bluuebunny/crossref_metadata_2025 huggingface dataset:
C3 cyclopolymerization. I. Is the cyclopolymerization of 1,3‐bis(p‐vinylphenyl)‐propane by means of radical or anionic initiators possible?
Authors: Nishimura J. , Ishida Y. , Mimura M. , Nakazawa N. , Yamashita S.
Published: April 2003

Polymerization of 1,3‐bis(p‐vinylphenyl) propane (St‐C3‐St) was investigated by using radical and anionic initiators. Radical polymerization yielded linear polymer with pendant styryl groups in pertinent conditions without gelation. Anionic polymerization with n‐butyllithium and sodium naphthalene produced insoluble polymers that, according to infrared (IR) spectroscopy, had no cyclized units. On the other hand, phenylmagnesium bromide gave soluble polymer in HMPA‐benzene mixed solvent. Zero‐valent nickel catalyst also gave soluble polymer. The soluble polymers could be analyzed by several spectroscopies, and it was confirmed that those obtained by anionic and coordination polymerization had no [3.3]paracyclophane units in the main chain. From these results it was concluded that cationic propagation could be assumed if the polymer Of St‐C3‐St contained [3.3]paracyclophane units in the main chain.
C3 cyclopolymerization. II. Charge‐transfer cyclopolymerization of 1,3‐bis(p‐vinylphenyl)‐propane
Authors: Nishimura J. , Mimura M. , Nakazawa N. , Yamashita S.
Published: April 2003

The thermal and photoinduced polymerization of 1,3‐bis(p‐vinylphenyl)propane was carried outby using tetracyanoethylene as a strong electron acceptor in several solvents. This cyclopolymerization produced polymer that contained [3.3]paracyclophane units in the main chain. The solvent and additive effect of polymerization inhibitors as well as the polymer structure suggest clearly that both polymerization proceeded in a cationic mechanism.
Trapping alloxan or ninhydrin radical anions with polymer cations
Authors: Endo Takeshi , Okawara Makoto
Published: April 2003

Alloxan or ninhydrin radical anions which are obtained from alloxantin or hydrindantin, respectively, by treatment with triethylamine could be trapped in stable condition by polymer cations that contains 1‐benzyl‐3‐carbamoyl pyridinium or 1‐benzylpyridinium salts structure.
Grafting vinyl monomers onto silk fibers. IX. Graft copolymerization of methyl methacrylate onto silk using peroxydiphosphate‐thiourea redox system
Authors: Nayak Padma L. , Lenka Subasini , Mishra Munmaya K.
Published: April 2003

The graft copolymerization of methyl methacrylate (MMA) onto silk in aqueous media initiated by the potassium peroxydiphosphate‐thiourea redox system was studied at 50°C. The rate of grafting was determined by changing [monomerl], [thiourea], [initiator], acidity of the medium, reaction medium, and temperature. A significant increase percent of grafting was noticed with increasing monomer concentration to 84.49 × 10−2 mole/liter and the further increase is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea (Tu) concentration to 25 × 10−5 mole/liter; then it decreases. A measurable increase in graft yield was observed with an increase in acidity of the medium. Graft yield increases to a certain temperature, i.e., 50°C, and then it decreases. The graft yield increases with an increase of initiator concentration to 60 × 10−4 mole/liter; then it decreases. The graft yield is medium dependent. A suitable kinetic path has been proposed and the rate equation has been derived.
Surface grafting of polyethylene by mutual irradiation in methyl acrylate vapor. IV. Kinetic analysis by quartz helix microbalances
Authors: Yamakawa Fumio , Yamakawa Shinzo
Published: April 2003

A detailed kinetic study of the γ‐ray‐induced surface grafting of methyl acrylate (MA) onto polyethylene (PE) has been investigated by using quartz helix microbalances. Under typical graft conditions, the grafting rate increases, levels off, and then accelerates with irradiation time; i.e., the typical growth process of the surface grafting consists of an initial stage having an increasing rate of grafting, an intermediate stage having a constant rate, and an advanced stage having an accelerated rate. A homopolymer layer (consisting only of an MA component) begins to be formed on the inner graft copolymer layer (consisting both of MA and PE components) at the transition zone in grafting rate after a duration of a constant rate of grafting. Therefore, the increasing rate in increasing rate in the intial stage of grafting reflects the graft copolymerization in the graft copolymer layer (inside the PE sheet), and the increasing rate in the advanced stage reflects the growth of the homopolymer layer. Under grafting reflects the graft tage reflects the growth of the homopolymer layer. Under grafting conditions by which the homolymer layer is not formed throughout the whole grafting process, the surface grafting remains remains in the initial stage. On the order hand, under grafting conditions by which the homopolymer layer begins to be formed from an early stage of grafting, the surface grafting proceeds rapidly from the initial stage to the advanced stage and thus skips the intermediate stage.
Studies on the graft polymerization of carbon fibers. I. The graft polymerization of acrylate monomers and their properties
Authors: Tanaka Akira , Fujisawa Takao , Yosomiya Ryutoku
Published: April 2003

