bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitro‐ and fluoropolyformals. II. Novel polyformals from α, ω‐fluoro‐ and nitrodiols
Authors: Adolph Horst G. , Nock Lori A. , Goldwasser Judah M. , Farncomb Robert E. 
Published: April 2003

AbstractThe scope of polyformal formation from nitro‐ and fluorodiols has been explored further with a series of α, ω‐diols. Polymers with M̄ns of 2000–4000 were generally obtained but M̄ns approaching 10,000 are possible in some cases. Effects of monomer structure and reaction parameters on polymer molecular weight are described. The polymers were characterized by GPC, 1H‐NMR, and DSC analysis.
Synthesis and characterization of novel aromatic polyamides from 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole and aromatic diacid chlorides
Authors: Jeong Hwa‐Jin , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractA new polymer‐forming monomer, 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole, was synthesized in three steps starting from 4′‐nitrodeoxybenzoin. Tetraphenylpyrrole‐containing aromatic polyamides and copolyamides were prepared from the diamine with various aromatic diacid chlorides and from a mixture of the diamine and 4,4′‐oxydianiline with terephthaloyl chloride, respectively. The resultant polymers had inherent viscosities in the 0.3–1.8 dL/g range and were generally soluble in various organic solvents including N,N‐dimethylacetamide and m‐cresol. They have glass transition temperatures in the range of 306–333°C and showed no weight loss below 380°C in both air and nitrogen atmospheres.
Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. V. Preparation and properties of polytitanosiloxanes from silicic acid and bis(2,4‐pentanedionato)titanium diisopropoxide
Authors: Gunji Takahiro , Nagao Yukinori , Misono Takahisa , Abe Yoshimoto 
Published: April 2003

AbstractPreparation and properties of polytitanosiloxanes (PTS) as a preceramic polymer for SiO2‐TiO2 fibers were investigated. The PTS was prepared by the reaction of bis(2,4‐pentanedionato) titanium diisopropoxide (PTP) with silicic acid (SA), extracted with tetrahydrofuran from an aqueous solution, in methanol. They were soluble in methanol, ethanol, and THF. The molecular weight (Mn) was 1500–4200 depending on the reaction molar ratio (SA/PTP). A Concentrated methanol solution of PTS showed an appreciable stability to self‐condensation and good spinnability. Dry spinning of the solution provided golden yellow precursor fibers which can be subjected to thermal‐treatment to give ceramic fibers. The PTS is considered to be a copolymer formed by the condensation of oligomeric silicic acid with PTP consisting of SiOTi and SiOSi linkages in the molecular main chain with the ligand and hydroxy groups as pendants.
Synthesis of aromatic polyethers by Scholl reaction. II. On the polymerizability of 4,4′‐bis(phenoxy)diphenyl sulfones and of 4,4′‐bis(phenythiol)diphenyl sulfone
Authors: Percec Virgil , Wang James H. , Oishi Yoshi 
Published: April 2003

Abstract4,4′‐Bis(phenoxy)diphenyl sulfone (1), 4,4′‐bis(phenylthio)diphenyl sulfone (2), and 1 substituted with various electron‐donating groups in the phenoxy units were synthesized and polymerized under oxidative reaction conditions. The presence of methyl, tert‐butyl, and methoxy groups as substituents on the phenoxy groups of 1 increases both the yield and the solubility of the resulting polymers. The structure‐reactivity relationship of the monomers and of the growing species were discussed based on a radical‐cation mechanism of polymerization. Monomers of high nucleophilicity and resonance stabilized radical‐cation growing species are crucial to achieve polymers of high molecular weight. The structure of the polymers and in several cases of their chain ends were determined by 1H‐NMR spectroscopy. The mechanism of termination and the side reactions occuring during this polymerization process were discussed based on the structure of the resulting polymers.
Synthesis and characterization of side‐chain liquid crystalline polysiloxanes containing 4‐alkanyloxyphenyl trans‐4‐alkylcyclohexanoate side groups
Authors: Hsu Chain S. , Lu Yong H. 
Published: April 2003

