bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal stability of modified telechelic polystyrenes
Authors: Charlier Pascal , Jérome Robert , Teyssié Philippe , Proud'Homme Robert E. 
Published: April 2003

AbstractThe thermal stability of telechelic polystyrenes bearing quaternary ammonium iodide or ammonium sulfonate end groups is presented. It appears that the ammonium iodide functions are stable below 200°C. Above that temperature, the polystyrene irreversibly looses its functional end groups. The weight loss then observed leads to the conclusion that a Hofmann‐type degradation mechanism is likely to take place. In contrast, the ammonium sulfonate‐terminated polystyrene begins to degrade at 180°C and leads to a polymer which is no longer end‐capped with sulfonic acid or sulfonate groups. This behavior is of importance, especially for the study of multiblock ionic copolymers which are prepared by blending two telechelic polymers, one of them bearing sulfonic acid end groups and the other one tertiary amine functional groups. © 1993 John Wiley & Sons, Inc.
Synthesis and thermal properties of aryl‐substituted rod‐like polyimides
Authors: Giesa Reiner , Keller Uwe , Eiselt Petra , Schmidt Hans‐Werner 
Published: April 2003

AbstractThis article describes the synthesis and thermal characterization of novel aryl‐substituted rod‐like homopolyimides. Synthetic aspects of monomer syntheses and one‐step polymer synthesis in m‐cresol are presented. Polyimides with rod‐like chain structure are based on monophenylated pyromellitic dianhydride (MPPMDA), diphenylated pyromellitic dianhydride (DPPMDA), and as rod‐like diamine units on phenylated para‐phenylene diamine and 1,1′‐binaphthyl‐4,4′‐diamine. As partial flexible units, which have the possibility to be converted into an extended chain conformation, commercially available 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 3,4′‐oxydianiline (3,4′‐ODA) were used. The polyimides were investigated with respect to solution properties and thermal behavior. © 1993 John Wiley & Sons, Inc.
Photochemical behavior of p‐dimethylaminobenzoylated polystyrene as polymerization photoinitiator: Synthesis of graft copolymers
Authors: Mateo J. L. , Bosch P. , Catalina F. , Sastre R. 
Published: April 2003

AbstractThe photochemical behavior of p‐dimethylaminobenzoylated polystyrene (PS‐MI) in benzene solution has been investigated, both in the presence and absence of methyl methacrylate (MMA). This behavior has been compared with that of the model compound, 4‐isopropyl‐4′‐N,N‐dimethylaminobenzophenone (CU‐MI). PS‐MI photoreduction takes place only through excimer formation due to the high local chromophore concentration, and therefore, PS‐MI disappearance quantum yield is close to the previously calculated limiting value (0.02) and independent of chromophore concentration. Several parameters that characterize the polymerization process have been determined; it has been found that the obtained PMMA is photografted onto PS‐MI backbone. This is in agreement with the proposed mechanism for radical generation. No homo‐PMMA formation has been detected. © 1993 John Wiley & Sons, Inc.
A study of polyurethanes synthesized from an arylsilane, bis(4,4′‐phenylisocyanato)dimethylsilane, and its carbon analog, 2,2‐bis(4,4′‐phenylisocyanato)propane
Authors: Thames S. F. , Malone K. G. 
Published: April 2003

AbstractBis(4,4′‐phenylisocyanato) dimethylsilane (SiDI) and 2,2‐bis (4,4′‐phenylisocyanato)propane (PrDI) were synthesized, polymerized to polyurethanes, and their chemical, thermal and physical properties studied. Nuclear magnetic resonance spectra confirm deshielding by silicon of both the phenyl ring and the urethane linkage. The glass transition temperatures, solubility parameters, and mechanical properties were independent of the diisocyanates. The silicon containing polyurethanes are more thermally stable than their carbon counterparts. © 1993 John Wiley & Sons, Inc.
Kinetic studies of photopolymerization using real time FT‐IR spectroscopy
Authors: Yang D. Billy 
Published: April 2003

