bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal properties and morphology of α‐methylstyrene‐butadiene‐α‐methylstyrene triblock copolymer
Authors: Hsiue Ging‐Ho , Yang Wen‐Rong 
Published: April 2003

AbstractPoly(α‐methylstyrene‐butadiene‐α‐methylstyrene) (mSBmS) was synthesized by two stages living anionic polymerization. Sodium naphthalene was used as initiator and HMPT as promoter to accelerate cross‐over reactions. The microstructure and composition of mSBmS were identified by infrared and nuclear magnetic resonance spectroscopes. The domain size was roughly calculated from TEM observation. It was observed that the morphology changed with the composition. The mSBmS exhibited two Tgs, −4 and 172°C, that associated with polybutadiene and poly‐α‐methylstyrene, respectively. Comparing stress relaxation behaviors of mSBmS and styrene‐butadienestyrene (SBS) at various temperatures, mSBmS showed a better thermal stability and degradation resistance than SBS. From the thermal gravimetric analysis, at 200°C, mSBmS gave a weight loss less than 1%, which provided a further evidence of better thermal stability of this material than of SBS.
The nature of active sites in butadiene polymerization catalyzed by organotitanium(III) derivatives
Authors: Dolgoplosk B. A. , Tinyakova E. I. , Guzman I. Sh. , Afinogenova L. L. 
Published: April 2003

AbstractThe stereospecificity of benzyl derivatives of trivalent titanium (Rn TiX3–n, where X = Cl, I, n = 1–3) in butadiene polymerization was studied. It was found that dibenzyltitaniumiodide is an efficient catalyst of the 1,4‐cis‐polymerization of butadiene and that tribenzyltitanium forms 1,2‐units. In both cases all the titanium‐benzyl bonds participated in the initiation reaction and the active sites were polymeric analogues of crotyl derivatives of Ti(III); namely, bis‐π‐oligobutadienyltitaniumiodide and tris‐π‐oligobutadienyltitanium. These sites are stable at room temperature. The nature of the active sites in the polymerization of butadiene with Ziegler's 1,4‐stereo‐specific systems Til4 (or Til2Cl2) + AIR3 are described.
Block copolymers derived from azobiscyanopentanoic acid. IV. Synthesis of a polyamide–polystyrene block copolymer
Authors: Ueda Akira , Nagai Susumu 
Published: April 2003

AbstractPolyamides 6.10 and 6.6 (PA* 6.10 and 6.6) containing small amounts of NN units in the main chains were prepared by interfacial polycondensation between hexamethylenediamine and sebacoyl chloride or adipoyl chloride with addition of azobiscyanopentanoyl chloride. Polyamide–polystyrene block copolymers (PA‐b‐PSt) were then prepared by decomposition of the NN units of PA*, initiating radical polymerization of styrene in m‐cresol. The average PA block length of PA‐b‐PSt thus formed was longer than that expected from the initially present PA segments between the NN units. This is probably due to recombination of PA radicals whose initiation efficiency is as low as 15%. The PSt blocks also had higher molecular weight (7000–79,000) in comparison with homopolystyrene produced from monomeric azobiscyanopentanoic acid used as an initiator due to higher viscosity of polymerization system. Variation of intrinsic viscosity and turbidimetric titration behavior along with the change in composition were also discussed.
Direct polycondensation of aromatic dicarboxylic acids and bisphenols with tosyl chloride and N,N‐dimethylformamide in pyridine
Authors: Higashi Fukuji , Akiyama Naoki , Takahashi Ikuo , Koyama Tsugio 
Published: April 2003

AbstractA Vilsmeier adduct derived from arylsulfonyl chlorides and DMF in pyridine was successfully used as a new condensating agent for the synthesis of aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols and also of hydroxybenzoic acids. Polymers of high molecular weights (M̄w = 78,000) with relatively narrow molecular weight distribution (M̄w/M̄n ≈ 3.0) were prepared by reacting aromatic dicarboxylic acids with the adduct in pyridine, followed by addition of bisphenols. The polycondensation was significantly affected by the amount of DMF, the nature of the arylsulfonyl chlorides, the conditions of initial reaction of the acids with the adduct, and the rate of reaction with bisphenols. The process was adaptable to the direct polycondensation of hydroxybenzoic acids, affording polymers of high molecular weight (ηinh = 1.73).
Cope elimination and complexation of poly(dimethylaminoethyl methacrylate N‐oxide)
Authors: Sato Tsuneyuki , Ito Osamu , Mori Shigeki , Otsu Takayuki 
Published: April 2003

