bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymerization of allyl esters of unsaturated acids. IX. Controlled ring closure in the radical cyclopolymerization of allyl methacrylate
Authors: Matsumoto Akira , Ishido Hirozo , Oiwa Masayoshi , Urushido Kunio
Published: April 2003

Radical cyclopolymerization of allyl methacrylate (AMA) was investigated in detail, especially under the specified conditions; that is, above the ceiling temperature for a head‐to‐tail propagation (ΔGht ≥ 0) in the polymerization of methacrylate. Thus the structure of the polymer obtained was examined by 1H‐ and 13C‐NMR and infrared (IR) spectroscopy; no existence of unreacted pendant methacrylyl groups was observed, which suggests that, as a cyclopolymerization mechanism of AMA, intermolecular propagation of growing radicals, followed by intramolecular cyclization or intermolecular propagation of the resulting uncyclized methacrylyl radical, occurs exclusively with methacrylyl group. Temperature dependency of cyclization constant Kc was unusual; Kc increased rapidly at elevated temperatures and no linear relationship of ln Kc vs. 1/T was observed. Five‐membered ring formation was favored at an elevated temperature and diluted monomer concentration. These results are discussed thermodynamically in terms of controlled ring closure in cyclopolymerization.
Densimeter detector in gel permeation chromatography of copolymers
Authors: Elsdon W. L. , Goldwasser J. M. , Rudin A.
Published: April 2003

A commercially available densimeter with a vibrating stainless steel tube was used as a detector in the GPC analysis of styrene/methyl methacrylate copolymers under normal GPC operational conditions. The densimeter was thermostated to ±0.001°C and sample injection concentrations were 4.0 mg/mL. The copolymer samples were polydisperse in molecular weight but uniform in composition. A refractive index detector and the densimeter detector produced comparable estimates of the parameters of the molecular weight distributions. The densimeter is less sensitive to the effects of variations in copolymer composition than differential refractive index or ultraviolet detectors. The only serious drawback to the densimeter is a relative lack of sensitivity. Variations in composition of styrene/methyl methacrylate copolymers over a fairly wide range have no signficant effect on the relation between gel permeation chromatographic elution volume and copolymer molecular weight. In general, however, conventional means of summarizing these data are not applicable to compositionally heterogeneous mixtures. Instrumental and data‐handling solutions to this problem are discussed.
Second moments of ESR signals from poly(p‐phenylene) and the deuterated analog
Authors: Kovacic Peter , Howe Russell F. , Khoury Issam
Published: April 2003

The second moments of the ESR signals obtained from poly(p‐phenylene) (PPP) and deuterated PPP were measured at 9.5 and 35 GHz. The theoretical and experimental contributions to the second moments were considered. It is shown that for deuterated PPP, deuteron hyperfine splitting makes a negligible contribution to the observed second moment. The proton hyperfine contributions to the second moments of the radical species in PPP and p‐sexiphenyl were estimated and it was concluded that the unpaired electron was delocalized over only 2‐4 phenylene units. A rationale is offered in terms of polarons present as defects in the PPP chains.
Functional monomers and polymers. CII. Synthesis and properties of oligomer models of polyethyleneimine derivatives containing pendant adenine bases
Authors: Sakuma Yo , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

A series of oligomer model compounds of polyethyleneimine derivatives with pendant adenine bases were prepared by the reaction of a carboxyethyl derivative of adenine with oligomeric amines, using an activated ester method. To evaluate the intramolecular interaction between pendant adenine bases in these compounds, ultraviolet spectra at various pH regions were measured. Ultraviolet hypochromicities and pKa values depended linearly on the chain length of the oligomers. The results showed that the intramolecular interactions of adenine bases were realized less in their protonated than neutral forms.
Poly(secondary amine)s from diacrylates and diamines
Authors: Shchori Ehud
Published: April 2003

Poly(secondary amine)s were prepared by the Michael‐type addition of diacrylates or bisacrylamides with diprimary amines carrying an α or β branching to the amino groups. The steric hindrance due to branching rendered the primary amine monofunctional in respect to the acrylate, thus producing soluble polymers.
Frictional coefficients in polymer solutions and the applicability of scaling laws to experimental data
Authors: Elmgren Hans
Published: April 2003

When defined in the conventional way, the relative frictional coefficient f/f0 of dissolved polymers is dependent on the method of determination used. Sedimentation and mutual diffusion‐light scattering give a common result, which by necessity differs from that obtained by self‐diffusion measurements. The difference is due to the neglect of the nonfree draining conditions in the polymer coils, causing an inadequate reference value f0 in the cases of sedimentation and mutual diffusion.

The scaling theory is also discussed in the view of an alternative theory (1‐4). Besides its partly unrealistic theoretical basis, the scaling theory suffers from several weaknesses:

(i) The significance of the reference frame of the studied motions is not analyzed.

(ii) When the polymer concentration is increased, the original two‐phase system (swollen coils and bulk solvent) is transformed into a single‐phase system. The effect of this, in combination with the conventional definition of f and f0 used, is not analyzed in the scaling theory.

