bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemistry of bisphenol‐a based polycarbonate: The effect of the matrix and early detection of photo‐fries product formation
Authors: Hoyle Charles E. , Shah Himanshu , Nelson Gordon L. 
Published: April 2003

AbstractThe effect of polymer matrices on a photoinduced rearrangement process has been shown to be dependent upon whether the photoreactive group is attached to a polymer backbone, or free. If diphenylcarbonate is simply embedded in a polymer matrix, the rearrangement process is independent of whether the host film is above or below its glass transition. However, if the diphenylcarbonate group is incorporated as part of a polycarbonate backbone, the Fries rearrangement process is significantly reduced for photolyses conducted at temperatures well below the glass transition of polycarbonate. The utility of fluorescence spectroscopy in identification of the initial salicylate type photo‐Fries type rearrangement product of polycarbonate is also demonstrated. The broad, structureless fluorescence spectrum with peak maximum at 470 nm produced by photolysis of polycarbonate films for short time periods is assigned to emission from phenyl salicylate type photoproducts. © 1992 John Wiley & Sons, Inc.
New water‐soluble polymers and copolymers by interaction of polyelectrolytes with formamide
Authors: Gooda Shaban R. , Huglin Malcolm B. 
Published: April 2003

AbstractViscometric measurements on aqueous solutions of the strongly acidic polyelectrolyte, poly(2‐acrylamido, 2‐methyl propane sulphonic acid) (PAS), have shown the necessity to include salt at a very high concentration in order to screen the charges. PAS was found to dissolve in formamide, but the properties of the isolated polymer demonstrated the occurrence of chemical changes during the dissolution process. Several procedures proved the conversion of sulphonic acid moieties to sulphonamide groups to an extent depending on the time and temperature of dissolution. At elevated temperature and extended times dissolution afforded complete conversion, i.e., a solution in formamide of a new neutral polymer, poly(2‐acrylamido, 2‐methyl propane sulphonamide) (PASAM), which does not require the inclusion of salts. By light scattering, the degree of polymerization of this PASAM was shown to be the same as that of the original PAS. The viscometric behavior of the PASAM in salt‐free water was that of a neutral polymer. Similar tests on the dissolution of the weakly acidic polyelectrolyte, poly(acrylic acid) (PAA) in formamide also showed the occurrence of amidation, but even after extended times PAA is not converted completely to polyacrylamide. © 1992 John Wiley & Sons, Inc.
Effect of the substituents on radical copolymerization of dialkyl fumarates with some vinyl monomers
Authors: Otsu Takayuki , Matsumoto Akikazu , Shiraishi Kohei , Amaya Naoyuki , Koinuma Yasumi 
Published: April 2003

AbstractRadical copolymerization of dialkyl fumarates (DRF) with various vinyl monomers was carried out in benzene at 60°C. The monomer reactivity ratios, r1 and r2, were determined from the comonomer‐copolymer composition curves. The relative reactivity of DRFs with various ester substituents toward a polystyryl radical was revealed to depend on both steric and polar effects of the ester groups. It has also been clarified that α‐substituents of the polymer radical have a significant role in addition of DRF, from the comparison of the monomer reactivity ratios determined in copolymerizations with monosubstituted and 1,1‐disubstituted ethylenes. The absolute cross‐propagation rate constants were also evaluated and discussed. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of aromatic polymers containing pendant silyl groups. I. Polyarylates
Authors: Choi Kil‐Yeong , Hie Mi Yi , Choi Sam‐Kwon 
Published: April 2003

