bluuebunny/crossref_metadata_2025 huggingface dataset:
The analysis of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO® resin) in mixtures of PPO resin, polystyrene, and copolymers of PPO resin and polystyrene
Authors: White D. M. , Hallgren J. E.
Published: April 2003

A method of determining the quantity of ungrafted poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO®

Trademark of General Electric Company.

resin) in mixtures of such polyphenylene oxide or PPO resin, polystyrene (PS), and graft copolymers of PPO resin and PS is described. The technique is a combination of physical and chemical separations and gel permeation chromatographic (GPC) analysis. The extent of grafting on PPO resin and the quantity of ungrafted PPO resin were calculated from molecular weight data and compositional analysis.
Free‐radical copolymerizations of N‐arylmaleimides. II
Authors: Patel J. D. , Patel M. R.
Published: April 2003

Free‐radical copolymerization of methyl acrylate (MA) with N‐p‐chlorophenylmaleimide (NPCMI) and N‐p‐bromophenylmaleimide (NPBMI) initiated by AIBN in cyclohexanone solution at 75°C was studied. The copolymer composition has been determined from the nitrogen content and NMR spectra of the copolymers. The reactivity ratios have been calculated by ML, FR, KT, and JJ methods. Q and e values of NPCMI and NPBMI have also been calculated by the Alfrey–Price Q‐e scheme.
Novel high‐temperature‐resistant metal phthalocyanine imide copolymers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

New metal phthalocyanine imide copolymers with high thermal stability, based on the reaction between metal (11) 4,4′,4″,4‴‐phthalocyaninetetraamine, 4‐aminophenylether, and 1,2,4,5‐benzenetetracarboxylic dianhydride, were prepared. Infrared (IR) spectra, thermogravimetric analysis (TGA), and viscosity measurements were used to characterize these polymers. All polymers exhibited good thermal and thermooxidative stability at polymer decomposition temperatures (PDT) greater than 500°C in air and nitrogen atmosphere. Another attractive feature is their high char yields—60–75% at 800°C in nitrogen atmosphere. The ratio of the polymer decomposition temperatures in air and nitrogen atmospheres, (PDTair)/(PDT), varied from 0.94 to 0.98. These polymers have promising applications in heat‐stable films, fibers, and coatings.
Solid‐state polymerization studies of conjugated diacetylenes deca‐2,8‐diene‐4,6‐diyne‐1,10‐diol and derivatives
Authors: Khandelwal P. K. , Talwar S. S.
Published: April 2003

The title diacetylenic compound (D3) and its derivatives dibenzoate (D3B), dinitrobenzoate (D3mNB), ditosylate (D3PTS), and diurethane (D3PU) were synthesized and their solid‐state reactivity examined under irradiation and thermal stimulation. D3, D3B, and D3PTS crystallized in reactive phases. The thermal and irradiation polymerization behavior of D3 and D3B was examined further by time‐conversion curves.
Effects of ionizing radiation on linear aromatic polyesters
Authors: Bell Vernon L. , Pezdirtz George F.
Published: April 2003

The influence of chemical structure on the response of aromatic polyesters to high‐energy ionizing radiation was studied. Systematic variations of polymers related to poly(ethylene terephthalate) were subjected to γ radiation, and the competitive chain scission and crosslinking reactions were determined by measuring changes in intrinsic viscosity and molecular weights. It was found that an increase in the paraffinic glycol segment of polyterephthalates facilitated crosslinking, while the protective nature of aromatic groups was demonstrated by modifying the dibasic acid segments. The influence of substituents on the terephthalate moiety was mixed: electronegative groups led to chain scission (as evidenced by decreased viscosities), but electropositive substituents exerted a stabilizing effect on polymer viscosity. In almost all cases, number‐average molecular weights were decreased by exposure to γ radiation, regardless of viscosity behavior. Crystalline melting temperatures of the polymers generally were decreased by the combined radiation effects of chain scission and crosslinking.
Structure of chlorinated poly(vinyl chloride). XII. Configuration and reactivity of low‐molecular‐weight models of poly(vinyl chloride) in the course of chlorination
Authors: Lukáš R. , Jakeš J. , Palečková V. , Pokorny S. , Kolínský M.
Published: April 2003

The chlorination of poly(vinyl chloride) (PVC) was investigated by means of low‐molecular‐weight models of PVC—a dimer and trimer of PVC, viz., 2,4‐dichloropentane (2,4‐DCP) and 2,4,6‐trichloroheptane (2,4,67‐TCH). Chlorinations of stereoisomeric mixtures of 2,4‐DCP and 2,4,6‐TCH have revealed that the d,1 form of 2,4‐DCP (syndio‐2,4‐DCP) is more reactive in the chlorination than the meso form of 2,4‐DCP (iso‐2,4‐DCP), while in the case of the chlorination of 2,4,6‐TCH the reactivity of stereoisomers decreases in the order iso‐> hetero‐>syndio‐2,4,6‐TCH; consequently, analogous structures of stereoisomers of 2,4‐DCP and 2,4,6‐TCH react in a reverse order and not in the same one. The qualitative order of reactivities of stereoisomers may be correlated formally with the magnitude of their dipole moments. The reactivity of stereoisomers of 2,4‐DCP and 2,4,6‐TCH decreases with increasing dipole moment.
Thermoswitching property in TCNQ salts of ionenes containing poly(ethylene oxide) segments
Authors: Takizawa Yoshio , Aiga Hirotsugu , Watanabe Masayoshi , Shinohara Isao
Published: April 2003

