bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zerovalent metal polymer composites. II. Metal–polymer microdispersions
Authors: Warshawsky A. , Upson D. A. 
Published: April 2003

AbstractMetallization of water‐soluble polymers incorporating metal‐binding ligand is achieved by binding palladium ions at substoichiometric quantities, followed by reduction to polymer–zero‐valent palladium complex and deposition of transition metal ions by electroless plating solutions. The polymers studied include poly[N,N,N‐trimethyl‐N‐(m‐ and p‐vinylbenzyl)ammonium chloride], poly‐L‐glutamic acid, poly‐L‐lysine, and a copolymer of 2‐phenylhydroquinone‐2‐amino‐phthalic acid. Noble metal polyelectrolyte solutions were directly reduced with dimethylamineborane to stable microdispersions. The reactive nickel, cobalt and copper microdispersions were coated on KODAK ESTAR filmbase. Scanning electron microscopy (SEM), ESCA, and IR were used for material characterization. Conductivity and magnetic properties were also measured. Hydrophobic materials such as graphite and fluorinated graphite were metallized in organic solvents using hydrophobic trioctylammonium–tetrachloropalladate as the activating noble metal complex. The metallized conductive graphites were evaluated for their electrochemical properties.
Zerovalent metal polymer composites. III. Metallization of metal oxide surfaces with the aid of metallized functional polymer microdispersions
Authors: Warshawsky A. , Upson D. A. , Ferrar W. T. , Monnier J. R. 
Published: April 2003

AbstractThe adsorption of poly[N‐(m‐ andp‐vinylbenzyl)‐N,N,N‐trimethylammonium tetrachloropal‐ladate] complex on inorganic oxide surfaces followed by reduction of the palladium salt to form a catalytically active zerovalent metal polymer composite dispersed on the oxide surface and further deposition of transition metals, e.g., nickel, cobalt, and copper, by “additive” or “subtractive” deposition from electroless plating solutions is described. γ‐Ferric oxide was used as a template for such intermetallic replacement reactions, providing materials with controlled amounts of metal. Multimetallic catalysts based on aluminum oxide, zinc oxide, lanthanum oxide, magnesium oxide, and silica were prepared. Iron oxide modified by subtractive deposition of rhodium and iridium on nickel‐clad iron oxide were evaluated in Fischer–Tropsch carbonylation reactions leading from synthesis gas to alkanols.
Interpenetrating polymer network from castor oil‐based polyurethanes and poly(methyl methacrylate). XV
Authors: Patel Prashant , Suthar Bhikhu 
Published: April 2003

AbstractThe polyurethanes have been prepared from 2.12 functional OH containing castor oil and diphenyl methane diisocyanate under identical experimental conditions with a varying NCO/OH ratio. These polyurethanes were swollen in methyl methacrylate and subsequently interpenetrated by free radical polymerization using benzoyl peroxide and crosslinker ethylene glycol dimethacrylate. A series of interpenetrating polymer network (IPN) PU/PMMA IPNs were obtained as films by a transfer moulding technique. These IPNs were characterized by their resistance to chemical reagents, thermal behavior, and mechanical properties. The morphology was shown by SEM and dielectric properties at different temperatures were measured.
Poly[3,3‐bis(hydroxymethyl) oxetane]—an analog of cellulose: Synthesis, characterization, and properties
Authors: Vandenberg E. J. , Mullis J. C. , Juvet R. S. 
Published: April 2003