AbstractPolyarylates containing pendant silyl group were prepared by the phase‐transfer catalyzed, two‐phase polycondensations of 2,2‐bis (4‐hydroxyphenyl) propane with corresponding dicarbonyl chlorides such as 2‐trimethylsilylterephthaloyl chloride, 5‐trimethylsilylisophthaloyl chloride, 5‐dimethylphenylsilylisophthaloyl chloride, and 5‐triphenylsilylisophthaloyl chloride. The resulting amorphous polyarylates with glass transition temperatures of 163–214°C had inherent viscosities in the range of 0.41–0.95 dL/g. These polyarylates were readily soluble in common chlorinated hydrocarbons and it was possible to obtain transparent, flexible, and tough films from the polymer solutions. The prepared polyarylates showed fairly good thermal stabilities as well as tensile strengths, i.e., the tensile strengths of the cast films from chloroform solution were 6.0–6.7 kg/mm2. And TGA data revealed 10% weight losses and residual weights at 800°C were 437–495°C and 27–40% under nitrogen atmosphere, respectively. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of aromatic polymers containing pendant silyl groups. II. Aromatic polyamides
Authors: Choi Kil‐Yeong , Yi Mi Hie , Choi Sam‐Kwon 
Published: April 2003

AbstractIn order to improve the solubility of aromatic polyamides without significant loss of thermal stability, synthesis of aromatic polyamides containing pendant silyl groups was carried out by direct polycondensation of silylated aromatic diacids such as 2‐trimethylsilylterephthalic acid (TSTA), 2,5‐bis (trimethylsilyl) terephthalic acid (BTSTA), 5‐trimethylsilylisophthalic acid (TSIA), 5‐dimethylphenylsilylisophthalic acid (DMSIA), and 5‐triphenylsilylisophthalic acid (TPSIA) with various aromatic diamines. The resulting polyamides had inherent viscosities in the range of 0.18–1.10 dL/g and showed improved solubilities toward aprotic polar solvents such as NMP, DMF, DMSO, etc. The prepared aromatic polyamides exhibited fairly good thermal stabilities, which were almost comparable to those of corresponding nonsubstituted aromatic polyamides. That is, thermogravimetric analysis (TGA) data revealed 10% weight losses at 358–500°C and residual weights at 700°C were 46–67% under nitrogen atmosphere. © 1992 John Wiley & Sons, Inc.
Photolysis of poly(o‐acetylstyrene) in solution
Authors: Weir N. A. , Whiting K. 
Published: April 2003

AbstractDilute solutions of poly(o‐acetylstyrene) (POAS) were exposed to long‐wave (λ ≥ 300 nm) UV radiation under high vacuum at 25 ± 1°C. Methane and much smaller amounts of ethane were formed, indicating α‐cleavage (Norrish Type I). The quantum yield for CH4 formation (5 × 10−5 mol einstein−1) was an order of magnitude lower than that observed for similar studies of POAS films. Molecular weight (Mn) measurements indicate that chain scission occurs, and this is attributed to β‐scission of the macroradicals formed by H‐abstraction at the α‐C atoms by the carbonyl triplet, and to a lesser extent, by the CH3 radicals. Quenching by both naphthalene and cyclooctadiene conformed to Stern–Volmer kinetics. The effects on chain scission of a number of additives with varying transfer activities were found to be complex and unexpected. Rates of scission not only increased, even when substances with high transfer activity (e.g., cumene) were present, but also varied with the concentration of additive, being higher at lower additive concentrations. It would appear that solvent quality has a dominant influence (these additives are poor solvents). Tighter coiling of the polymer in the solutions containing poorer solvents results in more segment‐segment contacts and with them more photoreduction and chain scission. However, at higher nonsolvent concentrations, diffusive separation of the fragments (and chain scission) becomes more difficult, and the balance is shifted in favor of cyclization (and perhaps also intermolecular crosslinking). The relative high photostability of POAS in solution (cf. thin film) has been interpreted in terms of increased competition from photoisomerization. © 1992 John Wiley & Sons, Inc.
Spectroscopic study of solid‐state photoreaction in organic crystal: Photopolymerization of dimethyl ester of α,α′‐dicyano‐p‐phenylenediacrylic acid and diethyl ester of p‐phenylenediacrylic acid
Authors: Chakrabarti Subhasis , Maity Ashim K. , Misra T. N. 
Published: April 2003