AbstractThe real time FT‐IR (RT/FT‐IR) technique has been recognized as a very vital tool to quantitatively study the curing parameters such as the effects of initiator (or catalyst) type and concentration, accelerator, stabilizer, irradiation wavelength, temperature, and curing environments. Herein, our results in studies of photoinduced polymerizations for adhesive and coating applications are reported. The photoinduced polymerizations studied included anionic and hydrosilation (a polyaddition polymerization) reactions. In photoinduced anionic polymerization our studies for ethyl cyanoacrylate polymerization are described. The effect of the concentration of photoinitiator and inhibitor on the ethyl cyanoacrylate polymerization kinetic rate will be discussed. In photoinduced catalytic hydrosilation reaction studies, the effects of the catalyst concentration and staging irradiation are disclosed. The hydrosilation reaction was monitored using a SiH silicone hydride stretching band located at 2169 cm−1. The cyanoacrylate polymerization was monitored using the CC stretching band occurring at 1617 cm−1. The hydrosilation conversion was completed with an appropriate formulation. For monofunctional cyanoacrylate monomer, the photoinduced conversion to straight chain polymer was approximately 85% for a 60 s period. The intrinsic rates of the reactions were calculated for kinetic comparisons. For very fast cyanoacrylate polymerization studies, new FT‐IR kinetic software was used to collect 204 spectra/min. Some detailed experimental techniques and polymerization reaction mechanisms are also discussed. © 1993 John Wiley & Sons, Inc.
Polymerization of ethylene using a high‐activity Ziegler–Natta catalyst. I. Kinetic studies
Authors: Marques Maria M. V. , Nunes Clemente Pedro , Tait Peter J. T. , Dias Alberto Romão 
Published: April 2003

AbstractFactors affecting the particular shape of kinetic rate–time profiles in the polymerization of ethylene with a MgCl2‐supported TiCl4catalyst activated by Al(C2H5)3have been investigated. Examination of the dependence of the polymerization rate on the concentration of Al(C2H5)3resulted in a Langmuir–Hinshelwood rate law. Analysis of the polymerization rate as a function of the polymerization temperature gave about 46 kJ mol−1for the overall activation energy. Examination of the rapid decay of the polymerization rate with time showed that this decay is represented better by a first‐order decay law than by a second‐order one. © 1993 John Wiley & Sons, Inc.
Ethylene–hexene copolymerization by heterogeneous and homogeneous Ziegler–Natta catalysts and the “comonomer” effect
Authors: Chien James C. W. , Nozaki Takashi 
Published: April 2003

AbstractHomopolymerization of ethylene and 1‐hexene and their copolymerizations were compared to investigate the influence of α‐olefin on the enhancement of ethylene polymerization rate (Rp), which is often referred to as the “comonomer” effect. With the two homogeneous Ziegler–Natta catalysts, Et[Ind]2ZrCl2/MAO and (π‐C5H5)2ZrCl2/MAO (MAO = methylaluminoxane), hexene causes reduction of Rp—in other words a negative “comonomer” effect. In the case of the high activity MgCl2 supported TiCl3 catalysts there is a slight positive “comonomer” effect; the Rp increases by 25 to 70% with the addition of 15 mol % of hexene. The “comonomer” effects in there catalyst systems are much smaller than that observed for the classical TiCl3 catalyst. © 1993 John Wiley & Sons, Inc.
Amino acid end‐group in commercial heparin. III. Determination of the number of amino groups of amino acid and hexosamine residues per heparin molecule
Authors: Arai Kozo , Matsunaga Atsushi , Yoneyama Masaru , Takigami Shoji , Nakamura Yoshio , Edwards Haydn E. , Phillips Glyn O. 
Published: April 2003

AbstractThe reactions of heparin with 2,4,6‐trinitrobenzenesulfonic acid (TNBS) were studied spectrometrically. Seven different commercial heparins were used in this study. The amino groups react with TNBS to form equimolar amounts of trinitrophenylated (TNP) amino groups and bisulfite ions. The TNP‐amino groups further react with bisulfite ions to form the monosubstituted anionic sigma complex. The absorption spectrum with two maxima at approximately 350 nm and approximately 420 nm, characteristic of either the TNP‐amino groups or the complex, was analyzed for the reaction of TNBS with heparin. It was shown that the reactivities of TNBS with amino groups from α‐amino acid and hexosamine residues are greatly different. By combining the results of the reaction kinetics and the reaction of heparin with Sanger's reagent, the number of the α‐amino groups and the free amino groups in hexosamine residues were determined. These data have been performed with a range of heparins from different commercial sources, of different activities and physical characteristics. No correlation was found between the free amino contents of these heparins and biological potency. © 1993 John Wiley & Sons, Inc.
Copolymerization of carbon monoxide with 1,3‐cyclopentadiene by palladium complexes
Authors: Liaw Der‐Jang 
Published: April 2003