AbstractThe synthesis and characterization of nine polysiloxanes containing 4‐alkanyloxyphenyl trans‐4‐alkylcyclohexane side groups are described. Six monomers which contain a pentenyloxy of a hexenyloxy flexible spacer display a nematic mesophase, while the other three monomers which contain an undecenyloxy flexible spacer display nematic, smetic A and smectic E mesophases. All synthesized polymers present two smectic mesophases except one containing 4‐hexanyloxyphenyl trans‐4‐n‐butylcyclohexanoate side groups presents one smectic mesophase and one containing 4‐undecanyloxyphenyl trans‐4‐n‐pentylcyclohexanoate side groups presents three smectic mesophases. Trans‐cis isomerization of mesogens and side chain crystallization did not occur for any of the synthesized polymers.
Kinetics and mechanism of emulsion polymerization initiated by oil‐soluble initiators. II. Kinetic behavior of styrene emulsion polymerization initiated by 2,2′‐azoisobutyronitrile
Authors: Nomura M. , Yamada A. , Fujita S. , Sugimoto A. , Ikoma J. , Fujita K. 
Published: April 2003

AbstractIn order to clarify the general kinetic behavior of emulsion polymerization initiated by oilsoluble initiators, the emulsion polymerization of styrene initiated by 2,2′‐azoisobutyronitrile was as a typical example, investigated thoroughly. The variations of the polymerization rate and the number of polymer particles produced with changes in emulsifier (sodium lauryl sulfate), initiator, and monomer concentrations initially charged and the reaction temperature were determined. It is shown from these experimental results that the kinetic behavior of this emulsion polymerization system is quite similar to that of styrene emulsion polymerization initiated by the water‐soluble initiator, potassium persulfate despite the difference in the principal loci of radical production in both systems.
Preparation and properties of aromatic polymides from 2,2′‐bibenzoic acid and aromatic diamines
Authors: Liou Guey‐Sheng , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractAromatic polyamides having inherent viscosities up to 1.8 dL/g were synthesized either by the direct polycondensation of 2,2′‐bibenzoic acid with various aromatic diamines or by the low temperature solution polycondensation of 2,2′‐bibenzoyl chloride with aromatic diamines. All the aromatic polyamides were amorphous and soluble in a variety of organic solvents including N,N‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone, dimethyl sulfoxide, m‐cresol, and pyridine. Transparent and flexible films of these polymers could be cast from the DMAc solutions. These aromatic polymides had glass transition temperatures in the range of 226‐306deg;C and began to lose weight around 350°C in air.
Elementary reaction and anionic polymerization of isopropenly t‐butyl ketone
Authors: Ito Hiroshi , Renaldo Alfred F. 
Published: April 2003

AbstractIsopropenyl t‐butyl ketone (IPTBK) does not undergo radical homopolymerization and its anionic polymerization is a slow equilibrium process with a low ceiling temperature, which is due to its limited conjugation imposed by steric hindrance. Equimolar reactions of IPTBK with several anionic initiators were carried out, products isolated and identified by 1H‐and 13C‐NMR, and product distributions determined by GC. While n‐butyllithium and phenyllithium preferentially produce allyl alcohols, Grignard reagents predominantly undergo β‐addition to produce mono‐adducts, and a significant amount of dimers. t‐Butyllithium and t‐butylmagnesium chloride provide the cleanest β‐addition with minimal dimer formation and no carbonyl addition. However, Grignard reagent do not yield a polymer. The 1:1 reaction mixture of IPTBK with t‐butyllithium is very stable at 0°C, providing a methyl‐terminated mono‐adduct quantitatively when quenched with methyl iodide after 29 h. Addition of a second IPTBK to the mono‐adduct anion appears to be affected by the low ceiling temperature. Although t‐butyllithium can efficiently reduce as well as add to di‐t‐butyl ketone, such reactions are minor in the presence of IPTBK. Anionic polymerization of IPTBK with t‐butyllithium was carried out under several conditions. The 1:1 model reactions and the lack of acidic hydrogens in its structure suggest that anionic polymerization of IPTBK with t‐butyllithium may be “living.” The molecular weight distribution of the polymers ranged from 1.1 to 1.6 with the number‐average molecular weight varying from 2,800 to 233,500. Group transfer polymerization of IPTBK produced only a six‐membered lactone.
Synthesis, characterization, and fire retardancy of ferrocene containing polyphosphate esters
Authors: Kishore K. , Kannan P. , Iyanar K. 
Published: April 2003