Graft polymerization was carried out on carbon fibers subjected to various types of oxidation treatment and on acrylate (methyl, ethyl, andn‐butyl) with benzene solvent and mainly benzoyl peroxide as initiator according to the nitrogen‐displacement sealed‐tube polymerization method. In comparison with carbon fibers subjected to air oxidation treatment, carbon fibers subjected to nitric acid oxidation treatment showed easier graft polymerization, and grafting became easier with increasing degree of nitric acid oxidation. The following relationship is established between the graft reaction ratio (a) and the polymerization time (t):da/dt=K(100−a). For graft polymerization with lauroyl peroxide (LPO), benzoyl peroxide (BPO), and α,α′‐azobisisobutyronitrile (AIBN) as initiator, LPO showed the largest transfer reaction constant, followed by BPO; AIBN showed the smallest value. Grafting showed a tendency to become easier for monomers with a larger displacement radical group. For the graft polymerization reported in this article, it was believed that the affinity between carbon fibers subjected to oxidation treatment and to monomer influenced the result. For graft polymerization using acrylic acid as the comonomer, percent grafting increased notably. It is believed that, in this, in this case, apparent grafting by dipole‐dipole interaction of the COOH group of the carbon fiber subjected to oxidation treatment and the COOH group of the polymer occurs according to the theory of Riess et al. Tensile strength and breaking elongation of graft carbon fibers showed a tendency to increase with an increase in percent grafting, whereas Young's modulus showed a tendency to decrease. The contact angle with water showed a tendency to increase with increasing percent, whereas the contact angle with ethylene glycol and phenylglycidilethyl showed a tendency to decreasing percent grafting.
The preparation of 1,4‐dicarbonyl, 4‐oxo nitrile, furan, and pyrrole monomers
Authors: Ponticello I. S. , Pastor P. C.
Published: April 2003

Treatment of cyclopentadiene‐blocked acrolein with α,β‐unsaturated ketones, esters, and nitriles in the presence of a thiazoliurn salt under basic conditions led to a simple method for the preparation of acetonylmethyl Vinyl ketone, 2‐carboxymethylethyl vinyl ketone, and 2‐cyanoethyl vinyl ketone. In addition, the cyclopentadiene‐blocked acetonylmethyl vinyl Ketone was converted to heterocyclic furan and pyrrole monomers.
Photochemistry of polymeric systems. I. Photocrosslinking of polymers and copolymers containing pyridine N‐oxide groups
Authors: Decout Jean‐Luc , Lablache‐Combier Alain , Loucheux Claude
Published: April 2003

Vinylpyridine‐N‐oxide units were introduced in polymeric chains in order to study their photocrosslinking. Copolymers of styrene and 4‐vinylpyridine‐N‐oxide were especially synthesized and studied. The methods used for characterization of photocrosslinked films were a “photoresist test” or the measurement of the insolubility and of the swelling ratio. The Cleavage of the N‐oxide bond was responsible for the photocrosslinking. The competitive formation of carbonyl compounds took place and decreased the rate of photocrosslinking. This last reaction is favored by triplet‐state quenchers. The photosensitivity of the copolymers was determined as a function of the wavelength of the radiation used. When the photocrosslinking proceeded, a film of the copolymeric material became transparent in the 280–320‐nm range. Thick films could therefore be completely photocrosslinked when irradiated in this range of wavelength.
Stabilization at high temperatures
Authors: Brun E. B. , Shustova O. A. , Kuchanov S. I. , Gladyshev G. P.
Published: April 2003

A general detailed model of polymer oxidative degradation in the presence of a stabilizer‐oxygen acceptor was considered. The motion of the degradation zone boundary and the sample lifetime were obtained for various conditions of the process. In particular, it is shown that within the given concentration immobile oxygen acceptor has the best stabilizing properties. The theoretical results are compared with the experimental data obtained by using two independent methods: polymer sample cracking and a change in the ESR signal. Good agreement between theory and experiment was obtained.
Synthesis of 1,1‐dichloro‐2,2‐bis(4‐hydroxyphenyl)‐ethylene via ammonia or methylamine dehydrochlorination. A bisphenol for the preparation of highly flame‐resistant polycarbonates
Authors: MacLaury M. R. , Chan A. D. , Colley A. M. , Saracino A. , Toothaker A. M.
Published: April 2003

Ammonia used as both reactant and solvent has been shown to dehydrochlorinate 1,1,1‐tri‐chloro‐2,2‐bis(4‐hydroxyphenyl)ethane smoothly to 1,1‐dichloro‐2,2‐bis(4‐hydroxyphenyl)ethylene. The reaction is complete in 1 hr at 100°C, and after two crystallizations from methanol/water affords polymerizable quality monomer for the synthesis of highly flame‐resistant polycarbonates. The use of organic solvents in combination with ammonia does not offer any rate advantages over pure ammonia. Primary and secondary amines also can be used to effect the dehydrochlorination but, except for the methylamine, are significantly less reactive and lead to less pure product than amonia.
Polymeric p‐benzoquinone‐tin derivatives as thermal stabilizers for rigid poly(vinyl chloride). I. Preparation of the stabilizers
Authors: Yassin Ahmady A. , Sabaa Magdy W.
Published: April 2003

The reaction of p‐benzoquinone with tin tetrachloride in the absence of solvents was investigated by isolation and identification of the reaction products. This reaction leads to the formation of polymeric quinone‐tin derivatives free from combined chlorine, chlorinated quinones, quinhydrone, and minute amounts of CI2 and HCI gases. The tin content varies accroding to the molar ratios of the reactants and reaches its maximum (72%) at the smallest SnCI4 ratio. The existence of the Sn‐Sn bond in the polymeric derivatives was confirmed chemically and spectroscopically. A mechanism based on the formation of radical intermediates which can account for the reaction products was developed. In view of their quinonoid nature, high thermal stability, and the presence of Sn‐Sn bonds, the polytin derivatives are to be investigated as radical traps in the stabilization of polymeric arcticles against radical degradation process.
Photorearrangements of hydrocarbon polymers with pendant double bonds
Authors: Golub Morton A. , Rosenberg Mark L.
Published: April 2003