Ionene polymers characterized by the alternating structure of ionene and crystalline poly(ethylene oxide) (PEO) segments were prepared as a function of PEO segment size. A microstructure of these ionenes and their 7,7,8,8‐tetracyanoquinodimethane (TCNQ) salts were investigated with x‐ray diffraction patterns, thermal scanning behavior, and polarizing micrographs. On the basis of this microstructure, the change in resistivity with temperature was studied. In Arrhenius' plots of the resistivity the simple salts in which the spherulites consisting of the PEO segments were observed showed a sharp decrease in resistivity with a rise in temperature [critical temperature resistor (CTR)] at about the melting point of the PEO segments, whereas the other simple salts in which the spherulites were not observed showed linear temperature dependence. The switching properties were confirmed similarly in repetitive heating/cooling cycles. This CTR characteristic was attributed to an increase in continuity in the conduction paths by melting spherulites. The apparent switching properties were not observed in the complex salts.
Bis‐, tris‐, and tetrakis‐maleimidophenoxy‐triphenoxycyclotriphosphazene resins for fire‐ and heat‐resistant applications
Authors: Kumar Devendra , Fohlen George M. , Parker John A.
Published: April 2003

Novel fire‐ and heat‐resistant polymers was obtained by the thermal polymerization of various maleimidophenoxy‐triphenoxycyclotriphosphazenes. These polymers, in which the cyclic triphosphazene structure is preserved, have thermal stability to 350°C and char yields of 82–78% at 800°C in nitrogen and 78–71% at 700°C in air. Two groups of monomers were synthesized by reacting tris(4‐aminophenoxy)‐tris(phenoxy)cyclotriphosphazene with maleic anhydride alone or in combination with benzophenonetetracarboxylic or pyromellitic dianhydride. The structures of cyclic phosphazene‐trimeric precursors and the polymers were characterized by Fourier‐transform infrared, proton nuclear magnetic resonance, and elemental analysis. The thermal stabilities of the polymers were evaluated by thermogravimetric analysis.
Head‐to‐head vinyl polymers. X. Cyclopolymerization of o‐dimethacryloyloxybenzene
Authors: Ohya Takahiro , Otsu Takayuki
Published: April 2003

To clarify the possibility of preparing a polymer that contained head‐to‐head (h–h) methyl methacrylate (MMA) unit radical cyclopolymerization of o‐dimethacryloyloxybenzene (o‐DMB) was investigated. p‐Dimethacryloyloxybenzene (p‐DMB) was also used in comparison. When the polymerizations were carried out with higher monomer concentrations than ca. 0.5 mol/L, benzene‐insoluble polymer was produced. The extent of cyclization (fc) in benzene‐soluble polymer increased with a decrease in the monomer concentration and an increase in the polymerization temperature. The 1H‐NMR and 13C‐NMR spectra of poly(MMA) derived from poly(o‐DMB) by hydrolysis and methylation were in fairly good agreement with those of ordinary head‐to‐tail (h–t) poly(MMA). Therefore, it was concluded that the intramolecular propagation in cyclopolymerization of o‐DMB was mainly performed by a h–t mechanism. However, the initial and maximum degradation temperatures of the poly(MMA) were observed to be somewhat higher than those of the ordinary poly(MMA), which suggests that a minor amount of the h–h unit was formed.
Glow discharge polymerization in the mixture of tetramethylsilane and ammonia gas
Authors: Inagaki N. , Nejigaki K. , Suzuki K.
Published: April 2003

Colorless, transparent, and filmy polymers prepared from mixtures of tetramethylsilane (TMS) and ammonia gas (NH3) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. These polymers contained a large amount of nitrogen residues in the form of amine, amide, and amine oxide groups. Their concentration varied with the composition of the starting TMS/NH3 mixtures. The mixing of NH3 gas with TMS influenced the chemical state of Si residues and accelerated the oxidation of Si atoms to form silicon oxides such as SiO, Si2O3, and SiO2. The polymers formed by glow discharge polymerization in the TMS/NH3 mixtures were combinations of Si‐ and N‐containing polymers and silicon oxides.
Reactive oligomers. I. Preparation and polymerization of ethylene glycol bis(methyl fumarate)
Authors: Matsumoto Akira , Jiang Guang‐Jie , Oiwa Masayoshi
Published: April 2003

Ethylene glycol bis(methyl fumarate) (EGBMF) was prepared as a new type of divinyl compound and reactive oligomer: a needle crystal, m.p. 104.5°C. Homopolymerization of EGBMF was carried out in dioxane with 0.1 mol/L AIBN at [M] = 1 mol/L and 60°C; the rate of polymerization was estimated to be 4.44 × 10−6 mol/L s in a good agreement with diethyl fumarate (DEF). The cyclization constant Kc was obtained as 1.64 mol/L, being rather low compared with diallyl oxalate which is 1,9‐diene having two ester groups analogous to EGBMF. Gelatin occurred at about 35% conversion. Finally, the copolymerization of EGBMF (M1) with diallyl phthalate (DAP) (M2) is tentatively explored with the intention of the improvement of allyl resins in mechanical properties; remarkable rate enhancement was observed for copolymerization. The monomer reactivity ratios were estimated to be r1 = 0.96 and r2 = 0.025, the r1 value being reduced compared with the DEF‐DAP copolymerization system. These results are discussed from the standpoint of steric effect on the polymerization of fumarate as an internal olefin.
Ignition of low‐density polyethylene slabs by a small flame
Authors: Clark Ferrers R. S.
Published: April 2003

