bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymerization of aromatic nuclei. XXIII. Investigation of oligomer and pyrrole red from pyrrole and trichloroacetic acid
Authors: Lamb Bruce S. , Kovacic Peter
Published: April 2003

A reinvestigation of the oligomerization of pyrrole by trichloroacetic acid was carried out to establish the structure of the product. Comparison of spectral data with those of model compounds suggests that the oligomer is best represented by I. Further comparison was made to the known trimer I, dimer V, and other substituted pyrroles and pyrrolidines. In addition, microanalytical and molecular weight data were obtained. Structure I is in disagreement with that of Wassermann et al., who proposed the presence of units possessing aliphatic unsaturation for the same product. Mechanistic aspects are discussed. A limited study was carried out with pyrrole red.
Polymerization of allyl esters of unsaturated acids. V. Cyclopolymerization of methyl allyl fumarate
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

The kinetics of radical polymerization of methyl allyl fumarate (MAF) is discussed in terms of cyclopolymerization and compared with the polymerization results of methyl allyl maleate (MAM) as a cis isomer. In the polymerization of MAF, the rate and degree of polymerization were quite enhanced compared with MAM, and gelation occurred at low conversion. The content of the unreacted allylic double bonds of the MAF polymer was quite large; whereas those of the unreacted fumaric double bonds and the cyclic structural units showed reverse tendencies. Only a slight presence of a five‐membered ring was observed in the MAF polymer. The cyclization constants KA and KV, the ratios of the rate constants of the unimolecular cyclization reaction to those of the bimolecular propagation reaction of the uncyclized allylic and fumaric radicals, were estimated to be 2.73 and 1.48 mole/liter, respectively. These values suggest the great difference in the cyclopolymerization behavior between two isomeric monomers. These results are discussed in detail in connection with the high reactivity of the fumaric double bond compared to the maleic double bond. In addition, the formation mode and the sequence distribution of the structural units of the polymer produced are discussed on the basis of these analytical results. Thus, for the MAF polymer obtained in the bulk polymerization, about 60% of the cyclic structure can be formed via the intramolecular attack of the uncyclized fumaric radical on the allylic double bond, as opposed to the case of MAM via the predominant intramolecular attack (ca. 90%) of the uncyclized allylic radical on the maleic double bond; these results and the low probability for the succession of cyclic structures and the rather high probability of a vinyl‐to‐vinyl addition are presented.
New processable polyaromatic amides curable by Diels‐Alder cycloaddition
Authors: Sankaran V. , Marvel C. S.
Published: April 2003

New processable polyaromatic amides were prepared from the acid chloride of bis‐m‐carboxyphenyl acetylene (V), the acid chloride of 1,4‐bis‐m‐carboxyphenyl‐1,3‐butadiene (VI), and several aromatic diamines. The polyamides that contained acetylene units were cured by Diels‐Alder cycloaddition reaction with 1,4‐diphenyl‐1,3‐butadiene, whereas the polyamides with 1,3‐butadiene units were cured with N‐phenyl maleimide. Cured polyamides showed an increase in tg, thermal, and heat stabilities. The polyamides can be cast into films and produce good glass‐fiber laminates.
Mechanism of thermal degradation of polyurethanes investigated by direct pyrolysis in the mass spectrometer
Authors: Ballistreri A. , Foti S. , Maravigna P. , Montaudo G. , Scamporrino E.
Published: April 2003

Direct pyrolysis in the mass spectrometer (MS) yielded unequivocal evidence regarding the mechanism of thermal decomposition of N‐monosubstituted and N‐disubstituted polyurethanes. It was ascertained that direct pyrolysis in the MS detects the primary thermal fragments that originate from polyurethane pyrolysis. This is particularly useful when, as in the thermal decomposition illustrated in eq. (1), it is necessary to distinguish between primary and secondary thermal fragments in order to assess the thermal degradation mechanism. Our results indicate that N‐monosubstituted polyurethane V undergoes a quantitative depolycondensation process. Instead, the thermal decomposition of the N‐disubstituted polyurethane VI which occurs selectively in eq. (1) is demonstrated by the detection of thermal fragments that contain secondary amine and olefinic end groups. Finally, polyurethane VI shows a higher thermal stability with respect to polymer V because of the absence of the depolycondensation process, which accounts for the thermal degradation of the N‐monosubstituted polyurethane V.
Synthesis and biodegradability of amylose block copolymers
Authors: Lynn M. M. , Stannett V. T. , Gilbert R. D.
Published: April 2003

The synthesis of amylose block co‐and terpolymers is described. Fully acetylated amylose triacetate was hydrolyzed by hydronium ions to give a hydroxy‐terminated amylose triacetate oligomer (HATA), which was reacted with diisocyanates to produce block copolymers. Prepolymers of HATA and MDI or TDI were reacted with both hydroxy‐terminated polybutadiene and polypropylene glycol to form block terpolymers. Block co‐ and terpolymer formation was demonstrated by intrinsic viscosity increases, gel permeation chromatographic results, and NMR and IR spectroscopy. The products were easily deacetylated by NaOMe in methanol to yield amylose block co‐ and terpolymers. These polymers were readily degraded by α‐amylase. The enzymatic hydrolysis was monitored by intrinsic viscosity measurements. The rate of biodegradation was influenced by the DS of the amylose block and the composition of the block terpolymers.
MacromolecularN‐nitroso‐acylamines as initiators for polyreactions. I. Synthesis of block copolymers from polycondensates and olefinic monomers,
Authors: Craubner Hans
Published: April 2003