AbstractPoly[3,3‐bis(hydroxymethyl)oxetane], PBHMO, was prepared in high molecular weight (ηinh up to 5.2) by polymerizing the trimethylsilylether of 3,3‐bis(hydroxymethyl)oxetane with the i‐Bu3Al–0.7 H2O cationic catalyst at low temperature, followed by hydrolysis. PBHMO is crystalline, very high melting (314°C) and highly insoluble, much like its analog, cellulose. It is soluble in 75% H2SO4 at 30°C, being 65% converted to the acid sulfate ester; these conditions are useful for viscosity measurement, since the degradation rate is low and at least an order of magnitude less than for cellulose in this solvent. PBHMO can be prepared as oriented films and fibers using the lower melting diacetate (184°C) which can be melt or solution (CHCl3) fabricated and then the oriented forms saponified to oriented PBHMO. BHMO can be directly polymerized to low molecular weight, perhaps somewhat branched, PBHMO (ηinh 0.1) with trifluoromethanesulfonic acid catalyst at room temperature. Poly(3‐methyl‐3‐hydroxymethyloxetane), (PMHMO), prepared in high molecular weight (ηinh up to 3.8) by the same method used for PBHMO, is more soluble and lower melting (165°C) than PBHMO, appears to be atactic and can be compression molded at 195°C to a tough, clear film which is readily oriented. Copolymers of BHMO with MHMO are crystalline over the entire composition range with a linear variation of Tm with composition, a new example of isomorphism in the polymer area.
Investigation of the thermal degradation of alkyl isocyanate polymers by direct pyrolysis mass spectrometry
Authors: Durairaj B. , Dimock A. W. , Samulski E. T. , Shaw M. T. 
Published: April 2003

AbstractThermal degradation mechanisms of alkyl isocyanate homo‐ and copolymers were studied using TGA and DP–MS. Both analyses showed that these polymers begin decomposing at around 190°C under inert or vacuum conditions. DP–MS analysis showed the formation of trace quantities of monomer from poly(butyl isocyanate) only and none from higher homologs. All polymers studied produced trimers as their principal decomposition product, implying that intramolecular cyclization is the dominant mechanism of decomposition.
Synthesis and properties of polyurethanes containing s‐triazine rings in the main chain
Authors: Sarwade Bhimrao D. , Wadgaonkar Prakash P. , Mahajan Sudhakar S. 
Published: April 2003

AbstractEight new diisocyanate monomers containing s‐triazine ring have been prepared from the parent diacids via the Curtius rearrangement of the corresponding diacyl azides. The parent diacids were synthesised by the reaction of p‐ and m‐hydroxybenzoic acid with 6‐methoxy‐2,4‐dichloro‐s‐triazine, 6‐phenoxy‐2,4‐dichloro‐s‐triazine, 6‐phenyl‐2,4‐dichloro‐s‐triazine, and 2‐diphenylamino‐4,6‐dichloro‐s‐triazine respectively. Polyurethanes have been synthesised by solution polymerization of these diisocyanates with ethylene glycol in N,N‐dimethylacetamide (DMAC). The resulting polymers were characterized by IR spectroscopy, viscosity measurement, solubility tests, and softening points.
Chemiluminescence studies of the low temperature thermooxidation of poly(phenylene sulfide)
Authors: Brauman S. K. 
Published: April 2003

AbstractChemiluminescence has been used to study the thermooxidation of poly(phenylene sulfide) film at 85–110°C in oxygen. To identify reaction products, the degraded surfaces were immediately analyzed by x‐ray photoelectron spectroscopy, then exposed to light and reanalyzed. In the proposed reaction sequence, thiyl radicals generated by oxidation of thiol end groups undergo chain transfer with polymer and bimolecular termination giving thiones, emitters that account for part of the chemiluminescence spectrum. Reaction is extensive at the surface, and subsequent exposure of the thermooxidized surface to light results in considerable loss of sulfur as well as carbon. The role of the thione products in subsequent degradation and chemiluminescence is discussed.
Living cationic polymerization of ethyl 2‐(vinyloxy)ethoxyacetate: A vinyl ether with an ether and an ester function in the pendant
Authors: Takeuchi Etsu , Hashimoto Tamotsu , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractEthyl 2‐(vinyloxy)ethoxyacetate (4; CH2CHOCH2CH2OCH2COOC2H5), a vinyl ether having both carboxylic acid ester and oxyethylene unit in its pendant, afforded well‐defined living polymers when polymerized by the hydrogen iodide/iodine (HI/I2) initiating system in toluene at −40°C. The polymers possessed a narrow molecular weight distribution (Mw/Mn ≤ 1.15), and their molecular weight (Mn) increased proportionally to monomer conversion or the molar ratio of the monomer to hydrogen iodide. The polymer molecular weight also increased upon addition of a fresh feed of the monomer to a completely polymerized reaction mixture. Polymers of high molecular weights (Mn > 5 × 105) and broad molecular weight distributions were obtained by BF3OEt2 in toluene at −40°C. Polymerization rate of 4 with HI/I2 is ca. 100 times greater than that of the corresponding alkyl vinyl ether, and thus 4 was found to be one of the most reactive vinyl ethers thus far studied. Alkaline hydrolysis of the pendant ester groups of the polymers gave a vinyl ether‐based polymeric carboxylic acid 6 with a narrow molecular weight distribution.
The mechanism of copolymerization of maleic anhydride with styrene and with vinyl acetate
Authors: Brown Anthony Stuart , Fujimori Kiyohisa , Craven Ian E. 
Published: April 2003