AbstractPoly(dimethylaminoethyl methacrylate N‐oxide) (poly(DMAEMNO)) was prepared by oxidation of poly(dimethylaminoethyl methacrylate) with hydrogen peroxide in methanol. From thermogravimetric and IR spectroscopic investigations Cope elimination of amine oxide group in poly(DMAENO) was found to occur at 120–150°C. The postpolymerization of partially pyrolyzed polymer carrying vinyl ester group as pendant was performed with azobisisobutyronitrile at 60°C in methanol to give cross‐linked polymer that was found to form hydrogel. Poly(DMAEMNO) gave metal–polymer complexes with CuCl2, ZnCl2, and CoCl2. Cobalt–polymer complex had a constitution of 1:2 of metal ion to amine oxide group, while copper– and zinc–polymer complexes seemed to have structures of 1:1 and 1:2 of metal ion to amine oxide group. Furthermore, polymer complexes of poly(DMAEMNO) with poly(methacrylic acid) and poly(acrylic acid) were found to be formed by mixing aqueous solutions of both polymers and also by radical polymerization of the acid monomers in the presence of poly(DMAEMNO). From elemental analysis, thermogravimetric investigation, and measurement of turbidity it was concluded that the resulting polymer–polymer complexes contained more than one acid monomer unit per one N‐oxide unit.
Synthesis and properties of polyamides of p‐phenylenedioxydiacetic acid
Authors: Srinivasan M. , Scariah K. J. , Krishnamurthy V. N. , Rao K. V. C. 
Published: April 2003

AbstractSeveral polyamides of p‐phenylenedioxydiacetic acid (PDDA) were synthesized by the low‐temperature solution polycondensation techniques. Six different diamines were condensed independently with p‐phenylenedioxydiacetyl chloride (PDC) in a mixture of N‐methyl pyrolidone (NMP) and hexamethyl phosphoramide (HMPA). The polymers were obtained in 80–95% yield and possessed inherent viscosities in the range 0.32–0.81 dL/g. The polymers were characterized by infrared (IR) and H1‐NMR spectra. The solubility, density, crystallinity, and thermal stability of the polyamides were also determined. A model diamide (MDA‐1) was also synthesized from aniline and PDC to confirm the formation of polyamides from diamines.
Solution properties of ion‐containing polymers in polar solvents
Authors: Peiffer D. G. , Lundberg R. D. 
Published: April 2003

AbstractThe placement of ionic groups within the molecular structure of a polymer produces marked modification in physical properties. A large number of studies have been performed on these ion‐containing polymers, but few have focused on the effects of anion–cation interactions (i.e., counterion binding or ionization) on hydrodynamic volume, especially as the molecular structure of the solvent and nature of counterion are varied. In this study changes in hydrodynamic volume are followed through reduced viscosity measurements as a function of the abovementioned molecular parameters.The dilute solution properties of various polyelectrolytes that contain sulfonate and carboxylate groups were investigated as a function of the counterion structure, charge density, molecular weight, and solvent structure. The polymeric materials were selected because of their specific chemical structure and physical properties. In the first instance a (2‐acrylamide‐2 methylpropanesulfonic acid)‐acrylamide‐sodium vinyl sulfonate terpolymer was synthesized and subsequently neutralized with a series of bases. Viscometric measurements on these materials indicate that the nature of the cation affects the ability of the polyelectrolyte to expand its hydrodynamic volume at low polymer levels. The magnitude of the molecular expansion is shown to be due in part to the ability of the counterion to dissociate from the backbone chain, which, in turn, is directly related to the solvent structure. The changes in solution behaviour of these inomers lend support for the existence of ion pairs (i.e., site binding) and ionized moieties on the polymer chains. Measurements performed in a variety of solvent systems further confirm this interpretation. In addition, and acrylamide‐sodium vinyl sulfonate copolymer was partially hydrolyzed with sodium hydroxide to study the effect of varying the charge density at a constant degree of polymerization and counterion structure. The results show that the charge density has a significant effect on the magnitude of the reduced viscosity and dilute solution behaviour. These observations, made in aqueous and nonaqueous solvents, are related to the interrelation of hydrodynamic volume, counterion concentration, and site binding. Again the controlling factor is the degree of site binding of the counterion onto the polymer backbone. Finally, we observe that the increased hydrodynamic volume affects viscosity behavior beyond the polyelectrolyte effect regime. If the average charge density on the macromolecule is relative high and/or the molecular weight is large (≥ 106) sufficient intermolecular interactions will occur to produce rapid changes in reduced viscosity.
Permanganate/glycine‐initiated polymerization of acrylamide
Authors: Bajpai U. D. N. , Bajpai A. K. 
Published: April 2003

