bluuebunny/crossref_metadata_2025 huggingface dataset:
Aromatic polyamides. V. A general synthesis of polyamides from aromatic diacids and aromatic diamines in sulfur trioxide
Authors: Silver Frank M.
Published: April 2003

The reaction of terephthalic acid (TA) and para‐phenylenediamine sulfate (PPD‐S) in sulfur trioxide to form anisotropic, sulfonated poly(p‐phenyleneterephthalamide) (SPT) dopes was reported in Part IV of this series. We have found now that the TA/PPD‐S polymerization is only one example of a more general polyamide condensation reaction of aromatic diamines and aromatic diacids. Sulfonation of the aromatic diamine ring during TA/PPD‐S polymerization in SO3 was a major side reaction. Sulfonation was reduced or eliminated by aromatic diamine ring substitution with unreactive substituents, particularly chlorine and fluorine. Polymerization of 2,3,5,6‐tetrafluoro‐phenylenediamine with TA in SO3 at 80°C (18% concentration) produced unsulfonated poly(tetrafluoro‐para‐phenyleneterephthalamide) (F‐PPT) with an inherent viscosity of 2.2. The halogenated, all‐para aromatic polymers formed highly anisotropic (liquid crystalline) dopes. Monomers that formed polymers in which the chain bond angle deviated from 180° (e.g., meta‐oriented monomers) yielded only isotropic polymer solutions. The mechanism and rate of diamine–diacid reactivity in SO3 was related to diamine basicity. Whereas the less basic aromatic diamines (as sulfates) polymerized with aromatic diacids in SO3, the more basic aliphatic diamines (as sulfates) would not. Aliphatic, cycloaliphatic, and aryl‐aliphatic diacids were degraded by or reacted with the solvent (SO3). Thermogravimetric analyses of F‐PPT and monosulfonated poly(chloro‐para‐phenyleneterephthalamide) at 20°C/min showed weight loss only above 380 and 370°C, respectively.
1H‐NMR study of polyisoprenes
Authors: Sato Hisaya , Tanaka Yasuyuki
Published: April 2003

1H‐NMR spectra of polyisoprene were assigned using polymers of isoprene‐1,1,4,4‐d4, isoprene‐1,1,5,5,5‐d5, and isoprene‐4,4‐d2 polymerized with various catalysts. The methylene‐proton signal at 2.1 ppm in cis‐1,4 ‐ and trans‐1,4‐polyisoprenes was divided into H4‐ and H1‐proton signals; H4 resonated at 2.21 ppm in both cis‐1,4 and trans‐1,4 units whereas H1 resonated at 2.05, 2.21, and 2.15 ppm. Splitting due to the dyad sequences of 1,4 and 3,4 units was apparent. The methine‐proton (H3) in a 3,4 unit showed a broad peak centered around 1.5 ppm in C6D6. The overlapping of this signal with the methyl‐proton signals at 1.73 and 1.63 ppm resulted in some uncertainty in the determination of the microstructure of polyisoprene which contained a considerable amount of 3,4 unit.
Polysiloxane dizwitterionomers. II. Morphology
Authors: Graiver D. , Litt M. , Baer E.
Published: April 2003

Small‐angle x‐ray and electron microscopy were used to study the morphology of polysiloxane dizwitterionomers. As in other polyelectrolytes, the zwitterions aggregate into ionic domains. In this case the domains are lamellar in nature and are in parallel arrays. The distance between these ionic regions is inversely proportional to the dizwitterion concentration in the polymer; their thickness is independent of the ionic concentration and is about 7 Å.
Polysiloxane dizwitterionomers. IV. Mechanical and dielectric relaxations
Authors: Graiver D. , Litt M. , Baer E.
Published: April 2003

The relaxation behavior of a series of polysiloxane dizwitterionomers has been studied by using dynamic mechanical and dielectric spectroscopy. The temperature range was 100–375 K and the frequency was ca. 1 Hz in the mechanical measurements and 50 Hz–50 kHz in the dielectric measurements. Three relaxation regions, labeled αs, β, αz in order of increasing temperature, were observed. The βs relaxation was assigned to the nonionic portion of the siloxane chain and correlated with the glass transition of polydimethylsiloxane. The β and αz processes are ionic‐related relaxations; β probably originated from the motion of a chain segment carrying a dizwitterion, and αz, from the collapse of the organization in the ionic domains. Absorbed water exerts a profound influence on relaxation behavior–primarily on αz ionic relaxation and the relative rigidity of the samples. The water molecules solvate the ions and thus shift the αz relaxation to lower temperatures.

Some aspects of the effect of thermal history on the microphase separation into domains have also been investigated. The results indicate that the organization of the zwitterions in the ionic domains is improved at slow cooling rates.
Polysiloxane dizwitterionomers. V. Microstructure and mechanical properties
Authors: Graiver D. , Litt M. , Baer E.
Published: April 2003

The mechanical properties of the polysiloxane dizwitterionomers change dramatically with a tenfold increase in the ionic content, from soft, weak materials to hard, strong rubbers. The effects of the zwitterion concentration and the unique morphology on the elastic modulus can be explained by treating this series of ionomers as composites. Macro‐ and microfibrillation were observed in 1‐ and 2‐mole % zwitterion samples before the ultimate break and are probably due to reorientation of the ionic domains parallel to the stress direction so that cracks could propagate in the direction of the stress.
Solid‐state synthesis of a ladder polymer
Authors: Yee K. C.
Published: April 2003