(iii) No attention is drawn to the influence of the segment mobility on the concentration dependence of the studied hydrodynamic parameter.
Pyrolysis of unsaturated polyester resin. Quantitative aspects
Authors: Ravey M.
Published: April 2003

The thermal decomposition of this resin was examined by quantitative pyrolysis—gas chromatography. The decomposition does not follow the Hurd–Blunck mechanism generally obeyed by beta‐hydrogen containing esters. Instead, phthalic anhydride is extruded almost quantitatively. It is proposed that the mechanism involves the rearrangement of the phthalate CO bonds to extrude the anhydride, leaving a maleic acid—dipropylene glycol polyester chain.
Trityl salt—initiated polymerization of α‐methylstyrene
Authors: Velichkova R. , Panayotov I. M. , Doicheva J. , Manolova N.
Published: April 2003

The initiation reaction of the polymerization of α‐methylstyrene by trityl tetrachloroferate and tritylhexachloroantimonate in 1,2‐dichloroethane at 20°C was studied. The rate constants were 14 × 10−3 and 27 × 10−3 L mol−1s−1, respectively. The dissociation constants of tritylterachloroferate (Kd = 0.88 × 10−4M−1) and tritylhexachloroantimonate (Kd = 2.64 × 10−4M−1) was determined. The effect of electron acceptors and donors on the dissociation equilibrium and initiation rate was investigated. It was shown that in strongly dissociated ion pairs such as stable carbenium salts the electron donors and acceptors have no appreciable effect on the magnitude of the dissociation. The temperature dependence of the rate constants in the −20–+20°C range yielded the following thermodynamic parameters for trityltetrachloroferate: Ei = 8.54 kcal/mol; A = 3.2 × 104 mol−1s−1; ΔH* = 8 kcal/mol; and S* = −39.8 eu.
Polymerization of acrylonitrile initiated by KO2‐ nitrobenzene
Authors: Han Yang Kyoo , Jin Moon Young , Choi Sam Kwon
Published: April 2003

Polymerization of acrylonitrile initiated by a potassium superoxide (KO2)‐nitrobenzene system was carried out in anhydrous dimethylsulfoxide (DMSO) at 25°C. The initial rate of polymerization was rapid and a high‐molecular‐weight polymer was obtained. The molecular weight was proportional to monomer concentration and inversely to concentration of initiator within 5 min. The overall activation energy was estimated as −2.6kcal/mol deg in the temperature range of 20–50°C. In addition to nitrobenzene anion radical, other anion radicals generated by one‐electron transfer from KO2 to charge transfer agents such as m‐dinitrobenzene benzoquinone, benzophenone, and naphthalene were effective in the polymerization of acrylonitrile. It is proposed that polymerization proceeds via an anionic mechanism that involves one‐electron transfer from anion radicals to monomer.
Determination of reaction variables for the starch xanthide encapsulation of pesticides
Authors: Wing R. E. , Otey F. H.
Published: April 2003

Optimization of reaction variables such as xanthation and oxidation conditions was determined for the encapsulation of EPTC (S‐ethyl dipropylthiocarbamate) and butylate (S‐ethyl diisobutylthiocarbamate) in a crosslinked starch xanthide matrix. Sonification of EPTC and butylate emulsifiable concentrates before encapsulation decreased the size of the cells within the matrix and increased pesticide retention. Pesticide release from the matrix as determined using a constant temperature‐humidity chamber showed that low‐xanthation and sonified encapsulated products gave the slowest pesticide release.
Thermoxidative degradation of vinyl alcohol/vinyl acetate copolymers. IV. Statistical copolymers
Authors: Vasile Cornelia , Paţachia Silvia Florica , Dumitraşcu V.
Published: April 2003

The thermoxidative degradation of vinyl acetate/vinyl alcohol statistical copolymers was studied under dynamic thermal conditions and compared with that of block copolymers. The dependence of thermal characteristics or kinetic parameters on the content of OH groups of copolymers was established.
Synthesis and polymerization of 8,9‐benzo‐2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane (BMTN)
Authors: Han Yang Kyoo , Choi Sam Kwon
Published: April 2003

8,9‐Benzo‐2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane (BMTN) was prepared by the reaction of phthalide with epichlorohydrin, followed by dehydrochlorination. BMTN was polymerized with di‐t‐butyl peroxide (DTBP) to give a solyble polymer with a high molecular weight and good thermal stability. The infrared (IR) and nuclear magnetic resonance (NMR) spectra indicated that the polymer structure contained aromatic ester and ketone in the backbone. Tg and Tm of homopolymer of BMTN were, respectively, 98 and 282°C. BMTN was also readily copolymerized with such vinyl monomers as methyl methacrylate (MMA), acrylonitrile (AN), and maleic anhydride (MA), but not with styrene, in the presence of radical initiators. AN and MA, in particular, were spontaneously copolymerized with BMTN in the absence of radical initiators at 40°C. From the results of ultra violet (UV) spectra it is suggested that spontaneous copolymerization proceeds via a charge‐transfer complex between BMTN as an electron donor and AN or MA as an acceptor.
Quantitative DSC evaluation of phase segregation rate in linear segmented polyurethanes and polyurethaneureas
Authors: Camberlin Yves , Pascault Jean Pierre
Published: April 2003

Linearly segmented polyurethanes and polyurethaneureas are known to be phase separated; one phase is the soft phase, the other, the hard domain. Quantitative evaluation of the degree of phase separation was obtained by DSC. An estimation of the dispersed soft segments outside the soft phase can be made by ΔCp measurements and the increase in glass transition (Tg) can be attributed to the presence of hard blocks in the soft phase. The segregation rate depends on the nature of the soft segments which decrease from hydrogenated polybutadiene to polybutadiene to polyether. It also depends on the nature of the chain extender from aliphatic to aromatic diol and from aliphatic to aromatic diamine. The presence of soft segments in hard domains can be related to the thermoplastic behavior of the polyurethanes and polyurethaneureas.
Binding of methyl orange and its homologs by polyion complexes consisting of a piperidinium cationic polymer and various polyanions in aqueous solution
Authors: Takagishi Toru , Kozuka Hiroshi , Kuroki Nobuhiko
Published: April 2003