AbstractA nonaqueous potentiometric direct titration method was used to determine the composition diagrams for the copolymerization of maleic anhydride with styrene and with vinyl acetate in methyl ethyl ketone at 50°C. The data were analyzed using nonlinear least‐squares minimization routines to fit composition equations for the terminal, penultimate, and complex models directly. The applicability of each model to both systems were evaluated statistically. The penultimate model was found to best describe both systems, although in the case of the maleic anhydride/vinyl acetate system this was only a small improvement over the terminal model. Although significant comonomer complexation occurs in both systems, the complex model did not provide statistically significant improvement in fit to the data compared with the terminal model.
Poly(aryline imide)s as E‐beam resist: Sensitivity and resolution
Authors: Chien James C. W. , Gong B. M. 
Published: April 2003

AbstractPolyamic acids synthesized from di‐trifluoromethyl methane bis(phthalic anhydride) and 4,4′‐diaminophenyl sulfone and 4,4′‐diaminophenyl ether were found to have excellent negative E‐beam resist properties. The best materials contain about 90% imidized structural units having sensitivities of 1.5–2.5 μC cm−2 and contrast of 1.0–1.3. Polyamic acid of pyromellitic dianhydride and 4,4′‐diaminophenyl sulfone imidized to 97% exhibits useful positive E‐beam resist properties. Radiation induces imidization or chain scission to alter the solubility of the resist polymers resulting in the formation of latent images.
Kinetic studies of grafting of maleic anhydride to hydrocarbon substrates
Authors: Sipos Anita , McCarthy Joan , Russell Kenneth E. 
Published: April 2003

AbstractThe kinetics of grafting of maleic anhydride to various hydrocarbon substrates has been investigated. Grafting to eicosane and squalane was effected in the pure hydrocarbons and in 1,2‐dichlorobenzene solution, while polyethylene was grafted only in solution. The initiator was 2,5‐dimethyl‐2,5‐di(t‐butylperoxy)‐3‐hexyne which has a half life of about 1 h at a typical reaction temperature of 150°C. At high concentrations of initiator (Ca. 0.02M), the rate of disappearance of maleic anhydride is linear with time. In the pure hydrocarbons the order with respect to initiator is close to 0.5. In squalane, the overall activation energy is 112 kJ mol−1; the average number of maleic anhydride molecules grafted per molecule of peroxide decomposed varies from 8 at high rates of initiation to 57 at low rates of initiation. The results are interpreted in terms of a chain mechanism, including a slow propagation step in which a succinic anhydride radical abstracts hydrogen from the same or a different chain. The same general mechanism is proposed for grafting of maleic anhydride to polyethylene and the hydrocarbons in 1,2‐dichlorobenzene solution.
Interpenetrating polymer networks of poly(2,6‐dimethyl‐1,4 phenylene oxide) and poly(urethane acrylate). I
Authors: Mengnjoh Paul C. , Frisch Harry L. 
Published: April 2003