A study was made of the microstructural changes that occur in ultraviolet irradiation under vacuum of thin films of 1,2‐poly(cis‐1,4‐hexadiene) (CHD), 1,2‐poly(trans‐1,4‐hexadiene) (THD), 1,2‐poly(trans‐1,3‐pentadiene) (TPD), equibinary (1,2,‐1,4) polybutadiene (EB), and equibinary (3,4‐1,4) polyisoprene (EI). These polymers—all containing pendant double bonds—undergo important photoinduced loss of unsaturation, presumably through cyclization of the double bonds, by analogy to the previously reported photocyclization of 1,2‐polybutadiene (VB) and 3,4‐polyisoprene (VI)films. For the equibinary polymers, which contain internal as well as external (or pendant) double bonds, the loss of unsaturation is considered to involve photocyclization of 1,2‐1,4 and 1,2‐1,2 dyads in EB and of 3,4‐1,4 and 3,4‐3,4 dyads in EI. Accompanying thecyclization process in CHD, THD, and TPD is a direct photochemical cis‐trans isomerization of CHCHdouble bonds analogous to that originally noted for 1,4‐polybutadiene. The photorearrangements in the above polymers with pendant double bonds were compared to the corresponding thermally induced rearrangements reported previoulsy;for VB and VI, in particular, the thermal, photo‐and radiation‐induced cycli‐zations were found to be very similar, possibly having a common nonradical, nonionic mechanism involving excited double bonds.
Mössbauer study of the γ‐induced polymerization of iron methacrylate
Authors: Sarma P. R. , Tripathi K. C. , Gupta H. M.
Published: April 2003

A Mössbauer spectroscopic study of the γ‐induced polymerization of iron methacrylate has been made. Iron‐methacrylate is a solid monomer. This monomer, in a powdered form, was polymerized by irradiating with γ rays from a 60Co source. A number of Mössbauer spectra were taken after subjecting the sample to different cumulative doses of γ rays. The spectra were asymmetric doublets and the asymmetry changed as the polymerization proceeded. The changes in asymmetry have been correlated with the percentages of polymerization which were determined by two different methods, viz., chemical analysis and resistivity measurement.
The topochemistry of the catalytic systems on the surface of polymer supports
Authors: Dyachkovskii F. S. , Pomogailo A. D. , Bravaya N. M.
Published: April 2003

The method of spin labels based on stable iminoxyl radicals has been applied to the investigation of the topochemistry of polymer‐supported polyethylene‐grafting diallylamine (PE‐gr‐PDAA)and ofimmobilized catalytic systetms. The effective distances between fixed radicals are comparatively large (r̄ ∼ 25‐35Å for the case of functional groups of PE‐gr‐PDAA and r̄ ≥ 35Å for the case of fixed components of the catalytic systems). The demonstration of step‐by‐step penetration of the label into the functional cover (100‐300 Å) has been made. Correlation times were calculated in the temperature range 290‐440K. The dependence of log τc on 1/T shows two linear parts to the curve.The activation energies in the α region for PE‐gr‐PDAA and for the product of its interaction with TiCl4. Ti(OC4H9)4, and Al(C2H5)2Cl are equal to 13, 14, 24, and 13 Kcal/mole, respectively. The method has been applied to the investigation of Ziegler‐Natta immobilized catalytic systems. It has been noted that the labels are fixed not far from each other (r̄ ≤ 12Å) after the interaction of the catalytic components.
Tricarbonylchromium‐complexed phenylsiloxane polymers as stereoselective hydrogenation catalysts: Preparation and properties
Authors: Awl R. A. , Frankel E. N. , Friedrich J. P. , Swanson C. L.
Published: April 2003

Soluble tricarbonylchromium complexes were made by reacting Cr(CO)6 with a ladder polyphenylsilsesquioxane and a linear polydiphenylsiloxane. These new polymer Cr(CO)3 complexes were characterized by elemental Cr, infrared (IR), gel permeation chromatography (GPC), viscosity, and thermal analyses and were evaluated as stereoselective hydrogenation catalysts. Thermogravimetry studies demonstrated that the new complexes were more stable at 180–200°C in N2 than the corresponding complex from crosslinked polystyrene. These silicone polymer complexes catalyzed stereoselective hydrogenation of methyl sorbate to cis‐3‐hexenoate in cyclohexane and tetrahydrofuran (THF) and could be recovered from THF for recycling by precipitation‐fiItration. Catalytic activity and recyclability, however, were highly influenced by the solvent. Loss of catalytic activity associated with loss of Cr(CO)3 was observed on recycling. These results support a mechanisim that involves dissociation of Cr(CO)3, a significant portion of which cannot become reassociated with the polymer phenyl groups.
A molecular approach to flavor synthesis. I. Menthol esters of varying size and polarity
Authors: Jabloner H. , Dunbar B. I. , Hopfinger A. J.
Published: April 2003

For a series of menthol esters of increasing size and polarity, “mintyness” decreased rapidly as molecular weight increased. For molecular weights above about 700, the compounds were tasteless to a significant proportion of the taste panel. As polarity increased, the “sweet minty” taste of hydrophobic menthol esters became increasingly bitter, until water‐soluble menthol esters were strongly bitter. Bitterness was still apparent in quite high‐molecular‐weight water‐soluble esters; a different receptor may be involved for bitterness than for mint. An overall hypothesis relating flavor to molecular solubility parameters is proposed.
Polymerization of substituted cyclopropanes. III. Anionic polymerizations of 2‐substituted cyclopropane‐1,1‐dicarbonitriles
Authors: Cho Iwhan , Kim Jin‐Bong
Published: April 2003

To investigate further the anionic ring‐opening polymerization of substituted cyclopropane 2‐phenylcyclopropane‐1,1‐dicarbonitrile (I), 2‐ethylcyclopropane‐1,1‐dicarbonitrile (II), and 2,2‐dimethylcyclopropane‐1,1‐dicarbonitrile (III) were prepared and polymerized with sodium cyanide in N,N‐dimethylformamide. Under these conditions only I polymerized well. The polymer in I was soluble in hot sulfolane and the inherent viscosity was 0.5 dl/g (conc. 0.5 g in 100 ml). This result supports the previously postulated mechanism that a cyclopropane ring with properly positioned electron‐donating and electron‐withdrawing substituents can polymerize by opening the bond activated by a “push–pull” system.
Metal ion‐promoted hydrolyses of ligand esters in the presence of polycarboxylates
Authors: Takeishi Makoto , Watanabe Toshio , Niino Shogo , Hayama Shigeru
Published: April 2003