A study was made of the formation of polyion complexes between a piperidinium cationic polymer and polyanions and of the binding of azo‐dye anions (methyl, ethyl, propyl, and butyl orange) by these complexes. Sodium poly(acrylate), poly(styrenesulfonate), dextran sulfate, and carboxy‐methylcellulose were used as polyanions. The resultant polyion complexes (insoluble in aqueous solutions) were compared for their ability to bind the small organic molecules in aqueous solutions, for example, of urea and an inorganic electrolyte (KCI), and exhibited a strong binding affinity toward these small anions. Polyion complexes that consisted of sodium poly(acrylate), dextran sulfate, and carboxymethylcellulose as polyanions cooperated in the binding, whereas the polyion complex of sodium poly(styrenesulfonate) did not. It was suggested that small organic anions interact with the polyion complexes primarily through electrostatic and hydrophobic forces.
Oligomers from biphenyl, biphenyl‐d10, or p‐terphenyl with aluminium chloride‐cupric chloride: Mechanism, ESR, and conductivity
Authors: Hsing Chih‐Fen , Kovacic Peter , Khoury Issam A.
Published: April 2003

Biphenyl and biphenyl‐d10 were coupled by aluminum chloride‐cupric chloride. For the two systems, the yields of p‐quaterphenyl, p‐sexiphenyl, and sublimation residue were compared. The results, which have mechanistic significance, are similar to those reported earlier for benzene versus benzene‐d6; that is, a decrease in DP for the deuterated substrate. p‐Sexiphenyl, obtained from biphenyl or p‐terphenyl and aluminum chloride‐cupric chloride, displayed a concentration of 3 × 1017 spins/g in ESR. There was little or no change in spin density after sublimation or crystallization. Even after drastic purification by a variety of techniques the radical character persisted. Biphenyl was polymerized by aluminum chloride‐cupric chloride at temperatures in the 50–155°C range. Processable polymers with m‐ and p‐phenylene linkages were produced. When doped with AsF5, the highest conductivity obtained was 7.3 × 10−2 Ω−1 cm−1.
Photocrosslinking of poly(2,3‐epithiopropyl methacrylate) film with 254 nm irradiation
Authors: Egawa Hiroaki , Ishikawa Masataka , Tsunooka Masahiro , Ueda Toshihiro , Tanaka Makoto
Published: April 2003

Poly(2,3‐epithiopropyl methacrylate) (PETMA) has an absorption maximum at 258 nm (εmax = 50) in dioxane which is due to episulfide groups. When irradiated at 254 nm under atmospheric pressure its film became insoluble. When kept at 70°C for several minutes a PETMA film became partially insoluble; however, the contribution of this thermal reaction to the photocrosslinking at room temperature was negligible. For photoreaction at 254 nm under nitrogen a low probability of main‐chain scission was ascertained by the use of the Charlesby‐Pinner equation. The IR spectrum of irradiated PETMA showed a decrease in episulfide groups and the formation of mercapto groups, which suggested that the photocrosslinking of PETMA results from free radicals formed by the cleavage of CS bonds. Free radicals in the irradiated PETMA were detected by ESR spectroscopy and the assignment is discussed. In this photocrosslinking process oxygen was a retarder at the early stage but an accelerator at the later stage.
Styrene emulsion polymerization: Kinetics and particle size distributions in highly swollen latex systems
Authors: Wood David F. , Whang Barry C. Y. , Napper Donald H. , Gilbert Robert G. , Lichti Gottfried
Published: April 2003

The results are reported of studies on the kinetics and the time evolution of the particle size distribution in seeded styrene emulsion polymerization systems wherein the seed latex particles were highly swollen with monomer as a result of prior swelling by dodecane. Conditions were such that no new latex particles were formed nor was a significant number of monomer droplets present (“Interval III”). The data were fitted to obtain values for the rate coefficients for entry and exit (desorption) of free radicals. It was found that, during the early part of the polymerization (when the polymer:monomer ratio in the latex particles is considerably less then in an equivalent emulsion polymerization system without dodecane), the entry rate coefficient was much smaller than that measured in systems without dodecane. This effect is consistent with an entry mechanism wherein entering free radicals must displace surfactant molecules from the latex particles.
Processable heat‐resistant polymers. XI. Synthesis and characterization of unsaturated polyamideimides
Authors: Maiti Sukumar , Ray Atanu
Published: April 2003

Polycondensation of the diacid chloride of 2‐(3‐carboxy vinyl)phenyl‐1,3‐dioxoisoindoline‐5‐carboxylic acid with m‐phenylenediamine and the diacid chloride of 2‐(4‐carboxy phenyl)‐1,3‐dioxoisoindoline‐5‐carboxylic acid with 1,5‐bis(3‐aminophenyl)1,4‐pentadien‐3‐one was carried out in polar solvents to produce new unsaturated polyamide–imides. The solution and the thermal, electrical, and a few other properties of the polymers were studies. The polymers were soluble in highly polar solvents. The solubility parameter of the polymers was calculated from the Small's group contribution. The polymers were fairly thermostable and underwent crosslinking creaction when heated, preferably in the presence of a suitable catalyst. The crosslinked polymers were in soluble even in highly polar solvents and possessed higher thermal stability. The swelling behavior of the polymers was studied and the molecular weight between two consecutive crosslinks was determined. X‐ray diffraction and the dielectric properties of the polymers and their crosslinked products were also studied.
Redox‐initiated cationic polymerization: The diaryliodonium salt/benzoin redox couple
Authors: Crivello J. V. , Lee J. L.
Published: April 2003

A new redox couple based on the copper‐catalyzed reduction of diaryliodonium salts with benzoins has been used to initiate cationic polymerizations of cyclic ethers and esters. A proposed mechanism for initiation by this redox couple is based on its stoichiometry and on the nature of the products. It was concluded that initiation of polymerization occurs both by direct arylation of the monomer and by protonation by strong Brønsted acids. The polymerization of several typical cationically polymerizable monomers using this new redox initiator were studied.
Polymerization of α‐methylene‐N‐methylpyrrolidone
Authors: Ueda Mitsuru , Takahashi Masami , Suzuki Toshiyuki , Imai Yoshio , Pittman Charles U.
Published: April 2003