AbstractRaman spectroscopy has been used to study solid‐state photopolymerization reactions in dimethyl ester of α,α′‐dicyano‐p‐phenylenediacrylic acid (p‐CPAMe) and diethyl ester of p‐phenylenediacrylic acid (p‐PDAEt). The reactants and products were characterized by infrared and Raman spectroscopy. Excitation and emission spectra suggest that in p‐CPAMe exciton–phonon coupling is strong, but in the other monomer it is very weak. Raman phonon spectroscopic study reveal that in both the samples the reaction mechanism is homogeneous in the initial stages. However, in the later stages the reaction becomes heterogeneous in p‐PDAEt. In p‐CPAMe the lattice becomes disordered with the progress of polymerization and finally becomes amorphous whereas in p‐PDAEt the lattice remains highly ordered. © 1992 John Wiley & Sons, Inc.
Investigation of molecular and chiroptical characteristics of optically active functional vinyl copolymers possessing main‐chain chirality
Authors: Dhal Pradeep K. 
Published: April 2003

AbstractOptically active styrene‐methyl methacrylate and styrene‐methacrylonitrile copolymers were obtained by template assisted asymmetric copolymerization of 3,4‐cyclohexyhdene‐D‐mannitol‐1,2;5,6‐bis‐O[(4‐vinylphenyl)boronate] (1) with the corresponding comonomers followed by removal of the template and deboronation. By polymer analog modification methods, several optically active functional copolymers were obtained starting with these copolymers. The resulting polymers were subjected to different types of spectroscopic analysis. Thus, the results obtained from IR, 13C‐NMR and GPC were of great value for detailed structural analysis of these polymers providing both qualitative and quantitative informations in terms of mode and neatness of substitution and degree of functionalization. The chiroptical measurement results obtained from circular dichroic (CD) studies have been utilized to analyze precisely the substituent dependent local solution stereochemistry of these chiral polymers. © 1992 John Wiley & Sons, Inc.
Accelerated imidization reactions using microwave radiation
Authors: Lewis D. A. , Summers J. D. , Ward T. C. , McGrath J. E. 
Published: April 2003

AbstractMicrowave radiation has been clearly shown to result in enhancement of the rate of reaction for an imidization reaction. Analysis of the kinetic parameters showed that the apparent activation energy for the reaction was reduced from 105 to 55 kJ/mol, under the conditions of this experiment. The mechanism which has been proposed to explain this enhancement is based on the concept of a nonuniform temperature on a molecular scale, rather than a true reduction in the activation energy. © 1992 John Wiley & Sons, Inc.
Polyethers derived from bisphenols and highly fluorinated aromatics
Authors: Irvin Jennifer A. , Neef Charles J. , Kane Kevin M. , Cassidy Patrick E. , Tullos Gordon , St. Clair Anne K. 
Published: April 2003

AbstractA series of fluorinated aromatic polyethers was synthesized via aromatic nucleophilic substitution of highly fluorinated aromatics (1,2,4,5‐tetrafluorobenzene, hexafluorobenzene, and decafluorobiphenyl) with bisphenol AF or bisphenol A. Polymerization with 1,2,4,5‐tetrafluorobenzene was not observed, and polymerization of hexafluorobenzene with bisphenol proceeded only if the potassium carbonate–bisphenol ratio was carefully controlled. The polymer condensed from decafluorobiphenyl and bisphenol AF was prepared in 77% yield with an inherent viscosity of 1.01 dL/g. The polymer prepared from the condensation of decafluorobiphenyl with bisphenol A was obtained in 48% yield with an inherent viscosity of 0.28 dL/g. These polymers were very soluble in common organic solvents, formed clear, colorless films, and were thermally stable (> 450°C by TGA). The fully fluorinated polymer exhibited low water uptake (0.3%) and dielectric constant (2.17). © 1992 John Wiley & Sons, Inc.
Synthesis and photochemistry of side‐chain liquid crystal polymers based on cinnamate esters
Authors: Whitcombe M. J. , Gilbert A. , Mitchell G. R. 
Published: April 2003