AbstractThe kinetics of aqueous polymerization of acrylamide with KMnO4/glycine redox pair was studied in an atmosphere of nitrogen at 35 ± 0.2°C. The rate of polymerization was found to be first power on monomer, activator, and catalyst concentration. The overall energy of activation was calculated to be 15.66 kcal/deg mol (65.54 kJ/mol) between 30 and 50°C. The effects of various additives (alcohols, neutral salts, complexing agents, addition of catalyst) were studied. The dependence of the polymerization rate on the activator and catalyst concentration was studied in DMF‐water mixture also. The molecular weight of polymer was determined at various temperatures of the reaction medium.
Glycidyl methacrylate–tert‐butyl acrylate copolymers: Synthesis, characterization, and thermal studies
Authors: Dhal Pradeep K. , Babu Gaddam N. 
Published: April 2003

AbstractGlycidyl methacrylate was copolymerized with tert‐butyl acrylate in bulk at 60°C using benzoyl peroxide as free radical initiator. The copolymer composition was determined by chemical analysis as well as from 13C‐NMR data. The monomer reactivity ratios were calculated by using the YBR method. The number average sequence length of the copolymers was determined from 13C‐NMR data and compared with those obtained from reactivity ratios. The intrinsic viscosity of the copolymers was determined in DMF, and thermal stability as well as mechanism of thermal degradation of the copolymers were evaluated.
Two‐component interpenetrating polymer networks (IPNs) from polyurethanes and epoxies. I. Studies on full IPN, pseudo‐IPN, and graft polymer alloys of polyurethanes and epoxies
Authors: Cassidy Edward F. , Xiao Han X. , Frisch Kurt C. , Frisch Harry L. 
Published: April 2003

AbstractIn this article we review the synthesis and morphology and the physical and mechanical properties of two‐component interpenetrating polymer networks (IPNs) from polyurethane and epoxy polymers; the corresponding pseudo‐IPNs and grafted IPNs are also discussed. A comparison was made of full IPNs, pseudo‐IPNs, grafted IPNs, and related homopolymers by examining their mechanical properties, mechanical spectra, and electron microscopy on an investigation of the effects of interpenetration or permanent entanglement in the IPN and related systems. This interpenetration has resulted in improved compatibility between the two polymer systems and has caused a decrease in the degree of phase separation. An observed shift in the dynamic glass transition temperatures (Tgs) of the two components which yielded a single IPN Tg further substantiates our results.
A regenerable immobilized NADH model. II. Reduction of α,α,α‐trifluoroacetophenone by immobilized 1,4‐dihydronicotinamide in aprotic solvent
Authors: Eling Berend , Challa Ger , Pandit Upendra K. 
Published: April 2003

AbstractA regenerable dihydronicotinamide, immobilized on a macroreticular polystyrene resin was used for the reduction of trifluoroacetophenone (TFA) in acetonitrile. Practical reutilization of the polymeric reagent (91% per cycle) was obtained when magnesium perchlorate was added to the reaction of the immobilized dihydropyridine with TFA. A possible explanation of the role of Mg ion in the reaction of benzyldihydronicotinamide and its polymeric analog is presented. This explanation also accounts for the results of other NADH model reactions, described in the literature, and for the role of the Zn ion in the enzyme liver alcohol dehydrogenase (LADH).
Solution behavior of ampholytic styrene ionomers
Authors: Salamone J. C. , Tsai C. C. , Anwaruddin Q. , Olson A. P. , Arnold M. , Nagabhushanam T. , Sawan S. , Watterson A. C. 
Published: April 2003

AbstractIn this article are described the solution properties of ampholytic ionomers obtained by the radical copolymerization of styrene with the ion‐pair comonomer 3‐methacrylamidopropyltrimethylammonium, 2‐acrylamido‐2‐methylpropanesulfonate. The solution properties were studied in mixed solvents, with a good solvent for the polystyrene backbone and another for the ionic moieties, and in the individual good solvent of benzyl alcohol. The data obtained strongly support extensive intermolecular ionic interactions in solution.
Differential scanning calorimetry studies of irradiated polyethylene: I. Melting temperatures and fusion endotherms
Authors: Zoepfl F. J. , Markovic̀ V. , Silverman Joseph 
Published: April 2003

