bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion‐controlled vinyl polymerization. IV. Comparison of theory and experiment
Authors: Soh S. K. , Sundberg D. C. 
Published: April 2003

AbstractBulk polymerization data of methyl methacrylate, ethyl methacrylate, ethyl acrylate, n‐propyl acrylate, vinyl acetate, and styrene were compared with the predictions of the theory proposed in the earlier parts of this series (I‐III). This theory of polymerization kinetics uses the concepts of free volume and chain entanglements to describe the relationship between chain mobility and chain length dependent termination reactions. Excellent agreement was found between the predictions of the theory and the polymerization rate and molecular weight data of the six polymerization systems studied. Emphasis was placed on the ability to explain the development of higher order molecular weight averages (M̄w, M̄z, etc.) because they provide the most crucial tests for such a model. No changes were required in the model as it was applied to the different polymerization systems for a variety of reaction conditions. The theory offers a unified understanding of the diverse polymerization behavior displayed by such systems.
Complex formation between poly(ethylene oxide) and alkali picrates
Authors: Dimov D. K. , Panayotov I. M. , Lazarov V. N. , Tsvetanov Ch. B. 
Published: April 2003

AbstractThe interaction of poly(ethylene oxide) with alkali picrates in tetrahydrofuran and dioxane was studied by optical and NMR spectroscopy and conductance measurements. Evidence was found of the formation of two kinds of solvation complex, differing in the nature of the ion pairs involved. A strong anion effect on cation binding to the polyether was demonstrated.
Preparation of water‐soluble photoresist derived from poly(vinyl alcohol)
Authors: Ichimura Kunihiro 
Published: April 2003

AbstractThe reaction of PVA with 2,2‐dialkoxyethoxystyrylpyridinium or quinolinium salts is described. The resultant water‐soluble polymers, which contain small amounts of the styrylpyridinium‐ or quinolinium group, exhibited high photosensitivity. Among the polymers prepared PVA‐bearing 4‐oxystyrylquinolinium group was photoinsolubilized with visible light that corresponded to an argon laser.
Polymerization of cyclohexene oxide with aluminum complex‐silanol catalyst. IV. Photopolymerization with Ph3SiCOPh‐Al complex‐alcohol catalyst system
Authors: Hayase S. , Ito T. , Suzuki S. , Wada M. 
Published: April 2003

AbstractA new catalyst system (Ph3SiCOPh‐aluminum complex‐alcohol) was investigated for photopolymerization of cyclohexene oxide. Polymer conversion and molecular weight increased with polymerization time. When a Ph3SiCOPh‐Al (n‐Praa)3‐alcohol catalyst system was used the catalyst activity decreased, depending on the alcohol: i‐PrOH > n‐PrOH > i‐BuOH > MeOH > t‐BuOH > H2O. When the Ph3SiCOPh‐Al complex‐i‐PrOH catalyst system was used the catalyst activity decreased, depending on the ligand of the Al complex: ß‐ketoester > orthocarbonyl phenol > ß‐diketone. Benzophenone derivatives were effective for catalyst activation as a photosensitizer.
Functionalization of polystyrene. III. Synthesis of polymeric thiol reagents
Authors: Stern Meir , Fridkin Mati , Warshawsky Abraham 
Published: April 2003