AbstractPolyphosphate esters containing ferrocene structures were synthesized from 1,1′‐bis (p‐hydroxyphenylamido) ferrocene and 1,1′‐bis (p‐hydroxyphenoxycarbonyl) ferrocene with aryl phosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by infrared, 1H‐, 13C‐, and 31‐NMR spectroscopy. The molecular weights were determined by end group analysis using 31P‐NMR spectral data. The thermal stability and fire retardancy were respectively determined by thermogravimetry and limiting oxygen index (LOI) measurements. The polyamide‐phosphate esters showed better thermal stability and higher LOI values than the polyester‐phosphate esters.
Synthesis of poly(arylene ether)s based on 9,9‐bis(3,5‐diphenyl‐4‐hydroxyphenyl)fluorene
Authors: Wang Z. Y. , Hay A. S. 
Published: April 2003

AbstractThe synthesis of a novel bisphenol, 9,9‐bis(3,5‐diphenyl‐4‐hydroxyphenyl)fluorene, in high yield by the transalkylation of 9,9‐bis(4‐hydroxyphenyl)fluorene is described. Three poly(arylene ether)s based on this hindered phenol were prepared with molecular weights (Mn) ranging from 34 800 to 51 300 and inherent viscosities ranging from 0.27 to 0.43 dL/g. The polymers have Tg's of 236–262°C and did not lose weight below 350°C, with 10% weight loss recorded above 550°C. They are readily soluble in chlorinated solvents such as methylene chloride, chloroform, and 1,2‐dichloroethane at room temperature. Attempts to synthesize an analogous monomer, bis (3,5‐diphenyl‐4‐hydroxyphenyl)diphenylmethane, are described.
The copolymerization behavior of acrylate dimers: Copolymers of methyl, ethyl, and n‐butyl acrylate dimers
Authors: Trumbo D. L. , Zander R. A. 
Published: April 2003

AbstractDimers of methyl, ethyl, and n‐butyl acrylate were synthesized in good yield through the use of a phosphine catalyst. The dimers synthesized in this manner have one double bond. The activity of this double bond was investigated in copolymerization reactions with styrene. The methyl acrylate dimer proved to have a slightly more favorable reactivity ratio than either the ethyl or n‐butyl acrylate dimers.
Intramolecular cyclization of pendant phenylethynyl groups as a route to solvent resistance in polyphenylquinoxalines
Authors: Lindley Patricia M. , Reinhardt Bruce A. 
Published: April 2003

AbstractBiphenyl‐based bisbenzil monomers which contain pendant phenylethynyl groups in the 2,2′‐positions were condensed with 3,3′‐diaminobenzidine to make polyphenylquinoxalines (PPQs) of high molecular weight. Thermal cure of these polymers at 193°C caused an intramolecular cyclization (IMC) of the phenylethynyl groups to give the rigid 9‐phenyldibenzanthracene system in the backbone of the polymer. The initial, uncured polymers formed though films which were soluble in m‐cresol and chlorinated solvents, but after thermal cure the films became insoluble in all common organic solvents and acids while maintaining their toughness. DSC scans of the cured materials showed small residual exotherms indicating that after vitrification even the intramolecular rotation required for the IMC reaction became restricted.
Epoxy modified polyurethane rigid foams
Authors: Lee Yng‐Long , Ku Wen‐Hsiung , Tsou Jenq‐Der , Wel Kuo‐Tung , Sung Po‐Hou 
Published: April 2003