Slabs of low‐density polyethylene (LDPE) were exposed to the wake of a lean hydrogen‐oxygen flat flame. The ignition delay and initial flame velocity after the ignition were measured at several gas‐air equivalence ratios and distances from the igniting flame. When ignition occurred, the surface temperature was far lower than that required for pyrolysis in the absence of oxygen. Small amounts of char formed on the polymer surface during the delay, consistent with the involvement of oxygen in solid‐phase preignition processes. Plots of In(delay) versus 1/(absolute temperature) were linear and the activation energy was derived from the Arrhenius equation, 64 ± 10 kJ/mol. Initial rates of flame development decreased with increased separation between the polymer and the igniting flame, but unlike those reported for poly(methyl methacrylate), they were independent of the duration of the preceding delay except when the polymer was very close to the flame. The results are explained by a model in which both the ignition delay and the subsequent rate of flame development depend on the concentration of species associated with the chain‐propagation steps of the combustion process.
Thermal stability of poly(vinyl bromide) and vinyl bromide‐methyl acrylate copolymers. I
Authors: Diab M. A.
Published: April 2003

The thermal stability of PVB and five VB‐MA copolymers with different compositions was studied by thermogravimetric analysis in dynamic nitrogen. The reactivity ratios of the copolymers were determined by using NMR techniques. It was found that r1(VB) = 0.5 ± 0.1 and r2(MA) = 7.3 ± 0.3. The stability of VB increases as the MA concentration in the copolymer compositions increases. Apparently, the formation of lactone and anhydride structures has a stabilizing effect. The stability imparted to the degrading copolymers by lactone and anhydride structures is insufficient to produce stability comparable to that of PMA itself.
Radiation‐induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. II. Studies on bromine labeling
Authors: Bhattacharyya S. N. , Maldas D.
Published: April 2003

Formation of the active sites on irradiated trunk polymer, for example, cellulose acetate, was determined by taking recourse to bromine labeling and the G values of active sites were accordingly evaluated. The G value was as well determined through analysis of peroxide. It has been concluded that the G value measured by bromine labeling corresponds to accessible radicals, while that evaluated through measurement of peroxide accounts for the total. The number‐average molecular weights of the graft chains were calculated and these were found to be dependent on monomer composition.
Radiation‐induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. III. A kinetic study
Authors: Bhattacharyya S. N. , Maldas D.
Published: April 2003

The kinetics of graft copolyermization of styrene and acrylamide from their binary monomer mixtures onto gamma‐irradiated cellulose acetate film was studied. The extent of grafting increased with a rise in reaction time and temperature. The nature of the radical site on the trunk polymer was acertained in a study of grafting at different temperatures when the trunk polymer was irradiated in the presence and absence of oxygen. The character of the radical was tested further in a study of the ESR spectrum. The variation in grafting rates and energies of activation required for graft copolyermization at various mole ratios of the monomers was observed. The grafting rates showed a maximum at 1:1 mol ratio of monomers which was also associated with minimum energy of activation. The Kkt values in the system were dependent on the composition of monomers.
Liquid crystal polymers. 15. Synthesis and liquid crystalline properties of alkyl‐substituted polyesters
Authors: Zhou Qi‐Feng , Lenz Robert W.
Published: April 2003

Alkyl substitution in a series of main chain, liquid crystal polyesters strongly depressed their glass temperatures, melting points, clearing points, and mesophase thermal stabilities. Polymers with pendant n‐alkyl substituents eight carbon atoms or longer did not form a liquid crystal phase.
The effect of ammonium polyphosphate on the mechanism of thermal degradation of polyureas
Authors: Montaudo G. , Scamporrino E. , Vitalini D.
Published: April 2003

The thermal decomposition of structurally related N–H and N,N′‐disubstituted polyureas (Table I) and their mixtures with ammonium polyphosphate (APP) was investigated by thermogravimetry (TG) and direct pyrolysis in a mass spectrometer (MS). The N–H polyureas (IV–VI) undergo a quantitative depolymerization process with the formation of oligomers with amine and isocyanate end groups. In contrast, the thermal degradation of the N,N′‐disubstituted polyureas (I–III) proceeds by a different mechanism as a function of their chemical structure. The addition of APP lowers the thermal stability of the N,N′‐disubstituted polyureas, whereas that of the N–H polyureas is unaltered. However, our data show that APP does not change the nature of the pyrolytic products. The destabilizing effect of the additive can be attributed to the catalytic action of the acid species formed by its thermal decomposition.
Effect of sulfur on the electrical conductivity of FEF‐loaded SBR during swelling
Authors: Amin M. , Hassan H. H. , Nasr G. M.
Published: April 2003

Following a series of experiments on the effect of different factors of the electrical conductivity of carbon‐black‐loaded styrene butadiene rubber, an attempt was made to study the effect on electrical conduction of changing the sulfur content. It was found that an optimum sulfur content leads to a swelling‐resistant composite with good electrical insulation. This was done for dry as well as wet specimens of rubber.
Intumescent flame retardants for polymers. II. The polypropylene‐ammonium polyphosphate‐polyurea system
Authors: Montaudo G. , Scamporrino E. , Vitalini D.
Published: April 2003

The mechanism of action of ammonium polyphosphate (APP) and polyurea (PU) as flame retardant (FR) agents for polypropylene (PP) was examined. The APP–PU system behaves as an intumescent flame‐retardant (IFR) formulation. Comparison of the oxygen index (OI) measured on molded pellets and rods, values of the polymer temperature measured just below the burning surface, and visual considerations describe the IFR action of this system. A strong synergism between APP and two of the four polyureas investigated here was ascertained with a maximum 3:1 ratio. Thermogravimetric (TG), OI, nitrous oxide index (NOI), and char‐residue measurements were made. On the basis of our data, it can be concluded that polyurea acts as a catalyst for the charring reactions of the APP on PP.
Spectroscopic investigation of organosilicon polymers. I. Vibrational analysis of poly(tetramethyl‐p‐silphenylene‐siloxane)
Authors: Neto N. , Sbrana G. , Muniz‐Miranda M. , Dobos S. , Zelei B. , Harsányi L.
Published: April 2003