Copper(II), nickel(II), cobalt(II), and zinc(II) accelerated the carboxylate‐catalyzed hydrolyses of 2,4‐dinitrophenyl isonicotinate (DNPI) and 2,4‐dinitrophenyl picolinate (DNPP). The rate enhancement effect of the metal ions in the partially neutralized poly(methacrylic acid)‐ or poly(acrylic acid)‐catalyzed hydrolysis of DNPI was greater than that in the monomeric acetate ion‐catalyzed hydrolysis of this ester. This feature of the reactions was explained by the formation of a ternary complex composed of the polymer, the metal ion, and the substrate, in which the metal ion serves as a template for the nucleophilic reaction between the carboxylate groups along the polymer chain and the coordinated substrate. In DNPP the metal ion effect on the polycarboxylate‐catalyzed hydrolysis was smaller than that on the acetate ion‐catalyzed hydrolysis. This was interpreted as the result of differences in the structure of the complex.
Synthesis and thermomechanical properties of alternating copolymers containing bisphenol‐A
Authors: Pacansky T. J. , Schank R. L. , Gruber R. J. , Brandt K. A. , Bernardo M.
Published: April 2003

Alternating copolymers containing 4,4‐isopropylidene‐bisphenol (BPA) and comonomers with various degrees of polarity have been evaluated to find comonomer structures which provide low melt viscosity and good thermal stability. The materials were prepared by pyridine‐catalyzed nucleophilic displacement reactions similar to that for the preparation of BPA polycarbonate. The molecular weights of the polycarbonates depend on the concentration and nucleophilicity of the attacking diol and the concentration and stability of a colored pyridine‐chloroformate adduct formed during polymerization. The greatest thermal stability occurs for BPA–DMS and BPA–DEG. Thermomechanical flow measurements and Tg measurements were used to evaluate melt viscosity. The shapes and magnitudes of the Tg vs. Tf curves are sensitive to the copolymer chemical structure.
Polymerization of 2,7,8‐trioxabicyclo[3.2.1]octane and 2,8,9‐trioxabicyclo[3.3.1]nonane
Authors: Yokoyama Y. , Hall H. K.
Published: April 2003

Treatment of 2,7,8‐trioxabicyclo [3.2.1] octane (I) with electrophilic initiators gave polyorthoester composed of five‐ (70‐86%), six‐, and seven‐ (the sum, 14‐30%) membered rings. Treatment of 2,8,9‐trioxabicyclo [3.3.1]nonane (VI) with electrophilic initiators gave mainly oligomers. Trifluoromethane sulfonic acid in dichloromethane was particularly effective for the formation of dimer, 2,8,10,16,17,18‐hexaoxatricyclo[11.3.1.1]hexadecane. The analysis of the structures of poly‐I and oligomer‐VI suggests that I and VI are polymerized through an SN1 mechanism.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). VII. Synthesis and characterization of α,ω‐di(hydroxy)polyisobutylene
Authors: Iván Béla , Kennedy Joseph P. , Chang Victor S. C.
Published: April 2003

A new telechelic polyisobutylene diol, HOCH2PIBCH2OH, carrying two terminal primary hydroxyl end groups has been prepared from α,ω‐di(isobutenyl)polyisobutylene, CH2C(CH3)‐ CH2PIBCH2C(CH3)CH2, by regioselective hydroboration followed by alkaline hydrogen peroxide oxidation. Infrared (IR) spectra, 1H‐NMR analysis of the pure and silylated products, and ultraviolet (UV) spectra of phenylisocyanate‐treated diols indicate quantitative yields and two CH2OH termini per polyisobutylene chain. The viscosity of HOCH2PIBCH2OH is higher than that of the starting α,ω‐diolefin. The telechelic diol prepolymer opens new avenues to the synthesis of many new materials, e.g., polyurethanes.
Estimation of morphology of composite polymer emulsion particles by the soap titration method
Authors: Okubo Masayoshi , Yamada Akira , Matsumoto Tsunetaka
Published: April 2003

The occupied area (Am) of a sodium dodecyl benzene sulfonate molecule adsorbed on particles was measured by the soap titration method. The Am values are 214, 133, and 53 Å2 for poly(methyl acrylate) (I), poly(methyl methacrylate) (II), and polystyrene (III), respectively. For methyl metharylate‐styrene copolymer emulsions the additivity was established between the Am value and copolymer composition. Composite emulsion particles consisting of I/II, I/III, and II/III were prepared by seeded emulsion polymerization. For these emulsions the relationship between polymer composition at the surface layer calculated from the Am value and that in a particle calculated from the polymerization process was investigated. This relationship is remarkably affected by the order of polymerization, the hydrophilicity of polymer, the flexibility of the seed polymer, and the monomer addition method. The models of the morphology of these composite particles explain the results successfully.
Photoreactions of radicals during polyolefin photooxidation
Authors: Garton A. , Carlsson D. J. , Wiles D. M.
Published: April 2003

Polypropylene (PP) and polyethylene (PE) peroxy radicals undergo photoreactions, but under commonly encountered photodegradation conditions these reaction rates are much lower than those of conventional radical reactions; for example, for PP peroxy radicals in noon summer sunlight at 25°C their rate of photolysis to alkyl radicals is less than one‐tenth of their rate of hydrogen abstraction from the polymer. At lower temperatures( < −10°C) or when more intense radiation is used, however, peroxy radical photolysis becomes a proportionately more important source of alkyl radicals. In addition, occurrence of photoinduced radical combination is confirmed but is shown to be important only when photolysis generates an alkyl radical sufficiently close to a peroxy radical that termination can occur before oxygen reconverts the alkyl radical to a peroxy radical. This termination mechanism therefore becomes more important for radicals generated at lower temperatures when the average separation of a radical pair is lower.
Studies on stable free radicals. XVI. Copolymerizationo of a stable N‐oxyl biradical with p‐xylylene
Authors: Fujita Takashi , Yoshioka Takao , Soma Nobuo
Published: April 2003

