Lee Yu‐Der 
Published: April 2003

AbstractTwo series of PA/PI block copolymers have been prepared from a two‐pot polycondensation reaction. Acid‐terminated poly‐p‐benzamide (PBA) prepolymer, composed of a rigid‐rod structure and lyotropic character, was synthesized by applying the phosphorylation reaction of Yamazaki. On the other hand, two amine‐terminated polyimide prepolymers with an amorphous structure were prepared by a typical low‐temperature condensation reaction from 4,4′‐(hexafluoroisopropylidene)‐bis(phthalic anhydride) (6FDA)/2,2′‐bis‐(4‐aminophenyl)‐hexafluoropropane (BAAF) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA)/2,3,5,6‐tetramethyl‐p‐phenylene diamine (TMPD). The molecular weight of these prepolymers was determined by intrinsic viscosity or GPC. The copolymerization was carried out by mixing two prepolymer solutions. The products were analyzed by extraction, IR, and ηinh so as to confirm that the copolymerization reaction was precisely accomplished. Thermal analysis and lyotropic behavior were studied for these block copolymers and the critical concentration in NMP–LiCl was found to be 6.0% for one among those block copolymers. The copolymers were observed to form anisotropic liquid‐crystalline domains under polarized light once the solutions had been prepared at (and beyond) the critical concentration. © 1993 John Wiley & Sons, Inc.