The synthesis of block copolymers in three‐step reactions from linear polycondensates (e.g., nylon 6. nylon 6,6, nylon 6,10 and polyurethane) and olefinic monomers (e.g., styrene, acrylic acid and acrylonitrile, methyl methacrylate, vinyl acetate, vinyl chloride, and isoprene) is reported. Macromolecular radicals are formed by the thermal decomposition of partly nitrosated peptide group containing polycondensates at elevated temperatures (60–200°C). These polyradicals initiate the copolymerization of the olefinic monomers. The conversion and reaction rates were generally high (up to 100% within a few hours). Most of the block copolymers prepared were soluble in organic solvents. Some, however, were insoluble or rubberlike. The reaction mechanism involved are analyzed. Applications are discussed.
Promotion by supports of the reactivity of propagating species of Ziegler supported catalytic systems for the polymerization and copolymerization of olefins
Authors: Ivanchev S. S. , Baulin A. A. , Rodionov A. G.
Published: April 2003

Kinetics for the polymerization of ethylene and the copolymerization of ethylene and propylene were studied by using highly effective heterogeneous metal organic catalysts produced by coating different organic and inorganic supports with the components of Ziegler systems. The activity of a supported Ziegler catalyst is characterized by the physical parameters of the support structure and its chemical nature. The active role of magnesium‐containing supports was established for the formation and functioning of the propagating species on their surfaces. This role is expressed not only by an increase in the portion of transition metal included in the propagating species, compared with typical Ziegler catalysts, but also by an increase in the reactivity of the propagating species, change in the nature of the elementary processes for polymerization and copolymerization, including control of copolymerization constants, and modification of the molecular structure of the polymers and copolymers. It was shown that by choice of support it is possible to control the activity of the same catalytic system and characteristics of the structure and properties of the polymers it produces under identical polymerization conditions.
Photochemistry of ketone polymers. XIV. Studies of ethylene copolymers
Authors: Li S. K. L. , Guillet J. E.
Published: April 2003

Studies have been made of the photochemistry of ethylene copolymers with carbon monoxide (CO), methyl vinyl ketone (MVK), and methyl isopropenyl ketone (MIPK) in solid films. Infrared (IR) evidence is presented to show that a variety of unexpected ketone structures is present in these polymers as a result of 1,5‐hydrogen transfer or “back‐biting” during the high‐pressure polymerization reaction. These additional structures complicate the analysis of the quantum yield data. The overall quantum yield for carbonyl disappearance (ϕ‐co) which increases from 0.074 to 0.24 to 0.26 in the series PE‐1% CO, PE‐2% MVK, and PE‐20% MIPK reflects the increasing stability of the alkyl radicals produced from the type I process in the respective ketone structures. It is also shown that ketone groups located in the backbone of the polymer, as in the 1% CO copolymer, have lower quantum yields for photochemical reactions, particularly those that produce free radical intermediates. Studies of the gaseous products from extensive photodegradation under nitrogen show that in all three cases carbon monoxide is the major product (46‐65% of the total). Acetaldehyde and methane, expected from the type I reaction, are major products only for the MVK and MIPK copolymers. Reaction schemes are presented to explain the major products observed.
Quaternary ammonium polyelectrolytes. IV. Addition reaction between poly(4‐vinylpyridinium chloride) and electrophilic vinyl compounds
Authors: Luca Cornelia , Bǎrboiu V. , Petrariu I. , Dima M.
Published: April 2003

It was found that the addition reaction between poly(4‐vinylpyridinium chloride) and electrophilic vinyl compounds, such as acrylic acid, acrylamide, methylacrylate, and acrylonitrile. leads to ammonium quaternary polymers with a transformation degree that depends oil the reactivity of vinyl compounds. The structure of addition compounds was established by using 1H‐NMR IR, and UV spectral methods. NMR‐determined values of transformation degree indicate that the reactivity of vinyl compounds decreases as follows:
Silylation of water glass. I. Solvent extraction and trimethylsilylation of silicic acid
Authors: Kohama Shigemi , Inoue Hiroshi , Yasuda Takahisa
Published: April 2003

Homogeneous trimethylsilylation of silicic acid in nonaqueous media was studied. The silylation process consisted of three steps: acidification of sodium silicate, solvent extraction. and trimethylation of silicic acid. Sodium silicate was first acidified with dilute sulfuric acid to form silicic acid: extraction followed with hydrophilic organic solvents. The Silicic acid obtained was finally allowed to react with trimethylchlorosilane to give trimethylsilylates with molecular weights of 1000–12,000. Optimum conditions for each step have been intensively sought to achieve trimethylsilylates in high yield. The trimethylsilylates exhibited excellent thermal stability and surface properties, such as water repellency and antifoaming properties, comparable to those of conventional polydimethylsiloxanes.
Polymerization of aromatic nuclei. XXIV. Investigation of oligomer and polymer from furan and trichloroacetic acid
Authors: Lamb Bruce S. , Kovacic Peter
Published: April 2003

A reinvestigation of the oligomeric and polymeric products obtained from furan and trichloroacetic acid was carried out to establish their structures. Comparison of spectral data with those of authentic materials indicated that the major oligomeric products are IV and V. The ratio of the products IV:V was 1:52. Comparison of the polymeric material with IV and V suggests that V is the primary component of the larger chains. In addition, microanalytical and molecular weight data were obtained. These findings are in disagreement with the structural designation of Wassermann et al., who proposed the presence of units that possessed aliphatic unsaturation (I), and of Kresta and Livingston, who put forth structure III for the same product. Mechanistic aspects are discussed. A limited study was carried out on insoluble polyfuran which was isolated from the reaction of furan with hydrochloric acid.
Studies on suspension and emulsion. XXXV. Effect of epoxy groups at the surface layer of ethyl acrylate–glycidyl methacrylate copolymer emulsion particles on its crosslinking reactivity
Authors: Okubo Masayoshi , Nakamura Yoshinobu , Matsumoto Tsunetaka
Published: April 2003