AbstractSimultaneous full and pseudo‐ interpenetrating polymer networks of poly(2,6‐dimethyl‐1,4 phenylene oxide) (PPO) and a poly(urethane acrylate) (PUA) have been synthesized and characterized by differential scanning calorimetry, ultimate mechanical properties, and electron microscopy. No evidence of phase separation was detected in both the full and pseudo‐ PPO/PUA networks. The networks exhibited a single glass transition temperature at all the compositions studied. A maximum in tensile strength to break was observed at 25 PPO/75 PUA composition by weight percent.
Synthesis and characterization of nylon‐grated polyphenylene ether
Authors: Chao H. S.‐I. , Hovatter T. W. , Johnson B. C. , Rice S. T. 
Published: April 2003

AbstractPolyphenylene ether (PPE) resin (a homopolymer made from 2,6‐xylenol with an i.v. of 0.46) was reacted with phenyl acrylate, p‐substituted phenyl acrylates, and diphenyl fumarate in an extruder or in solution. The number of olefinic molecules that had been grafted onto the PPE backbone was determined by FTIR or NMR methods, and the grafting efficiency and mechanism were examined. The grafted PPE resins were used to promote the anionic polymerization of ε‐caprolactam, and the quantity and the composition of the PPE–nylon 6 copolymers isolated were correlated with the number of promoter groups attached to the PPE resin.
Surface modification of polymers. III. Grafting of stabilizers onto polymer films
Authors: Allmér K. , Hult A. , Rånby B. 
Published: April 2003

AbstractPolypropylene, polystyrene, and polyethylene have been grafted with glycidyl acrylate and glycidyl methacrylate. After 5 min of grafting with UV irradiation, polystyrene was extensively grafted to 91% coverage of glycidyl acrylate according to ESCA, while polypropylene was grafted to only 50% coverage. With glycidyl acrylate the grafting depth is estimated to be 0.1 μm for PP and 0.23 μm for PS. Glycidyl methacrylate is grafted in a thinner layer than glycidyl acrylate. The stabilizers 2,4‐dihydroxybenzophenone, phenyl 4‐aminosalicylate, and 4‐amino‐2,2,6,6‐tetramethylpiperidine were attached to LDPE surfaces containing grafted glycidyl acrylate by opening of the epoxide bond. The reaction between epoxide and stabilizer is diffusion controlled at high concentrations of stabilizer. UV spectroscopy on an LDPE film grafted and reacted with 2,4‐dihydroxybenzophenone showed that 227 nmol stabilizer/cm2 was bound to the surface.
Study of the morphology of poly(methyl methacrylate) as polymerized by the redox system Ce(IV)–isopropyl alcohol
Authors: Fernández M. D. , Fernández M. J. , Guzmán G. M. 
Published: April 2003

AbstractMethyl methacrylate has been polymerized in aqueous nitric acid at 30°C, with the redox system ceric ammonium nitrate–isopropyl alcohol as initiator. The gravimetric method has been used to follow the reaction. After a short induction period polymerization started, and conversion attained a maximum value with extent of reaction, whereas the ceric ion is exhausted. The size, distribution, and number of PMMA particles formed were measured by scanning electron microscope. From the electron micrographs it was found that the particles are formed over a short period, and that the particle size distribution seems to be determined by flocculation and coagulation of the particles, because these are not stabilized. Average‐molecular weight was found to increase at high conversions and the molecular weight distribution became broader as particle size increased. Particle size increased with conversion, whereas the number of particles remained constant.
Synthesis and characterization of bigraft copolymers based on grafted type peracid polymer
Authors: Huang Wen‐Kuei , Hsiue Ging‐Ho 
Published: April 2003