This article is a detailed, normal coordinate analysis of an isolated chain of poly(tetramethyl‐p‐silphenylene‐siloxane), based on results obtained for the corresponding monomer and a recent x‐ray structure. Predicted vibrational frequencies are compared with new experimental infrared (IR) and Raman data obtained from powder and well oriented films. Vibrational spectra were also obtained for a deuterio derivative in which all hydrogens in the benzene rings were replaced with deuterium atoms. The results indicate that an intermode mixing occurs between vibrations of the ring and the saturated part which lead to low frequency normal modes characteristic of the chain. The simplified valence force field obtained for this polymer should provide a useful tool for understanding the vibrational spectra of other members of the class of polysiloxanes.
Charge transfer polymerization of 2‐vinyl pyridine initiated by n‐butyl amine and carbon tetrachloride
Authors: Gogoi A. K. , Dass N. N.
Published: April 2003

2‐Vinyl pyridine (2‐VP) can be initiated by a charge‐transfer complex formed by the interaction of aliphatic amines such as n‐butylamine (nBA) and carbon tetrachloride (CCl4) in a solvent like NN‐dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This article describes the polymerization of 2‐VP by n‐butylamine (nBA) in the presence of carbon tetrachloride in DMSO at 60°C. The rate of polymerization Rp increases rapidly with carbon tetrachloride (CCl4) up to a concentration of 3.93 mol/L, but for a higher concentration it is almost independent of the carbon tetrachloride concentration; Rp is proportional to [nBA]0.5 and [2‐VP]1.5 when [CCl4]>[nBA]. The average rate constant k is 1.03 × 10−5 L/mol s. When [CCl4] < [nBA] the rate constant in terms of [2‐VP] was 1.06 × 10−5 s−1 at 60°C and the overall rate constant was 1.035 × 10−5 L/mol s at 60°C.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). XXX. Synthesis and quantitative terminal functionalization of α,ω‐diarylpolyisobutylenes
Authors: Kennedy Joseph P. , Hiza Misao
Published: April 2003

Novel aromatic‐telechelic polyisobutylenes were prepared and characterized: α,ω‐diphenylpolyisobutylene, α‐phenyl‐ω‐tolylpolyisobutylene, and α,ωditolylpolyisobutylene. The syntheses involved the preparation of asymmetric telechelic prepolymers (α‐phenyl‐ω‐tert‐chloropolyisobutylene and α‐tolyl‐ω‐tert‐chloropolyisobutylene) by the minifer method and quantitative alkylation of benzene and toluene by the prepolymer. The terminal aromatic rings of these telechelic polyisobutylenes were quantitatively nitrated, acetylated, and chlorosulfonated and a series of further novel telechelic products was obtained. Characterization of these derivatives provided additional proof for the telechelic structure of the starting prepolymers. The quantitative reduction of nitroaryl‐telechelic polyisobutylene by SnCl2/HCl led to aminoaryl‐telechelic polyisobutylene which was used to cure bisphenol‐A diglycidyl ether. These new flexible epoxy networks exhibited outstanding heat and hydrolytic stability combined with satisfactory mechanical properties.
Plasma polymerization. X. A systematic investigation of materials synthesized in inductively coupled plasmas excited in tetrafluoropyridazine
Authors: Clark D. T. , Abu‐shbak M. M.
Published: April 2003

A detailed investigation was made by ESCA of the gross structural features and chemical composition of ultrathin plasma polymer films prepared from tetrafluoropyridazine. The data reveal evidence of extensive rearrangement that accompanied polymerization and that the C:F and C:N stoichiometries of the polymer films were similar to those of the starting monomer. From an initially high contact angle with water the surfaces became completely wettable with time and this is attributed to surface hydrolysis. A comparison is made between surface and bulk compositions. Brief consideration is also given to sleeve effects.
Cationic polymerization of 1,4,6‐trioxaspiro [4,4]‐nonane
Authors: Matyjaszewski Krzysztof
Published: April 2003

Cationic polymerization of 1,4,6‐trioxaspiro [4,4]‐nonane (1) with (CH3)3O+SbF6−(2) and CH3OSO2CF3(3) initiators has been investigated. Although the observed rates of initiation and propagation are relatively slow, they consist of rapid reversible elementary reactions. In 1H‐NMR spectra, a broadening of the monomer signal was observed, indicating a fast exchange between “free” monomer and monomer engaged in the active species. The variety of orthoester bonds were observed in the polymer formed at the early stages of monomer conversion. The final polymer has, however, structure of a linear poly(ester–ether) including two subsequent ester or ether linkages. To account for these new facts, the mechanism of polymerization was proposed, consisting of a rapid reversible opening of one of the rings in the monomer molecule involved in the growing species, followed by the slower opening of the second ring with formation of the ester linkages. It appears that the rings originally present in the chains rearrange into the linear units intramolecularly.
Radiation‐induced copolymerization of phenylvinyl alkyl ethers and maleic anhydride
Authors: Ranogajec F. , Vuković R. , Fleš D.
Published: April 2003