AbstractRigid IPN foams were prepared by sequential polymerization of polyurethane and epoxy systems. Significantly higher compressive modulus and strength were observed with the IPN foams in comparison to the corresponding polyurethane rigid foams. The IPN foams show one glass transition temperature. The single Tg indicates the very small domain size in the PU‐epoxy IPN's.
Effect of alkyl substituents on initiator activity in cationic polymerization of styrene with p‐methoxybenzyldialkylsulfonium salts as initiators
Authors: Kikkawa Atsushi , Takata Toshikazu , Endo Takeshi 
Published: April 2003

AbstractThe effect of alkyl substituents on cationic polymerization of styrene with p‐methoxybenzyldialkysulfonium salts was studied. p‐Methoxybenzyl tetramethylene (1), dimethyl (2), diethyl (3), dibuty (4), and diisopropylsulfonium salts (5) were synthesized by the reaction of p‐methoxybenzyl bromide with the corresponding sulfides, followed by exchange of the counter anion Br− with SbF−6. These sulfonium salts served as potent cationic thermal initiators of which activity was estimated by the bulk and solution polymerizations of styrene. The bulk polymerizations with 1–4 (0.1 mol %) for 30 min gradually proceeded at 30–50°C, but the exothermic polymerization occurred vigorously at 40–60°C. The Polymerization with 5 took place exothermically even at room temperature. Temperature‐conversion curves of the polymerizations for 30 and 5 min revealed that the activity of the sulfonium salts was in the following order: 5 > 4 > 3 > 2 ≈ 1. This order was explained by the order of the bulkiness of the alkyl substituents on the sulfur atom. Number‐average molecular weight (M̄n) of polystyrene obtained by the polymerization undergoing no exothermic process was in a range of 6600–16000, which depended on the structure of the alkyl substituents: the more bulky the substituent was, the higher M̄n was.
Hydrosilylation of m‐TMI: New siloxane based aliphatic polyisocynates
Authors: Zhou Guangbin , Smid Johannes 
Published: April 2003

AbstractWell‐characterized polyfunctional aliphatic isocyanates were obtained in high purity and quantitative yield by the hydrosilylation of m‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (m‐TMI) with cyclic and acyclic hydrogementhylsiloxance. The products were characterized by 1H‐ and 13C‐NMR, IR, and GPC, and all result exclusively from ß‐addition to m‐TMI. Polymers with SiH Groups are also effective hydrosilylating agents of m‐TMI. The isocyanato siloxanes can be used as precursors for star and network polymers as well as other poly‐functional reagents, and examples of reactions with methoxy polyethylene glycol and with amine‐containing compounds are discussed.
Nitro‐ and fluoropolyformals. III. Copolyformals from mixtures of fluoro‐ and nitro‐α,ω‐diols
Authors: Nock Lori A. , Goldwasser Judah M. , Adolph Horst G. 
Published: April 2003

AbstractPolyformals of fluoro‐, nitramine‐, and C‐nitrodiols show widely differing properties with respect to glass transition temperature, melting transition, and solubility. Polymers with desirable combinations of these properties, e.g., low Tg, high nitro content, and good solubility in polar solvents, were expected to result from acid‐promoted copolycondensation of appropriate mixtures of diols with formaldehyde. A series of such condensations were carried out and the polymers obtained from binary mixtures of fluoro‐ and nitrodiols, different nitrodiols, and fluoro‐ or nitrodiols and carboranediols, were characterized by GPC, 1H‐NMR, and DSC analysis.
Synthesis and properties of aliphatic‐aromatic poly(amide‐imide)s from sulfonyldianilines and N,N′‐bis(ω‐carboxyalkyl)pyromellitimides
Authors: Yang Chin‐Ping , Lin Jiun‐Hung , Hsiao Sheng‐Huei 
Published: April 2003