Six copolymers were obtained by the reaction of a sterically hindered N‐oxyl biradical with pseudodiradical p‐xylylene using the reactivity of an N‐oxyl toward the carbon radical. The feed ratio of the N‐oxyl biradical to α‐chloro‐p‐xylene, which was used as the precursor of the pseudodiradical p‐xylylene, governed the properties of the copolymers produced. The copolymers with a terminalN‐oxyl group, were obtained when a 0.4‐1.2 molar ratio of the N‐oxyl biradical to α‐chloro‐p‐xylene. The polymerization process was also discussed.
Preparation of esters of styrene sulfonic acid and their emulsion copolymerization with isoprene
Authors: Siadat B. , Lenz R. W.
Published: April 2003

Sulfonate‐containing rubbers were prepared by emulsion copolymerization of isoprene and the secondary butyl ester of styrene sulfonic acid. Substantially gel‐free copolymers of relatively high sulfonate content were prepared. It was shown that hydrolysis of the ester copolymers with a suitable base can lead to the formation of ionically crosslinked elastomers.
Radiation‐induced polymerization at high dose rate. IV. Chloroprene in bulk
Authors: Hayashi Kanae , Tachibana Michhinori , Okamura Seizo
Published: April 2003

Bulk polymerization of chloroprene was studied at 25°C in a wide does rate range. Variations of the rate of polymerization (Rp) and molecular weight as a function of does rate were essentially the same as those in several monomers that are capab;e of radical and cationic polymerizations. The polymerization proceeds with radical mechanism at low dose rate ans with radical and cationic mechanism concurrently at high dose rate. The number‐average molecular weight of the high‐dose‐rate was ca. 2400. Microstructure of the polymers was mainly of trans‐1,4 unit with small fraction of cis‐1,4 and 3,4‐vinyl unit. Fractions of the vinyl unit and the inverted unit in trans‐1,4 sequence which increased at high does rate inflected the change of dominant mechanism of polymerization.
The characteristics of lanthanide coordination catalysts and the cis‐polydienes prepared therewith
Authors: Zhiquan Shen , Jun Ouyang , Fusong Wang , Zhenya Hu , Fusheng Yu , Baogong Qian
Published: April 2003

The stereoregularity of polydienes is almost the same in regard to the individual elements of the lanthanide series, whereas the activity of the Ln catalysts in diene polymerization varies from one to the other within the series. The latter may be attributed to the difference in the number of electrons that occupy the 4f orbitals. It has been proved that the polymerization of dienes with Ln catalysts under certain conditions proceeds by a “living polymer” mechanism. With regard to the polymerization of butadiene, the most active catalyst is a Nd3+species a new binary system of NdCl3‐3ROH + AlR3 has been discovered. The cis‐ 1,4 content in polybutadiene is about 97% and the 1,2 content, less than 1%. For the polymerization of isoprene with a Nd3+ catalyst system, the effects of ligand and alkyl groups in AIR3 on cis‐1,4 content (ca. 95%) in polyisoprene can be neglected. For the copolymerization of butadiene and isoprene, the cis‐1,4 contents of these two monomeric units in the copolymer are greater than 95% the reactivity ratios r1 and r2 are determined. and the Tg's of the copolymers of various compositions deviate slightly from the calculated values for random copolymers. A linear relationship exists between the yield strength from the stress‐strain curve of Ln‐polvbutadiene and its [n] This relationship is verified by Ln‐polyisoprene and natural rubber but different slopes are obtained
Complex formation of poly(4‐vinyl‐N‐alkylpyridinium) salts or polymer containing flavin mononucleotide with indole derivatives
Authors: Ishiwatari Tsutomu , Okubo Tsuneo , Ise Norio
Published: April 2003

A charge‐transfer‐type complex formation between poly(4‐vinyl‐N‐propylpyridinium bromide) (C3PVP), poly(4‐vinyl‐N‐butylpyridinium bromide) (C4PVP) or poly(4‐vinyl‐N‐benzylpyridinium chloride) (BzPVP), and indole derivatives or between polymer containing flavin mononucleotide residues and indole derivatives was studied in the presence of simple and polyelectrolytes. The association constant (K) of the complex formation with indole acetate increased in the order BzPVP > C4PVP > C3PVP, which indicated an important contribution by hydrophobic interaction. The addition of simple and polyelectrolytes decreased the association constants. This was explained by the “secondary salt effect” of the salts. The importance of the electrostatic interactions in the complexation systems was obvious. The influence of simple electrolytes on the K values was discussed theoretically according to Manning's theory.
Kinetics of the metal‐catalyzed condensations of phenols and polyflavonoid tannins with formaldehyde
Authors: Pizzi A. , Van Der Spuy P.
Published: April 2003

The rate constants and free energies of activation of Zn2+ ‐accelerated and Cr3+ ‐retarded condensations of resorcinolic A rings of polyflavonoid wattle tannins, as well as of the model compounds resorcinol and catechol with formaldehyde, were determined. A quantitative indication of the effect of strong metallic ion catalysts on phenol/aldehyde reactions was obtained. Second‐order kinetics have been found to fit these metallic ion‐catalyzed reactions. The dependence of the tannin/formaldehyde reaction on the concentration of Zn2+ and Cr3+ under acid and alkaline reaction conditions has been investigated and the respective catalytic coefficients determined. In the presence of the metallic ions used the reaction proved to be considerably less sensitive to variations of OH‐concentration, hence of pH.
Adsorption of charged diblock copolymers on porous silica
Authors: Pefferkorn E. , Tran Q. , Varoqui R.
Published: April 2003