Solid‐state synthesis of a cyclically bound ladder polymer from a cyclic tetradiyne (cyclodotriaconta‐1,3,9,11,17,19,25,27‐octayne) is described. Irradiation of the colorless, needlelike monomer crystals with interstitially incorporated chloroform with 50 Mrad of 60Co γ‐ray radiation results in red‐brown polymer fibers in nearly quantitative yield. Infrared, Raman, and x‐ray diffraction analyses of the polymer are consistent with polymerization by a 1,4‐addition reaction at each diacetylene linkage to produce four fully conjugated chains joined together in pairs by a total of four (CH2)4 interchain linkages per 4.8‐Å polymer repeat unit. Conformationally, it appears that the cyclic tetradiyne monomer polymerizes via a chair form. The results of the mechanical and thermal analyses indicate the presence of unreacted diacetylene functionality in the ladder polymer crystals.
Monomer‐isomerization polymerization. XX. Monomer‐isomerization polymerization of 2‐, 3‐, and 4‐octenes with Ziegler–Natta catalyst
Authors: Endo Kiyoshi , Nagahama Hiroharu , Otsu Takayuki
Published: April 2003

A study of the monomer isomerization polymerization of 2‐, 3‐, and 4‐octenes has been made with TiCl3–(C2H5)3Al catalyst at 80°C in comparison with the ordinary polymerization of 1‐octene. It was found that all these octenes underwent monomer‐isomerization polymerization to give high‐molecular‐weight homopolymer consisting exclusively of the 1‐octene unit. The addition of an isomerization catalyst such as nickel acetylacetonate accelerated this polymerization. The rates of polymerization were found to decrease in the following order: 1‐octene > 2‐octene > 3‐octene > 4‐octene. These results indicate that the isomerization proceeded by a stepwise double‐bond migration. It was also found that the monomer‐isomerization copolymerization of 2‐octene and 2‐butene occurred under similar conditions and produced copolymers of both 1‐olefin units.
Preparation of polymers containing 1,4‐dihydronicotinamide structure and their use in the reduction of vicinal tricarbonyl compounds
Authors: Endo Takeshi , Okawara Makoto
Published: April 2003

The definite polymers containing 1,4‐dihydronicotinamide structure were prepared by reduction with sodium dithionite‐potassium carbonate in the presence of benzyltriethylammonium chloride. The reduction of vicinal tricarbonyl compounds such as alloxan and ninhydrin by polymers having the 1,4‐dihydronicotinamide moiety was performed to isolate the polymers' trapped radical anion of alloxan or ninhydrin.
Anionic polymerization and copolymerization of S‐methyl thiomethacrylate
Authors: Okamoto Yoshio , Toki Motoyuki , Yuki Heimei
Published: April 2003

S‐Methyl thiomethacrylate (methyl thiolmethacrylate, MTMA) was polymerized with a variety of anionic initiators such as n‐BuLi, octylpotassium, PhMgBr, and Et2AlNPh2 in toluene and THF. Stereoregularity of the polymer (PMTMA) was determined from the 1H‐NMR spectrum of poly(methyl methacrylate), which had been derived from PMTMA, because the α‐methyl resonance in the 1H‐NMR spectrum of PMTMA was not satisfactorily solved owing to the overlap of pentad signals. The 13C‐NMR spectrum of PMTMA also showed the splitting due to pentad sequences. Stereoregularity of PMTMA was always low compared with that of poly(methyl methacrylate), which was prepared under the same reaction conditions. MTMA was much more reactive than methyl methacrylate and methacrylonitrile in the copolymerization with n‐BuLi in toluene and in THF at −78°C. The lower stereoregulation of the polymerization of MTMA and the higher reactivity of MTMA were mainly ascribed to the higher resonance effect of MTMA.
Polyaromatic ether‐ketone‐sulfones containing 1,3‐butadiene units
Authors: Sankaran V. , Marvel C. S.
Published: April 2003

The acid chloride of 1,4‐bis‐p‐carboxyphenyl‐1,3‐butadiene (XI) and isophthaloyl chloride (XIV) were polymerized with 4,4′‐diphenoxy‐diphenyl sulfone (XII) and diphenyl ether (XIII) in a Friedel‐Crafts type of polymerization. The polymers obtained, which contained 5–20 mole % of butadiene units, were insoluble in all solvents. The polyamides prepared from the acid chloride of 1,4‐bis‐p‐carboxyphenyl‐1,3‐butadiene (XI) and aromatic diamines were also insoluble in all solvents.
Radiation‐induced terpolymerization of tetrafluoroethylene with propylene and isobutylene in bulk
Authors: Kostov G. K. , Matsuda O. , Watanabe T. , Machi S. , Tabata Y.
Published: April 2003

Terpolymerization of tetrafluoroethylene (TFE) with propylene (P) and isobutylene (iB) by γ radiation at temperatures of −78 to 40°C, a dose rate of 5 × 104−5 × 105 rad/hr, and an iB/P molar ratio of 40/10−5/45 in the monomer mixture was carried out. Alternating copolymers of TFE and α‐olefins, that is, P and iB, were formed at various monomer compositions. No crystalline structure was observed in the terpolymer obtained below an iB/P molar ratio of 15/35 in the monomer mixture but a partly crystalline order increased with the amounts of iB in terpolymer. The crystal lattice of the TFE–iB copolymer was affected by the introduction of P. The dose rate dependencies of the polymerization rate and inherent viscosity were 0.8 and −0.2, respectively. The activation energy of polymerization was 2.4 kcal/mole, and the relative reactivity ratio of iB and P for a TFE radical chain end was estimated as 4.50 by the treatment of the free propagating mechanism.
A two‐stage stress‐dependent creep mechanism in plasticized poly(vinyl chloride) (PVC)
Authors: Kamel R. , Najeeb E. , Badr Y. A. , Semary M. A. , Hadhoud M. A.
Published: April 2003

The temperature dependence of tensile creep of plasticized poly(vinyl chloride) (PVC) was tested under differently applied stresses. The steady creep rate showed two distinct stages, depending on stress and temperature. At relatively low stresses the activation energy (0.2 eV) which characterized the steady creep mechanism of stage I, showed no stress sensitivity. Under high stresses (stage II) the energy‐activating steady creep was of the order of 1 eV and increased excessively with increasing stress. The model for plastic flow of PVC suggested here assigns the extension of the twisted zigzag molecular conformation to creep in stage I. In stage II creep is controlled by the reorientation of molecular segments by rotation from initially random orientations in a direction parallel to the principal tensile axis. γ Irradiation of the samples before testing increased the steady creep rate and reduced the creep lifetime. This was attributed to chain scission and greater mobility of the molecular segments.
Application of environmental relaxation model to the transport behavior of glass‐forming melts
Authors: Islam N. , Kochi Ismail
Published: April 2003