AbstractThe synthesis of polymer‐bound thiol reagents, supported on macroporous 4% divinylbenzene co‐polymer (Amberlite XE‐305), via three synthetic approaches is described: (i) Alkylation or acylation of XE‐305 with 3‐nitro‐4‐halogen‐substituted benzyl chloride or benzoyl halide yielding 3‐nitro‐4‐halobenzene‐bound species, followed by substitution of the activated polymeric halogen atom with sulfur (see Scheme 1). (ii) Formation of a thiol ether by a direct substitution of an active polymeric halogen by reaction with benzylthiol, followed by chlorination, thiolation, and reduction (see Scheme 2). (iii) Attachment of a prepared tailor‐made disulfide to aminomethyl function of a polymeric support, followed by reduction (see Scheme 3). The polymers were tested for their free‐thiol content by 5, 5′‐dithiobis(2‐nitrobenzoic acid) (Ellman's reagent12) in DMF. Their thiolytic activity was investigated in the removal of 2‐nitrophenylsulphenyl (Nps) group from Nps‐protected amino acid (Scheme 4). Site‐site interaction between the polymer‐bound thiol with its activated halide precursor to yield polymeric sulfide during displacement reaction, and the interconversion of the polymeric thiols into polymeric disulfides at equilibrium or during reaction with Nps‐amino acids, observed, and is attributed to the flexibility of the polymeric matrices.
Copolymerization of glycidyl methacrylate with alkyl acrylate monomers
Authors: Dhal Pradeep K. , Ramakrishna M. S. , Babu G. N. 
Published: April 2003

AbstractA newer approach to obtaining acrylic thermoset polymers with adequate hydrophilicity required for various specific end uses is reported. Glycidyl methacrylate (GMA) was copolymerized with n‐butyl acrylate (n‐BA), isobutyl acrylate (i‐BA), and 2‐ethylhexyl acrylate (2‐EHA) in bulk at 60°C. with benzoyl peroxide as free radical initiator. The copolymer composition was determined from the estimation of epoxy group. Reactivity ratios were calculated by the Yezrielev, Brokhina, and Roskin method. For copolymerization of GMA (M1) with n‐BA (M2) the reactivity ratios were r1 = 2.15 ± 0.14, r2 = 0.12 ± 0.03; with i‐BA (M2) they were r1 = 1.27 ± 0.06, r2 = 0.33 ± 0.031; and with 2‐EHA (M2) they were r1 = 2.32 ± 0.14, r2 = 0.13 ± 0.009. The reactivity ratios were the measure of distribution of monomer units in a copolymer chain; the values obtained are compared and discussed.
Template effects in chelating polymers
Authors: Gupta S. N. , Neckers D. C. 
Published: April 2003

AbstractPoly(4′‐methyl‐4‐vinyl‐2,2′‐bipyridine) has been prepared as have various copolymers with divinylbenzene. When polymerization is carried out in the presence of metal ions (Ni2+, Co2+, Cu2+) a metal‐containing copolymer is obtained which, when the metal ion is removed with acid, retains some memory of the original chelating metal.
Liposomes from α,ω‐dipolar amphiphiles with a polymerizable diyne moiety in the hydrophobic chain
Authors: Bader H. , Ringsdorf H. 
Published: April 2003

AbstractSymmetric polymerizable α,ω‐dipolar C22‐diacetylenes were prepared by oxidative coupling of 10‐undecynoic acid and 10‐undecynol, respectively, by means of copper II salts in ethanolic solution. 10,12‐Docosadiyne‐1,22‐diphosphate (3)—by reaction of 10,12‐docosadiyne‐1,22‐diol (2) with POCl3—was polymerized in aqueous solution using UV irradiation to form deep blue, thermochromic solutions. By consonication of 3 with cholesterol, monolayer vesicles were formed. This was proven by encapsulation of 6‐carboxyfluorescein. These monomeric vesicles were polymerized by UV light to yield stable, deep blue polymeric vesicle suspensions.
Complexes of polyacids with poly(vinylbenzocrown ether)s and polyvinylbenzoglymes in water
Authors: Jaycox Gary D. , Sinta Roger , Smid Johannes 
Published: April 2003

AbstractInsoluble complexes are formed in acidic aqueous media when poly(acrylic acid) (PAA) and poly‐(vinylbenzo‐18‐crown‐6) (P18C6) or polyvinylbenzoglymes are mixed. Complex formation results from hydrogen bonding between carboxyl groups and crown ether‐ or glyme–oxygen atoms as well as from hydrophobic interactions. The precipitation is pH dependent and was determined as a function of the ratio PAA to P18C6 or to polyglyme at different HCl concentrations in 10−4M solutions of polycrown or polyglyme. Precipitation is nearly quantitative in 0.01N HCl. The compositions of PAA/P18C6 precipitates were determined as a function of the initial PAA/P18C6 ratio in solution. The complexes with P18C6 can be solubilized in acidic media when crown‐complexable cations (K+, Cs+, Ba2+) are added, but the charged P18C6 reprecipitates in basic solution as a polysalt complex with the PAA–polyanion. More stable PAA–P18C6 complexes in the form of fibers can be obtained by interfacial complex formation. Poly(methacrylic acid) is less effective as a complex former.
Modification of PET with sterically hindered diols
Authors: Prasadarao M. , Pearce Eli M. 
Published: April 2003