AbstractSeven imide‐containing dicarboxylic acids IIa‐g were synthesized from pyromellitic dianhydride and amino acids of the formula HOOC—(CH2)m—NH2, with m—1,2,3,4,5,10,11. These diacids were condensed directly with 3,3′‐ or 4,4′‐sulfonyldianiline using triphenyl phosphite in N‐methyl‐2‐pyrrolidone (NMP)‐pyridine solution containing calcium chloride and lithium chloride. The resulting poly(amide‐imide)s have moderate to high inherent viscosities ranging from 0.47 to 2.02 dL/g in dimethylacetamide. These polymers showed excellent solubility in polar solvents such as NMP, and most of them could be cast into transparent and tough films. Glass transition temperatures (Tgs) of these poly(amide‐imide)s were recorded in the range 116–258°C and increased with decreasing number of methylene groups in the repeated unit. The polymers with longer aliphatic chains (e.g., m = 10 and 11) exhibited higher crystallinity, higher initial decomposition temperature, and lower solubility in polar solvents.
Catalytic epoxidation of styrene–butadiene triblock copolymer with hydrogen peroxide
Authors: Jian Xigao , Hay Allan S. 
Published: April 2003

AbstractStyrene‐butadiene‐styrene linear block copolymer (SBS) can be epoxidized with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate(3‐) as the catalyst in a biphasic system. The effects of reaction time, temperature, solvent, the ratio of the organic phase to the aqueous phase, the concentration of the catalyst, hydrogen peroxide and polymer, respectively, are studied on the conversion of double bonds to oxirane groups. 1H‐NMR analysis confirms the absence of ring opening side reaction in this epoxidation reaction system up to at least 70% conversion of the double bonds. When the conversion of double bonds is over about 70% the resultant polymer is insoluble in chloroform even at reflux but soluble in polar solvents such as DMSO when heated. Toluene is a better solvent for the reaction than dichloroethane. The reaction rate constants are measured at four temperatures and the activation energy for the reaction with toluene as solvent is determined as 49.9 kJ/mol.
Preparation and thermal properties of polyquinazolones: Effect of the chemical structure of bisbenzoxazinones on the thermal properties
Authors: Kubota Shigeru 
Published: April 2003

AbstractFour kinds of polyquinazolones were synthesized from 4,4′‐diaminodiphenylether and bisbenzoxazinones having different central aromatic nuclei (benzene, biphenyl, benzophenone, diphenylmethane). All the polymers were prepared by solution polycondensation at 190°C at a concentration of 15% solid in m‐cresol, and were obtained with intrinsic viscosities in the range of 0.3–0.8 dL/g in 97–98% yield. Their thermal properties were studied by using dynamic thermogravimetry and isothermal weight loss. All the polymers were found to produce high char yields (55–75%) in nitrogen. Oxidative thermal stability of the polymers was dependent on the chemical structure of bisbenzoxazinone and was governed by the stability of the bonds in the quinazolone units. The following order of oxidative thermal stability of the quinazolone units was determined from this study: diphenylmethane < benzophenone < biphenyl < benzene.
Syndiospecific polymerization of styrene. II. Monocyclopentadienyltributoxy titanium/methylaluminoxane catalyst
Authors: Chien James C. W. , Salajka Zdenek 
Published: April 2003

AbstractSyndiospecific polymerization of styrene was catalyzed by monocyclopentadienyltributoxy titanium/methylaluminoxane [CpTi (OBu)3/MAO]. The atactic and syndiotactic polystyrenes were separated by extracting the former with refluxing 2‐butanone. The activity and syndiospecificity of the catalyst were affected by changes in catalyst concentration and composition, polymerization temperature, and monomer concentration. Extremely high activity of 5 × 107 g PS (mol Ti mol S h)−1 with 99% yield of the syndiotactic product were achieved. The concentration of active species, [C*], has been determined by radiolabeling. The amount of the syndiospecific and nonspecific catalytic species, [C] and [C] respectively, correspond to 79 and 13% of the CpTi(OBu)3. The rate constants of propagation for C and C at 45°C are 10.8 and 2.0 (M s)−1, respectively, the corresponding rate constants for chain transfer to MAO are 6.2 × 10−4 and 4.3 × 10−4s−1. There was no deactivation of the catalytic species during a batch polymerization. The rate constant of chain transfer with monomer is 6.7 × 10−2 (M s)−1; the spontaneous β‐hydride transfer rate constant is 4.7 × 10−2 s−1. The polymerization activity and stereospecificity of the catalyst are highest at 45°C, both decreasing with either higher or lower temperature. The stereoregular polymer have broad MW distributions, M̄w/M̄n = 2.8–5.7, and up to three crystalline modifications. The Tm of the s‐PS polymerized at 0–90°C decreased from 261.8 to 241°C indicating thermally activated monomer insertion errors. The styrene polymerization behaviors were essentially insensitive to the dielectric constant of the medium.
Chemical modification of the reducing chain end in dextrans and trimethylsilylation of its hydroxyl groups
Authors: Hashimoto Kazuhiko , Imanishi Shin‐Ichiro , Okada Masahiko , Sumitomo Hiroshi 
Published: April 2003