AbstractCopolymerization of carbon monoxide with 1,3‐cyclopentadiene (CPD) by palladium complexes, [Pd(CH3CN)4−n (PPh3)n] (BF4)2, n = 1–3 (especially n = 1), was studied at 60°C. Results of elementary analysis, infrared spectra, and NMR spectra showed that copolymers containing ketone and ring structures were produced. Phosphorus compounds such as PPh3 were found to be more effective stabilizing ligands for the catalytic activity compared to arsenic or nitric ligands. A higher activity of the catalyst for the copolymerization of CPD with carbon monoxide was observed in noncoordinating solvents such as CHCl3 even at a pressure as low as 300 psi. The amount of 1,2 structure for the CPD‐CO copolymer increased as the polarity of solvent increased. The copolymer was confirmed to be partially crystalline by the x‐ray diffraction. TGA shows that weight loss of copolymer starts at 120°C and the maximum peak of decomposition occurs at 469°C. © 1993 John Wiley & Sons, Inc.
Triphase catalysis. II. Alkylation of phenylacetone with 1‐bromobutane catalyzed by aqueous NaOH and polystyrene‐supported benzyltriethyl ammonium chloride
Authors: Balakrishnan T. , Babu S. Hari , Shabeer T. K. 
Published: April 2003

AbstractInsoluble microporous polystyrene‐bound benzyltriethyl ammonium chloride has been used as a catalyst in the alkylation of phenylacetone with 1‐bromobutane, and the kinetics of this reaction was investigated under phase‐transfer catalytic conditions. The observed reaction rates depend on many experimental parameters, viz., stirring speed, substrate amount, basicity of aqueous NaOH, amount of 1‐bromobutane, temperature, order of addition of the reactants and particle size, percent active site, and percent crosslinking of the polymer. The rates are nearly 12 times higher at lower concentrations of base than at higher concentrations and do not vary appreciably with a variation in stirring speed from 200 to 700 rpm. The rate of alkylation increases with a decrease in the particle size of the catalyst and crosslinking of the polymer. Based on the results obtained, a suitable mechanism in which a combination of intraparticle diffusion and intrinsic reactivity limit the reaction rates has been proposed. © 1993 John Wiley & Sons, Inc.
Miscibility of poly(vinyl methyl ether) and poly(styrene‐co‐2‐vinylnaphthalene) blends by FT‐IR spectroscopy and Tg measurements
Authors: Ryou Jin Ho , Ha Chang Sik , Cho Won Jei 
Published: April 2003

AbstractMiscibility of blends consisting of poly(vinyl methyl ether) (PVME) and poly(styreneco‐2‐vinylnaphthalene) [P(S‐co‐2VN)] was investigated by means of Fourier transform infrared (FT‐IR) spectroscopy and thermal analysis. Copolymers containing 21, 51, and 84 wt % of styrene were synthesized by radical polymerization. Based on optical clarity and glass transition temperatures, it was shown that the miscibility in P(S‐co‐2VN)/PVME blends is largely affected by compositions of the copolymers as well as concentrations of the blend. From the FT‐IR results, the relative intensity at 1100 cm−1 peak of COCH3 band of PVME and the position of naphthyl ring of 2VN were sensitive to the miscibility of the blends. It was observed that blends of PVME with P(S‐co‐2VN) of 84 wt % styrene or P(S‐co‐2VN) of 51 wt % styrene are miscible over the entire concentration ranges of the blends. Blends of PVME with P(S‐co‐2VN) containing 21 wt % of styrene are immiscible below 65 wt % PVME. In the miscible P(S‐co‐2VN)/PVME blends, there was observed a large shift in the naphthyl frequency at a characteristic wavelength of 748 cm−1. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of poly(dipropargyl sulfoxide)
Authors: Gal Yeong‐Soon , Choi Sam‐Kwon 
Published: April 2003

AbstractThe preparation and cyclopolymerization of dipropargyl sulfoxide were studied. The polymerization of dipropargyl sulfoxide was carried out by various transition metal catalysts. WCl6–EtAlCl2, MoCl5, and PdCl2 catalyst systems were very effective. The resulting poly(dipropargyl sulfoxide) structures were characterized by NMR (1H and 13C), IR, and elemental analysis to have conjugated polyene units. Poly(dipropargyl sulfoxide) prepared by PdCl2 was mostly soluble in organic solvents such as DMF and DMSO. Thermal and oxidative properties of poly(dipropargyl sulfoxide) were also studied. The electrical conductivity of iodine‐doped poly(dipropargyl sulfoxide) was 5.2 × 10−2 Ω−1 cm−1. Comparisons of poly(dipropargyl sulfoxide) properties with other similar polymers from dipropargyl sulfur derivatives such as dipropargyl sulfide and dipropargyl sulfone were also carried out. © 1993 John Wiley & Sons, Inc.
Studies of reactions with polymers. VII. The reaction of acrylonitrile‐grafted polyvinyl alcohol copolymer (PVA‐g‐AN) with NaOH/HCHO aqueous solution
Authors: Chiang Wen‐Yen , Huang Ching‐Chong 
Published: April 2003