α‐Methylene‐N‐methylpyrrolidone (α‐MMP) was synthesized and homopolymerized by bulk and solution methods. The poly(α‐MMP) is readily soluble in water, methanol, methylene chloride, and dipolar aprotic solvents at room temperature. Thermogravimetric analysis of poly(α‐MMP) showed a 10% weight loss at 330°C in air. The kinetics of α‐MMP homopolymerization and copolymerization were investigated in acetonitrile, using azobisisobutyronitrile (AIBN) as an initiator. The rate of polymerization Rp could be expresed by Rp = k[AIBN]0.49[α‐MMP]1.3. The overall activation energy was calculated to be 84.1 kj/mol. The relative reactivity ratios of α‐MMP (M2) copolymerization with methyl methacrylate (r1 = 0.59, r2 = 0.26) in acetonitrile were obtained. Applying the Q‐e scheme led to Q = 2.18 and e = 1.77. These Q and e values are larger than those for acrylamide derivatives.
Synthesis of aminimide monomers and polymers
Authors: Mehta Avinash C. , Rickter Donald O. , Kolesinski Henry S. , Taylor Lloyd D.
Published: April 2003

A convenient and practical synthesis of trimethylamine acrylimide, 1, starting from 1, 1, 1‐trimethylhydrazinium p‐toluenesulfonate, 3, and 3‐chloropropionyl chloride is described. The intermediate, trimethylamine 3‐chloropropionimide, 2, is easily transformed into 1 either through a single‐step dehydrohalogenation or through a two‐step process consisting of very facile thermal rearrangement to 1,1,1‐trimethylacrylylhydrazinium chloride, 4, and subsequent deprotonation. Two new polymerizable monomers, 5, and 6, containing aminimide functionality were synthesized from trimethylamine imine, 7, and the appropriate vinyl oxazolones, 8, and 9. Synthesis of hitherto unreported trimethylamine chloroacetimide, 10, which offers unique opportunities for incorporating water‐solubilizing and alkali‐stable aminimide functionality into a variety of structures through nucleophilic displacement, is also described.
Polycarbonate‐poly(methyl methacrylate) block copolymers: Synthesis and characterization
Authors: Gardlund Zack G. , Bator Mary Ann K.
Published: April 2003

The interfacial copolymerization of bisphenol A polycarbonate, bisphenol A‐terminated poly‐(methyl methacrylate), and bisphenol A bischloroformate is described. Monofunctional hydroxy‐terminated poly(methyl methacrylates) were synthesized by the chain transfer polymerization of methyl methacrylate with 2‐mercaptoethanol. Further reaction with bisphenol A bischloroformate yielded monofunctional bisphenol A‐terminated poly(methyl methacrylates). The structure and functionality of these polymers were proven by proton nuclear magnetic resonance (PNMR) spectroscopy. Block copolymers prepared by the interfacial copolymerization were washed with methanol and extracted with acetone to remove unreacted bisphenol A bischloroformate and bisphenol A‐terminated poly(methyl methacrylates). The series of block copolymers, which contained from 0.11 to 0.86 mole fraction polycarbonate, were characterized by infrared, PNMR, and molecular weight analysis.
Synthesis of crosslinked poly(α‐amino acids) with various functional groups
Authors: Kuroyanagi Yoshimitsu , Kim Kea‐Young , Senō Manabu , Kawai Tohru
Published: April 2003

The esterification of the carboxyl group in copoly(γ‐benzyl‐L‐glutamyl‐L‐glutamic acid) was carried out using N‐hydroxysuccinimide and dicyclohexylcarbodimide to yield the activated site for the coupling reaction with amino compounds. The α‐helix stability of the reactive copolymer thus obtained is remarkably affected in the presence of succinimide ring. This copolymer was proved to react nearly completely with amino alcohols such as 2‐aminoethanol, 3‐aminopropanol, and diethanolamine. The copoly(N5‐hydroxyalkyl‐L‐glutamine) thus prepared is insoluble in water, since the benzyl ester remains in this copolymer. The copoly(α‐amino acids) having another functional group were also prepared using aminoalkylsilane. Crosslinked poly(α‐amino acids) were prepared by the reaction of the reactive copolymer with a low‐molecular‐weight polymer of PBLG having one amino group on each end of its main chain which was obtained from the corresponding NCA using p‐diaminobenzene as an initiator. Another crosslinked polymer was prepared using an alkyl diamine such as 1,6‐diaminohexane or 1,12‐diaminododecane as a crosslinking reagent. The crosslinked copoly(α‐amino acids) bearing the activated site are able to further react with various compounds having amino groups.
Mechanism of thermal depolymerization of trimethylsiloxy‐terminated polydimethylsiloxane
Authors: Zeldin Martel , Qian Bo‐Rong , Choi Sung J.
Published: April 2003

“Catalyst‐free” trimethylsilyl end‐blocked polydimethylsiloxanes of Mn = 68,300 and 111,000 were isothermally depolymerized above 400°C. The volatilized products were a mixture of cyclic oligomers and trace quantities of Me3Si(OSiMe2)nOSiMe3 (n = 0,1). The relative degree of polymerization was followed as a function of fractional conversion. The data were consistent with the oretical curves for a mechanism involving initiation by random siloxane bond cleavage followed by a rapid and complete unzipping of the kinetically active fragments. It is suggested that catalysis may be responsible for the initiation process, thus accounting for the low activation energy (43 Kcal/mol) relative to the siloxane bond energy (108 kcal/mol).
Kinetics of photopolymerization of acrylamide initiated by copper (II)–bis(amino acid) chelates in aqueous solution. II
Authors: Namasivayam C. , Natarajan P.
Published: April 2003