The environmental relaxation model was applied successfully to explain the temperature dependence of viscosity, conductance, and the Walden product of molten Ca(NO3)2.3.91H2O + NiCl2 system in the non‐Arrhenius region. This model was applied to pure melts, binary molten salt systems with ideal solutions marked by the absence of complex ions, and systems in which octahedral or tetrahedral complexes are formed. The values of the glass transition temperature obtained from the free volume and environmental relaxation models are in good agreement. The values of apparent activation energies for viscous and conductance flows derived from these two models are also comparable.
Crosslinking and scission yields for polystyrene subjected to γ irradiation in vacuo
Authors: O'donnell J. H. , Rahman N. P. , Smith C. A. , Winzor D. J.
Published: April 2003

Measurements of molecular weight averages and distributions have been made on three samples of narrow molecular size distribution polystyrene with molecular weights from 100, 000 to 400, 000 subjected to 60Co γ irradiation in vacuo for various doses within the pregel region+ G(X), the radiation chemical yield of crosslinking, has been determined as 0.043 ± 0.002 and G(S)/G(X), the ratio of scission to crosslinking, as 0.02; no effect of molecular weight was observed. By comparison with previous experimental results for polystyrene irradiated in air it has been established unequivocally that an oxygen environment leads to enhanced scission at the expense of crosslinking. Literature values of G(X) and G(S)/G(X) are reviewed in the light of these results and explanations are offered to account for major discrepancies.
Polymerization of allyl esters of unsaturated acids. IV. Cyclopolymerization of diallyl maleate
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

Radical polymerization of diallyl maleate is kinetically discussed in terms of cyclopolymerization using 2,2′‐azobisisobutyronitrile as an initiator and benzene as a solvent at 60°C. Thus, the kinetic equations involving bicyclo‐intramolecular cyclization are derived by assuming steady‐state conditions for the different types of radicals, and various parameters involved in the equations are then estimated approximately from an extension of the corresponding model experimental results. The validity of these treatments is confirmed from the comparison with the experimental data including the relationships between the contents of the unreacted allylic and maleic double bonds and the monomer concentrations. In addition, the sequence distribution of the structural units of the polymer produced is discussed; for example, the content of the bicyclic structural units is estimated to be 47.2% at a 10% dilution of the pure monomer.
Kinetics of polymerization initiated by Mn3+–substrate redox system. I
Authors: Elayaperumal P. , Balakrishnan T. , Santappa M. , Lenz R. W.
Published: April 2003

The kinetics and mechanism of polymerization of acrylamide (AM) initiated by manganese (III) acetate (MTA)–diglycolic acid (DGA) redox system in aqueous sulfuric acid were studied in the temperature range 20‐35°C. The overall rates of polymerization and the disappearance of Mn3+ and the kinetic chain lengths of polyacrylamide were determined. The polymerization reaction is initiated by the organic free radical arising from the Mn3+–diglycolic acid reaction and the termination is by the metal ions. The rate of polymerization of acrylamide was found to be proportional to the first power of monomer and diglycolic acid and independent of manganese(III) acetate. The various rate parameters were evaluated.
Cellulose organic solutions: A nuclear magnetic resonance investigation
Authors: Gagnaire Didier , Mancier Daniel , Vincendon Marc
Published: April 2003

Four solvents of cellulose have been studied by using 13C‐NMR spectroscopy. All these solvents, N‐methyl morpholine‐N‐oxide, methylamine, hydrazine, and paraformaldehyde (PF), contained dimethyl sulfoxide (DMSO) as a cosolvent. Oligomers of cellulose of DP = 10 soluble in hot DMSO have been used as model compounds. 13C chemical shifts and line shapes show that three of the mentioned solvents are “true solvents” of cellulose. On the other hand, dissolution of cellulose in DMSO‐PF system occurs by the formation of a statistical derivative of cellulose. Enriched 13C bacterial cellulose on C‐1 and C‐6 positions have been used to identify the 13C positions mainly in DMSO‐N‐methyl morpholine‐N‐oxide system. This solvent has been found to be degradative for the macromolecule when the solution is kept at 100°C over a long period. Viscosity measurements show a reduction of the molecular weight in these conditions. Polarimetry indicates that no glucose is present in solution and hence there is a statistical break of the chain. Enriched cellulose solution in DMSO–N‐methyl morpholine‐N‐oxide has been also used for relaxation time (T1) determination both of the solvent and of the enriched carbons of the polymer. Nuclear Overhauser enhancement (NOE) was found to be 1.8 for C‐1 and 2.1 for C‐6 showing that relaxation phenomenon is not purely dipolar. T1 values of 97 and 65 msec are found for C‐1 and C‐6 of cellulose, in good agreement with the values known for polysaccharides. Determination of T1 for the different carbon atoms of the solvent DMSO‐N‐methyl morpholine‐N‐oxide with and without cellulose shows a large reduction of T1 for N‐methyl morpholine‐N‐oxide molecule. This denotes a slower molecular motion of this molecule and a preferential interaction with the cellulose macromolecule.
Plasma polymerization. II. An ESCA investigation of polymers synthesized by excitation of inductively coupled RF plasma in perfluorobenzene and perfluorocyclohexane
Authors: Clark D. T. , Shuttleworth D.
Published: April 2003