AbstractThe reducing ends of dextrans, of which number‐average molecular weights were 3600 and 16000, were almost quantitatively converted to lactone, amine, and acyllactam groups, successively, by iodine oxidation followed by lactonization, aminolysis with 1,4‐diaminobutane, and finally reaction with terephthaloylbis (ϵ‐caprolactam). Hydroxyl groups in dextrans were also trimethylsilylated for protection with a mixture of 1,1,1,3,3,3‐hexamethyldisilazane and trimethylchlorosilane. In advance of every run, the adequate reaction conditions were search by using D‐maltose as a low molecular weight model compound for dextrans.
Synthesis and polymerization of racemic and optically active substituted β‐propiolactones. VI. α‐Phenyl β‐propiolactone
Authors: Hmamouchi Mohammed , Prud'Homme Robert E. 
Published: April 2003

AbstractThe synthesis and optical resolution of α‐phenyl β‐amino‐ethylpropionate led to the preparation of optically active α‐phenyl β‐propiolactones (PhPL) of different optical purities. The enantiomeric excess of PhPL was determined using 200 MHz 1H‐NMR spectroscopy, after complexation with tris[3‐(trifluoromethyl hydroxymethylene)‐d‐camphorato]europium III. It was then polymerized, in bulk and in solution, using a potassium acetate/crown ether complex as initiator. The optically active poly(PhPL)s thus obtained are insoluble in most organic solvents, whereas atactic poly(PhPL)s are soluble in CCl4, CHCl3, and dichloroethane. Several differences are observed between the physical properties of optically active and atactic poly(PhPL)s. However, atactic poly(PhPL)s are semi‐crystalline polymers, similar to poly(α‐disubstituted β‐propiolactone)s, but in contrast with poly(α‐methyl β‐propiolactone). Melting (Tf) and glass transition temperatures, as well as enthalpy of fusion (ΔH), vary with the optical purity of the polymers. For example, atactic poly(PhPL) exhibits a Tf = 94°C and ΔH = 9 J/g as compared to Tf = 119°C and ΔH = 37 J/g for a poly(PhPL) having an enatiomeric excess of 50%.
Synthesis and characterization of novel polyarylates from 2,5‐bis(4‐hydroxyphenyl)‐3,4‐diphenylfuran and aromatic diacid chlorides
Authors: Jeong Hwa‐Jin , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew tetraphenylated heterocyclic diol, 2,5‐bis(4‐hydroxyphenyl)‐3,4‐diphenylfuran, was synthesized by the oxidative coupling of 4‐methoxydeoxybenzoin as a starting material, followed by simultaneous cyclodehydration and demethylation. Tetraphenylfuran‐containing polyarylates with inherent viscosities of 0.2–0.7 dL/g were prepared from various diacid chlorides by both solution polycondensation and phase transfer catalyzed two‐phase polymerization methods. All the polymers were easily soluble in dichloromethane, o‐chlorophenol, 1,4‐dioxane, pyridine, and N‐methyl‐2‐pyrrolidone and showed semicrystalline patterns as evidenced by the X‐ray diffraction studies. These polyarylates have glass transition temperatures in the range of 222–236°C and 10% weight loss was observed above 430°C in both air and nitrogen.