AbstractPoly(ethylene terephthalate) was modified by incorporating bis(hydroxyethyl) tetrasubstituted terephthalates (methyl, chlorine, and bromine) as a third component in the mole ratios of 2–50% (based on dimethyl terephthalate) which resulted in random copolyesters. The presence of steric hindrance imparted additional chain rigidity to the copolymer structure, as shown by increased glass transition temperature (Tg). The effectiveness of the steric groups for conferring rigidity to the copolymer structure was CH3 > Cl≃Br. The copolyesters which contained halogen substituents showed substantial enhancement in flame retardency compared with PET.
Solid‐state polymerization of acrylamide and its derivatives complexed with some lewis acids. II. Radiation‐induced in‐source polymerization
Authors: Żurakowska‐Orszagh J. , Mirowski K. , Chajewski A. 
Published: April 2003

AbstractRadiation‐induced solid‐state polymerizations of complexes of N‐tert‐butylacrylamide, N‐tert‐amylacrylamide, and N‐tert‐hexylacrylamide with zinc chloride and zinc bromide have been studied. An accelerating effect of temperature and an inhibiting effect of oxygen on the polymerization process were observed. The activation energies have been established. The influence of monomer structure as well as the halide used on the polymerization rate have been discussed and some regularities have been pointed out. The polymers obtained show good solubilities in common solvents, which proves that they are not crosslinked.
Phthalocyanine polymers. II. Synthesis and characterization of some metal phthalocyanine sheet oligomers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractMetal phthalocyanine oligomers that possess peripheral carboxylic acid groups were prepared by the reaction of pyromellitic dianhydride, a metal salt, urea, and a catalyst. These materials have blue to purple colors with a metallic luster and are soluble in sulfuric acid, dimethylsulfoxide, dimethylformamide, and dimethylacetamide. Their thermal stability is high in an anaerobic atmosphere with char yields of 80–85% at 800°C. Elemental, spectral, and titrimetric analyses and thermal studies were carried out to characterize them.
Unusual swelling behavior of films of polyvinyl‐ and polyvinylidene/fluorides in various solvents
Authors: Chapiro A. , Mankowski Z. , Schmitt N. 
Published: April 2003

AbstractThe swelling of PVF and PVDF films in various solvents was investigated. It was found that in the swollen state both polymers show little tendency to retain the solvent that leaks out under a mild pressure and evaporates quickly when the specimen is exposed to air. The equilibrium swelling ratios were measured in numerous solvents. From the results it is concluded that the solubility parameters are δPVDF = 12.0–12.3, δPVF = 12.0–12.1. The unusual swelling behavior is explained by strong polymer–polymer interactions via dipoles which tend to replace polymer–solvent interactions once the sample is withdrawn from the solvent.
Polymerization of phenylacetylene by triethyl aluminum and titanium tetraethoxide
Authors: Chiang Albert C. , Waters Paul F. , Aldridge Mary H. 
Published: April 2003