AbstractIn this study, a radiation‐induced copolymer, namely, polyethylene‐g‐acrylic acid and EVA‐g‐acrylic acid, in the form of a membrane, particulate, or tube was used as a substrate. The carboxyl groups of the grafted acrylic chains were oxidized into peracids. Optimal conditions for the oxidation, including the catalyst, reaction time, and temperature were investigated. Novel bigraft copolymers were then synthesized from the grafted polymeric peracid. A third component (e.g., 2‐hydroxyethyl methacrylate) was grafted through the decomposition of peracid groups. Abnormality in morphology of the acrylic acid grafted and HEMA bigraft membrane was investigated by SEM and TEM observation, which showed the levelling effect of the third component and manifested a third circular domain generated inside the membrane at high degree of grafting.
New heat‐resistant polymers derived from azomethine bismaleimides and maleimide‐terminated azomethine prepolymers
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractA novel class of bismaleimides containing azomethine linkages was synthesized by reacting the monomaleamic acid derived from an aromatic diamine with terephthaldehyde (TPA) in a molar ratio 2 : 1 and subsequent cyclodehydration. In addition, a series of maleimide‐terminated azomethine prepolymers (MTAPs) was synthesized. More particularly, 4,4′‐diaminodiphenylsulfone (DDS) reacted with TPA in nonstoichiometric molar quantities (2 : 1 or 5 : 4 or 8 : 7) to prepare amine‐terminated azomethine prepolymers (ATAPs). The latter reacted with maleic anhydride and then cyclodehydrated. Furthermore, a maleimide‐crosslinkable azomethine prepolymer (MCAP) was synthesized by reacting tris(3‐aminophenyl)phosphine oxide with an equimolar amount of maleic anhydride and subsequently with TPA. The polymer precursors were characterized by IR, 1H‐NMR, DTA, and inherent viscosity. The thermal stability of the cured resins was evaluated by TGA and IGA. The thermal properties of the cured resins derived from the MTAPs were compared with those of the ordinary polyazomethine prepared from the reaction of DDS with TPA. It was shown that crosslinking of these polymer precursors during their curing was attained both via the maleimide and azomethine double bonds.
Exactly alternating silarylene–siloxane polymers. VII. Thermal stability and degradation behavior of p‐silphenylene–siloxane polymers with methyl, vinyl, hydrido, and/or fluoroalkyl side groups
Authors: Dvornic Petar R. , Perpall Holly J. , Uden Peter C. , Lenz Robert W. 
Published: April 2003

AbstractThe thermal stability and degradation behavior of a series of nine different exactly alternating silphenylene‐siloxane polymers which contained methyl, vinyl, hydrido, 3,3,3‐trifluoropropyl, and tridecafluoro‐1,1,2,2‐tetrahydrooctyl side groups, or their combinations, were investigated by dynamic and isothermal gravimetric analyses in air and in nitrogen. Two distinctly different mechanisms were observed in these atmospheres: a complex multi‐step weight loss process in air and a single‐step process in nitrogen. In nitrogen all polymers produced black, insoluble, highly stable degradation residues which were characterized by high carbon content. In contrast, in air the nonfluorine containing polymers degraded to pure silica, while the fluoroalkyl substituted polymers may have formed fluorosilicates of unspecified structures. There appears to be no significant molecular weight effect on the thermal stability of these polymers, at least not above an Mw value of about 35,000. Isothermal investigations indicate that 300°C in air and 350°C in nitrogen may be possible upper use temperatures for the methylvinyl substituted, exactly alternating silphenylene–siloxane polymers for extended periods of time. A strong thermostabilizing effect by vinyl side groups on the degradation behavior of these polymers was established. The extent of stabilization depends on the content of vinyl units, but it can already be clearly seen at the 5 mol % vinyl level, and it increases exponentially with increasing vinyl concentration. In contrast to this behavior, by comparison with the parent all‐methyl substituted, exactly alternating silphenylene–siloxane polymers, the hydrido and fluroalkyl side groups reduce overall polymer thermal stability in terms of the degradation onset temperature, the temperature for 50% weight loss, and the amount of degradation residue. The presence of these groups also extends the later stages of the degradation processes to higher temperatures. Based on these and previous results, an order of stability is proposed as a function of the type of the substituent side groups for the thermal degradation of these polymers.
Synthesis of optically active polynucleotide analogs with poly(vinyl alcohol)s as backbones and adenine and 5‐bromouracil derivatives as pendants
Authors: Overberger C. G. , Chang Ji Young 
Published: April 2003