Alternating copolymers of phenylvinyl ethyl ether (I) and phenylvinyl sec‐butyl ether (II) with maleic anhydride (MAn) were prepared in bulk or in benzene solution by high‐energy irradiation at dose rates of 42, 160, and 540 Gy/h, respectively. The overall energies of activation in copolymerization of I and II with MAn were 15.5 and 18.8 kJ/mol, respectively. The reaction proceeds by the free‐radical mechanism and was found to be largely dependent on the bulkiness of the alkyl group. In the copolymerization of I and MAn, the molecular weight increases with conversion. By applying the model described by Shirota and co‐workers, it was established that participation of charge‐transfer‐complex monomers increases with the increase of the total monomer concentration and with the bulkiness of the alkyl group in electron donor monomer.
Photoinitiation of cationic polymerization. III. Photosensitization of diphenyliodonium and triphenylsulfonium salts
Authors: Pappas S. Peter , Gatechair Leslie R. , Jilek Josef H.
Published: April 2003

Photoinitiated cationic polymerization by photosensitization of diphenyliodonium and triphenylsulfonium salts is shown to proceed by two distinct electron transfer process: (1) direct electron transfer from excited‐state photosensitizers and (2) indirect electron transfer from photogenerated radicals. The efficiency of the former process is attributed to the instability of the reduction products (from diphenyliodonium and triphenylsulfonium salts), which dissociate in competition with undergoing energy‐wastage reverse electron transfer. Amplification of photons in the production of protons (or other reactive cations) is postulated to account for the high quantum yields observed in the latter process. Potential advantages of utilizing the indirect redox process in the design of UV curable hybrid systems, which contain functionality for both radical and cationic polymerization, are noted. The results also provide evidence against the importance of triplet states of the onium salts in photoinitiator activity.
Attempted polymerization of substituted pipecolic acid NCA's: Dimerization and mechanism
Authors: Shalati Mohamad D. , Overberger C. G.
Published: April 2003

Racemic and optically active N‐carboxyanhydrides (NCA)s of 2‐methyl‐ and cis‐6‐methylpipecolic acid, when subjected to polymerization conditions in solution or in bulk whether with “weak” or “strong” base initiators, resisted polymerization under all conditions tried. Instead, the NCA of 2‐methylpipecolic acid gave the corresponding cyclic dipeptide and the NCA of cis‐6‐methylpipecolic acid formed the cyclic dipeptide derived from trans‐6‐methylpipecolic acid. The mechanism of dimerization of these NCA's was investigated. Evidence was provided for the proposed mechanism in which the active moiety is not a carbamate ion but an amino group. Methyl 2‐methylpipecolate underwent an intermolecular SN2‐type reaction upon heating, yielding equimolar quantities of methyl N‐methyl‐2‐methylpipecolate and 2‐methylpipecolic acid.
The binding of organic anions by polyvinylpyrrolidone: Determination of intrinsic binding constant and number of binding sites by competitive binding
Authors: Takagishi Toru , Yoshikawa Kiyoaki , Kuroki Nobuhiko , Kozuka Hiroshi , Mitsuishi Masaru
Published: April 2003

The binding of 4′‐dibutylaminoazobenzene‐4‐sulfonate (butyl orange, BO) and 1‐amino‐4‐methylaminoanthraquinone‐2‐sulfonate (AQ) by crosslinked polyvinylpyrrolidone and the competition between BO and AQ for binding sites of the polymer were examined. The equilibrium data showed competitive binding. Thus the intrinsic binding constants and the number of binding sites can be evaluated easily and precisely by competitive binding. The thermodynamic parameters that accompained the binding were calculated from the intrinsic binding constant and its temperature‐dependence. The thermodynamic data for BO showed that the binding process is athermal and stabilized entirely by the entropy term. The binding of BO to the polymer is entropically favorable as a result of the operation of the hydrophobic effect. In contrast, with AQ a favorable free energy for a dye‐polymer complex formation is associated with a large negative enthalpy and a small entropy. Therefore it is likely that the binding of AQ occurs by energetic forces and that the large aromatic ring of the dye contributes to the binding energy. On the average, BO and AQ can bind to the crosslinked polymer to the extent of 1 dye/ca 73 basemol in 0.1M tris‐acetate buffer, pH 7.0.
Organosilane polymers: Formable copolymers that contain methyl(β‐phenethyl)silylene or cyclohexyl(methyl)silylene units
Authors: Zhang Xing‐Hua , West Robert
Published: April 2003

High molecular weight polysilane copolymers which contain the units in the title were prepared in high yield by sodium coupling the corresponding organodichlorosilanes in toluene. These copolymers are highly soluble in common solvents and can be drawn into fibers or formed into films by molding or casting. They are also photoactive.
Thermoplastic resins, polyquats, and membranes based on epoxies
Authors: Renner Alfred , Michaelis Klaus Peter
Published: April 2003

High‐molecular‐weight branched‐addition polymers made from oligomeric solid epoxy resins and amines carrying two active hydrogen atoms are described. The reaction with aliphatic amines like ethanolamine, 2‐ethylhexylamine, or piperazine can easily be controlled carrying out the polymerization in about 15% solutions of boiling 2‐methoxyethanol. Less basic derivatives of aniline and epoxy resins are processed at 200°C in the molten state. Polymers with Mn up to 33,000 and Mw to 720,000 are obtained. Properties of films and injection moldings are described. The tertiary nitrogen atoms present in the polymer chain can be quaternized with alkylating agents, like dimethylsulfate, methyliodide, or trimethyl phosphate. Thin membranes cast from the polyquats thus obtained exhibit a good flow rate for water and a high salt rejection under reverse osmosis conditions.
A Mössbauer study of polymers prepared from polyvinylpyridine and ferric chloride or ferric nitrate
Authors: Coey J. M. D. , Meagher A. , Kelly J. M. , Vos J. G.
Published: April 2003