The plasma polymers formed in glow and nonglow regions of an inductively coupled RF plasma with perfluorobenzene and perfluorocyclohexane are discussed as a function of operating conditions of the plasma by means of ESCA. The core levels of the plasma polymers are shown to be strikingly different but characteristic of a well‐defined but complex polymerization scheme. For the nonglow regions fluorine incorporation is shown to be greater than for polymers prepared in the glow regions and a preponderance of CF2 features is apparent. Perfluorobenzene deposits polymer faster than perfluorocyclohexane and changes in component composition of the C1s profile are studied as a function of operating conditions of the gas plasma.
Substituent effects in polymerization reactions in terms of generalized substituent constants F and R and generalized weighting factors f and r
Authors: Patnaik Lalit N. , Rout M. K. , Rout Anuradha , Rout Swoyam P.
Published: April 2003

In this investigation an approach to correlate the composite rate constants of some redox polymerization reactions [acrylonitrile‐Ce(IV)‐organic substrate] with a new type of multiparameter equation is described. The multiparameter equation is based on Swain and Lupton's F and R, the field and resonance components of the substituents, respectively, and the unique positional weighting factors f and r suggested by Williams and Norrington. The statistical parameters of the correlation involving the substituent constants (fF and rR) and the rate data have been found to be quite satisfactory, the average coefficient of determination being 0.91. The significance levels of the correlation also indicate that the present model is applicable to the kinetics of redox polymerization. The sign and magnitude of the reaction‐dependent regression constants α and β suggest that three different types of reaction mechanisms are operative for the substrates benzaldehyde, phenylthiourea, acetophenone, and toluene.
Copolymers of vinyl fluoride
Authors: Korin Amos , Levy Moshe , Vofsi David
Published: April 2003

Vinyl fluoride was polymerized by photochemical initiation in a continuous‐flow cylindrical reactor at room temperature and at pressures of up to 30 atm. Copolymers with vinyl acetate were prepared in order to improve the solubility and processability of poly(vinyl fluoride) (PVF). The copolymers were hydrolyzed to the corresponding vinyl alcohol copolymers and yielded hydrophilic films that are strong and flexible only when swollen by water. It was found that on hydrolysis the Tg, Tm, and heat of fusion as well as degree of crystallinity increased. It was suggested that PVF and the copolymers with vinyl alcohol are isomorphous.
Mechanistic studies on ceric‐thiourea‐initiated polymerization of methyl methacrylate in acid‐aqueous media from end group analysis
Authors: Pramanick D. , Chatterjee A. K.
Published: April 2003

The mechanism of the redox polymerization of methyl methacrylate in acid‐aqueous medium was studied for ceric‐thiourea initiator system by analysis of polymer end groups using the dye partition method. Polymerization at room temperature and at pH 2.30 with this initiator system incorporates mostly amino end groups in the polymers to the extent of 1.18‐1.31 and a small amount of hydroxyl end group not exceeding 0.08 per polymer molecule. Under the same pH condition, a higher polymerization temperature increases the amine end group content to 2.17‐2.30 and hydroxyl end group content to 0.14‐0.18 per polymer molecule. A lower polymerization temperature (5°C), or a lower pH (ca. 1) of the reaction medium, produces polymers with exclusively amine end groups, hydroxyl end groups being totally absent. At pHs greater than 3, amine end group incorporation decreases significantly, with simultaneous increase in hydroxyl incorporation. On the basis of end group results the initiating radical has been identified and the mechanism of initiation has been suggested. The possible mode of termination has also been discussed.
Kinetic evidence of a “matrix effect” in the bulk polymerization of acrylonitrile
Authors: Burillo G. , Chapiro A. , Mankowski Z.
Published: April 2003

The kinetics of the γ‐ray‐initiated polymerization of acrylonitrile in bulk are reexamined in broad ranges of temperatures and radiation dose rates. The discussion of the results coupled with an analysis of earlier data indicate that the polymerization of acrylonitrile proceeds by different mechanisms depending on the reaction temperature. Above 60°C the precipitated growing chains recombine readily; therefore, the autoaccelerated conversion curves cannot be accounted for by an “occlusion effect.” It is suggested that autoacceleration is caused by a fast propagation taking place in oriented monomer aggregates which result from dipole‐dipole association of the monomer with the polymer chains formed in the early stages of the reaction (“matrix effect”). Below 10°C the precipitated growing chains are buried in the dead polymer and monomer diffusion toward the occluded chain ends is very limited (“occlusion effect”). Between 10 and 60°C the system gradually changes from one dominated by “occlusion” to one where the “matrix effect” determines the kinetic behavior. The conclusion based on kinetic data is in agreement with results obtained from studies of the postpolymerization in these various systems.
Functional monomers and polymers. LXI. Photochemical reactions on the synthetic polymers containing thymine bases
Authors: Kita Y. , Inaki Y. , Takemoto K.
Published: April 2003

Photodimerization of N‐2‐isobutyloxyethyl thymine (T‐M), bis[2‐(5‐methyl‐1‐primidinyl)‐ethyl] glutarate (T‐T), poly(N‐2‐methacryloyloxyethyl thymine) (polyMAOT), and poly(N‐2‐acryloyloxyethyl thymine) (poly AOT) was studied in dimethylformamide solution. The rate of intramolecular photodimerization of polyMAOT and polyAOT was 5.7 and 7.2 times faster, respectively, than that of T‐T. In T‐M, however, intermolecular photodimerization did not occur under the reaction condition used. Quenching studies with isoprene suggest that the photodimerization of T‐T occurs predominantly in an excited triplet state, whereas that of polyMAOT and polyAOT occur in singlet and triplet states. It was concluded that the photodimers of T‐T, polyMAOT, and polyAOT are two syn‐fused cyclobutane‐type dimers (cis‐syn and trans‐syn). Quantum efficiencies of thymine base disappearance were determined by ultraviolet (UV) analysis to be 0.0012 for T‐T, 0.0084 for polyMAOT, and 0.010 for polyAOT.
Reaction of cellulose phosphonate with N‐vinyl‐2‐pyrrolidone and flame‐retardant properties of the product
Authors: Inagaki Norihiro , Katsuura Kakuji
Published: April 2003