Block copolymers of styrene and 2‐vinylpyridine of different molecular weights were synthesized and chemically modified to poly(vinyl pyridine)/poly(styrene sulfonate) or polystyrene/poly(2‐vinyl pyridinium) salts. Adsorption on “Spherosil” silica with a high specific surface area was performed from aqueous solutions of polyelectrolyte copolymers or from noncharged copolymer in an organic medium and subsequent sulfonation or quaternization in the adsorbed state. The adsorption mechanism was studied under various solvent conditions to give silica maximal ion‐exchange properties. Modification of silica resulted in a highly stable coated material which combines the mechanical properties of the porous beads and the ion‐exchange properties of the “supported” and “pellicular” ion‐exchangers and should have potential use in chromatography.
Anionic synthesis of poly[ethylene methylene bis(4‐phenyl‐carbamate)‐g‐acrylonitrile]
Authors: Adibi K. , George M. H. , Barrie J. A.
Published: April 2003

A relatively high‐molecular‐weight polyurethane based on MDI and ethylene glycol was prepared and characterized. This polymer was metalated with sodium hydride in N,N‐dimethylformamide (DMF) at about 0°C. Metalation was confirmed principally by spectroscopic identification of the N‐methyl derivative obtained by coupling the metalated polymer with methyl iodide. Under appropriate reaction conditions the metalated polyurethane was used for the anionic graft polymerization of the reactive monomers acrylonitrile and ethylene and propylene sulfides. Attempted anionic graft polymerizations with other monomers, including styrene and ethylene and propylene oxides, were unsuccessful. The polyurethane grafted with acrylonitrile was separated by fractionation from accompanying small amounts of polyacrylonitrile, a low‐molecular‐weight homopolymer. One sample of polyurethane grafted with acrylonitrile was identified by microanalysis, IR, NMR, and increase in weight and was also characterized by differential thermal analysis.
Dispersion polymerization of styrene: Effect of surfactant
Authors: Almog Yaacov , Levy Moshe
Published: April 2003

The influence of poly(vinyl alcohol) (PVA), a steric stabilizer, and sodium dodecyl sulfate (SDS), an electrostatic stabilizer, on the stability of styrene dispersion polymerized systems was studied. It was shown that in stabilization by PVA there was pronounced bridging of the submicron emulsion particles to 10‐μ dispersion particles and that the emulsion particles could not be washed off. In SDS stabilization, on the other hand, the emulsion formed was easily washed off because bridging with SDS does not occur. The surface tension of the aqueous phase measured during polymerization showed different characteristics for stable and unstable systems.
Thermal degradation of polyurethane based on MDI and propoxylated trimethylol propane
Authors: Gaboriaud F. , Vantelon J. P.
Published: April 2003

A polyurethane based on diphenyl methane diisocyanate (MDI) and propoxylated trimethylol propane was thermally degraded by using the techniques of pyrolysis and thermogravimetric analysis (TGA) in an inert atmosphere. Identification of pyrolysis gaseous products at 600°C showed that the first degradation step consists of a reversal of the polycondensation process, i.e., dissociation into starting polyol and diisocyanate, followed by the polyol degradation and a probable diisocyanate polymerization. Kinetic parameters were determined using dynamic and isothermal TGA curves. It is shown that the degradation can be closely compared with a random chain scission process.
Polymerization of N‐acryloyl pyrrolidone and synthesis of graft copolymer by using the mechanism of initiation of anionic ring‐opening polymerization
Authors: Sur G. S. , Noh S. K. , Choi Sam K.
Published: April 2003

N‐acryloyl pyrrolidone (NAP) was synthesized by reaction of pyrrolidone with acryloyl chloride. First, the polymerization of NAP and copolymerization of NAP with styrene (St) were carried out at 60°C, using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. Kinetic studies showed that the rate of polymerization (Rp) could be expressed by Rp = K [AIBN]0.5 [NAP]1.0. The reactivity of NAP was found to be larger than that of N‐methacryloyl pyrrolidone. The overall activation energy was calculated to be 24.3 kcal mole−1. The following monomer reactivity ratio and Q and e values were obtained. NAP(M1)—St(M2): r1 = 1.50, r2 = 0.35, Q1 = 0.42, and e1 = 1.60. Second, graft copolymers were synthesized by reacting pyrrolidone, in the presence of a catalytic amount of its potassium salt, with poly(NAP‐co‐St).
Solid‐state polymerization of long‐chain vinyl compounds. V. Two‐step postpolymerization of octadecyl acrylate by temperature increase and by stepwise γ‐ray irradiation
Authors: Shibasaki Yoshio , Fukuda Kiyoshige
Published: April 2003

The mechanism of two‐dimensional polymerization of octadecyl acrylate in lamellar crystal was investigated in two‐step postpolymerizations by temperature increase and stepwiseγ‐ray irradiation in lieu of the usual one‐step reaction. Two‐step postpolymerizations by these procedures are interpreted satisfactorily by the cone model, which assumes that the polymerization probability of the monomer molecules in a single layer is distributed conically around the initiation point. It was found that the propagating radicals were living, even in the saturated stage, and the effect of the polymer chains already formed on the propagating and terminating reactions was evident. Furthermore, molecular weight distributions of the resultant poly(octadecyl acrylate) measured by gel permeation chromatography (GPC) were broad. The values of Mw/Mn for the two‐step post polymerizations were 4.71–7.03, whereas those for one‐step reactions were 3.26–5.54.
Synthesis and properties of conjugated enyne polysulfones
Authors: Reinhardt Bruce A. , Arnold Fred E.
Published: April 2003