AbstractThe effect of ionizing radiation on the melting behavior of high‐density and low‐density polyethylene was examined with data obtained by differential scanning calorimetry. Melting temperatures and fusion endotherms were obtained after absorbed doses of gamma radiation up to 3 MGy. The changes in melting temperatures and heat of fusion for the first and second meltings are related to the radiation chemistry of polyethylene. The changes in the first melting temperature are caused by radiation‐induced links that decrease the melt entropy and increase the flod surface free‐energy‐per‐unit area of chain‐folded polyethylene crystals. These effects are dependent on the lamellar thickness distribution and on the types of links formed (intramolecular or intermolecular). The changes in melting temperature and heat of fusion obtained in the second melting are related to the inhibition of crystallization caused by the presence of radiation‐induced links.
Synthesis, characterization, and properties of novel aromatic bispropenyl ethers
Authors: Crivello James V. , Conlon David A. 
Published: April 2003

AbstractAromatic bispropenyl ethers are a new class of highly reactive thermosetting monomers that have been prepared and characterized. Two synthetic routes to their preparation have been developed. The first of these involves the base‐catalyzed isomerization of bisallyl ether precursors that gives predominantly the Z bispropenyl ether isomers. The second method employs tris(triphenylphosphine)ruthenium(II) dichloride as an isomerization catalyst and produces predominantly the E isomers. Using these methods, a number of bispropenyl ether monomers containing different aromatic groups have been synthesized. The cationic polymerization of these novel monomers to give crosslinked network polymers using diaryliodonium salts as photo and thermal initiators has been studied.
Direct polycondensations of hydroxybenzoic acids by use of diphenyl chlorophosphate in the presence of N,N‐dimethylformamide
Authors: Higashi Fukuji , Yamada Yukiharu , Hoshio Atsushi 
Published: April 2003

AbstractDirect polycondensation reaction of hydroxybenzoic acids with diphenyl chlorophosphate (DPCP) in pyridine was largely improved by carrying out the reaction in the presence of a formamide. Among the formamides examined, N,N‐dimethylformamide (DMF), N,N‐dimethylformamide, and N,N‐dimethylacetamide were favorably used. A Vilsmeier adduct thus derived from DPCP and DMF was very effective especially for the preparation of high‐molecularweight copolyesters from hydroxybenzoic acids. Copolymers of several combinations of hydroxybenzoic acids were prepared and their solubility and thermal properties were investigated. The polycondensations of aromatic dicarboxylic acids and bisphenols with the adduct were also studied.
Synthesis and characterization of soluble polymides from 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene and aromatic tetracarboxylic dianhydrides
Authors: Imai Yoshio , Maldar N. N. , Kakimoto Masa‐Aki 
Published: April 2003

Abstract2,5‐Bis(4‐aminophenyl)‐3,4‐diphenylthiophene, a polyimide‐forming monomer, was prepared in three steps starting from benzyl chloride and sulfur. Novel polyimides were synthesized from the diamine and pyromellitic dianhydride or 3,3′, 4,4′‐benzophenonetetracarboxylic dianhydride (BTDA). Polymerization was carried out either by the usual two‐step procedure that included ring‐opening polyaddition giving polyamic acids, followed by cyclodehydration to polyimides, or by the direct one‐pot procedure involving cyclodehydration in situ. The polyimide derived from the diamine and BTDA, especially that prepared by the one‐pot procedure in m‐cresol containing isoquinoline, is soluble in various organic solvents and gave a yellow, transparent, tough, and flexible film. Solubility of this polyimide varied by the preparative method and by the copolymerization with bis(4‐aminophenyl) ether. All the polyimides are highly thermally stable and exhibited no appreciable decomposition up to 450°C in air and nitrogen atmospheres.
Polymerization of methyl methacrylate up to high degrees of conversion: Experimental investigation of the diffusion‐controlled polymerization
Authors: Stickler M. , Panke D. , Hamielec A. E. 
Published: April 2003

AbstractThe kinetic model given by Marten and Hamielec that describes the bulk polymerization of methyl methacrylate (MMA) and accounts for diffusion‐controlled termination and propagation was modified to include termination by combination and reaction diffusion and was then tested using isothermal conversion/time and molecular weight data obtained dilatometrically at various temperatures and with three different initiators. For each series of measurements two adjustable parameters were fitted to the conversion/time data. Excellent fits were obtained and the adjustable parameters were found to be the same for all concentration levels of the three initiators and to vary in a simple manner with temperature. The predicted molecular weight averages and molecular weight distributions were in satisfactory agreement with those found experimentally considering the difficulty of measuring high molecular weight PMMA by GPC. This model thus satisfies the specifications for a polymer reactor model that can be used to optimize commercial production systems.
Linear polythioesters. IX. Products of interfacial polycondensation of 4,4′‐dimercaptobenzophenone with some aliphatic acid dichlorides
Authors: Podkościelny Wawrzyniec , Kultys Anna 
Published: April 2003