The reaction of cellulose phosphonate and N‐vinyl‐2‐pyrrolidone in ethanol in the presence of sodium ethoxide was investigated and thermal stabilities and flame‐retardant properties for cellulose phosphonate modified with N‐vinyl‐2‐pyrrolidone were discussed. The results in this study point out the following important aspects of flame retardation of cellulose fabrics: (1) The reaction of cellulose phosphonate and N‐vinyl‐2‐pyrrolidone in the presence of sodium ethoxide results in graft polymerization of N‐vinyl‐2‐pyrrolidone at PH sites in cellulose phosphonate; an average chain length of the graft polymer is about five units of vinylpyrrolidone. (2) The graft polymerization of N‐vinyl‐2‐pyrrolidone can improve both stabilities, especially the flame‐retardant properties of cellulose fabrics. (3) Amides, whether noncyclic or cyclic, are suitable for nitrogen compounds that can effectively operate as synergists.
Stepwise polymerization of 1,1‐diphenylethylene derivatives by acid catalysts
Authors: Nishimura J. , Tanaka N. , Hayashi N. , Yamashita S.
Published: April 2003

The polymers containing units of 1,1,3,3‐tetraphenylbut‐1‐ene [unit (I)] and/or units of 3‐methyl‐1,1,3‐triphenylindan [unit (II)] in the main chain were prepared by acid‐catalyzed dimerization of 1,1‐diphenylethylene applied to its bifunctional derivatives, for example bis[p‐(1‐phenylvinyl)phenyl]methane. The structure of yielded polymers depended on catalyst, solvent, temperature, and the molar ratio between the catalyst and the monomer. The molecular weight of polymer having unit (I) was determined by the equilibrium existing between 1,1‐diphenylethylene moiety and unit (I). It was shown clearly by gel permeation chromatography that the molecular weight of polymer having unit (II) grew further after the equilibrium mentioned above had been accomplished. The mechanism of the polymerization is discussed.
Aminolysis of crosslinked polysiloxanes: Tautomeric catalysis by 2‐pyridone
Authors: Pappas S. Peter , Just Ronald L.
Published: April 2003

Results are presented which extend earlier findings on the transformation of insoluble crosslinked polysiloxanes into soluble linear polymers by selective aminolysis at crosslink sites. The present study provides evidence of a substantial steric effect and catalysis by 2‐pyridone. The results with 2‐pyridone are attributed to tautomeric catalysis which, to our knowledge, had not been observed before in substitution reactions at silicon. Evidence is also presented that unhindered, difunctional primary amines effect aminolysis with both amine groups to produce insoluble crosslinked polymer, presumably with silylamine functionality at crosslink sites.
Photochemical synthesis of new polymer structures. II. Photocycloaddition of olefins to polyvinylbenzophenone and poly(styrene‐co‐vinylbenzophenone)
Authors: Holden D. A. , Guillet J. E.
Published: April 2003

The photocycloaddition of simple olefins to poly(4‐vinylbenzophenone) (PVB) and poly(styreneco‐4‐vinylbenzophenone) (PS‐VB) was studied in benzene solution and in the solid polymer. In solution oxetane yields of 61–82% were obtained with di‐, tri‐, and tetrasubstituted olefins, which are visualized as capable of giving a radical on a 3° carbon atom in the biradical preceding ring closure to form the oxetane. Photocycloaddition of isobutene to PVB and PS‐VB occurs in solid polymer films to more than 90% conversion of the polymer ketone. Quantum yields of oxetane formation are 0.013 ± 0.003 on irradiation at 366 nm, independent of film thickness between 1.9 and 10.6 μm and of temperature between 23 and 65°C. The absence of a pronounced effect of the polymer glass transition on the efficiency of the cycloaddition in PVB suggests that large‐scale molecular motion is not required by this solid‐state photoreaction. Crosslinking by photochemical cycloaddition was demonstrated in mixed films of PVB and squalene, a polyfunctional olefin.
Polycarbonates from 1,1‐dichloro‐2,2‐bis(4‐hydroxyphenyl)ethylene and bisphenol A: A highly flame‐resistant family of engineering thermoplastics
Authors: Factor Arnold , Orlando Charles M.
Published: April 2003

Although the preparation of polycarbonates based on bisphenol A and 2,2‐bis(4‐hydroxyphenyl)‐1,1‐dichloroethylene was disclosed in 1964 by Porejko et al., little has been reported on their physical and flammability properties. To define the properties of this system these materials were prepared and evaluated. The results indicate that the copolymers and blends of the homopolycarbonates of the two different bisphenols result in transparent thermoplastics that have almost the same attractive physical properties as the homopolycarbonate from bisphenol A. In addition, many of these formulations possess flame‐resistant properties that exceed those of other transparent thermoplastics; for example, highest OI and lowest smoke and lowest ratings in the ASTM E84 tunnel and E162 radiant panel tests. Preliminary bioassay results with rats of the products from 500°C air pyrolysis gave an ALC50 value greater than that of other common thermoplastics.
Comparative study of the photodegradation of polybenzoxazoles and related model compounds. Stabilization of polybenzoxazoles
Authors: Despax B. , Paillous N. , Lattes A. , Paillous A.
Published: April 2003

Polybenzoxazoles (PBO) are thermally stable polymers whose possible use under space conditions as a transparent coating aboard spacecraft is restricted by their photodegradability. This photodegradability, which results in a loss of optical properties, is due to the structural features of benzoxazoles as well as to the presence of residual impurities from the synthesis (ketones, esters, amides). Suitable structural changes, which were intrinsic (increase in the conjugation) or extrinsic (addition of nickel salts able to complex the benzoxazole units), allowed the PBO photochemical stability to be increased and subsequently their optical transparency to be maintained. The fluorescence inhibition observed when nickel salts were added suggests that, in this case, stabilization results from a singlet‐singlet energy transfer. The effect of the various structural factors investigated on the stability of polybenzoxazoles was correlated with the photochemical behavior of the corresponding model compounds.
Extended‐chain polyamides: Polyoxamides and polyfumaramides
Authors: Pletcher T. C. , Morgan P. W.
Published: April 2003