High‐molecular‐weight polysulfones that contained 1,3‐enyne linkages in the polymer backbone were prepared by the reaction of potassium salts of (E)‐1,3‐bis(3‐hydroxyphenyl)‐1‐buten‐3‐yne and 4,4′‐dihydroxybiphenyl with 4,4′‐dihalodiphenylsulfones in DMSO‐sulfolane solvent mixtures. The polymers were soluble in methylene chloride and exhibited intrinsic viscosities as high as 0.74 (in DMAC at 30°C) with glass transition temperatures ranging from 179 to 214°C. It was postulated that on heating the polymers would cure via a intramolecular cycloaddition reaction to from a 2‐phenylnaphthalene fused ring system along the polymer backbone. Thermal analytical data studies on cured polymer films and investigations of the products obtained from the thermal reactions of model compounds indicated that the primary curing reaction was intermolecular rather than intramolecular in nature. Additional data from testing fabricated composites indicated that the enyne polysulfones have suitable properties for use as high‐temperature thermoplastic composite materials.
Self‐consistency of fractional precipitation method for determining molecular weight distribution in a polymer sample
Authors: Lei George Y.
Published: April 2003

Molecular weight distribution curves have been determined for two samples of polystyrene by fractionating them with a conventional single‐stage precipitation technique and followed by measurement of the average molecular weights of the fractions by viscometry. The experimental results obtained were analyzed by the usual method of plotting cumulative distribution curves. Subsequently, the distribution curve for a mixture of aliquots of the two samples was obtained and found to agree with the expected curve, which would be the sum of the curves in the two constituent samples. This finding confirms the internal self‐consistency of this method for determining molecular weight distribution curves.
Binding heavy metal ions with polymerized onion skin
Authors: Kumar Pawan , Dara S. S.
Published: April 2003

Red onion skin is highly effective for binding heavy metal ions from aqueous solutions. Color leaching can be prevented and the physical characteristics of the substrate can be improved by treatment with formaldehyde in an acidic medium. Batch and column experiments have been conducted with Cu2+, Cd2+, Zn2+, Ni2+, Hg2+, and Pb2+. Almost quantitative removal of the metal ions from solution can be achieved by using columns of the treated onion skin. Competition of the various metal ions for the substrate has been investigated. The capacity of the substrate in the majority of the metal ions studied is well above 1 meq/g. The use of polymerized onion skin to remove heavy metal ions from domestic and industrial wastewater to safe levels has been recommended as a cheap and effective alternative for commercial ion‐exchange resins.
Functional monomers and polymers. LXXXVI. Photochemical reactions on synthetic polymers with pendant thymine bases: Effect of solvents
Authors: Kita Yasuo , Uno Taizo , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

Photodimerization of thymine bases present on the side chain of acryloyl and methacryloyl‐type polymers was studied in dimethyl sulfoxide, dimethylformamide, and dimethyl sulfoxide—ethylene glycol mixture. Quantum efficiencies for photodimerization and quenching with isoprene were influenced by the solvents. The self‐association of thymine bases estimated from their ultraviolet (UV) spectra and intrinsic viscosity were related to the effect of solvent on the photodimerization.
Telomerization kinetics by redox catalysis
Authors: Boutevin Bernard , Maubert Claude , Mebkhout Ahmed , Pietrasanta Yves
Published: April 2003

A new formula for redox catalyzed telomerization kinetics was set up: 1/DPn = CMe(Me)/(M) + CXY(XY)/(M), where CMe is the transfer constant for the metallic ion Me, CXY is the transfer constant for the telogen XY, M the monomer, and DPn is the degree of polymerization. This study has shown that classic transfer and termination reactions can be neglected because of their slow rates and that the metal transfer constant (CMe) is the predominant factor influencing telomer molecular weight. This formula was verified by telomerizations of three monomers [chlorotrifluoroethylene (CTFE), acrylic acid, and ethyl acrylate] with CCl4, catalyzed with ferric chloride‐benzoin. In this last case the initiation rate constant (fKi), the initiation and termination rates, and the radical concentration were measured.
Synthesis and properties of ABA propylene‐ethylene block copolymers
Authors: Prabhu P. , Schindler A. , Theil M. H. , Gilbert R. D.
Published: April 2003

Experimental data, which includes catalyst lifetimes, thermal analyses, fractionation by urea complexation, x‐ray diffraction, and 13C‐NMR spectroscopy, are presented to confirm the successful synthesis of ABA propylene‐ethylene block copolymers. A dry catalyst system of DEAC‐TiCl3(AA) and a gas‐phase polymerization technique was used to prepare the copolymers. PRP‐and ERE‐type copolymers (P‐isotactic polypropylene, E‐polyethylene, and R‐random propylene‐ethylene copolymer block) were prepared. Some preliminary physical property data are given which indicate that PRP‐type copolymers can behave as elastomeric fibers. The stress‐strain behavior also indicates block copolymer formation.
New processable polyaromatic esters curable by intramolecular cyclization. XVIII
Authors: Chen Paul Y. , Marvel C. S.
Published: April 2003

New processable polyaromatic esters were prepared from 2,2′‐diiododiphenyl‐4,4′‐dicarbonyl dichloride (I), isophthaloyl chloride (II), and/or terephthaloyl chloride (III) with 4,4′‐isopropylidene diphenol (IV), 4,4′‐sulfonyldiphenol (V), or resorcinol by interfacial condensation. In these polymers phenylacetylenyl groups were introduced by replacing the iodine. This process led to soluble and curable polymers. Polymer films can be prepared. After curing the polymers were insoluble and showed excellent thermal and chemical resistance. The curing process increased the polymers' softening temperature about 20°C.
The mechanism of the high‐pressure free radical polymerization of ethylene
Authors: Stoiljkovich D. , Jovanovićch S.
Published: April 2003