The effect of epoxy groups at the surface layer of ethyl acrylate–glycidyl methacrylate copolymer (1) emulsion particles on its crosslinking reactivity has been investigated. For this purpose two series of I emulsions were prepared. In the Y series, of which emulsion particles have epoxy groups at the surface layer, the epoxy content in the polymerization recipe was varied. For preparing the X series, of which emulsion particles have few epoxy groups at the surface layer, the high epoxy content of a given emulsion was reduced by various degrees of cleavage reaction with HCl–CaCl2. In emulsion blend films with amine‐group‐containing copolymer (II) emulsion, where the crosslinking reaction was expected to proceed only at the interfacial layer of I and II emulsion particles, the Y series, compared to the X series at the equal overall epoxy content in particles, showed less swelling and higher gel fraction in dioxane, less swelling in water, and higher tensile strength and modulus. On the other hand, this difference was not observed in the next two crosslinked films in which crosslinking was expected to be homogeneous. First, blends of I and II, which were isolated from the corresponding emulsions discussed above, were cast from dioxane solutions. Second, I emulsions were cast with BF3 ether complex which was expected to penetrate into the particles. It is concluded that the response of I emulsion cleaving the epoxy groups at the surface layer of particles to subsequent interfacial crosslinking is obviously reduced. However, even such an emulsion can be crosslinked to an extent similar to that of an uncleaved emulsion with similar overall epoxy content, if the crosslinking reaction is conducted so as to give an homogeneous effect.
Synthesis and free radical polymerization of N‐substituted citraconimides
Authors: Pyriadi Thanun M. , Mutar Eisa H.
Published: April 2003

N‐phenyl and N‐cyclopropylcitraconimides did not polymerize as free radicals with azobisisobutyronitrile (AIBN) as initiator. N‐allylcitraconimide, however, depending on the temperature and concentrations of the reactions, readily polymerized to produce polymers of different molecular weights. These polymers contained as much as 85% cyclic repeating units when the polymer exhibited an average molecular weight of ca. 4000. The softening point of the polymer was higher than 350°C and the compound was highly soluble in many organic solvents. The allylic CH3group in N‐substituted citraconimides and in their corresonding citraconamic acids could not be brominated with N‐bromosuccinimide.
13C‐NMR spectroscopy of polyamic acids and polyimides
Authors: Seshadri K. S. , Antonoplos P. A. , Heilman W. J.
Published: April 2003

13Carbon chemical shifts are reported for polyimide and polyamic acid prepared from 3‐aminophenylacetylene, 1,3‐bis(3‐aminophenoxy) benzene, and 3,3′,4,4′‐benzophenoetetracarboxylic dicanhydride. The shielding parameters are correlated with the structure. A spectral analysis of model compounds, monomers, and other oligomers is also included. This analysis resulted in an analytical method by 13C‐NMR spectroscopy of determining the amic acid‐imide ratio in the partly cured polyamic acid. The development of the method is discussed.
Transfer reaction and molecular weight distribution in the anionic polymerization of formaldehyde
Authors: Bianchi Gaudenzio , Colombo Paolo , Custro Sergio , Radici Pierino
Published: April 2003

The anhydrous formaldehyde polymerization is examined. The influence of initiator and monomer concentration on the molecular weight and molecular weight distribution are emphasized. A mechanism for the transfer to the monomer is introduced. This mechanism is confirmed by experimental results and leads to the formation of formyl end groups. The influence of various initiators on the transfer reaction also is evaluated.
Coordination polymers. VIII. IR spectroscopic studies on the mechanism of the reaction between polyesters and zinc oxide
Authors: Szilágyi A. , Izvekov V. , Vancsó‐Szmercsányi I.
Published: April 2003

This article was written for the purpose of investigating the mechanisms of reactions between unsaturated polyester resins and base anhydridelike metal oxides (CaO, MgO, ZnO) which cause an increase in viscosity. As a model system ethyl‐hydrogen‐succinate (ESH) and ZnO were reacted in CCl4 and complexes that contained Zn‐hydroxocarboxylate units took an essential part in this reaction. Solubility measurements of the model compounds and infrared (IR) spectra of the reaction products led to the conclusion that further molecular associates were formed from the mixed metal‐hydroxocarboxylate complex by the carbonyl oxygens of ester groups, which resulted in end products of polymeric structure. It is suggested by IR spectroscopical analogies between the model compounds and reaction products of an adipic acid/butanediol‐1,4 polyester with ZnO that similar reactions can account for the polyesters as well.
Polymerization and polymers of silicic acid
Authors: Bechtold Max F. , Mahler Walter , Schunn Robert A.
Published: April 2003

Linear relationships among molecular weight, polymerization time, and gelation for the condensation of any monomer, including those of unknown size and functionality, are developed and applied to data on soluble silicic acids generated from tetraethyl silicate and from sodium silicate. The results suggest the formation of monomers containing ca. 12–15 OSi units with functionality of ca. 2.05 that condense with a rate constant of ca. 10−4 liter/mole sec and an activation energy of 40–70 kJ/mole. One model compatible with these characteristics and the stoichiometry involved is a ladder polymer ca. 3 SiO units wide. Polymer isolation was achieved by replacing residual OH with (CH3)3Sio, as well as by freezing of of aqueous solutions, which yielded fibers under special conditions. Solutions of the uncapped and capped polymers and melts of the latter had low viscosity even for fractions with M̄n ∼100,000. This implies a coiled or globular nature for the polymers, which is supported by their limited propensity for film and fiber formation. Attemps to improve this situation by copolymerization, the use of other capping agents, and by the polymerization of precapped monomers were unsuccessful.
A chemical study of thermally activated chromic titanate on silica ethylene polymerization catalysts
Authors: Pullukat T. J. , Hoff R. E. , Shida M.
Published: April 2003