The synthesis of polyamides from short‐chain aliphatic diacids, such as oxalic and fumaric acids, is difficult because of the thermal instability and volatility of the intermediates and side reactions with the polymerization media. A variety of synthetic routes to these polymers has been explored. Several aromatic polyoxamides with high molecular weight were obtained in high yield by an acid chloride vapor‐solvent‐water interfacial process. Polyoxamides of intermediate molecular weight also were obtained by preparation of oligomers from diamines and oxalic diesters and condensing these oligomers further in a thermal polymerization step. Aromatic polyfumaramides and terephthalamidefumaramides were prepared by modified solution procedures in amide solvents. Another route to polyfumaramides was the synthesis of N,N′‐bis(4‐aminophenyl) fumaramide and its use as a diamine with diacid chloride. The 1,4‐phenylene and benzidine polyfumaramides and oxamides have extended‐chain structures in solution in sulfuric, chlorosulfonic, and fluorosulfonic acids. Some of the polymers were soluble enough to yield liquid crystalline solutions. High‐tenacity high‐modulus fibers from poly(1,4‐phenylene fumaramide/terephthalamide)s are described.
Studies on polyyne polymers containing transition metals in the main chain. IV. Polymer synthesis by oxidative coupling of transition metal‐bis(acetylide) complexes
Authors: Takahashi S. , Murata E. , Sonogashira K. , Hagihara N.
Published: April 2003

The metal‐polyyne polymers consisting of transition metals and conjugated tetrayne systems
magnified image
where M represents Pt(PBu3)2 or Pd(PBu3)2 moiety were prepared by the oxidative coupling method and characterized by spectral analysis, associated with novel depolymerization giving binuclear transition metal complexes, and
Polycondensation of diethyl mucate with hexamethylenediamine in the presence of poly(vinyl pyridine)
Authors: Ogata Naoya , Sanui Kohei , Nakamura Hiroyuki , Kishi Hiroyuki
Published: April 2003

The polycondensation reaction of diethyl mucate (DEM) with hexamethylenediamine (HMD) was carried out in dimethyl sulfoxide (DMSO) at 60°C in the presence of poly(vinyl pyridine) (P‐VPy) as a matrix polymer, which was expected to interact with DEM or the resulting polyamide which had pendant hydroxyl groups due to a hydrogen bonding. It was found that the polycondensation of DEM with HMD in the presence of poly(4‐vinyl pyridine) (P‐4VPy) produced a polyamide with a higher molecular weight than those in the presence of poly(2‐vinyl pyridine) (P‐2VPy) or in the absence of P‐4VPy. The rate of the polycondensation, however, was rarely enhanced by polymer matrixes such as P‐4VPy and P‐2VPy. During polycondensation in the presence of P‐4VPy a gelation of the reaction mixture was observed when the solution was kept at 30°C for several days. This might be ascribed to the formation of the polymer complex between resulting polyamide and P‐4VPy during the polycondensation.
Polycondensation reaction of dimethyl tartrate with hexamethylenediamine in the presence of various matrices
Authors: Ogata Naoya , Sanui Kohei , Nakamura Hiroyuki , Kuwahara Masato
Published: April 2003

The polycondensation reaction of dimethyl tartrate (DMT) with hexamethylenediamine (HMD) was carried out in dimethyl sulfoxide (DMSO) at 60°C in the presence of various polymer matrices, which were expected to interact with DMT or the resulting polyamide which had pendant hydroxyl groups due to hydrogen bonding. It was found that the rate of polycondensation was enhanced by polymer matrices such as poly(vinyl pyrrolidone) (PVP), Pullulan (polysaccharide) (PF), and poly(vinyl alcohol) (PVA). The rate enhancement became more pronounced with increasing molecular weight of the polymer matrix. When polycondensation in the presence of PVA was carried out in DMSO, a polymer complex was produced. The formation of the polymer complex between the resulting polyamide and PVA during polycondensation was dependent on the concentration of monomers and also on PVA; a gelation of the solution was observed at a concentration of PVA.
Organosilane polymers. II. Poly(ethylmethyl‐co‐dimethylsilylene) and poly(methylpropyl‐co‐dimethylsilylene)
Authors: Wesson J. P. , Williams T. C.
Published: April 2003

Polydimethylsilylene is a largely crystalline, high‐melting polymer that is soluble only above 200°C and does not thermoform below its decomposition temperature. Introduction of ethyl and propyl substituents into the linear silylene system by random copolymerization of dimethylsilylene with ethylmethyl‐ and methylpropylsilylenes leads to tractable polymers that are soluble in common solvents at normal ambient temperatures.
Photoinitiated cationic polymerization by dialkyl‐4‐hydroxyphenylsulfonium salts
Authors: Crivello J. V. , Lam J. H. W.
Published: April 2003

On irradiation with ultraviolet light, dialkyl‐4‐hydroxyphenylsulfonium salts undergo reversible photodissociation and in the process generate ylids and Brønsted acids. When the anions are nonnucleophilic in character, as, for example, BF4−, AsF6−, PF6−, and SbF6−, the strong acid which is produced is capable of initiating cationic polymerization. The polymerization of several monomers was carried out to demonstrate the general applicability of these new photoinitiators.
The synthesis and thermal polymerization of 4,4′‐diethynylphenyl ether
Authors: Ratto J. J. , Dynes P. J. , Hamermesh C. L.
Published: April 2003