The kinetics of photopolymerization reactions of acrylamide initiated by copper (II)–bis(amino acid) chelates with amino acids glutamic acid, serine, or valine were studied at 30°C. The extent of monomer conversion increases with increased initiator concentration and falls off after reaching a maximum. Analysis of the results shows that for lower concentrations of the initiator, the rate of monomer disappearance is proportional to light absorption fraction f[monomer] and the square root of the intensity. At higher concentrations of the initiator, the rate of monomer disappearance is proportional to Fε/[initiator]1/2; the monomer exponent is 1.5 and the intensity exponent 0.5. Mutual termination of the radicals is proposed at lower concentrations of the initiator; at higher concentrations of the initiator termination of the initiator radical by the copper (II) complex along with mutual termination occurs. The initiator radical species is identified from flash photolysis studies of these complexes as the Cu(I)‐coordinated radical. The effect of pH on the monomer conversion is explained. The data indicate a free‐radical mechanism of polymerization and a reaction scheme is proposed for the polymerization reactions.
Radiation curing of methacryloyloxyalkyl carbonates
Authors: Barkalov I. M. , Kiryukhin D. P. , Munikhes V. M.
Published: April 2003

The results of studying the radiation curing of methacryloyloxyalkyl carbonates (MC), a new type of oligomer, are presented. These oligomers are notable for their high rates of radiation curing. The radiation yield G(–M) is 2 × 105 for MC and 2 × 104 for triethylene glycol dimethyacrylate. The polymerization rate of MC appeared to be proportional, independent of the conversion degree, to the irradiation dose rate in the power of 0.9–1.0 (for dose rates ranging from 0.4 to 15 rad/s). In regard to the temperature dependence of the polymerization rate of MC for small conversion degrees, two temperature regions with different values of effective activation energy (18–20 kcal/mol and 2 kcal/mol, respectively) were observed. When an irradiated MC sample is being unfrozen, its polymerization occus in the region of devitrification (220–240°K). As distinct from mass polymerization, in the polymerization of MC solutions in acetone and benzol the mobility of growing chains increases so that the bimolecular termination becomes possible and the limiting conversion of double bonds is derived. Rather small irradiation doses necessary for curing MC and the proportionality of the radiation‐induced polymerization rate to the dose rate make these oligomers valuable for various industrial applications.
Determination of in‐cage and out‐of‐cage recombination of initiator radicals in solution polymerization using labeled initiators
Authors: Fink J. K.
Published: April 2003

The amount of in‐cage and out‐of‐cage recombination of initiator radicals has been measured by recovering the recombination products of simultaneous decomposition of an unlabeled and a deuterium‐labeled initiator. The occurrence of recombination products generated from both an unlabeled and a deuterium‐labeled initiator fragment, which can be monitored in a mass spectrometer, indicate out‐of‐cage recombination. It turned out that in the course of decomposition of dibenzoylperoxide in benzene, biphenyl was not produced by direct recombination of the phenyl radicals originally generated, but rather by interaction with benzene. Upon decomposing azoisobutyronitrile in various solvents, however, both in‐cage recombination and out‐of‐cage recombination were observed. When small amounts of styrene were added to such systems, the initiator radicals tended rather to react with styrene than to undergo out‐of‐cage recombination.
Photoinduced electron transfer at the polymer‐solution interface. II. Effects of ionic environment
Authors: Tazuke Shigeo , Takasaki Ryuichiro
Published: April 2003

Three types of polymer electron transfer sensitizer were prepared by copolymerization of 1‐pyrenylmethyl methacrylate with styrene (I), vinylbenzyltriethylammonium chloride (II), and sodium p‐styrenesulfonate (III). Irradiation of the pyrenyl group in the presence of leuco crystal violet (LCV), in homogeneous or in heterogeneous systems, induced the formation of crystal violet cation (CV+) in air. The reactivity of I, II, and III was in the order of II > I > III in both systems; this was rationalized in terms of the Coulombic effect. The effect of charge is much greater for the heterogeneous systems. High‐charge density on the polymer surface and enhanced polymer‐solvent affinity account for the high reactivity of II. The high quantum efficiency, coupled with the advantage of facile product separation, warrants the practical application of interfacial sensitization.
Polymerization of acrylamide with ceric ion–malic acid redox pair
Authors: Misra G. S. , Khatib J. I.
Published: April 2003

The polymerization of acrylamide (M) in aqueous sulfuric acid medium initiated with ceric ammonium sulfate–malic acid redox pair was investigated at 35 ± 0.2°C under nitrogen atmosphere. The initiation was caused by the free radical generated by the decomposition of the complex formed between ceric ion and malic acid (MA). The rate of monomer disappearance was proportional to the first power of malic acid, ceric ion, and monomer concentrations at lower ceric ion concentrations. However, at higher ceric ion concentrations the rate was independent of [Ce(IV)]. The rate of ceric ion disappearance was proportional to [MA] and [Ce(IV)] but independent of [M] at lower ceric ion concentrations. The activation energy was found to be 57.74 kJ/mol. Sulfuric acid retarded the reaction. Molecular weights increased with increasing [M] and decreasing [Ce(IV)].
Isomerization polymerization of β‐propiolactones carrying side‐chain ester groups
Authors: Araki Takeo , Hayase Shuzi , Nakamura Akira
Published: April 2003

Based on our recent discovery of the isomerization polymerization of β‐(2‐acetoxyethyl)‐β‐propiolactone into poly‐δ‐ester,1,2 we examined the generality of this phenomenon by using two related monomers. The catalysts were (EtAlO)n and Et(ZnO)2ZnEt. The side‐chains in the monomers selected were the (CH3)2CHCOOCH2CH2(2) and (CH3)CICHCOOCH2CH2(3) groups in which steric effects are almost identical but electronic effects are in opposition. The monomers yielded isomerized poly‐δ‐ester units, depending on the terminal substituent groups in the side‐chain. These observations can be interpreted with the bicyclic intermediate proposed in the earlier work. Monomer (2) was reactive and produced a poly‐δ‐ester structure most readily, probably because of the higher electron density at the side‐chain ester group which coordinated with the catalyst. In contrast, monomer (3) was less reactive, and the probability of isomerization was the lowest, i.e., the electron deficient side‐chain ester group apparently interfered with the formation of the intermediate, especially in the Zn‐catalysis. Equibinary random copolymers were prepared from (2) and (3) according to the catalyst and polymerization conditions chosen.
Optically active copolymers from p‐vinyltrifluoroacetophenone
Authors: Altomare A. , Carlini C. , Ciardelli F. , Pearce E. M.
Published: April 2003