Thermally activated ethylene polymerization catalysts which contain chromium and titanium on silica differ from those catalysts which contain only chromium on silica. The characteristics of chromium‐titanium catalysts vary with the method of incorporating the titanium and the thermal activation procedure. Titanated catalysts of the kind examined in this article have faster initiation and a higher polymerization rate per unit catalyst weight than corresponding catalysts without titanium. High‐density polyethylene produced by this type of titanium‐chromium catalyst tends to have a higher melt index and a broader molecular weight distribution than polyethylene made with chromium on silica catalysts. Iodometric titration showed that reduction from the initial hexavalent chromium to trivalent occurs when the dry, catalyst starting material is treated with titanium tetraisopropoxide. A study of the reaction between chromium trioxide and titanium tetraisopropoxide in carbon tetrachloride revealed that (1) it is not necessary to have a reaction between surface silanols and titanium tetraisopropoxide for the reduction to occur, and (2) the reaction product has an absorption near 660 nm in the visible range. Comparison of spectra showed that chromium trioxide on silica reduced by isopropyl alcohol has a shifted absorption, i.e., 600 nm. These findings are interpreted to mean that titanium atoms come sufficiently close to chromium atoms to change their electron density in the starting material and remain close neighbors in the activated catalysts. The interpretation is further supported by ESCA data and leads to the proposal that in this case the activated catalysts contain titanium chromate structures.
Alternating copolymerization of 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone with styrene and polymerization behavior with vinyloxy compounds
Authors: Iwatsuki Shouji , Itoh Takahito
Published: April 2003

2,3‐Dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ) was found to copolymerize alternatingly with styrene (St). DDQ–isobutyl vinyl ether and DDQ–2‐chloroethyl vinyl ether systems gave homopolymers of vinyl ethers, while DDQ–phenyl vinyl ether and DDQ–vinyl acetate systems gave oligomers containing both monomer units. In the terpolymerization of DDQ, p‐chloranil (pCA), and St, terpolymers obtained were found to have about 50 mole % of St units regardless of monomer feed ratio and DDQ was incorporated much more rapidly into the terpolymer than pCA. The difference in the reactivity of the acceptor monomers could be attributed to that in their electron‐accepting character.
Free radical grafting of monomers to polydienes. IV. Kinetics and mechanism of methyl methacrylate grafting to polybutadiene
Authors: Cameron G. Gordon , Qureshi M. Younus
Published: April 2003

The radical grafting of methyl methacrylate (MMA) onto polybutadiene (PBD) in benzene solution at 60°C is more efficiently induced by benzoyl peroxide (BP) than by azoisobutyronitrile (AIBN). PBD exerts a pronounced retardation on the polymerization of MMA and the grafting efficiency is governed by the ratio of rubber to monomer in the system. With BP as initiator, a fairly simple kinetic expression, relating grafting efficiency with reactant concentrations, can be derived by making certain approximations, including the neglect of termination grafting. The experimental data are reasonably consistent with this equation and yield acceptable values of several kinetic parameters. With AIBN, termination grafting is more significant. In consequence the relevant kinetic equation can be only qualitatively validated.
The formation of radical cations of styrene and α‐methylstyrene in the irradiation of mixtures of these monomers with TiCl4 and SnCl4 in a semicrystalline heptane matrix
Authors: Pilař Jan , Marek Miroslav , Toman Luděk
Published: April 2003

The formation of paramagnetic intermediates following the irradiation of styrene, α‐methylstyrene, and their mixtures at −90°C in the presence of TiCl4 and SnCl4 in the polycrystalline heptane matrix was investigated. The effect of light on vinyl aromatic monomers leads to the formation of radical cations of styrene and α‐methylstyrene, which subsequently initiate the polymerization. The polymerization of styrene and α‐methylstyrene supposedly proceeds via the cationic mechanism.
High‐conversion polymerization. VII. A definition of the explosive region and the influence of free volume on it
Authors: Dionisio J. M. , O'Driscoll K. F.
Published: April 2003

The easily observed autoacceleration of free radical Polymerization is defined as the explosive region and an arbitrary but quantitative definition of it is made. Using this definition it is shown that the explosive regions of solution polymerizations of methyl methacrylate occur at constant values of the product of polymer concentration times (molecular weight)1/2. This upholds the concept that polymer entanglements control the termination reaction in this region. It is also shown that this region does not, as previously suggested, occur at a constant value of free volume, but that free volume does play a role in determining the rate of termination at a given level of chain entanglements.
Synthesis and metal binding properties of novel sulfur‐containing functional oligomer
Authors: Tsukube Hiroshi , Araki Takeo , Nakamura Akira , Maruyama Kazuhiro
Published: April 2003

The synthesis and metal ion binding properties of a new class of functional oligomers are described. Oligo[1‐(N‐phenylthiocarbamoyl)aziridine] (DP ca. 8) and its analogs are prepared by ring‐opening oligomerization of the corresponding aziridine monomers in good yields. These oligomers contain sulfur groups capable of binding “soft” metal ions, and the selective binding properties of the novel oligomer for Cu(II) and Hg(II) ions are investigated by liquid‐solid adsorption and liquid‐liquid extraction experiments.
Synthesis and radiation degradation of vinyl polymers with fluorine: Search for improved lithographic resists
Authors: Pittman Charles U. , Chen Chi‐Yu , Ueda Mitsuru , Helbert J. N. , Kwiatkowski J. H.
Published: April 2003