AbstractThe syntheses of three methacrylate monomers with cinnamate ester side‐chains and of a further monomer with a corresponding cinnamide side‐chain are described. Two of the monomers, with isomeric structures, were thermotropic liquid crystals. Although the clearing points were very similar the crystal melting points differed by 8°C. One compound also exhibited a monotropic smectic phase, behavior not shown by its isomer. The other two monomers were not liquid crystalline. The monomers were polymerized by free radical polymerization, both as homopolymers and as copolymers with methyl methacrylate. In the case of one of the mesogenic ester monomers, copolymers with a cyanophenyl benzoate monomer were also prepared. Three of the four monomers formed thermotropic liquid crystalline homopolymers and the copolymers with the benzoate monomer were also liquid crystalline. The monomers were considered as photoactive components of polymeric liquid crystals. As a preliminary investigation of their photochemistry, copolymers with methyl methacrylate were prepared and irradiated in solution with a broad‐band source. Under these conditions two of the materials show a facile photo‐Fries rearrangement of the aryl cinnamate ester group. © 1992 John Wiley & Sons, Inc.
Polymer gel films with simple organic electrochromics for single‐film electrochromic devices
Authors: Tsutsumi Hiromori , Nakagawa Yoko , Miyazaki Koii , Morita Masayuki , Matsuda Yoshiharu 
Published: April 2003

AbstractPolymer gel films [poly(1‐vinyl‐2‐pyrrolidinone‐co‐N,N′‐methylenebisacrylamide) (PVPD)] which contain simple organic electrochromics [p‐diacetylbenzene (p‐DAB), dimethyl‐ or diethyl terephthalate (p‐DMP or p‐DEP)] are prepared and their optical responses to applied voltage are investigated. p‐DAP/PVPD film is colored in green by the application of 1.2 V vs. Pt wire (quasireference electrode) across the film, and p‐DMP/PVPD and p‐DEP/PVPD films are colored in red by the application of −2.5 and −1.5 V vs. Pt, respectively. Their coloring responses are about a few seconds and the bleaching process also occurs rapidly. The films have no optical memory effect. © 1992 John Wiley & Sons, Inc.
Fundamental aspect and behavior of saturated fluorocarbons in glow discharge in absence of potential source of hydrogen
Authors: Iriyama Yu , Yasuda H. 
Published: April 2003

AbstractThe glow discharge of a series of saturated fluorocarbons, CnF2n+2 (n = 1, 2, 4, 6, and 8), was studied with glass substrates which do not contain any hydrogen. It was found that the deposition rate was a function of the F/C ratio of the starting fluorocarbons. That is, fluorocarbons with higher F/C ratio, such as CF4 and C2F6, hardly polymerized, while fluorocarbons with lower F/C ratio, such as C8F18, polymerized as well as C2F4. After plasma exposure, the surface of glass substrate was characterized by measurements of water contact angle, water droplet rolling‐off angle, and ESCA. Although all saturated fluorocarbon plasmas could alter the surface more hydrophobic than before, the deposited materials from fluorocarbons with higher F/C were not stable. Also, in plasmas with high F/C fluorocarbons, i.e., CF4 and C2F6, sputtering of the electrode material was observed. © 1992 John Wiley & Sons, Inc.
Thermally reversible crosslinking of polystyrene via the furan–maleimide Diels–Alder reaction
Authors: Canary Stephen A. , Stevens Malcolm P. 
Published: April 2003

AbstractMixtures of maleimidomethylated polystyrene with difurfuryl adipate or with furfuryl alcohol‐esterified poly[styrene‐co‐(maleic anhydride)] underwent thermally reversible Diels–Alder crosslinking. Reversal of crosslinking occurred rapidly at 150°C. The instability of the furfuryl group, however, limits the practicability of the reaction. © 1992 John Wiley & Sons, Inc.
Condensation and structure of silicic acid in tetrahydrofuran
Authors: Gunji Takahiro , Nagao Yukinori , Misono Takahisa , Abe Yoshimoto 
Published: April 2003