Copolymers of p‐vinyltrifluoroacetophenone (VTFA) with optically active (−)‐menthyl acrylate (MtA) have been prepared by free radical initiation. The values of reactivity ratios (rVTFA = 4.28 and rMtA = 0.26) indicate that counits are inserted substantially at random into the copolymer macromolecules. CD spectra show a couplet typical of exciton splitting in the absorption region of trifluoromethylphenyl (TFA) chromophore. Dependence of ellipticity on composition and sequence distribution suggests that TFA chromophores are in a chiral environment provided by the dissymmetric conformation of the copolymer macromolecules.
Alternating copolymerization of methyl acrylate with donor monomers having a protected amine group
Authors: Majumdar Ramendra N. , Yang Shih‐Liang , Harwood H. James
Published: April 2003

Attempts were made to copolymerize p‐aminostyrene, p‐acetamidostyrene, N‐methyl‐p‐aceta‐midostyrene, N‐(4‐vinylphenyl) phthalimide, N‐vinyl succinimide, and N‐vinyl phthalimide with methyl acrylate complexed with ethyl aluminum sesquichloride. Only reactions involving N‐(4‐vinylphenyl)phthalimide and N‐vinyl phthalimide yielded alternating copolymers. N‐vinyl succinimide gave nonalternating copolymers insoluble in common solvents and the other monomers did not copolymerize. In some cases, the conventional radical copolymers were prepared for comparison purposes. The reactivity ratios of the free‐radical initiated copolymerization of methyl acrylate (I) with N‐(4‐vinylphenyl)phthalimide (II) were r1 = 0.14 and r2 1.56. The alternating copolymers were studied by 1H‐NMR and 13C‐NMR spectroscopy. The alternating copolymer of N‐(4‐vinylphenyl)phthalimide with methyl acrylate was hydrazinolyzed to form the alternating copolymer of methyl acrylate with p‐aminostyrene. Hydrazinolysis of the alternating copolymer of methyl acrylate with N‐vinyl phthalimide removed the phthalimide moiety and generated vinyl amine units which readily cyclized with neighboring methyl acrylate units to form copolymers that contained five‐membered lactam rings. The infrared (IR) spectra of the hydrazinolyzed products contain bands due to amine or amide groups and are devoid of the characteristic bands of the phthalimide ring.
Dehydrochlorination of vinylidene chloride‐vinyl chloride copolymer by aqueous sodium or potassium hydroxide solutions under two‐phase conditions
Authors: He Fei‐Feng , Kise Hideo
Published: April 2003

The reaction of solid copolymer of vinylidene chloride and vinyl chloride with aqueous sodium or potassium hydroxide solutions in the presence of quaternary ammonium or phosphonium salts as phase transfer catalysts gave dehydrochlorinated products with chlorine‐substituted polyene structure. Among the catalysts used tetrapropylammonium bromide was the best and potassium hydroxide was more active than sodium hydroxide. The activity of quaternary ammonium salts was discussed in terms of hydrophile–lipophile balance. The effects of temperature and the concentration of the bases and catalysts were investigated to obtain the optimum reaction condition. Treatment of the polymer films and solutions in tetrahydrofuran with aqueous bases under two‐phase conditions also produced dehydrochlorinated films and powders.
Mutarotation of optically active poly(cis‐5‐ethyl‐D‐proline)
Authors: Yang Wayne W.‐Y. , Overberger C. G. , Venkatachalam C. M.
Published: April 2003

The mutarotation between form I and form II of poly(cis‐5‐ethyl‐D‐proline) has been experimentally realized. A number of hydrogen‐bond‐forming solvents have been found effective in initiating the mutarotational process. The rate of mutarotation seems to be proportional to the acidity of the active solvent. The enthalpy of activation energy for the mutarotation is estimated from the first‐order kinetics at the lower conversion by means of the Arrhenius equation to be approximately 16.7 kcal/mol. The solvent‐polymer interactions are proven to be one of the important driving forces for the mutarotation. The specific site at which hydrogen bonding takes place has been determined to be the carbonyl group of the amide by infrared spectroscopic techniques. The molecular reason for the greater susceptibility of poly(cis‐5‐ethyl‐L‐proline) II to the solvent effect than poly(cis‐5‐ethyl‐L‐proline) I can be satisfactorily explained by the relatively more extended structure of form I than form II. The mechanism for the mutarotation undoubtedly involves a cis‐trans isomerization of the amide bond. The conformation of the transient states during the mutarotational process is still evidently helical in nature, probably consisting of long poly(cis‐5‐ethylproline) I and II segments.
The structure of plasma‐polymerized toluene: A solid‐state 13C‐NMR study of isotopically labeled polymers
Authors: Kaplan S. , Dilks A.
Published: April 2003