Homopolymers of methyl α‐fluoroacrylate (MFA), trifluoroethyl methacrylate (TFEM), and hexafluoroisopropyl methacrylate (HFIM) were prepared, as were their methyl methacrylate (MMA) copolymers. Copolymers of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE) with MMA were also prepared. The radiation susceptibilities of these polymers were measured by the60Co γ‐irradiation method, in which molecular weights were measured by membrane osmometry and gel permeation chromatography (GPC). All the copolymers degraded by predominant chain scission except poly(methyl α‐fluoroacrylate), (PMFA), which crosslinks even at low doses (ca. 1 Mrad). TheGs‐GxandGsvalues of the chain scissioning polymers and copolymers are higher than those of poly(methyl methacrylate) PMMA reference. The high susceptibility of PMFA homopolymer to crosslinking is in contrast to that of poly(methyl α‐chloroacrylate), as we reported earlier. This effect is interpreted as resulting from extensive hydrogen fluoride and polyenlyl radical formation, which leads to facile crosslinking. However, incorporation of the MFA monomer unit causes the (22/78) MFA/MMA copolymer to degrade with a larger value ofGsthat PMMA. Apparently a second‐order process leads to crosslinking in PMFA and this is retarded in the copolymer. In the hehomopolymers of HFIM and TFEM and in the HFIM‐MMA and TFEM‐MMA copolymers the HFIM and TFEM components facilitate degradation with negligible crosslinking. The increased degradation susceptibility of VDF and CTFE copolymers with MMA over that of PMMA is attributed to processes at the VDF or CTFE components present in smaller concentrations (3‐5 mole %) than the threshold levels (25‐50% necessary for significant crosslinking).
The synthesis of sulfonated polymers by free radical copolymerization. Poly(butadiene‐co‐sodium styrene sulfonate)
Authors: Weiss R. A. , Lundberg R. D. , Werner A.
Published: April 2003

The copolymerization of butadiene with sodium styrene sulfonate was studied and the copolymer products characterized. In general these copolymers contain 0.5–4 mole% of sulfonated monomer. The effects of the following reaction variables are described: emulsifier type and concentration, monomers feed ratio, chain transfer agent concentration, and reaction conversion. The products were heterogeneous with regard to composition, molecular weight, and solubility behavior. Copolymers prepared under certain conditions exhibited strong intermolecular interactions derived from associations of the ionic species as observed in other ionomers.
Spectrophotometric studies of some CT complexes of 2,4,7‐trinitrofluorenone with poly(vinyl halogenocarbazole)
Authors: Pielichowski Jan , Obrzut Jan
Published: April 2003

The modified UV‐Vis spectrophotometry has been applied to study of spectral and thermodynamic properties of charge‐transfer complexes of poly‐N ‐vinylhalogenocarbazole with 2,4,7‐trinitrofluorenone. The application of numerical calculation allows for the separation of the absorption bands which result only from donor‐acceptor interaction. The equilibrium constants, entropies, and enthalpies of complexing reaction studied in a wide range point out the beneficial influence of introduced chlorine, bromine, and iodine substituents in position 3 and 6 of carbazole ring over the complexing properties of poly‐N‐vinylhalogenocarbazole and properties of its complexes with 2,4,7‐trinitrofluorenone.
Hydrolysis of Egyptian medicated cotton by HCL–FeCl3 reagent
Authors: Shinouda H. G. , Moteleb M. M. Abdel
Published: April 2003

The initial rate of hydrolysis of Egyptian medicated cotton with HCl or HCL‐FeCl3 as reagent, as well as the total carbonyl content of the hydrolysis products, were determined. The results obtained showed that although cellulose fibers are hydrolyzed more rapidly in an acid‐FeCl3 medium than in acid alone, the fibers resisted oxidation in a Fe3+ solution. Therefore the observed rate increase in Fe3+ solution cannot be explained on the basis of increased oxidation of hydroxyl groups. Consequently it has been suggested that the increase in the rate of hydrolysis is due to complexing between Fe3+ and the carbonium/oxonium ion or the leaving group. A comparison between the fine structure of the hydrolysis products of cotton cellulose by the use of HCl and HCl‐FeCl3 reagent is also given.
Kinetics of hydrolysis of side groups in polyphenylmethacrylate
Authors: Połowiński S. , Bortnowska‐Bareła B.
Published: April 2003

Ultraviolet (UV) spectrophotometry was used to study the kinetics of basic hydrolysis of side groups in polyphenylmethacrylate in DMSO/H2O at various temperatures. Keller's mathematical analysis was applied to the description of the kinetics. Three rate constants which describe the reaction of ester groups with 0, 1, and 2 reacted neighboring groups, respectively, were determined. Activation energies for the hydrolysis reaction of the respective triads were calculated. The data confirmed the applicability of Keller's model to the computation of rate constants for the reaction of the respective triads in the polymer chain.
Organosilane polymers. III. Block copolymers
Authors: Wesson J. P. , Williams T. C.
Published: April 2003

Chloro‐ and lithio‐terminated diorganosilylene oligomers were coupled to form block copolymers that were soluble in common solvents and deposited coherent films from solution. Copolymer UV (ultraviolet) spectra showed a red shift in absorption maxima attributed to increased silicon chain length and phenyl‐silicon spine interactions.
The adsorption of fluoride containing polyelectrolytes on hydroxyapatite
Authors: Bartels T. , Arends J.
Published: April 2003