AbstractSilicic acid (SA) was extracted with THF from aqueous sodium metasilicate (SMS) solutions neutralized with hydrochloric acid, followed by silylation to give silylated SA from which the condensation and structure of SA in tetrahydrofuran (THF) were investigated. The degree of extraction markedly depends on SA and HCl concentrations. The condensation of 0.86 and 3.5 mol/L SA‐THF solutions was followed by measuring the viscosity of the solutions at 0 and 20°C. The silylated SA was isolated as a distillate (LS) and a residue (HS) with low and high M̄ns (ca. 1300 and 3800) by vacuum distillation. The ratio of LS against HS decreased as a SA concentration in THF increased. In an aqueous solution, SA exists as lower molecular weight SAs compared with those in THF. SAs such as monomer, dimer, cyclic tri‐ and tetramer were the main components in a 0.1 mol/L aqueous solution. On the extraction with THF from an aqueous solution, SA was found to undergo condensations to form more polymerized SAs. From the THF solutions of SA concentration above 0.5 mol/L, the HS was obtained as a main component (73%) which was expected to have ladder‐like structures. © 1992 John Wiley & Sons, Inc.
Amphiphilic comb‐shaped polymers from poly(ethylene glycol) macromonomers
Authors: Bo Gao , Wesslén Bengt , Wessléen K. Bodil 
Published: April 2003

AbstractComb‐shaped amphiphilic graft copolymers composed of hydrophobic backbones and hydrophilic side chains were prepared by radical copolymerization of poly(ethylene glycol) monomethacrylate macromonomers, and methacrylate and acrylate comonomers in toluene. The copolymerizations were very sensitive to the reaction conditions, and insoluble cross‐linked gels were easily formed. The yields of soluble copolymers were affected by the initiator concentration, the macromonomer concentration, and the choice of chain transfer agents and comonomers. Solubilities of the copolymers in water or methanol were found to depend on the sizes and the numbers of the PEG side chains. The copolymers showed surface activity with CMC:s in the order of 0.1–1.5 g/L and surface tensions of 36–56 dyn/cm. When tested as emulsifiers most of the copolymers gave oil‐in‐water type emulsions at room temperature. Polymers carrying MPEG 2000 side chains were crystalline with melting points of 38–44°C, while those based on PEG 400 and 1000 were mostly amorphous with glass transition temperatures between ‐55 and ‐60°C. © 1992 John Wiley & Sons, Inc.
The synthesis of poly‐L‐amino acids and their characterization by size exclusion chromatography with low‐angle laser light scattering (SEC‐LALLS/UV/DRI)
Authors: Zeng J.‐N. , Magiera D. J. , Krull I. S. 
Published: April 2003

AbstractThe synthesis and characterization of polyamino acids are described in this paper. Detailed polymerization descriptions of newly synthesized polyamino acids are discussed. The final polyamino acids were characterized by elemental analysis, infrared (IR) spectroscopy, mass spectra, and low‐angle laser light scattering (LALLS). LALLS was used to determine the weight average molecular weight (MW) indicating the extent of the polymerization procedure. Isocratic size exclusion chromatography (SEC) coupled to a tri‐detection system consisting of a LALLS, ultraviolet/visible detector (UV/VIS), and a modified differential refractive index detector (DRI) was used to calculate on‐line specific refractive index increment (dn/dc), MW, percent recovery, and polydispersity, all in one injection once one determines the on‐line molar absorptivity value of the synthesized polyamino acid. © 1992 John Wiley & Sons, Inc.
Synthesis and polymerization of N‐[4‐N′‐ (α‐methylbenzyl)aminocarbonylphenyl]maleimide
Authors: Oishi Tsutomu , Fujimoto Minoru 
Published: April 2003