Iron‐ion‐containing polymers were prepared by reacting atactic polyvinylpyridine with ferric chloride or ferric nitrate in methanol solution. Molar ratios of Fe3+ to 4‐vinylpyridine (Fe:PVP) were 1:2, 1:6, and 1:20. Three kinds of iron center were characterized from 57Fe Mössbauer spectra recorded over a temperature range of 4.2–290 K. Infrared (IR) spectra of the samples were measured also. All samples contained amorphous hydrated ferric‐oxide particles that exhibited superparamagnetic behavior at low temperatures. The size of the clusters (102–103 iron atoms per particle) was estimated from the average blocking temperatures TBav, which is sensitive to the Fe:PVP ratio. For FeCl3:PVP preparations with Fe:PVP of 1:2, 1:6, and 1:20 TBav was 37, 10, and <4 K, respectively. A small proportion (<10%) of high‐spin ferrous iron centers was found in most samples. A third type of signal attributable to oxygen‐bridged ferric dimers was found in FeCl3–PVP preparations with Fe:PVP of 1:2 or 1:6 but not in Fe(No3)3–PVP samples. This species is probably [Cl3FeOFeCl3]2−. Interactions between the polymer and the various iron centers were weak.
Studies on heat‐resistant poly(metal phthalocyanine)‐imide copolymers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

Several new poly(metal phthalocyanine)imide copolymers have been prepared using 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BPTDA), metal(11) 4,4′,4″,4″′‐phthalocyanine tetraamines (MPTA), p‐phenylenediamine, 4,4′‐methylenedianiline, and 9,9‐bis(4‐aminophenyl)‐fluorene (BAF). The attractive feature of these polymers is their high thermooxidative and thermal stability. The polymer decomposition temperatures of all the imide copolymers are greater than 500°C in air and N atomspheres. Another noteworthy property is their high char yield: 60–78% at 800°C in a N2 atmosphere. Variation of the metal phthalocyanine concentration has a remarkable effect on the thermal stability and degree of polymerization. The most preferred molar proportion of the reagents MPTA, diamine, and BTDA is 1.25:7.5:10. These polymers may be useful in the preparation of heat‐resistant films and fibers.
Synthesis and characterization of poly(ethylene glycol) derivatives
Authors: Harris J. Milton , Struck Evelyn C. , Case Martha G. , Paley M. Steven , Yalpani Manssur , Van Alstine James M. , Brooks Donald E.
Published: April 2003

Five general routes for the preparation of polyoxyethylene [generally referred to as poly(ethylene glycol) or PEG] derivatives are described. These routes are (1) nucleophilic displacements with the alkoxide of PEG, (2) nucleophilic displacement on PEG–tosylate, –mesylate, or –bromide, (3) reductive amination of PEG–aldehyde, (4) reductive amination of PEG–amine, and (5) nucleophilic displacements on the s‐triazine derivatives prepared from s‐triazine trichloride (cyanuric chloride) and PEG. Eighteen derivatives are prepared and potential applications to catalysis, cell purifications, and other areas are discussed briefly.
IBMA–metal containing polymers
Authors: Gunesin B. Z. , Schulz D. N. , Kang J. W. , Cain A. R. , Hamed G. R.
Published: April 2003

A new convenient route to metal containing polymers is described. This method involves emulsion co(ter) polymerization of a polar hydrocarbon soluble monomer, N‐isobutoxymethylacrylamide (IBMA), with styrene or styrene/butadiene, followed by addition of metals. Metal incorporation is effected by latex or solution techniques. Preparative, atomic adsorption, spectroscopic, film observation, and dilute solution data are presented in support of metal complexation. Structures for the complexes are proposed.
ESCA and contact‐angle studies of the surface modification of poly(ethylene terephthalate) film: Photooxidation and aging
Authors: Peeling James , Courval Gregory , Jazzar Mohammad S.
Published: April 2003

ESCA and contact‐angle (H2O and CH2I2) measurements are used to follow changes in the surface of poly(ethylene terephthalate) film photooxidized (254 nm radiation in O2) for varying times, followed by aging for as many as three weeks or washing with water. Photooxidation occurs uniformly throughout the outermost 50 Å of the film to give a surface stoichiometry that corresponds to C10O6.6. Oxidation produces mainly carboxyl (acid) and alcohol/phenol groups, carbonyls form after extensive treatment. Low molecular weight products formed by chain scission and oxidation are removed by washing and diffuse into the bulk when aged. Oxidized products in higher molecular weight chains are not removed by washing, but can diffuse into the polymer bulk or reorient because of their chain mobility; therefore they are directed toward the polymer bulk rather than the surface. Extended photooxidation produces a stable oxidized surface more resistant to aging changes. The results are compared with those obtained for poly(ethylene terephthalate) film oxidized in an electrical discharge.
Thermal and radiation‐induced polymerizations of N‐tert‐butylacrylamide and (N‐tert‐butylacrylamide)2–ZnCl2 complex
Authors: Kiliç Soner , Baysal Bahattin M.
Published: April 2003

The thermal and radiation‐induced in‐source and postirradiation polymerizations of N‐tert‐butylacrylamide and (N‐tert‐butylacrylamide)2–ZnCl2 complex of this monomer were studied at various temperatures. In in‐source, solid‐state polymerizations of monomer and complex the conversion was about 95% at 21°C in about eight days. Their postirradiation polymerizations were also studied in solid state. The conversion‐time curves of these two systems show an autoacceleration as in‐source polymerization. In both types of polymerization the overall rate of polymerization of complex was higher than that of pure monomer at the same polymerization temperature. In investigations of the thermal polymerization of N‐tert‐butylacrylamide and ZnCl2‐complex it was observed that the ZnCl2‐complex system can be polymerized in air in the molten and solid state. The conversion of monomer to polymer reaches limiting values in solid state in about 1 hr. The thermal polymerization of ZnCl2‐complex in the molten state was also studied and 100% conversion was obtained in 30 min. The thermal polymerization of pure monomer was studied in vacuum and an appreciable amount of polymer was obtained in the molten state; however, the thermal polymerization of this monomer is negligible in solid state. In this work rates of polymerization for N‐tert‐butylacrylamide and (N‐tert‐butylacrylamide)2–ZnCl2 are compared under various experimental conditions and overall activation energies are calculated.
Polymerization of para‐xylylene derivatives (parylene polymerization). I. Deposition kinetics for parylene N and parylene C
Authors: Kramer P. , Sharma A. K. , Hennecke E. E. , Yasuda H.
Published: April 2003