The reaction path of the free radical polymerization of ethylene is usually considered identical to the polymerization mechanism of other vinyl monomers. Available experimental data on the polymerization of ethylene, however, hardly fitted the well‐established path of free radical polymerization. Obviously the mechanism of ethylene polymerization is more complex and not well understood. One reason for this, in our opinion, is insufficient knowledge of the physicochemical state of ethylene under high pressure. A model that described the behavior of ethylene under compression has been proposed. According to the model, and increase in pressure causes the formation of various supermolecular forms of ethylene, each accompanied by transition of the second order. By proposing a stereochemical shape for each supermolecular form calculation of activation volumes for each of these transitions was made. Good agreement was obtained when calculated volumes of activation were compared with corresponding experimental values in the literature.
Polymerization of chlorophenyl glycidyl ethers. VIII. Initiation of the polymerization of p‐chlorophenyl glycidyl ether and phenyl glycidyl ether by the system aluminum isopropoxide and zinc chloride (1:1)
Authors: Jedliński Z. , Bero M. , Szewczyk P. , Dworak A.
Published: April 2003

Labeled aluminum alcoholate was used to determine the content of end groups of polyethers formed in polymerization reactions initiated by the system Al(OiPr)3 + ZnCl2 (1:1). The polymerization process proceeded in several successive stages. Polymerization initiation and propagation mechanisms were proposed.
Spontaneous copolymerization of 1,3‐cyclohexadiene with polar vinyl monomers
Authors: Nagai Katsutoshi , Machida Shuji , Nonaka Toshiaki
Published: April 2003

In the reactions of 1,3‐cyclohexadiene(1,3‐CHD) with polar vinyl monomers, CH2C(X)Y (X is ‐CN and CO2CH3; Y is CI, H, and CH3), the two α‐chlorosubstituted monomers underwent rapid spontaneous copolymerization, accompanied by the formation of a small amount of cycloadduct. Both polar monomers also gave predominantly copolymers in the reaction with 1,3‐cycloheptadiene(1,3‐CHpD) in lower yield. 1,3‐Cyclooctadiene (1,3‐COD) reacted only with α‐chloroacrylonitrile (CAN) to give a copolymer, while only cycloaddition took place in systems involving cyclopentadiene(CPD) as diene. The charge–transfer (CT) complex formation of 1,3‐CHD with CAN and methyl α‐chloroacrylate(MCA) was confirmed by ultraviolet spectroscopic studies and the equilibrium constants estimated were 0.18 and 0.07 liter/mole, respectively, at 25°C in chloroform as solvent. The activation energies for the copolymerizations of 1,3‐CHD with CAN and MCA in benzene were determined to be ca. 6.6 and 9.6 kcal/mole, respectively. In the system composed of 1,3‐CHD and CAN, only the copolymerization was affected by solvents used and oxygen. Although addition of ZnCl2 to the system resulted in the acceleration of the both reactions, the variation in the product ratio of copolymer to cycloadduct with ZnCl2 concentration showed a maximum. Based on the results in the present and preceding studies for systems involving 1,3‐cyclodienes and acceptor monomers, the relationship between the cycloaddition and the spontaneous copolymerization is discussed.
Preparation of macroreticular redox resins with hydroquinone and catechol units as pendant groups and their properties
Authors: Iwabuchi Susumu , Nakahira Takayuki , Fukushima Yoshitaka , Saito Osamu , Kojima Kuniharu
Published: April 2003

Macroreticular redox resins with hydroquinone and catechol units as pendant groups were prepared by the Friedel‐Crafts reaction of macroreticular styrene/divinylbenzene copolymer with 2,5‐ and 3,4‐dimethoxybenzyl chlorides, followed by removal of the methyl groups with hydrobromic acid. The redox capacity of the macroreticular resins was determined by oxidation of hydrazobenzene with resins in oxidized form. Resins with 1,4‐benzoquinone units were capable of oxidizing hydrazobenzene, whereas those with 1,2‐benzoquinone (catechol quinone) units exhibited no apparent oxidative ability; this seems to be due to a complex formation between azobenzene and the catechol units in the reduced resins. Adsorption of metallic ions onto catechol‐containing resins showed a high selectivity for Hg2+ ion. The effects of pH, reaction time, and ion concentration on the adsorption were also studied.
Formation of polymer‐bonded nitroxyl radicals in the UV stabilization of polypropylene by a bifunctional hindered amine light stabilizer
Authors: Hodgeman Daryl K. C.
Published: April 2003

The formation of polymer‐bonded stabilizer derivatives during photooxidation of isotactic polypropylene, which contains the hindered amine light stabilizer bis(2,2,6,6‐tetramethyl‐4‐piperidinyl) sebacate and the corresponding bisnitroxyl radical, was investigated. The photooxidized polypropylene films that contain these additives were studied by ESR, IR, and nitrogen analysis before and after exhaustive solvent extraction of the photooxidized films. ESR showed that under the conditions in use a maximum of 20% of the nitroxyl radicals formed from the hindered amine was bonded to the polymer chain. Regeneration of nitroxyl radicals from the polymer‐bonded stabilizer derivatives under photooxidative conditions indicated that the stabilizer was bonded to the polymer chain by O‐alkyl‐substituted hydroxylamine linkages >NOPP.
Catalyzed chain transfer to monomer in free radical polymerization
Authors: Enikolopyan N. S. , Smirnov B. R. , Ponomarev G. V. , Belgovskii I. M.
Published: April 2003

The kinetics and the molecular weight distribution in the radical polymerization of methyl methacrylate in the presence of a cobalt complex of hematoporphyrin tetramethyl ether is investigated. The whole complex of experimental data indicates the new kinetic phenomenon—catalyzed chain transfer to monomer. The possible mechanism of the chain transfer and the chain transfer agent regeneration acts is suggested.