bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water‐soluble copolymers. XXV. Ion‐binding studies of N‐substituted acrylamide copolymers using potentiometric and spectroscopic methods
Authors: McCormick C. L. , Elliott D. L. 
Published: April 2003

AbstractSpectroscopic and potentiometric methods have been used to study the ionic properties of several N‐substituted acrylamide copolymers that display unusual ion‐binding character. The ionic groups and the amide groups (both on the same repeating unit and on adjacent acrylamide units) in the copolymers are found to chelate calcium ions. The stabilizing effect of this amide chelation is found to be dependent on copolymer composition. A model is proposed to explain the unusual binding behavior of the acrylamide polymers. This involves the formation of an intramonomer chelate or one with neighboring acrylamide units that prevent precipitation of the polymers.
New thermo‐crosslinking reactions of polymers containing pendant epoxide groups with various polyfunctional active esters
Authors: Nishikubo Tadatomi , Saita Seiji , Fujii Takato 
Published: April 2003

AbstractNew thermo‐crosslinking reactions of poly(glycidyl methacrylate), copolymers of glycidyl methacrylate with methyl methacrylate, styrene or ethyl acrlate with various active esters such as di[S‐(2‐benzothiazoly)] thioadipate (BTAD), di(S‐phenyl) thioadipate (PTAD), di(4‐nitrophenyl) adipate (NPAD), diphenyl adipate (PAD), and di(S‐phenyl) thioisophthalate (PTIP), and other polyfunctional esters were carried out in the film state using various catalysts such as quarternary ammonium or phosphonium salts, tert amines, or the crown ether 18‐crown‐6 = potassium salts system. Addition reactions of pendant epoxide groups in the polymer with the active esters such as NPAD and PTAD proceeded selectively to give gel compounds without other side reactions. The rates of reaction with the thioesters such as BTAD and PTAD were relatively faster than those with the phenyl esters such as PAD and NPAD at 70°C. The rates of reactions with the esters having flexible segments such as PTAD were also faster than those with the esters having rigid skeletons such as PTIP. Furthermore, it was found that the rate of reaction was affected strongly by reaction temperature, catalyst concentration, length of alkyl chain in the catalyst, kind of counterion of quarternary ammonium salts as a catalyst, content of pendant epoxide groups in the polymer, and kind of copolymer unit in the polymer, respectively.
Esterification reactions on syndiotactic poly(2‐methallyl alcohol). II. Esterification with protected (L)‐aspartic and (L)‐glutamic acids
Authors: Frey W. , Klesper E. 
Published: April 2003

AbstractThe esterification of syndiotactic poly(2‐methallyl alcohol) by Nα‐ and Oω‐ protected aspartic and glutamic acids by the DCC/HOBT method is described. Depending on the extent of conversion, either homopolymers or copolymers are obtained. Both homo‐ and copolymers are characterized by 1H‐ and 13C‐NMR. A second route to the homopolymers has been followed, whereby the poly(2‐methallyl alcohol) is first esterified by Nα‐protected aspartic or glutamic acid anhydrides and, in a second step, the resulting free carboxyl group on the side chain is esterified by alcohols which are the same as the alcohol moiety of the Oω‐protecting groups. Because the homopolymers were identical to those of the first route, the formation of α‐esters with the acid anhydrides is indicated.
Spectroscopic study of the interaction of poly(ε‐N‐methacryloyl‐L‐lysine) with copper(II)
Authors: Castellano Azélio , Lekchiri Abdenbi , Morcellet Joëlle , Morcellet Michel 
Published: April 2003

AbstractThe complexes formed between copper(II) and a polymeric ligand derived from L‐lysine, poly(ε‐N‐methacryloyl‐L‐lysine) have been investigated by electronic absorption, circular dichroïsm, and EPR spectroscopy. The model molecule, ε‐N‐isobutyroyl‐L‐lysine was also studied with the purpose to distinguish between the effects due to the polymeric nature of the ligand and its intrinsic complexing properties. All experiment results are consistent with the existence of two CuL and CuL2 complexes for both model and polymer Cu systems with no deprotonation of the amide group. The two complexes involve only the carboxyl and amino groups. With the polymer, the CuL2 complex is the main species, even at low pH and low [ligand]/[metal] ratio. This is attributed to the high local concentration of ligand in the vicinity of the polymer chain. With the model molecule, on the contrary, the distribution of the two complexes is strongly dependent on the pH and the [ligand]/[metal] ratio.
Synthesis and electrical conductivity of polymers containing trans‐1,2‐bis(9‐carbazolyl)cyclobutane units
Authors: Subramaniam Prema , Sasakawa Tomoyoshi , Ikeda Tomiki , Tazuke Shigeo , Srinivasan Mahalingam 
Published: April 2003