AbstractThe reaction mechanism of acrylonitrile (AN)‐grafted polyvinyl alcohol (PVA) with NaOH/HCHO aqueous solution was studied. It was found that intermolecular reactions occur between the nitrile groups in PAN side chains with formaldehyde initiated by sodium hydroxide. The resultant structure proposed is based on IR analysis and elemental analysis of the composition before and after NaOH/HCHO treatment. Its thermal properties of modified membranes were also determined. © 1993 John Wiley & Sons, Inc.
Aggregational behavior in water, of some polyamphiphiles derived from reactive polymers
Authors: Tsiourvas Dimitris , Paleos C. M. , Malliaris Angelos 
Published: April 2003

AbstractSelected polyamphiphiles were prepared by the method of reactive polymers, i.e., interaction of polymaleic anhydride and polyacryloyl chloride with certain long chain alcohols. The aggregational behavior of these polyamphiphiles in water was studied by video‐enhanced differential interference contrast microscopy, as well as by absorption and fluorescence spectroscopy. The formation of large aggregates was observed by video technique, while inter‐ and intramolecular micelles were detected by spectroscopic © 1993 John Wiley & Sons, Inc.
Effect of substitution on the reactivity of some new p‐phenylacrylamide derivatives with organotin monomers
Authors: Tawfik S. Y. , Messiha N. N. , El‐Hamouly S. H. 
Published: April 2003

AbstractThree new monomers of p‐phenylacrylamide derivatives were prepared by either the reaction of p‐methyl‐, p‐nitro‐, and p‐chloroaniline with acryloyl chloride or with acrylic acid in the presence of dicyclohexyl carbodiimide (DCCI). The prepared monomers were copolymerized with each of tri‐n‐butyltinacrylate and tri‐n‐butyltinmethacrylate. Copolymerization reactions were carried out in dioxane at 70°C using 1 mol % azobisisobutyronitrile as a free radical initiator. The structure of the new monomers and the prepared copolymers were investigated by IR and 1H‐NMR spectroscopy. The monomer reactivity ratios for the copolymerization of p‐chlorophenylacrylamide (M1) with each of tri‐n‐butyltinacrylate (TBTA) and tri‐n‐butyltinmethacrylate (TBTMA) (M2) were found to be r1 = 2.6; r2 = 0.83 and r1 = 1.3; r2 = 1.71, respectively. In case of p‐tolyacrylamide (M1) with TBTA and TBTMA (M2) r1 = 0.35, r2 = 1.03 and r1 = 1.38, r2 = 0.366 respectively. The Q and e values for the prepared p‐tolyl‐ and p‐chlorophenylacrylamide were calculated © 1993 John Wiley & Sons, Inc.
Synthesis of poly(2‐cyclohexenone‐4‐yl methacrylate) and acidolysis of pendant protecting groups in the polymer
Authors: Iizawa Takashi , Nishiyama Kazuaki , Nishikubo Tadatomi 
Published: April 2003

Abstract4‐Acetoxy‐2‐cyclohexenone (ACH) and 2‐cyclohexenone‐4‐yl methacrylate (CHM) were obtained from the condensation reaction of 4‐bromo‐2‐cyclohexenone (BCH) with acetic acid and methacrylic acid using 1,8‐diazabicyclo‐[5,4,0]‐7‐undecene (DBU), respectively. Poly(2‐cyclohexenone‐4‐yl methacrylate) (P‐1) containing acid‐sensitive 2‐cyclohexenone‐4‐yl group was prepared from the radical polymerization of CHM and the esterification of poly(methacrylic acid) with BCH using DBU. Furthermore, P‐1 and CHM copolymers (P‐2 and P‐3) were easily synthesized from the radical polymerization of methacrylic acid and comonomers in dimethylsulfoxide using 1 mol % of 2,2′‐azobis (isobutyronitrile) followed by esterification of the resulting polymers with BCH using DBU by one‐pot method. The deprotection reaction of ACH and P‐1 was carried out in dichloromethane using an acid catalyst. The reaction proceeded smoothly in solution to give phenol and the corresponding carboxylic acid. Therefore, the 2‐cyclohexenone‐4‐yl group is a useful protecting group for carboxylic acids, because the protection and deprotection reactions are very easy. In the case of polymer films, however, the acid was trapped by carbonyl group on the 2‐cyclohexenone‐4‐yl group, and did not cause the deprotection reaction. © 1993 John Wiley & Sons, Inc.
Polyesterification reactions of adipic acid‐based polyesters
Authors: Chang Wally L. , Karalis Tom 
Published: April 2003