Kinetic aspects of parylene N [unsubstituted poly(para‐xylylene)] and Parylene C [monochlorosubstituted poly(para‐xylylene)] were studied. The conversion of starting material (dimer of either p‐xylylene or chloro‐para‐xylylene) to polymer is quantitative (ca. 100%). Consequently, the total polymer formed in a closed system is directly proportional to the amount of dimer charged. However, the percentage of the total amount of polymer formed which deposits on substrate surfaces, placed in the deposition chamber, as well as the polymer film growth rate are dependent on operational factors such as the temperature of the substrate, sublimation of dimer temperature, flow pattern of the reactive species, etc. Parylene C, being a heavier and more polar molecule, has the tendency to deposit easily in the deposition chamber compared to the deposition of Parylene N. Parylene C also has a higher ceiling temperature for deposition than Parylene N. This situation has been investigated from the viewpoint of excess thermal energy which hinders polymer formation (deposition) due to the exceedingly high entropy change necessary for polymer deposition to occur. The addition of a cool (i.e., room temperature) inert gas was shown to increase the deposition of Parylene N on substrate surfaces placed in the deposition chamber. The deposition increase and acceleration of deposition (film growth) rate were found to be related to the size and molecular weight of the inert gas pressure maintained in the system. The accelerating effect is explained by the increase in third‐body collisions to dissipate the excess thermal energy of the reactive species.
Acid–base complexes of polymers
Authors: Fowkes F. M. , Tischler D. O. , Wolfe J. A. , Lannigan L. A. , Ademu‐John C. M. , Halliwell M. J.
Published: April 2003

The physical interactions of polymers with neighboring molecules are determined by only two kinds of interactions: London dispersion forces and Lewis acid–base interactions. These two kinds of attractive energies (together with certain steric restrictions) determine solubility, solvent retention, plasticizer action, wettability, adsorption, adhesion, reinforcement, crystallinity, and mechanical properties. The London dispersion force interaction energies of polymers have been quantified by the dispersion force contribution to cohesive energy density (δ2d) and the dispersion force contribution to surface energy (δd). The Lewis acid–base interactions, often referred to as “polar” interactions, can be best quantified by Drago's CA and EA constants for acid sites and CB and EB constants for basic sites. In this article infrared spectral shifts are featured as a method of determining enthalpies of acid–base interaction, and the C and E constants for polymers, plasticizers, and solvents. Examples are given where acid–base complexation of polymers with solvents dominate solubility and swelling phenomena. Enthalpies of acid–base complexation in polymer blends are determined from spectral shifts.
Partial miscibility in multicomponent polymer system
Authors: Jung Hae Young , Jhon Mu Shik
Published: April 2003

It has been shown, using the significant structure theory of liquids, that a lower critical solution temperature behavior as well as a upper critical solution temperature behavior can be expected for polymer–polymer systems and that a phase diagram of closed‐loop‐type in a polymer–polymer–solvent system can be possible. In this article the sublimation energy of a mixture was expressed as a quadratic form of segment surface fractions on pure components rather than that of mole fractions, and the effect of the segment surface fractions on critical compositions was explained. The calculated partial miscibilities were in good agreement with the experiment.
Characterization of copolymers of vinyl acetate with ethyl α‐cyanocinnamate
Authors: Kharas Gregory , Kohn David H.
Published: April 2003

Alternating and random copolymers of ethyl α‐cyanocinnamate and vinyl acetate were studied. Infrared, 1H, and 13C spectra of the copolymers are discussed by comparison with a model compounds, poly(vinyl acetate), and various copolymers. The decomposition temperature and Tg of copolymers of various composition, studied by TMA and DSC, increase both with increasing content of ethyl α‐cyanocinnamate.
Copolymerization of vinyl acetate with benzylidenemalononitrile
Authors: Kharas Gregory , Kohn David H.
Published: April 2003

Vinyl acetate was copolymerized with benzylidenemalononitrile in bulk by radical initiation at 80°C up to low conversions. Alternating copolymers were formed over a wide range of monomer feed ratios. The copolymerization parameters were determined by the conventional scheme. The copolymers were characterized by IR, proton, and 13C spectroscopy and their basic properties, solubility, viscosity, and thermal behavior were determined.
Cationic polymerization of β‐pinene
Authors: Martinez Francisco
Published: April 2003

β‐Pinene was polymerized with cationic initiators in reactions that were carried out to study the solvent, temperature, initiator, and monomer‐to‐solvent ratio. Polymers obtained under different conditions were characterized by intrinsic viscosity, softening point, and gel permeation chromatography.
Matrix polycondensation through hydrogen bonding interaction
Authors: Ogata Naoya , Sanui Kohei , Iwaki Fusako , Nomiyama Atsuko
Published: April 2003