AbstractNovel poly‐Schiff bases (PSB's) that contain trans‐1,2‐bis(9‐carbazolyl)cyclobutane(DCZB) units were synthesized by the direct polycondensation of trans‐1,2‐bis(3‐formyl‐9‐carbazolyl)cyclobutane with aromatic diamines in n‐amyl alcohol at 160°C. Complexation of these PSB's and of poly(vinyl DCZB) (PVDCZB) with iodine produced cation‐radical salts which resulted form the transfer of an electron from DCZB moieties to iodine. All the undoped polymers were insulators having electrical conductivity of the order of 10−10–10−12 S cm−1 depending on the structure of polymers. By doping with iodine, the electrical conductivity increased by several orders of magnitude and reached a value of 10−3 S cm−1 in the case of PVDCZB and 10−5–10−6 S cm−1 in the case of PSB's. The electrical conductivity of doped PSB's increased with decreasing diamine length. PVDCZB having the same iodine content per carbazole unit as poly(9‐vinyl‐carbazole) (PVK) has a greater electrical conductivity than PVK.
Novel method for preparation of photocrosslinkable poly(vinyl alcohol)
Authors: Ichimura Kunihiro , Komatsu Toshio 
Published: April 2003

AbstractA convenient procedure to prepare photosensitive poly(vinyl alcohol) by acetalization with 1‐methyl‐4‐(p‐formylstyryl)pyridinium methosulfate in heterogeneous condition is described. The reaction of fully saponified poly(vinyl alcohol) was carried out in suspension in acidic aqueous solution, while partially saponified poly(vinyl alcohol) was acetalized in acidic aqueous organic solvent. The photosensitive poly(vinyl alcohol) thus prepared was purified by filtration and successive washing out with methanol. The effect of the preparative condition on the electronic absorption spectra of the styrylpyridinium group attached to poly(vinyl alcohol) is discussed.
Polymerization ofpara‐xylylene derivatives (parylene polymerization). IV. Effects of the sublimation rate of di‐p‐xylylene on the morphology and crystallinity of parylene N deposited at different temperatures
Authors: Surendran G. , Gazicki M. , James W. J. , Yasuda H. 
Published: April 2003

AbstractThe effect of the sublimation rate of di‐p‐xylylene on the crystallinity and morphology of Parylene N deposited on stainless steel was studied as a function of substrate temperature. For a given rate of dimer sublimation, the deposition rate increases with decreasing substrate temperature. Increasing the sublimation rate of the dimer increases the deposition rate 10‐fold, decreases the crystallinity, and shifts the appearance of the hexagonal β structure towards higher substrate temperature for samples synthesized from room temperature (RT) to −60°C. Solution annealing resulting from solvent extraction, and isothermal annealing, increase the crystallinity of the polymers and result in structures containing both α and β polymorphs. The surface topology, as revealed by scanning electron microscopy (SEM), for polymers synthesized from RT to −40°C shows a globular structure, whereas low temperature samples exhibit a rod‐type morphology. For higher sublimation rates of the dimer, SEM micrographs show that oligomeric species start appearing on the polymer films after a period of 4–5 days. Solvent extraction removes the oligomeric crystals, and GPC analysis of the resulting extract indicates that most of the oligomers range in molecular weight from 100 to 900. The cross‐sectional morphology for fractured low temperature samples, however, reveals different morphologies as polymerization proceeds. It is postulated that in the temperature range −50 to −78°C, both surface condensation and surface adsorption of monomer occurs, leading to different morphologies and lower crystallinity. The polymer synthesized at liquid nitrogen temperature shows the presence of voids along with different morphologies. X‐ray diffractograms of polymers synthesized at liquid nitrogen reveal a considerable amount of amorphous phase in the films. Hence, it is inferred that, although the liquid nitrogen polymerization is a solid state polymerization of the crystalline monomer, it does not lead to 100% crystalline material, and the reasons for this are discussed.
ESR study of the molecular dynamic of peroxyradicals in the post‐irradiation oxidation of isotactic polypropylene
Authors: Faucitano A. , Buttafava A. , Martinotti F. , Bortolus P. , Comincioli V. 
Published: April 2003