Diethynylphenyl ether (DEPE) was synthesized and its thermal polymerization studied by NMR, IR, and DSC techniques. DEPE is a crystalline solid that melts at 72–73°C and undergoes polymerization beginning at about 150°C. The heat of polymerization measured by DSC was 53 ± 2 kcal/mole. Thermomechanical analysis (TMA) of the fully cured resin showed softening behavior at temperatures in excess of 400°C. Weight loss up to 720°C was only 21%. A mechanism of polymerization based on the analysis of IR and NMR data for party polymerized material below 300°C is proposed.
N‐methyl‐substituted aromatic polyamides
Authors: Greenwood Thomas D. , Kahley Richard A. , Wolfe James F. , Clair Anne St. , Johnston Norman J.
Published: April 2003

A series of N‐methyl‐substituted aromatic polyamides derived from the secondary aromatic diamines 4,4′‐bis(methylamino)diphenylmethane, 3,3′‐bis(methylamino)diphenylmethane, 4,4′‐bis(methylamino)benzophenone or 3,3′‐bis(methylamino)benzophenone and isophthaloyl dichloride, and terephthaloyl dichloride or 3,3′‐diphenylmethane dicarboxylic acid dichloride was prepared by high‐temperature solution polymerization in s‐tetrachloroethane. Compared with analogous unsubstituted and partly N‐methylated aromatic polyamides, the full N‐methylated polyamides exhibited significantly lower glass transition temperatures (Tg), reduced crystallinity, improved thermal stability, and good solubility in chlorinated solvents.
Evolution of aromatic compounds in the thermal decomposition of vinyl polymers
Authors: Ballistreri A. , Foti S. , Montaudo G. , Scamporrino E.
Published: April 2003

The thermal decomposition products that evolve from poly(vinyl chloride) (PVC), poly(vinylbromide) (PVB), poly(vinyl alcohol) (PVA), and poly(vinylacetate) (PVAc) were analyzed by direct pyrolysis in the ion source of a mass spectrometer (MS). Our results indicate that in both stages of the decomposition process which occurred in the four vinyl polymers investigated several aromatic hydrocarbons were produced and that the relative amounts of benzene, napthalene, and anthracene were different in the two stages. This previously unreported information determines in a single scheme the thermal behavior of the title compounds.
Graft copolymerization onto jute fiber: Ceric ion‐initiated graft copolymerization of methyl methacrylate
Authors: Huque M. M. , Habibuddowla Md. , Mahmood A. J. , Mian A. Jabbar
Published: April 2003

Graft copolymerization of methyl methacrylate (MMA) was carried out on both defatted and bleached jute fibers using ceric ammonium sulfate (CAS) as the initiator. In order to obtain the optimum condition for grafting, the effects of initiator concentrations, temperature, time of reaction, lignin content of jute, and the monomer concentration were studied. The maximum percent grafting and grafting efficiency were found to be 132% and 0.71, respectively. Kinetic studies showed that at 0.03M CAS, the reaction appeared to obey the second‐order process. The activation energies were found to be 7.74 and 5.12 kcal/mole for defatted (lignin content, 15.7%) and chlorite‐bleached jute (lignin content 10%), respectively. The activation energies of graft copolymerization of MMA onto jute fiber are compared with the energies of activation of graft copolymerization of acrylonitrile (AN).
Stereochemistry in cationic polymerization of alkenyl ethers. V. Stereochemistry of acetal additions as model reactions for the polymerization of alkenyl ethers
Authors: Higashimura Toshinobu , Hirokawa Yoshitsugu , Matsuzaki Kei , Uryu Toshiyuki
Published: April 2003

Acetal additions to β‐substituted vinyl ethers having a variety of substituents (alkenyl ethers) were stereochemically investigated as model reactions for their cationic polymerization. The reactions catalyzed by BF3O(C2H5)2 in CH2Cl2 at O°C gave 1:1 adducts, the steric structure of which was determined by means of 13C‐NMR spectroscopy. trans‐Alkenyl ethers always gave adducts with a single structure stereospecifically, indicating that the intermediate carbocation attacks a trans‐alkenyl ether from a definite direction independent of the bulkiness of substituents. On the other hand, cis‐alkenyl ethers formed adducts with two steric structures, and the direction of cation addition was found to depend on the bulkiness of the alkoxy group involved. The above trends were in agreement with the results for poly(alkenyl ether)s and allowed detailed discussion of the stereochemistry of the propagation processes in alkenyl ether polymerizations.
Monte Carlo‐studium der ireversiblen terpolymerisation: Das modell und anwendungen
Authors: Moţoc I. , Muşcutariu I. , Holban St. , Dragomir O.
Published: April 2003

The Monte Carlo model of the ternary irreversible copolymerization is presented. The computer program MEMøRY‐4, which implements the described model, is used to study the methyl methacrylate/methyl acrylate/maleic anhydride, butadiene/styrene/2‐methyl‐5‐vinylpyridine, and styrene/methacrylonitrile/α‐methyl styrene terpolymers. One discusses the problem of transferability of reactivity ratios determined for binary copolymerizations to the ternary ones. It can be concluded that the transferability is not assured, but using only composition data it is difficult to achieve a safe conclusion (Fisher statistics).
Peroxo salts as initiators of vinyl polymerization. IV. Polymerization of methacrylamide initiated by peroxodisulfate ion and metal ion catalysis
Authors: Manickam S. P. , Subbaratnam N. R. , Venkatarao K.
Published: April 2003

The polymerization kinetics of methacrylamide (M) initiated by S2O ion in the presence and absence of the metal ions Ag+ and Cu2+ has been studied. The rate laws have been established and are compared with those of acrylamide. The results indicate that steric hindrance from the α‐methyl group affects the initiation reaction. Cu2+ ions are found to reduce the rate of polymerization.
Head‐to‐head polymers. XV. A facile synthesis of 2,3‐disubstituted succinates and butanediols‐1,4
Authors: Yamada A. , Grossman S. , Vogl O.
Published: April 2003