AbstractA novel type of optically active N‐[4‐N′‐(α‐methylbenzyl)aminocarbonylphenyl]maleimide [(R)‐MBCP] was synthesized from maleic anhydride, p‐aminobenzoic acid, and (R)‐methylbenzylamine. Radical homopolymerization of (R)‐MBCP was performed in tetrahydrofuran (THF) at 50 and 70°C for 24 h to give optically active polymers having [α]25D = ‐141° and ‐129°, respectively. Anionic polymerization of (R)‐MBCP with n‐butyllithium in THF and N,N‐dimethylformamide gave an optically active polymer having −78 to −81° of [α]25D. Radical copolymerizations of (R)‐MBCP (M1) were performed with styrene (ST, M2) and methyl methacrylate (MMA, M2) in THF at 50°C. The monomer reactivity ratios (r1, r2) and the Alfrey‐Price Q‐e values were determined as follows: r1 = 0.009, r2 = 0.091, Q1 = 1.30, e1 = 1.87 in the (R)‐MBCP‐ST; r1 = 0.27, r2 = 1.21, Q1 = 0.93, e1 = 1.46 in the (R)‐MBCP‐MMA system. Chiroptical properties of the polymers were also investigated. © 1992 John Wiley & Sons, Inc.
Liquid crystalline epoxy thermosets based on dihydroxymethylstilbene: Synthesis and characterization
Authors: Barclay G. G. , Ober C. K. , Papathomas K. I. , Wang D. W. 
Published: April 2003

AbstractThis article describes the synthesis and characterization of a new series of liquid crystalline thermosets. Nematic epoxy‐terminated oligoethers based on dihydroxy‐α‐methylstilbene were synthesized for this study. These prepolymers were crosslinked within the nematic mesophase using methylenedianiline. Depending upon the molecular weight and polydispersity of the oligoether, the crosslinking reaction resulted in networks with either a smectic or nematic molecular organization in contrast to the simple nematic phase of the oligoether. The formation of a smectic‐like structure on curing was found to be related to the breadth of the prepolymer molecular weight. In those networks with a low crosslink density a clearing transition could be observed, whereas in the more highly crosslinked networks the molecular organization was frozen in until decomposition. The glass transition temperature of these LC networks rose as the crosslink density was increased, ranging from 35 to 152°C. In agreement with theory, the clearing transition of the networks was found to be dependent on the phase state during curing © 1992 John Wiley & Sons, Inc.
New poly(amide‐imide)s syntheses. II. Soluble poly(amide‐imide)s derived from 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene and various N‐(ω‐carboxyalkyl)‐trimellitimides, N‐(carboxyphenyl)trimellitimides, or N,N″‐bis(ω‐carboxyalkyl)pyromellitimides
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Lin Jiun‐Hung 
Published: April 2003

AbstractVarious dicarboxylic acids with preformed imide rings were readily obtained by the condensation of ω‐amino acids and aminobenzoic acids with trimellitic anhydride, and omega;‐amino acids with pyromellitic dianhydride. New tetraphenylthiophene‐containing poly(amide‐imide)s having inherent viscosities of 0.58‐1.54 dL/g were prepared by the direct polycondensation reaction of 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene with the imide‐containing dicarboxylic acids using triphenyl phosphite and pyridine as condensing agents. These polymers were amorphous and readily soluble in a variety of solvents such as dimethylacetamide (DMAc), dimethylformamide (DMF), and N‐methyl–2‐pyrrolidone (NMP), and could be easily solution cast into transparent, flexible, and tough films. Most of the poly(amide‐imide)s showed clear glass transition on the heating traces of differential scanning calorimetry (DSC) in the range of 146–244°C. Almost all the poly(amide‐imide)s exhibited no appreciable decomposition below 400°C, with 10% weight loss being recorded above 420°C in nitrogen. © 1992 John Wiley & Sons, Inc.