AbstractBy interfacial polycondensation of 4,4′‐dimercaptobenzophenone with oxalyl, succinyl, adipolyl, suberoyl, and sebacoyl chlorides new polythioesters were obtained. To determine the optimal conditions of interfacial polycondensation the influence of the following factors on yield and value of reduced viscosity was studied: type of organic phase, the quantitative ratio of aqueous to organic phase, concentration of hydrogen chloride acceptor, molar ratio of reagents, temperature of reaction, rate of acid chloride addition, and contribution of catalyst. A thorough examination of the polycondensation of dithiol with adipolyl and sebacoyl chlorides was carried out. The structure of all polythioesters obtained under model conditions was determined by elemental analysis and infrared spectra. Initial decomposition and intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Mechanical and electrical properties of the polythioesters obtained from 4,4′‐dimercaptobenzophenone and adipoyl and sebacoyl chlorides were determined. The molecular weight was not measured because of the low solubility of the polythioesters.
Probes of the microenvironments of the cationic copolymers of styrene and vinylbenzenetrialkylammonium halides
Authors: Herkstroeter W. G. 
Published: April 2003

AbstractThe microenvironments of the cationic copolymers of styrene and vinylbenzenetrialkylammonium halides were explored by use of fluorescence spectroscopy. 5‐Dimethylamino‐1‐naphthalenesulfonate (DANS) and 1‐pyrenebutyrate (PB) were the fluorescent probes selected to bind to the polymers. The fluorescence energy of the former responds to the polarity or hydrophobicity of the microenvironment, whereas the absorption and fluorescence of the latter reveal the extent of ground‐state and excited‐state interactions. Polyelectrolyte coiling occurs in proportion to the fraction of binding sites occupied with charge‐neutralizing, probe molecules. The bound DANS probe shows that coiling makes the binding‐site environment more hydrophobic, and the bound PB probe shows that coiling facilitates excimer formation not only with nearest‐neighbor pyrene moieties, but also with non‐nearest neighbors. With methyl groups at the quaternary nitrogen binding sites, pyrene moiety interactions preceding excimer fluorescence occur in both ground and excited states. When the methyl groups are replaced with butyl or pentyl groups, pyrene excimers still form in the excited state, but the weak, hydrophobic interactions of the pyrene ground state decrease, because the longer alkyl groups serve as hosts for the hydrophobic pyrene moieties.
Functional monomers and polymers. CX. Methylation and interaction studies on uracil‐containing polymethacrylate derivatives
Authors: Fang Shi‐Bi , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractA polymethacrylate derivative containing uracil bases was methylated by using methyl iodide or dimethyl sulfate to give polymers containing 3‐methyluracil derivatives. In the case of methylation with dimethyl sulfate, sulfonation at 5‐position of the bases occurred in addition to the methylation at N‐3 position. The methylated polymers thus obtained were used further for the study of polymer complex formation with polymethacrylate containing adenine base.
Complexation and rate of polymerization of acrylic acid and methacrylic acid in the presence of poly(4‐vinylpyridine) in dilute methanol solution
Authors: Fujimori Kiyohisa , Trainor Gregory T. , Costigan Marion J. 
Published: April 2003

AbstractA 1:1 hydrogen‐bonded complex was formed between acrylic acid (AA) or methacrylic acid (MA) and the pyridine group of poly(4‐vinylpyridine) (P4VP) in dilute solutions. A shift of infrared absorption of the hydrogen‐bonded acid OH to a lower energy direction and an upfield shift of acid proton in the NMR were observed when the monomers were added with pyridine. The equilibrium constants of the 1:1 complexation with P4VP measured by using a semipermeable membrane were 0.58 and 0.26 for AA and MA, respectively, at 25°C in methanol. The bromometrically measured initial rate of radical polymerization showed only a slight enhancement in the presence of P4VP, the rate being maximum at the 4VP unit:monomer mole ratio of 0.25 and 0.5 for AA and MA, respectively, in dilute methanol solution at 60°C.