AbstractThe polymerization of phenylacetylene to polyphenylacetylene was accomplished with the combined catalysts triethyl aluminum and titanium tetraethoxide. The progress of the reaction was monitored by gas chromatography. The parameters included temperature (−80, 25, 140°C), solvent (benzene, chlorobenzene, toluene, cyclohexane, and nitrobenzene), mole ratio of catalysts (Al/Ti; 1.5, 3.0, 4.5, 6.0, and 9.0), aging times of catalysts (2, 10, and 40 min), and order of addition of reagents. Derivatives of polyphenylacetylene were obtained by the acylation of polyphenylacetylene with p‐nitrobenzoyl chloride, the sulfonation of polyphenylacetylene with benzenesulfonyl chloride, and the formation of polyphenylacetylene complexes with complexing agents such as bromine, iodine, iodine chloride, boron trifluoride, and ferric chloride. A new phenylacetylene‐acetylene product mixture was produced by the polymerization of phenylacetylene and acetylene at 25 and −80°C. The electrical conductivity of polyphenylacetylene and its derivatives is in the range of 10−10−10−3 Ω−1 cm−1.
Kinetics of polyesterification. II. Foreign acid‐catalyzed dibasic acid and glycol systems
Authors: Chen Show‐an , Wu K.‐ C. 
Published: April 2003

AbstractPolyesterification of diacid and diol in the presence of the foreign acid p‐toluene sulfonic acid as catalyst was carried out under constant reaction temperatures of 140–166°C (rather than at the usual constant oil‐bath temperature) and at molar ratios r of diol to diacid of 1.2–3.5. The experimental data obtained do not fit conventional rate equations as they appear in the literature. On the basis of ion pair formation, consideration of proton transfer from acid to alcohol, variation in dielectric constant of the reaction mixture as conversion increases, and inclusion of reverse reaction due to presence of unremoved water, we proposed a reaction mechanism and rate equations. The rate equation fitted our experimental data quite well. In addition the self‐catalysis (absence of foreign acid) also showed promise, as confirmed by the experimental data measured under constant reaction temperatures, which appear in Part I.
Effect of pressure on the crystallization of poly(ethylene terephthalate)
Authors: Ihm Dae Woo , Cuculo John A. 
Published: April 2003

AbstractThe effect of pressure on the crystallization of poly(ethylene terephthalate) (PET) was studied. The Instron capillary rheometer was adapted as a high‐pressure/high‐temperature dilatometer to carry on experiments up to 40,000 psi. Isothermal measurements of PET melt density were made with a precision of ±0.5%. Analysis of the kinetics of crystallization of PET melt at high pressures reaffirmed the existence of low Avrami exponents and their noninteger values. To rationalize the crystallization mechanism with the observed low exponents it is proposed that an appropriate increase in pressure would effectively reduce the free volume of a crystallizable substance to a point at which an alteration of the crystallization mechanism or nucleation mode could occur. It is further shown that PET clearly exhibits two different and sharply defined stages of crystallization behavior at pressures above 10,000 psi. Based on the Avrami equation, the fraction of uncrystallized polymer for the initial stage is defined as an empirically determined function of time and pressure. There is good agreement between the predicted and experimental values over the pressure range investigated.
Laser‐initiated polymerization of charge‐transfer monomer systems
Authors: Williamson M. A. , Smith J. D. B. , Castle P. M. , Kauffman R. N. 
Published: April 2003

AbstractThe laser‐initiated polymerization of charge‐transfer monomer complexes was investigated with a pulsed nitrogen laser and an argon laser. Several donor‐acceptor monomer charge‐transfer systems were screened for polymerization in different solvents. Polymerization by laser initiation was achieved in two of these systems; that is, 2‐vinylnaphthalene/fumaronitrile and 9‐vinylanthracene/fumaronitrile. The best polymer yields were obtained with the 2‐vinylnaphthalene/fumaronitrile system in sulfolane solvent. The influences on the polymer yield and composition of solvents, varying focal path length, glass conditioning, initiation sources, environment, and monomer feed ratios were evaluated. Infrared (IR) spectral studies, gel permeation chromatography (GPC), and chemical analyses were performed to characterize the polymer products arising from the polymerization of 2‐vinylnaphthalene/fumaronitrile in sulfolane. The polymer contained a high percentage of sulfolane (ca. 1/3 mol fraction), presumably arising from solvent transfer to the growing polymer chains during the propagation phase of the polymerization.
Synthesis of corrosion‐inhibiting polythioesters
Authors: Truesdell J. W. , Van De Mark M. R. 
Published: April 2003