AbstractA series of studies of uncatalyzed and catalyzed polyesterification experiments have been investigated using different glycols at different temperatures. The experimental results for uncatalyzed reactions agreed quite well with the kinetic equation as proposed by P. J. Flory. However, Flory proposed a second‐order reaction for an externally added strong acid as a catalyst. In contrast to Flory's theory, a mixed mechanism, based on a combination of carboxylic acid groups from the raw material and an external organotin catalyst, was proposed for the catalyzed reaction. In this article, the reaction rate of catalyzed and uncatalyzed polyesterifications using different glycols was compared, and the effect of different temperatures and catalyst levels was also discussed. The reaction rate constant decreases in the following order for both catalyzed and uncatalyzed polyesterification: 1,6‐HD > 1,4‐BD > NPG > DEG > EG ≫ PG. © 1993 John Wiley & Sons, Inc.
Macromolecular engineering of polylactones and polylactides. X. Selective end‐functionalization of poly(D,L)‐lactide
Authors: Barakat I. , Dubois Ph. , Jérôme R. , Teyssié Ph. 
Published: April 2003

AbstractFunctional aluminum alkoxides, such as Et3–pAl(OCH2X)p, where p = 1,3 and X = a functional group, are very effective initiators for the (D, L)‐lactide polymerization in toluene at 70°C. The coordination‐insertion type of polymerization is living. Linear polyesters of a predictable molecular weight and a narrow molecular weight distribution are obtained within the period of time required for the total monomer conversion. The functional group (X) associated with the active alkoxy group of the initiator is selectively and quantitatively attached to one chain end, whereas the second end group is systematically a hydroxyl function resulting from the hydrolysis of the living growing site. Asymmetric telechelic polylactides are thus obtained in a perfectly controlled way. A kinetic study has shown that the polymerization is first order in both the monomer and initiator. © 1993 John Wiley & Sons, Inc.
Radiation‐induced graft polymerization of acrylic acid onto fluorinated polymers. II. Graft copolymer–metal complexes obtained by radiation grafting onto poly(tetrafluoroethylene‐ethylene) copolymer
Authors: Hegazy El‐Sayed A. , Dessouki Ahmed M. , El‐Sawy Naeem M. , Abd El‐Ghaffar Mahmoud A. 
Published: April 2003

AbstractA study has been made on the graft copolymers obtained by radiation‐induced grafting of acrylic acid onto poly(tetrafluoroethylene‐ethylene) (ET) films. The conversion of the graft copolymer into metal acrylate copolymer complex was carried out by treatment with different metal salts. Such a prepared graft copolymer–metal complex was confirmed by different methods: IR, UV spectrometry, degree of coloration, and x‐ray fluorescence. Some selected properties of the graft copolymer–metal complexes such as electrical conductivity, swelling behavior, and mechanical properties were investigated. The influence of metal complexes in the graft copolymers was determined and compared with the grafted films. The possibility of the practical uses for such prepared graft copolymer–metal complexes was discussed and determined. It was assumed that such materials may be of great interest in the field of semiconducting materials in addition to their applicability as cation‐exchange membranes. © 1993 John Wiley & Sons, Inc.
Formation of aromatic polyetherketone and trans‐etherification of aromatic polyetherketone
Authors: Fukawa Isaburo , Tanabe Tsuneaki 
Published: April 2003

AbstractHigh molecular weight aromatic polyetherketone (PEK) was found to react with 4,4′‐difluorobenzophenone (DFB) in the presence of potassium carbonate in benzophenone or diphenyl sulfone at 300°C, yielding low molecular weight PEK with fluorophenyl end groups, while neither polyetheretherketone (PEEK) nor poly‐thioetheretherketoneketone was found to react under similar conditions. Reaction model experiments showed that 4‐fluoroben‐zophenone reacts with potassium carbonate at 300°C to yield benzoyldiphenyl ether and that benzoyldiphenyl ether undergoes spontaneous trans‐etherification in the presence of potassium carbonate at 300°C. These results indicate that the overall reaction yielding PEK of reduced molecular weight consists essentially of DFB oligomerization followed by trans‐etherification between the DFB oligomer and PEK. © 1993 John Wiley & Sons, Inc.