Polycondensation of diesters having hydroxyl or pyridine groups was carried out with hexamethylenediamine (HMD) in the presence of (vinyl alcohol/vinyl acetate) copolymers as a matrix polymer. Apparent rates of the polycondensation of dimethyl tartrate (DMT) with HMD increased with increasing contents of PVA units in the copolymers and a strong entanglement between growing polyamide chains and PVA copolymers took place through the adsorption of HMD and DMT on the matrix copolymers. 2,6‐Dimethyl pyridine dicarboxylate (2,6‐DMP) reacted with HMD in the presence of the PVA copolymers or polysaccharide, while the rate enhancement effect of the matrix polymers was not significantly observed, as in the case of DMT. The effect of the matrix polymers on the polycondensation was discussed in terms of hydrogen bonding interactions.
Synthesis of some graft polymers of uracil
Authors: Brahme Nanda M. , Smith Walter T.
Published: April 2003

Poly‐6‐(acryloyloxymethyl)uracil was prepared by radical‐catalyzed polymerization of monomeric 6‐(acryloyloxymethyl)uracil. The reaction of 6‐chloromethyluracil with the potassium salt of polyacrylic acids of molecular weights 5000 and 90,000 gave polymers with both carboxylate groups and 50–70% pendant uraciles. Some inferences concerning the arrangement of uracil groups are drawn from the nuclear magnetic resonance (NMR) spectra of the latter polymers. No interaction between poly(A) and the synthetic polymers could be observed.
Hydrophilic polymer‐immobilized lipoamides‐iron(II) system as a new reducing catalyst for the reduction of O‐benzylhydroxylamine by sodium borohydride
Authors: Kijima Masashi , Nambu Yoko , Endo Takeshi , Okawara Makoto
Published: April 2003

Based on a redox function of 1,2‐dithiolane ⇌ 1,3‐dithiol, lipoamide immobilized on hydrophilic polymers such as polyacrylamide, polyethyleneimine, and chitosan was found to work as polymeric reducing catalysts for the reduction of O‐benzylhydroxylamine to benzyl alcohol and ammonia with sodium borohydride in the presence of ferrous ion. These polymers were easily separable and maintained high reactivities even after repeated uses.
Phase‐transfer reactions catalyzed by polymer‐supported crown ethers
Authors: Tomoi Masao , Yanai Noriyuki , Shiiki Satoshi , Kakiuchi Hiroshi
Published: April 2003

Polymer‐supported crown ethers were prepared from chloromethylated or ω‐bromoalkylated polystyrene resins and hydroxymethylbenzo‐18‐crown‐6 and 15‐ or 18‐membered monoazacrown ethers. Effects of the cavity size of crown ethers, the degree of crosslinking, the degree of ring substitution, particle size, spacer chains, and solvents on the activity of the polymer‐supported crown ethers in the reaction of 1‐chloro‐ or 1‐bromo‐octane with aqueous NaI or KI were investigated and mechanisms of the reaction were discussed in terms of mass transfer, intraparticle diffusion, and intrinsic reactivity.
Synthesis and characterization of polymers and copolymers of vinylruthenocene
Authors: Willis T. Chad , Sheats John E.
Published: April 2003

Homopolymers of vinylruthenocene and its copolymers with methyl acrylate, styrene, and n‐vinylpyrrolidinone have been prepared by free‐radical polymerization. No evidence for the electron transfer termination mechanism postulated for polymerization of vinylferrocene was observed. Yields of soluble polymers were 40–90% with Mw (4–25) × 103 and Mw/Mn = 3.0–13.2. TGA analysis showed little weight loss up to 300°C but rapid decomposition above 300°C. Polyvinylruthenocene is a highly brittle material with Tg above 250°C. Torsional braid analysis of the copolymer samples showed Tg in the range 90–130°C which in some samples increased upon cooling and reheating. Several samples showed weak thermal transitions occurring prior to or following Tg. The rise in Tg upon cooling and reheating is indicative of possible decomposition, crosslinking, or realignment of the polymer chains.
Ring formation on heating poly(methyl vinyl ether‐alt‐ammonium maleamate)
Authors: Field Nathan D. , Li Chi
Published: April 2003

Poly(methyl vinyl ether‐alt‐ammonium maleamate), when heated at up to 100°C while removing volatiles, is converted to polymer whose infrared, elemental analysis and Tg are consistent with a structure predominantly that of poly(methyl vinyl ether‐alt‐maleic anhydride). Maleimide comonomer units are a substantially lesser component. Evidence is presented that a part of the reaction sequence may involve hydrolysis of imide or amide.
Chemistry of alkenyl azlactones. I. Radiation‐sensitive materials derived from azlactone‐containing copolymers
Authors: Heilmann Steven M. , Rasmussen Jerald K. , Palensky Frederick J. , Smith Howell K.
Published: April 2003

2‐Vinyl‐4,4‐disubstituted azlactones were shown to be effective comonomers in free radical addition polymerizations for purposes of subsequently preparing radiation‐sensitive materials by attaching an unsaturated nucleophile. The azlactone‐functional copolymers could be reacted with amine‐, thiol‐, and hydroxy‐functional nucleophiles over the course of a few hours in solution at room temperature to effect covalent attachment of the nucleophile. The electron beam‐ and UV‐sensitive materials were shown to be useful as photoresist and embossable video disk recording media.
Direct mass spectrometry of polymers. XI. Primary thermal fragmentation processes in aromatic–aliphatic polyesters
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio
Published: April 2003

The thermal decomposition of two series of isomeric aromatic–aliphatic polyesters was studied by direct pyrolysis‐mass spectrometry. The results indicate that intramolecular exchange reactions predominate in the primary thermal fragmentation processes to cause the formation of cyclic oligomers. Several secondary thermal processes may occur after the primary step: hydrolytic cleavage of the ester bond, decarboxylation, and β‐hydrogen transfer.