AbstractBinary condensation copolymers of five monomers known to be corrosion inhibitors were synthesized by solution polymerization. The copolymers synthesized were poly(1,2‐ethanedithiol‐thiodiglycolate), poly(1,3‐propanedithiol‐3,3′‐thiodipropionate), poly(1,2‐ethanedithiol‐3,3′‐thiodipropionate), and poly(2,5‐dimercapto‐1,3,4‐thiadiazole‐3,3′‐thiodipropionate). Yields ranged from 77 to 89% and molecular weights from 10,100 to 24,300. Attempts to produce the condensation copolymers of thiodiglycolic acid chloride and 1,3‐propanedithiol or 2,5‐dimercapto‐1,3,4‐thiadiazole failed, yielding only telomeric products. The copolymers that were synthesized demonstrated significant corrosion‐inhibitory properties on steel samples in salt water.
Copolymerization of 3,4‐dimethyltetrahydrofuran with cyclic ethers
Authors: Malanga M. , Vogl O. 
Published: April 2003

AbstractThe copolymerization of 3,4‐dimethyltetrahydrofuran with selected cyclic ethers was studied. Although 3,4‐dimethyltetrahydrofuran did not homopolymerize, it readily copolymerized with propylene oxide and epichlorohydrin in an alternating fashion using the cationic initiator PF5. The reactivity ratios r1 and r2 for the copolymerization of 3, 4‐dimethyltetrahydrofuran and epichlorohydrin were r1 = 0.22 ± 0.05 and r2 = 0.11 ± 0.01, respectively.
Effect of stabilizers on the preparation of poly(ethylene terephthalate)
Authors: Chang Shuya , Sheu Ming‐Fa , Chang Nien‐Hsi 
Published: April 2003

AbstractPrevious investigators have indicated that stabilizers will block the transesterification catalyst in the preparation of PET by the DMT process. This was not the case when triphenyl phosphate (TPP) or Irganox 1010 was used as the stabilizer and manganous acetate as the catalyst. Stabilizers in this study included TPP, trimethyl phosphate (TMP), tetraethylammonium hydroxide (TEAOH), Irganox 1010, and Irganox 1222. Their effect on the properties of PET made by the TPA process was investigated. It was observed that TPP and TMP greatly reduced the carboxyl content of PET and that the others had little or no effect. All stabilizers lowered the diethylene glycol content of PET. The rate of polycondensation was slightly increased when a small amount of Irganox 1010, Irganox 1222, or TMP was added. Proper concentration of stabilizer should be chosen to obtain good stability and low diethylene glycol content. Among the five stabilizers studied TPP was the best with respect to carboxyl and diethylene glycol content and thermal stability. The concentration of TPP should be kept under 0.04% by weight of PET.
Mechanism of thermal degradation of polyurethane based on MDI and propoxylated trimethylol propane
Authors: Gaboriaud F. , Vantelon J. P. 
Published: April 2003

AbstractThe various pathways of degradation of polyurethane based on MDI and propoxylated trimethylol propane were studied from the analysis of degradation gases sampled at various temperatures during the heating rise. From the beginning of degradation (250°C) to 400°C, we suggest that the main mechanism is the fracture of the polyurethane molecule into primary amine, carbon dioxide, and propenyl ether, the last leading to propene. Beyond this temperature, the mechanism may be reduced to a depolymerization process followed by radical breakdown of the polyol chain and by stripping and rearrangement of simple radicals, all of these giving the gaseous species obtained.
High‐molecular‐weight poly(p‐phenyleneterephthalamide) by the direct polycondensation reaction with triphenyl phosphite
Authors: Higashi Fukuji , Ogata Shin‐Ichi , Aoki Yasuhiro 
Published: April 2003