In this study the preparation of three polyvinylpyridinium fluorides with different hexadecyl group contents is described. Their adsorption on hydroxyapatite (the main constituent of dental enamel) was studied as a function of time and concentration. It was found that increasing hexadecyl group content resulted in lower amounts of adsorbed polymer. The adsorption of the polyelectrolytes is accompanied with the uptake of fluoride by hydroxyapatite at a higher rate and with greater amounts. Phosphate ions present in aqueous suspensions of hydroxyapatite were responsible for this phenomenon. Desorption experiments showed that the adsorption of these macromolecules was irreversible in water. Excess calcium resulted to some extent in desorption.
X‐Ray and thermal studies of nylon 5,7
Authors: Lin Ju‐Chui , Litt M. H. , Froyer Gerard
Published: April 2003

The unit cell and probable space group of Nylon 5,7 has been determined. The unit cell is monoclinic with the dimensions a = 0.483 nm, b = 0.935 nm, c = 1.662 nm, and γ = 58.9°. The space group is probably Pb which is noncentrosymmetric. Rolled, annealed samples show three‐dimensional orientation. The melting point peak of a rapidly cooled sample is about 213°C when it is heated at 20°C/min. Slow cooling, ≤°1°C/min generates a higher melting species, Tm = 228°C. Crystallinities are in the normal nylon range, up to 50% for a slow cooled sample.
Structure of chlorinated poly(vinyl chloride). X. Conclusions on the chlorination mechanism
Authors: Lukáš R. , Světlý J. , Kolínský M.
Published: April 2003

The chlorination of poly(vinyl chloride) (PVC) was investigated by using deuterated polymeric models of PVC, viz., α‐deuterated PVC (α‐d‐PVC) and β,β‐dideuterated PVC (β,β‐d2‐PVC). The chlorinated samples of PVC, α‐d‐PVC, and β,β‐d2‐PVC were examined by combining infrared (IR), 1H‐NMR, 13C‐NMR, and mass spectroscopy. The results obtained were used in a study of the reaction mechanism of PVC chlorination. The selectivity of chlorination and the extent of the substitution and elimination‐addition mechanism of chlorination are discussed with respect to the degree of chlorination and chlorination conditions.
Synthesis and optical properties of asymmetric polyamides derived from cyclopropyl diacids and diamines
Authors: Overberger C. G. , Nishiyama T.
Published: April 2003

The polyamides were prepared from the dicarbonyl chloride of (+) (S)‐ or (−)(R)‐trans‐1,2‐cyclopropanedicarboxylic acid (C3A) with either the dihydrochloride salt of (+)(S)‐ or (−)(R)‐trans‐1,2‐diaminocyclopropane (C3B) or the dihydrobromide salt of (+)(S)‐ or (−)(R)‐trans‐1,2‐bis(methylamino)cyclopropane (C3MB) by interfacial polycondensation. Several diamide model compounds composed of these monomers were also synthesized. The polyamides [poly(C3A‐C3B)] derived from C3A and C3B have the capability of hydrogen bonding, while the polyamides [poly‐(C3A‐C3MB)] derived from C3A and C3MB do not. Poly(C3A‐C3B) were insoluble in common organic solvents except strong acids. Poly(C3A‐C3MB) were soluble in common organic solvents. Poly(C3A‐C3B) had melting points higher than 300°C. Poly(C3A‐C3MB) melted at 180–235°C. The ORD and CD study has shown that poly(+)C3A(+)C3B in methane sulfonic acid (MSA), 2,2,2‐trifluoroethanol (TFE) (5 v % MSA), and tetramethylenesulfone (TMS) (5 v % MSA) exhibits a very strong Cotton effect or CD peak at 212–218 mμ, attributable to a component of the split π–π* transition of the amide chromophores. Poly(+)C3A(+)C3MB in MSA and TFE (5 v % MSA) shows a strong Cotton effect or CD peak at 217–223 mμ and an intermediate Cotton effect or CD trough at 202–204 mμ as well as an intermediate Cotton effect or CD trough at 220–222 mμ and an intermediate Cotton effect or CD peak at 202–204 mμ in TFE and TMS. These peaks and troughs may be assigned to splitting of the π–π* transition. The CD spectra of poly(+)C3A(+)C3MB in nonacidic media are quite different from those in acidic media: they are almost mirror images. The CD spectra in this transition induced by MSA suggests that a transition from a compact helix to another more extended helix with opposite handedness occurs similar to poly‐L‐proline I ⇄ II. This transition may be explained by electrostatic repulsion between protonated amide groups. Viscosity data have shown that the conformation is changed to a highly extended from in acidic media. The polyamides and diamides derived from enantiomers exhibit mirror image spectra. Poly(+)C3A(+)C3B and poly(+)C3A(+)C3MB in every solvent studied exhibit a marked enhancement of the rotatory strength of ORD and CD with respect to the corresponding diamide models.
Solid‐state polymerization of acrylamide and its derivatives complexed with lewis acids. I. Synthesis of complexes
Authors: Żurakowska‐Orszagh J. , Mirowski K. , Kaim A.
Published: April 2003

Complexes of acrylamide, methacrylamide, and their homologs with zinc, cadmium, and mercury halides were prepared by various methods. Molecular compositions, the nature of the coordination, and some physicochemical properties (melting points and initial decomposition temperatures) were determined. The effect of the chemical structure of particular monomers, metal ion, and halide on the possibility of complex formation and on the properties of the complex compounds were observed. Most of these complexes have not been described in the scientific literature.
Functional polymers. IX. Polycarbonates and alternating copolycarbonates of bithionol
Authors: Deits W. , Vogl O.
Published: April 2003