AbstractBy adopting the modified Bloch equations, the analysis of the motion of macroperoxyradicals during the post‐irradiation oxidation of isotactic polypropylene at room temperature has been performed. Rotations about the chain axis and cubic jumps are the motion of prominent importance in the early stages of reaction involving mostly radicals trapped at defects or in amorphous phase; on the other hand rotations about the CO bonds at decreasing rates are dominant in the latter stages. Clear evidence of the progressive immobilization of peroxyradicals, which may be reckoned with monomolecular termination mechanism and of the trapping of peroxyradicals in the crystalline phase, have been obtained.
Effects of organometallic cocatalysts on the polymerization of disubstituted acetylenes by TaCl5 and NbCl5
Authors: Niki Akihiro , Masuda Toshio , Higashimura Toshinobu 
Published: April 2003

AbstractThe effects of organometallic cocatalysts on the polymerization of disubstituted acetylenes were investigated. Diphenylacetylene did not polymerize with TaCl5 alone, while it produced a polymer quantitatively in the presence of appropriate cocatalysts (Me4Sn, Et3SiH, etc.). The poly(diphenylacetylene) formed was an insoluble yellow solid. 1‐Phenyl‐1‐alkynes (1‐Phenyl‐1‐butyne and ‐1‐octyne) polymerized with TaCl5 and NbCl5 alone to yield polymers whose weight‐average molecular weights (Mw's) were ca. 5 × 105. Use of cocatalysts (nBu4Sn etc.) to the polymerization of these monomers accelerated the reaction, and increased the polymer molecular weights up to ca. 1.5 × 106. The poly(1‐phenyl‐1‐alkynes) were soluble white solids. Internal octynes (2‐, 3‐, and 4‐octynes) gave mixtures of a polymer and cyclotrimers with TaCl5 alone. In contrast, cyclotrimers formed virtually selectively by addition of cocatalysts. Thus, various effects of organometallic cocatalysts were observed depending on the kind of monomer.
Photocrosslinkable polymers having p‐phenylenediacrylate group in the side chain: Argon laser photoresist
Authors: Ichimura Kunihiro , Nishio Yoshihiro 
Published: April 2003

AbstractPreparative methods and photosensitivity characteristics of polymers bearing the p‐phenylene‐diacrylate (PDA) group are described. Condensation of a copolymer of methyl methacrylate and glycidyl methacrylate with p‐phenylenediacrylic acid monoester gave highly photosensitive polymers. An alternative method to introduce PDA group is the substitution of chloromethyl‐styrene polymer with p‐phenylenediacrylic acid monoester monoalkali salt. The latter method was found to be more favorable for preparing soluble photosensitive polymers. The polymers thus prepared showed high sensitivity to light of 488 nm from an Argon laser when sensitizers are used, and the photocrosslinking quantum efficiency was 0.44. Preliminary results on holographic recording with this polymer is also mentioned.
Separation and characterization of cyclic sulfides formed in the polycondensation of dibromoalkanes with aromatic dithiols
Authors: Montaudo G. , Scamporrino E. , Puglisi C. , Vitalini D. 
Published: April 2003

AbstractMS and GPC analyses are used to identify the cyclic oligomers formed in the polycondensation reactions of aromatic dithiols and dibromoalkanes leading to aromatic‐aliphatic polysulfides. A correlation exists between the two sets of data obtained by these techniques. Mass spectra of the cyclic oligomers formed in the polymerization reactions are reported.
Degradation of vinylidene chloride/phenylacetylene (VDC/PA) copolymers. Effect of internal unsaturation on poly(vinylidene chloride) stability
Authors: Howell B. A. 
Published: April 2003