AbstractPoly(p‐phenyleneterephthalamide) of high molecular weight was obtained when the polycondensation of terephthalic acid and p‐phenylenediamine was carried out in N‐methylpyrrolidone (NMP) that contained dissolved CaCl2 and LiCl in the presence of pyridine. The molecular weight of the polymer obtained varied with the amount of pyridine relative to the metal salts and with the molar ratios of CaCl2 to LiCl, the maximum ηinh value of 4.5 being obtained under the conditions Py/(CaCl2 + LiCl) ≈ 2.5 (mol/mol), CaCl2/LiCl ≈ 1.2 (mol/mol), and LiCl + CaCl2 ≈ 4 g. Among the solvents tested, NMP was significantly effective for the reaction. Polycondensations of several combinations of other dicarboxylic acids and diamines were carried out with limited success.
Synthesis and characterization of polyethylenimine backbone polynucleotide models
Authors: Ludwick Adriane G. , Overberger C. G. 
Published: April 2003

AbstractNucleic acid analogs with a PEI backbone and uracil‐ and thymine‐containing pendants and their monomer and dimer models have been synthesized and characterized by means of 360‐MHz 1H‐NMR as well as 90‐ and 20‐MHz 13C‐NMR. 13C‐NMR was particularly useful in characterizing the primary structures of the polymers. While data from the monomer and dimer models can be assumed transferable to the polymers, some unique features of the 1H and 13C spectra of the polymers compared to the model compounds, give insight to the polymer structures.
Effects of diphenyliodonium hexafluorophosphate in the radiation‐induced cationic polymerization of styrene. Formation and decay processes of styrene dimer radical cation
Authors: Mah Soukil , Yamamoto Yukio , Hayashi Koichiro 
Published: April 2003

AbstractThe radiation‐induced cationic polymerization of styrene in methylene chloride is promoted by the addition of (C6H5)2IPF6, while the polymerization is inhibited in the presence of (C6H5)2ICl. The pulse radiolysis study reveals that both the yield and the lifetime of styrene dimer radical cation are increased by the addition of (C6H5)2IPF6, and, on the contrary, both are decreased in the presence of (C6H5)2ICl. The kinetic plots for the decay of the dimer radical cation in the presence and absence of the salts show that the decay is predominantly due to the neutralization with Cl−. The lengthening of the lifetime of the dimer radical cation in the presence of (C6H5)2IPF6 is believed to be due to the stabilization toward Cl− by the ion‐pair formation with PF6−. Slow formation of the dimer radical cation was also observed in the presence of (C6H5)2IPF6, which is attributable to the oxidation of radical species by the salt followed by the charge transfer to monomer. Such a slow formation of radical cation in the presence of (C6H5)2IPF6 was confirmed with biphenyl in methylene chloride.
Pyrolysis of polyacetylene
Authors: Chien James C. W. , Uden Peter C. , Fan Ju‐Li 
Published: April 2003

AbstractThermal degradation of polyacetylene has been studied by pyrolysis gas chromatography mass spectrometry (PGC–MS). The most abundant product is benzene, but significant quantities of other products are also produced. In decreasing order of yield, these are methane, ethylene, propylene, ethane, butadiene, toluene, and xylenes. A simple mechanism capable of accounting for most of the observed products is random chain scission followed by electron–proton exchanges and in some cases ring closure. The total material balance between proton‐rich and proton‐depleted products is within 10%.
Electron transfer between insoluble dihydronicotinamide polymer and insoluble benzoquinone polymer
Authors: Tsubokawa Norio , Endo Takeshi , Okawara Makoto 
Published: April 2003

AbstractThe electron transfer between insoluble polymer containing 1‐benzyl‐1,4‐dihydronicotinamide (BNAH) structure (P‐BNAH) and benzoquinone (Q) structure (P‐Q) by use of alloxan (A) as an electron carrier was investigated. Although no reaction occurred on suspending the P‐BNAH and P‐Q in ethanol/water, P‐Q was reduced smoothly to hydroquinone structure (P‐HQ) by addition of A. The results suggest that A was reduced by P‐BNAH to give A radical (A·) or dialuric acid (D) and then A· (or D) reduced P‐Q, whereby A was regenerated and thus indicated that the oxidation reduction between insoluble solid polymers was mediated by A as an electron carrier.