A number of polycarbonates, alternating copolycarbonates, polyurethanes, and terpolymers with carbonate and/or urethane linkages utilizing bithionol [2,2'‐thiobis(4,6‐dichlorophenol)] as the bisphenol component of the polymers have been synthesized. Bithionol has been demonstrated to give a polycarbonate with an inherent viscosity of about 0.5 dl/g. The polycarbonate is amorphous and has a glass transition temperatureTgof about 105°C. Alternating copolycarbonates and polyurethanes involving bithionol are most conveniently prepared from the bischloroformate of bithionol. An alternating copolycarbonate of bithionol and poly(ethylene glycol) of molecular weight 4000 has an inherent viscosity of more than 1.2 dl/g, is water soluble, and has characteristics similar to those of low‐density polyethylene. Alternating copolymers of bithionol and other hindered bisphenols have been synthesized and can be visualized as having an antibacterial agent and an antioxidant in the same polymer chain. These polymers have the potential to act as very useful materials for the controlled release of drugs while only forming carbon dioxide as the additional small molecule fragment on hydrolysis.
Crosslinking mechanism of an anhydride‐cured epoxy resin as studied by fourier transform infrared spectroscopy
Authors: Antoon M. K. , Koenig J. L.
Published: April 2003

Fourier transform infrared spectra, including absorbance difference spectra, are presented which indicate that the accepted mechanism of tertiary amine‐catalyzed copolymerization of cyclic anhydrides and epoxy resins requires modification. Results also show that the kinetic model is complicated by the lack of steady‐state concentrations of the active species. The effect of silica filler and silane coupling agents on the reaction are also examined.
Spontaneous copolymerization of 1,3‐cycloheptadiene with acrylonitrile in the presence of zinc chloride
Authors: Nagai Katsutoshi , Machida Shuji
Published: April 2003

The reaction of 1,3‐cycloheptadiene (1,3‐CHpD) with acrylonitrile (AN) in the presence of ZnCl2 leads spontaneously to the simultaneous formation of an alternating copolymer and a small amount of cycloadduct. The copolymer has a predominantly cis‐1,4‐structure. The formation of the charge—transfer complex between 1,3‐CHpD and (AN)c (AN coordinated to ZnCl2) in AN was detected by ultraviolet (UV) spectroscopy. The activation energies for the cycloaddition and for the copolymerization under the conditions used were determined to be 17.6 (in the presence of 1,1‐diphenyl‐2‐picrylhydrazyl) and 16.3 kcal/mole, respectively. The rate of copolymerization in AN was found to depend on the 1.5th power of the concentrations of (AN)c and of 1,3‐CHpD. Oxygen and UV irradiation causes an acceleration of the copolymerization only. On the basis of these results the mechanism of the spontaneous copolymerization is discussed and its relation to the cycloaddition in systems of 1,3‐cyclodienes and AN in the presence of ZnCl2 is mentioned.
Synthesis of polysulfone‐sulfides by polyadditions of dithiols to divinyl sulfones
Authors: Imai Yoshio , Asamidori Yasunobu , Inoue Tomihiro , Ueda Mitsuru
Published: April 2003

Polyadditions of 1,6‐hexanedithiol and 1,10‐decanedithiol to divinyl sulfone (DVS) in hexamethylphosphoramide in the presence of triethylamine or potassium fluoride afforded polysulfone‐sulfides (IIIa and IIIb) with inherent viscosities as high as 0.8 dl/g. Polymerizations of other dithiols with DVS and distyryl sulfone (DSS) were also carried out, however, only low‐molecular‐weight polymers were obtained. A series of polymers derived from DVS were highly crystalline and soluble in hot dimethylacetamide and hot m‐cresol, whereas a polymer from DSS was quite amorphous and showed excellent solubility in a wide range of solvents. Polymers IIIa and IIIb had melting temperature below 150°C.
Reactions of 2‐methoxy‐ and 2‐substituted 4,6‐diamino‐s‐triazines with formaldehyde: Kinetics and adaptability of the rate constants to hammett and taft equations
Authors: Tashiro Tatsuo , Oiwa Masayoshi
Published: April 2003

The reactions of 2‐methoxy‐4,6‐diamino‐s‐triazine (MT) with formaldehyde (F) were studied in the pH region 2–11. In an alkaline medium the rate constants were proportional to the concentration of hydroxyl ion in the pH range 9.90–10.95; in a neutral medium they were approximately constant and in an acidic medium they achieved the maximum value at pH 3.50 (half‐neutralization point of MT). The hydroxymethylation mechanism of MT was similar to that of melamine. The hydroxymethylation rate constants of various 2‐substituted 4,6‐diamino‐s‐triazines(XT) were determined at pH 7.00, 10.26, and 4.00. Linear relationship was observed between the rate constants at pH 7.00 and pKb of XT, σm, and σ* but not at pH 10.26 and 4.00.
Peculiarities of polyacrylamide analysis by aqueous GPC
Authors: Klein Joachim , Westerkamp Aloys
Published: April 2003