AbstractThe thermal degradation of vinylidene chloride/phenylacetylene copolymers containing small but varying amounts of phenylacetylene has been examined in both the solid phase and in bibenzyl solution. Incorporation of phenylacetylene into the poly(vinylidene chloride) structure greatly facilitates degradative dehydrochlorination. Indeed, the presence of phenylacetylene promotes the formation of polyene segments during the polymerization process so that all the copolymers, even at very low phenylacetylene loading, are tan in color. The decreased stability of polymers containing interal unsaturation arises from an increased rate of initiation for degradative dehydrochlorination. The propagation rate is largely unaffected by the level of unsaturation initially present in the polymer. The ratio of hydrogen chloride to stilbene formed for degradation of these copolymers in bibenzyl solution is approximately 35:1. This suggests that the chlorine atom of the initially‐formed radical pair preferentially abstracts an adjacent hydrogen atom rather than interacting with solvent, i.e., the chain‐carrying radical pair does not dissociate appreciably as the unzipping dehydrochlorination occurs. Thus random double bonds introduced in a variety of ways may be identified as principal defect sites responsible for the initiation of the degradative dehydrochlorination of poly(vinylidene chloride). Species which promote the degradation of poly(vinylidene chloride) probably do so by facilitating the introduction of random double bonds into the structure.
Degradation of vinylidene chloride/methyl acrylate/phenylacetylene (VDC/MA/PA) terpolymers. Effect of internal unsaturation on the stability of Saran copolymers
Authors: Howell B. A. , Delassus Phillip T. 
Published: April 2003

AbstractThe thermal degradation of vinylidene chloride/methyl acrylate/phenylacetylene (VDC/MA/PA) terpolymers containing a constant 9 wt % methyl acrylate and small but varying amounts of phenylacetylene has been examined in the solid phase and in bibenzyl solution. Thermally promoted degradative dehydrochlorination, largely uncomplicated by methyl chloride formation, readily occurs at temperatures approaching 200°C. Incorporation of phenylacetylene into the polymer structure greatly facilitates degradative dehydrochlorination. Indeed, the presence of phenylacetylene induces the formation of polyene segments during the polymerization so that all the terpolymers, even at very low phenylacetylene loading, are tan in color. The decreased stability of polymers containing internal unsaturation arises from an increased rate of initiation for the degradation reaction. The propagation rate is largely unaffected by the level of unsaturation initially present in the polymer. Thus random double bonds have been identified as the principal defect sites responsible for the facile degradation of Saran copolymers. Species which promote the degradation of Saran polymers probably do so by facilitating the introduction of double bonds into the structure. The ratio of hydrogen chloride to stilbene formed for degradation of the terpolymers in bibenzyl solution is ca. 35:1. This is strongly reminiscent of PVDC degradation and suggests that for degradation of either the homopolymer or Saran copolymers the chain‐carrying allylic radical pair does not dissociate to any appreciable extent as dehydrochlorination occurs.
Ethylene–chlorotrifluoroethylene copolymers. I. Synthesis and evaluation of compositions resistant to thermal stress cracking
Authors: Reimschuessel H. K. , Rahl F. J. 
Published: April 2003

AbstractCopolymerization of ethylene, chlorotrifluoroethylene, and small amounts (less than 5 mol %) of a perfluoroalkylethylene yields terpolymers in which the concentration ratio of the ethylenederived units to the units derived from the fluorine‐containing monomers is unity, indicating that the perfluoroalkylethylenes are incorporated at the expense of chlorotrifluoroethylene. The resulting polymer compositions are characterized by improved resistance to thermal stress cracking.
Effects of ammonia/ammonium thiocyanate on cotton fabric
Authors: Bober Hope L. , Cuculo John A. , Tucker Paul A. 
Published: April 2003

AbstractThe effect of ammonia/ammonium thiocyanate (NH3/NH4SCN) treatment of the swelling behavior, structural changes, and physical properties of cotton sheeting was compared with that of sodium hydroxide and liquid ammonia mercerization. Increased percent shrinkage, accessibility to a large dye molecule, dyestuff absorption, swelling with water, and water imbibition showed that NH3/NH4SCN had improved the accessibility of the cotton fabric. X‐ray diffractograms showed the characteristic Cellulose I crystal lattice. X‐ray diffraction and infrared absorption spectroscopy indicated that the crystallite size was unchanged and the swelling from the NH3/NH4SCN treatment occurred in the amorphous regions of the cellulose since the observed crystal structure was unchanged. Moisture regain determinations and barium hydroxide absorption suggested that some recrystallization of the cellulose may have occurred from the NH3/NH4SCN treatment. Fibers treated with NH3/NH4SCN showed a cross sectional shape similar to that of the origianl fibers but with reduced lumen area.
Ethylene polymerization over organochromium catalysts: A comparison between closed and open pentadienyl ligands
Authors: Freeman Jeffrey W. , Wilson David R. , Ernst Richard D. , Smith Paul D. , Klendworth Douglas D. , McDaniel Max P. 
Published: April 2003