A synthetic approach that makes symmetrically 2,3‐dialkyl‐substituted succinates and compounds prepared from 2,3‐dialkyl‐substituted succinates easily available has been developed. Coupling of α‐bromoalkanoic esters with a zinc/copper couple produced in about 40% yield 2,3‐disubstituted succinates which were reduced with LiAlH4 to 2,3‐disubstituted butanediols‐1,4 in nearly quantitative yields. Some 2,3‐disubstituted butanediols‐1,4 were cyclodehydrated under reduced pressure with KHSO4 to 3,4‐disubstituted tetrahydrofurans or acetylated and the diacetyl compounds pyrolyzed at 525°C to 2,3 disubstituted butadienes‐1,3. The length of the alkyl chains of the 2,3‐dialkylsuccinates and consequently the 2,3‐dialkylbutanediols‐1,4 ranged from C2 to C16. 2,3‐Disubstituted butanediols‐1,4, 2,3‐disubstituted butadienes‐1,3, and 3,4‐disubstituted tetrahydrofurans are interesting monomers for polymerization experiments.
Aromatic polymides. VII. Synthesis of sulfonated poly(para‐phenyleneterephthalamide): Polymerization of 1,4‐bis(trichloromethyl) benzene with para‐phenylenediamine sulfate in SO3
Authors: Silver Frank M.
Published: April 2003

para‐Phenylenediamine sulfate polymerized with 1,4‐bis(trichloromethyl)benzene in SO3 at > 20% polymer concentration to form highly anisotropic (liquid crystalline) sulfonated poly(para‐phenyleneterephthalamide) (S‐PPT) solutions with inherent viscosities as high as 1.2. Analogous to the polymerization of para‐phenylenediamine sulfate with terephthalic acid in SO3 reported previously, sulfonation of the aromatic diamine ring of S‐PPT was not competitive with the polymerization reaction, but it was a major side reaction.
On the reactivity of cellulose free radicals in graft copolymerization reactions
Authors: Hon David N. ‐S.
Published: April 2003

The formation and behavior of photo‐and mechanoinduced free radicals in cellulose were studied by ESR spectroscopy and the capability of these free radicals to initiate graft copolymerization reactions was demonstrated. Although an 11‐line ESR signal was detected from cellulose irradiated with ultraviolet (UV) light, a higher‐intensity ESR signal with a five‐line pattern was detected from a sample mechanically milled at 77 K. The decay of photoinduced free radicals when heated took place monotonously, whereas mechanoradicals exhibited an anomalous behavior with an increased signal intensity at 150 K before decaying at a higher temperature. Mechanoradicals have been found to react more efficiently and rapidly with oxygen and methyl methacrylate (MMA) than photoinduced free radicals. The peroxy mechanoradicals, however, were mobile and decayed more rapidly than the peroxy photoinduced radicals. Simultaneous graft copolymerizations of MMA to cellulose demonstrated that mechano‐and photoinduced free radicals are capable of initiating grafting reactions, but a higher degree of grafting efficiency was obtained from cellulose treated mechanically.
Effect of tin tetrachloride on thermal decompositions of α,α′‐azobisisobutyronitrile and dimethyl α,α′‐azobisisobutyrate
Authors: Yamada Bunchiro , Kamei Hiroaki , Otsu Takayuki
Published: April 2003

Thermal decomposition of α,α′‐azobisisobutyronitrile (AIBN) and dimethyl α,α′‐azobisisobutyrate (MAIB) in the presence of a large amount of tin tetrachloride was investigated to determine the effect of complex formation on the decomposition rates and yields of the recombination products. The addition of tin tetrachloride significantly increased the decomposition rates; the observed first‐order rate constant increased by factors of 4.5 and 17 at molar ratios of [SnCl4]/[AIBN] = 21.65 and [SnCl4]/[MAIB] = 19.53, respectively. It was found that the decomposition of these azo compounds was also accelerated by the addition of a comparable amount of donor solvent such as ethyl acetate or propionitrile to tin tetrachloride and that the enhancement in rate was accounted for by a larger frequency factor in the Arrhenius equation. Furthermore, the addition of tin tetrachloride seemed to suppress the formation of recombination products, tetramethyl succinonitrile and dimethyl tetramethylsuccinate, of the radicals produced by decomposition.
Kinetic features of cationic oligomerization of epoxides
Authors: Ivanchev S. S. , Pavlyuchenko V. N. , Khaikin S. Ya. , Vladimirova L. G. , Balaev G. A. , Shevchuk V. I.
Published: April 2003

The kinetic features of the cationic oligormerization of epoxides of various structures influenced by Lewis acids (BF3OEt2, SnCl4) were investigated. It was shown that the systems studied could he divided into three groups, based on the nature of conversion‐time kinetic curves of oligomerization: (1) (Epoxypropane‐BF3OEt2, 3,4‐epoxybutene‐1‐BF3OEt2) oligomerization stops before the monomer is exhausted completely. (2) (1‐Chloro‐2,3‐epoxypropane‐BF3OEt2 or SnCl4, 2‐methyl‐2,3‐epoxybutane‐BF3OEt2) oligomerization can be carried out almost up to complete conversion of the monomer. The reaction rate, however, decreases more rapidly than that expected from the kinetics of monomer consumption. (3) (1‐tert‐Butylperoxy‐2,3‐epoxypropane‐SnCI4) oligomerization kinetics are described by a simple exponential function with regard to monomer concentration. Determination of the propagating species concentration in the systems studied suggests that the initiation of cationic oligornerization of epoxides with Lewis acids is an instantaneous process and the discrepancy observed is a result of the different nature of kinetics of the active site destruction. In the first group of systems the rapid destruction of the propagating species prevents the oligomerization to complete conversion. In the second group a somewhat lower rate of decrease in concentration of the propagating species with time is explained by their regeneration during the process. In the third system, which is a unique case, the concentration of the propagating species remains constant with time. It is assumed that these features are the result of the stability or pseudostability of the active sites which depends on the nature of the epoxide and initiator.