Various commercially available stationary phases of gel permeation chromatography (GPC) were tested to determine their effectiveness in aqueous exclusion chromatography. It was found that controlled pore glass (GPG) is the most suitable material for the separation of polyacrylamides and poly(acry1amide‐co‐sodium acrylate), dextrans, and poly(sodium styrene–sulfonates) in 0.1M aqueous Na2S04 solutions of ionic strength 0.3. A calibration curve was established by using broad molecular weight distribution polyacrylamide standards in a trial and error procedure. To avoid artificial oscillations on the evaluated distribution curves a cubic B‐spline representation of the calibration curve was used instead of the conventional polynomials. By applying this system the solution instability of polyacrylamides was observed by GPC and is discussed because of its general importance to the applicability of indirect molecular weight determination methods for polyacrylamides. The effectiveness of aqueous GPC was demonstrated in an evaluation of thermal degradation measurements of polyacrylamides. Finally, the feasibility of universal calibration of aqueous GPC by means of poly(sodium styrene–sulfonates) was investigated. It is apparent that in spite of some problems concerning adsorption of the polymer universal calibration is a successful tool for calibrating aqueous GPC.
Condensation polymerization of pyromellitic dianhydride with aromatic diamine in aprotic solvent: A reaction mechanism
Authors: Kumar Devendra
Published: April 2003

Based on nuclear magnetic resonance (NMR) studies, a probable reaction mechanism was proposed for the condensation polymerization of pyromellitic dianhydride with aromatic diamines in aprotic solvent, N,N‐dimethylacetamide (DMAc), to yield aromatic polyimides. The mechanism shows the essential role played by the solvent during polymerization reaction and in imidization. It explains the formation of polyamic acid and that of its high molecular weight buildup under the conditions in which solid dianhydride was added to the solution of diamine in DMAc. A prepolymer complex formation was observed, along with the main polyamic acid, when solid diamine was added to the solution of dianhydride in DMAc. The structure of the prepolymer was derived on the basis of NMR and its formation explained in the mechanism. The nature of the prepolymer was such that on treatment with anhydride it goes to polyamic acid.
Styrene emulsion polymerization: Particle‐size distributions
Authors: Lichti Gottfried , Hawkett Brian S. , Gilbert Robert G. , Napper Donald H. , Sangster David F.
Published: April 2003

Data are presented on the time evolution of particle‐size distributions (PSDs) in seeded and ab initio styrene emulsion polymerization systems. Initiation was by chemical reagent (potassium persulfate) or γ‐radiation. The unswollen PSDs at various times during interval II of the polymerization were obtained by direct measurement of calibrated electron micrographs. Experimental results were fitted with the equations that describe the time evolution of an initial PSD. Analytic solutions to these equations that allow for entry, exit, and propagation of free radicals were obtained. The values of the rate coefficients for these processes used to fit the experimental data were in excellent agreement with those obtained from dilatometric kinetics experiments.
Theory of emulsion copolymerization kinetics
Authors: Ballard Mathew J. , Napper Donald H. , Gilbert Robert G.
Published: April 2003

An extended Smith–Ewart theory is presented which provides a description for kinetic properties of an emulsion copolymerization system during intevals II and III (i.e., after completion of latex particle formation). Differential equations are derived specifying the time evolution of the copolymer compositions and of the copolymer sequence distributions in terms of the rate coefficients for free radical entry, exit, homopropagation, cross propagation, cross transfer, and cross termination. Solutions to these equations show how an emulsion copolymer system may be designed to give formed polymer with desired composition and/or sequence distribution functions.
Polymerization of aromatic nuclei. XXVII. ESR studies on polymers and oligomers from reaction of benzenoid and naphthalene monomers with lewis acid catalyst–oxidant systems
Authors: Hsing Chih‐Fen , Jones Martin B. , Kovacic Peter
Published: April 2003

Chlorobenzene and toluene were polymerized with aluminum chloride–cupric chloride to produce materials that consist mainly of poly(o‐phenylene) structures. These species exhibited radical cation concentrations comparable to that of poly(p‐phenylene). Polymerization of naphthalene and 1‐chloronaphthalene with aluminum chloride–cupric chloride or ferric chloride–water also resulted in products with high radical cation concentrations. Polynuclear structures may be responsible for the paramagnetic character; alternatively, p‐quinoidal moieties may be present in naphthalenes. The depth of color in the samples is directly related to the concentration of radical cations.
Kinetics and mechanism of the polymerization of styrene–acrylonitrile in the presence of polybutadiene
Authors: Hayes Robert A. , Futamura S.
Published: April 2003

The mechanism of free radical grafting of styrene–acrylonitrile with polybutadiene was studied. By assuming a copolymerization mechanism an equation that related the amount of homopolymer formed and its molecular weight to a reactivity ratio and the charged ratio of monomer to polydiene was derived. Polymerizations that contained a variety of ratios of monomer to polybutadiene, two different catalysts, and variable amounts of a mercaptan modifier were studied. The weight fraction of homopolymer and its molecular weight were determined by high‐speed GPC. The results were analyzed by the new equation and all showed a constant value of the reactivity ratio, which strongly suggests that the mechanism of the grafting reaction is copolymerization. Evidence that suggests that none of the grafting is a result of a hydrogen abstraction mechanism is also presented.
Radiation‐induced cationic dimerization and polymerization of styrene in methylene chloride solution. I
Authors: Gotoh Tetsuya , Yamamoto Masahide , Nishijima Yasunori
Published: April 2003

Radiation‐induced polymerization of styrene in methylene chloride solution or bulk system was investigated to explain the initiation mechanism of cationic polymerization. It was found that high energy radiation produces polymers and dimers. The main dimers were identified as trans‐1,2‐diphenylcyclobutane, 1‐phenyl‐1,2,3,4‐tetrahydronaphthalene, and 1‐phenyl‐1,2‐dihydronaphthalene. The dimerization procedure was cationic in a pattern similar to that obtained in photoexcited EDA systems. It was shown clearly by product analysis that the bonded dimer cation radical intermediate, which was assumed to be an initiating species of the cationic polymerization, was produced in a radiation‐induced polymerization system. The observed polymerization was composed of two types; cationic and radical, the latter initiated by radical species.