AbstractThe optically active polynucleotide analogs were prepared by grafting nucleic acid base derivatives onto poly(vinyl alcohol). The (R)‐ethyl 2‐(5‐bromouracil‐1‐yl)propanoate was obtained either by reaction of 5‐bromouracil sodium salt with (S)‐ethyl 2‐[(methylsulfonyl)oxy]propanoate or reaction of 5‐bromouracil with (S)‐ethyl lactate in the presence of triphenyl phosphine and diethyl azodicarboxylate. Subsequent hydrolysis of the ester is aqueous acid provided the optically pure (R)‐bromouracilypropanoic acid. The monomer model compounds were prepared by an esterification reaction of the pendant groups with 3‐pentyl alcohol in the presence of dicyclohexylcarbodiimide and a catalytic amount of 4‐pyrrolidinopyridine. Poly(vinyl alcohol) underwent reaction with the (R)‐bromouracilylpropanoic acid or the (R)‐adeninylpropanoic acid in the presence of dicyclohexylcarbodiimide and a catalytic amount of 4‐pyrrolidinopyridine. The resulting polymers were optically active and percents grafting were almost quantitative.
Preparation and characterization of phenyl and undecyl oxazoline block copolymers
Authors: Cai Gangfeng , Litt Morton H. 
Published: April 2003

AbstractUndecyl and phenyl oxazolines were synthesized. They were copolymerized in different mole ratios using methyl nosylate as initiator. A series of di‐ and triblock copolymers with narrow molecular weight distributions as indicated by GPC were obtained. A three‐armed block copolymer was also obtained by using 1,3,5‐tris(bromomethyl)benzene as initiator. When the nonpolar undecyl block crystallized as a coating, the critical surface energy approached 21.0 dyn/cm, and the contact angle of water on the surface could be higher than 107°. The melting point increased as the chain length of crystallizable undecyl block increased, and the melting peak on DSC was very sharp when the length was equal to or longer than 25 monomer units. When these copolymers were coated on substrates, the work of adhesion with pressure sensitive adhesives was greatly reduced.
Nylon 6/polyisocyanurate interpenetrating polymer networks (IPNs)
Authors: Chang Wally L. , Frisch Kurt C. , Ashida Kaneyoshi 
Published: April 2003

AbstractTwo component interpenetrating networks (IPNs) of the SIN type (simultaneous interpenetrating networks), composed of a polyisocyanurate network and a star‐shaped nylon 6, were made. The overall polymerization rates and physical properties for reaction injection molding (RIM) have been studied by the quasi‐adiabatic process. In order to model the actual rapid molding conditions, time versus temperature reaction profiles were measured, and the relative rates of polymerization subsequently determined from these data.
Anionic polymerization of star‐shaped nylon 6 with a trifunctional initiator
Authors: Chang Wally L. , Frisch Kurt C. , Ashida Kaneyoshi 
Published: April 2003

AbstractThe anionic polymerization of ϵ‐caprolactam (CLM) has been shown to proceed at high reaction rate when catalyzed by metallic lactamates and initiated by acyllactams. The role of initiator and catalyst concentration on the process of ϵ‐caprolactam anionic polymerization has been explored, with the aim of selecting the most suitable experimental conditions for reaction injection molding (RIM). The overall polymerization rates and physical properties for reaction injection molding of star‐shaped nylon 6 homopolymer have been studied by the quasi‐adiabatic process. In order to model the actual rapid molding conditions, time vs. temperature reaction profiles were measured, and the relative rates of polymerization subsequently determined from these data.