AbstractDivalent organochromium compounds, Cr(Lig)2, often become active catalysts for the polymerization of ethylene when deposited onto an oxide carrier such as silica or aluminophosphate. Hydroxyl groups are thought to react, releasing one ligand and binding the chromium to the surface. The behavior of the catalyst is then governed by the remaining ligand and the type of carrier. In this study two types of ligands were investigated: cyclopentadienyl and its open ring analog dimethylpentadienyl. This small difference in the type of ligand produces a fundamental difference in the polymerization mechanism. For comparison the mixed ligand chromocene, with one open and one closed ligand, was also synthesized and tested for polymerization.
Polymerization of para‐xylylene derivatives. V. Effects of the sublimation rate of di‐p‐xylylene on the crystallinity of parylene C deposited at different temperatures
Authors: Surendran G. , Gazicki M. , James W. J. , Yasuda H. 
Published: April 2003

AbstractPoly(chloro‐p‐xylylene) was synthesized in a manner similar to poly(p‐xylylene) using Gorham's method at various cryogenic temperatures. The effect of the sublimation rate of dimer on the kinetics of deposition, crystallinity, and crystalline structure was studied. Increasing the sublimation rate of the dimer increases the deposition rate similar to that of poly(p‐xylylene). However, an increase in crystallinity, in contrast to Parylene N, is observed, although, in general, Parylene C has lower crystallinity relative to Parylene N. No polymorphism is observed either by decreasing the deposition temperature or by increasing the sublimation rate of the dimer. Solution annealing and isothermal annealing both bring about crystallization without any structural transformation. Solution annealing removes the oligomers and dimers, but no crystalline oligomers are ever detected under the scanning electron microscope (SEM). The surface topology of films synthesized from ambient temperature to −40°C is very similar to Parylene N. At lower temperatures, in the region −50 to −60°C, a rod‐type morphology is observed similar to Parylene N. The surface topology of samples synthesized at −196°C is totally different from that of Parylene N. All low temperature synthesized samples are amorphous.
Grafting onto poly(vinyl alcohol). II. Graft copolymerization of methyl acrylate and vinyl acetate and their binary mixture using γ‐rays as initiator
Authors: Misra B. N. , Mehta I. K. , Kanthwal M. , Panjloo S. 
Published: April 2003

AbstractMethyl acrylate (MA), vinyl acetate (VAc) and their binary mixture (MA + VAc) have been graft copolymerized onto poly(vinyl alcohol) using γ‐rays as initiator by mutual radiation method in aqueous medium. The optimum conditions for affording maximum grafting have been evaluated. The percentage of grafting has been determined as a function of total dose, concentrations of poly(vinyl alcohol), MA, VAc, and their binary mixture. Rate of grafting (Rp) and induction period (Ip) have been determined as a function of total initial mixed monomer concentration and concentration of poly(vinyl alcohol). The graft copolymer has been characterized by thermogravimetric method. The effect of donor monomer (vinyl acetate) on percent grafting of acceptor monomer (methyl acrylate) has been explained.
Polyurethane anionomers. I. Structure properties of polyurethane anionomers
Authors: Al‐Salah H. A. , Frisch K. C. , Xiao H. X. , McLean J. A. 
Published: April 2003

AbstractThe influence of mono and divalent nontransition and transition metals on the glass transition and mechanical properties of polyurethane anionomers have been investigated. NCO‐terminated prepolymer prepared from 4,4′‐methylene‐bis(phenyl isocyanate) (MDI) and poly(caprolactone) glycol (PCL) was chain extended with dimethylolpropionic acid (DMPA), and the anionomers obtained by neutralization of the prepolymer. The glass transition temperatures of polyurethane anionomers have been studied as a function of the counterion. From simple electrostatic considerations, it is shown that a linear relationship exists between the glass transition temperature and ionic potential (ϕ) for these particular materials. The relation is; Tg = Aϕ + B. The mechanical properties are greatly affected by the type of the counterion, and in some cases, such as monovalent and nontransition metals, the mechanical properties of the anionomers improved by increasing the ionic potential. On the other hand, transition metals containing anionomers exhibited good mechanical properties but no relationship was observed between the mechanical properties and the ionic potential. The extent of water absorption of PU anionomers follows the same relative trends as the tensile strengths of the transition metals with filled and partially filled d‐orbitals.