A detailed magic angle spinning 13C‐NMR investigation of the intractable polymer prepared by plasma polymerization of toluene and isotopically labeled toluene led to a proposed model for the structure of the polymer and suggested some of the likely processes that occur in the gas phase leading to film formation. From the 13C spectra four resolved resonances permitted the determination of the contribution of nonprotonated and protonated unsaturated as well as methyl and other aliphatic carbons to the polymer structure. Specific 13C isotopic labeling of the methyl and phenyl C‐1 toluene carbons in the injected liquid vapor allowed the destination of these carbons in the deposited polymer to be traced. The dominant structure is derived primarily from two precursors: benzyl radical and toluene itself. The 13C data further requires a net saturation of ca. 30% of the toluene double bonds and a net displacement of hydrogen by carbon on ca. 20% of the toluene ring carbons.
Syndiotactic 1,2‐polybutadiene with Co‐CS2 catalyst system. I. Preparation, properties, and application of highly crystalline syndiotactic 1,2‐polybutadiene
Authors: Ashitaka Hidetomo , Ishikawa Hideo , Ueno Haruo , Nagasaka Akira
Published: April 2003

Highly crystalline syndiotactic 1,2‐polybutadiene (s‐PB) having melting point (mp) up to 216°C was obtained by using a Co(acac)3‐AIEt3‐CS2 catalyst. The polymer with mp 208°C was found to have 99.7% 1,2 content and 99.6% syndiotacticity by 1H and 13C‐NMR measurements. The s‐PB can be molded by addition of a stabilizer such as 2,6‐di‐t‐butyl‐4‐hydroxymethylphenol into fiber, film, and various shaped articles. The physical properties presented in the present article include stress‐strain and dynamic mechanical behavior. The highly crystalline syndiotactic 1,2‐polybutadiene was applied to a carbon fiber and UBEPOL VCR (cis‐1,4‐polybutadiene reinforced by fibrous syndiotactic 1,2‐polybutadiene).
The reactions of polyacetylene with trimethyloxonium hexachloroantimonate. Covalent doping of (CH)x
Authors: Brant P. , Weber D.
Published: April 2003

Polyacetylene, (CH)x, has been doped with trimethyloxonium hexachloroantimonate, (CH3)3O+SbCl(1), in dichloromethane and acetonitrile. The maximally doped (CH)x films have moderate conductivities [σRT(CH2Cl2) = 10, σRT(CH3CN) = 0.7 Ω−1 cm−1]. Reactions between 1 and (CH)x CH2Cl2 or CH3CN were followed in situ by 1H nuclear magnetic resonance spectroscopy and x‐band electron spin resonance spectroscopy. It was found that the reactions in the two solvents are different. In dichloromethane the dopant is SbCl5, which forms from the decomposition of 1, and doping proceeds by electron removal from (CH)x chains. Based on the ESR signal loss, an estimate can be made of the diffusion rate of SbCl5, into the (CH)x fibrils in CH2Cl2; it is found to be ca. 10−17 cm2/s. In acetonitrile the dopant appears to be either CH3CNCH, H+, CH, or a combination of one or more of these dopants. It is postulated that the CH3CNCH, CH, and/or H+ dopant covalently binds to the (CH)x chain. X‐ray photoelectron spectra show that films doped with excess 1 in both solvents have approximately one SbCl per 33 CH units.
Syndiotactic 1,2‐polybutadiene with Co‐CS2 catalyst system. II. Catalysts for stereospecific polymerization of butadiene to syndiotactic 1,2‐polybutadiene
Authors: Ashitaka Hidetomo , Jinda Kazuya , Ueno Haruo
Published: April 2003

Butadiene is polymerized by cobalt compound–organoaluminum–CS2 catalysts to give highly crystalline syndiotactic 1,2‐polybutadiene (s‐PB) having melting point up to 216°C. An aluminum‐free catalyst, Co(C4H6)(C8H13)‐CS2, is also effective. Syndiotactic polymerization with Co(C4H6)(C8H13)‐CS2 is not interrupted by the addition of protic substances such as water and alcohol, but is influenced by donor or acceptor substances. The donor molecule, e.g., dimethylsulfoxide or dimethylformamide, decreases the stereoregularity, i.e., syndiotacticity and 1,2 content. An acceptor molecule of organoaluminum with appropriate acidity such as AlEt3‐AlEt2Cl or tetraethylaluminoxane increases the molecular weight, stereoregularity, and yield of the polymer. In the presence of CS2 a mixture of cis‐PB and s‐PB was obtained by using Co(octoate)2‐AlEt2Cl‐H2O, with molar ratio H2O/Co less than unity. In the case of H2O/Co > 1, only cis‐PB was obtained. By the addition of donor substances such as ester, ether, nitrile, and AlEt3, s‐PB was obtained even when H2O/Co > 1. The amount and ratio of cis‐PB and s‐PB are dependent upon the nature and amount of the additives.
Syndiotactic 1,2‐polybutadiene with Co‐CS2 catalyst system. III.1H‐ and 13C‐NMR study of highly syndiotactic 1,2‐polybutadiene
Authors: Ashitaka Hidetomo , Inaishi Kazutoshi , Ueno Haruo
Published: April 2003

The 1H and 13C‐NMR spectra of highly crystalline syndiotactic 1,2‐polybutadiene (s‐PB) are discussed in order to clarify the mechanism of butadiene polymerization with cobalt compound–organoaluminum–CS2 catalysts. Cis opening of the double bonds in the syndiotactic polymerization is affirmed by the study of the copolymer from perdeuteriobutadiene and cis,cis‐1,4‐dideuteriobutadiene. S‐PB (mp 210°C) has 99.7% 1,2 units, 0.3% isolated cis‐1,4 units, and 99.6% syndiotacticity. Polymer ends (2‐methyl‐3‐butenyl group and conjugated diene structure) are also determined. The differences in free energy of activation between 1,2 and cis‐1,4 propagation and between syndiotactic and isotactic propagation are 14.0 and 9.6 kcal/mol, respectively, for Co(acac)3‐AlEt3‐AlEt2Cl‐CS2, and 6.7 and 5.7 kcal/mol, respectively, for the aluminum‐free Co(C4H6)(C8H13)CS2 system. The conformation of s‐PB in o‐dichlorobenzene at 150°C is described by the sequence (tt)1.6(gg)(tt).
Surface ozonation and photooxidation of polyethylene film
Authors: Peeling James , Clark David T.
Published: April 2003

High‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) films were oxidized by treatment with ozone and by photooxidation with a low‐pressure mercury lamp. The changes that resulted in the surfaces of the films were followed by ESCA. On ozonation, the surface of LDPE initially is oxidized more rapidly than that of HDPE; however, extended ozonation produces a surface composition that corresponds to C8O for HDPE and to C18O for LDPE. The surface oxidation products are mainly carboxyl groups, with lower levels of carbonyl and CO groups. For both polymers photooxidation provides more extensively oxidized surfaces than ozonation, although the surface of HDPE oxidizes slightly faster than that of LDPE treated under identical conditions. In both cases the surface stoichiometry after extensive photoxidation is C6O. The functional groups formed are mainly carboxyl and CO. The effects of ozonation and photooxidation on the polyethylene surfaces are compared with those produced by several other means of surface oxidation.
New polymer‐supported catalysts. (Polyvinylchloride‐containing redox) catalyst cyclopentadienyl iron moiety: [η5C5H5Feη6C6(CH3)5CH2]+
Authors: Román E. , Valenzuela G. , Gargallo L. , Radic D.
Published: April 2003

New polymer‐supported catalysts that contain the redox cyclopentadienyl iron moiety [η5C5H5Feη6C6(CH3)5CH2]+ were prepared with polyvinylchloride (PVC) as support. The active center is attached as a pendant organometallic moiety in the side groups of the PVC chain. Metallocenic groups and the supported polymers with various Fe content were analyzed by spectroscopic techniques and by polarographic and cyclic voltammetry. The absorption spectra show a similar profile to that of the nonsupported cation, which indicates that the supported polymer contains side groups in the chain with metallocenic structures. The new polymer‐supported catalysts were characterized by viscometric measurements and by differential calorimetry (DSC). A linear relationship between intrinsic viscosity/[η] and the Fe content was observed. The glass transition temperature (Tg) values are higher than those of PVC without modification.
Oligomerization of styrene over molybdenum oxide on silica‐alumina catalyst
Authors: Kumar V. G. , Rao M. Rama , Ravindran P. V. , Rao K. V. C.
Published: April 2003

Styrene was found to yield saturated and unsaturated linear oligomers in the presence of a surface‐supported catalyst, molybdenum oxide on silica‐alumina. The reaction rates, the structure, and the molecular weight distribution of the products were found to be controlled by the choice of the solvent. Higher‐molecular‐weight fractions were favored in isooctane, whereas low‐molecular‐weight oligomers were preferred in dioxane. The reaction followed first‐order kinetics with respect to the monomer. End‐group analysis suggests a probable cationic mechanism. Approximate transfer constants KtrKp were deduced from product distribution data. The behavior of the surface‐supported catalyst was compared with other cationic catalyst systems.
Conformational aspects of a “very simple” chain: Polyacetylene
Authors: Cernia Enrico , D'Ilario Lucio
Published: April 2003

Potential energy calculations of the isolated chains of trans‐ and cis‐polyacetylene (PA) were made to obtain information on the most probable conformations. Different sets of van der Waals potential functions, different values for the barrier height to the bond rotation, and different geometries for the repeating unit were used. Calculations were also made of the seven‐atom chains of PA for which independent rotations were allowed around three consecutive “quasi‐single” bonds. The deepest minima on the potential energy map of the trans three‐atom chain were consistent with an all‐trans conformation (the most stable one) and with a “distorted cis” conformation, which deviated from the planarity because of the repulsion between hydrogen atoms 1 and 4. The energy maps of the cis polymer showed two minima, both of which corresponded to nonplanar conformations. From the seven‐atom chain analysis of trans‐ and cis‐ PA, in addition to the stable conformations obtained for the three‐atom chains, other minima corresponded to triplets formed from both conformers.
Degradation of PVCs obtained by controlled chemical dehydrochlorination
Authors: Iván Béla , Kennedy Joseph P. , Kelen Tibor , Tüdõs Ferenc , Nagy Tibor Tamás , Turcsányi Béla
Published: April 2003

Thermal and thermo‐oxidative degradation of poly(vinyl chloride)s (PVCs) containing increased concentrations of allylic chlorines, PVC(A)s, prepared by controlled chemical dehydrochlorination with potassium‐t‐butoxide (t‐BuOK) have been studied. The introduction of small amounts of internal allylic chlorines into PVC significantly decreases the thermal and thermo‐oxidative stability of the resin. A linear relationship exists between the initial rates (VHCl)0 of thermal and thermooxidative dehydrochlorination of solid PVC(A)s and the concentration S of internal allylic chlorines. Both the slope and the intercept of the thermo‐oxidative (VHCl)0 vs. S plot are higher in oxygen than those obtained in nitrogen at the same temperature; this finding is attributed to fast oxidation of polyenes, and to peroxy radicals formed during polyene oxidation, which initiate subsequent HCl loss by attacking normal repeat units in PVC. The extent of HCl loss as a function of time during thermal degradation of PVC(A)s in intert solvent shows a rapid initial phase followed by a slower stationary phase. The first phase is due to dehydrochlorination involving the labile chlorines, while the stationary phase indicates random initiation of HCl loss at normalCH2CHCl repeat units. Initial rates of HCl loss increase with S, while the rates of HCl loss during the stationary phase are independent of S. The rate constant of initiation of HCl loss at internal allylic chlorines is almost four orders of magnitude higher than that of random initiation; however, the former is still orders of magnitude lower than that of chain propagation. Quantitative analysis of UV‐visible spectra of PVC(A)s degraded in solution suggests geometric polyene distribution. The average length of polyenes decreases as the extent of HCl loss increases and reaches a constant value of ca. 3 at ca. 1% HCl loss for all the investigated PVC(A) samples.