bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of cyclic acetals. II. Synthesis of amphiphilic block copolymers
Authors: Velichkova R. S. , Gancheva V. B. , Krüger H. , Rübner J. 
Published: April 2003

AbstractThe sequential copolymerization of 1,3,6‐trioxacyclooctane (TOC) and 1,3‐dioxolane (DOL) (B) with various vinyl monomers (A) was investigated. Under appropriate conditions amphiphilic block copolymers of the type AB and ABA were formed. The reaction mixtures and the isolated polymers were analyzed by GPC (double detection—IR and UV at 254 nm), IR, 1H‐, and 13C‐NMR spectroscopy. Block copolymers with chosen molecular weights and low polydispersity could be obtained only by sequential copolymerization of p‐methoxystyrene on “living” TOC. In the polymerization of DOL with α‐methylstyrene and i‐butyl vinyl ether (IBVE) transfer reactions take place to a larger degree.
Aspects of the thermal properties of poly(2‐vinyl anthraquinone)
Authors: Gradwell A. J. , Guthrie J. T. , Kazlauciunas A. 
Published: April 2003

Abstract2‐Vinyl anthraquinone was synthesized as described previously. In this article, three approaches to polymerization of 2‐vinyl anthraquinone are examined bulk thermal, chemical, and γ‐radiation‐induced. Polymerization in both the bulk phase and in solution were attempted. Thermal characterization has been carried out using differential scanning calorimetry (DSC), x‐ray diffraction (XRD), scanning electron microscopy (SEM) and hot‐stage optical microscopy (HSOM). Thermogravimetric analysis (TGA) has been used to provide procedural “apparent” activation energies for decomposition of the polymer.
Rigid‐Rod benzobisthiazole polymers with reactive fluorene moieties: Synthesis and characterization
Authors: Dotrong My , Evers Robert C. 
Published: April 2003

AbstractHigh purity 2,7‐fluorenedicarboxylic acid chloride was synthesized in a multistep reaction scheme from 2,7‐dibromofluorene. Subsequent polycondensation in polyphosphoric acid of 2,5‐diamino‐1,4‐benzenedithiol dihydrochloride with terephthaloyl chloride and 2,7‐fluorenedicarboxylic acid chloride led to rigid‐rod benzobisthiazole polymers with reactive fluorene moieties. The proportion of fluorene in the resultant polymers was controlled through reaction stoichiometry. Soluble polymers with intrinsic viscosities as high as 33.7 dL/g (methanesulfonic acid, 30°C) were obtained if the polymerization temperature was not allowed to exceed 165°C. Insoluble, presumably crosslinked polymers were obtained at higher temperature (190–200°C). Thermal characterization of the polymers by differential thermal analysis and thermal gravimetric analysis/mass spectroscopy did not disclose any thermal transition to 450°C. Onset of weight loss in air did not occur until over 550°C.
Synthesis and ring‐opening polymerization of novel bicyclic oxalactams: 2‐oxa‐5‐azabicyclo[2.2.2]octan‐6‐one
Authors: Okada Masahiko , Sumitomo Hiroshi , Mori Hiroto , Hall H. K. , Chan Ray J. H. , Bruck M. 
Published: April 2003

AbstractA novel bicyclic oxalactam 2‐oxa‐5‐azabicyclo [2.2.21 octan‐6‐one (2,5‐BOL) was synthesized from sodium 3,4‐dihydro‐2H‐pyran‐2‐carboxylate through a seven‐step reaction sequence. Anionic ring‐opening polymerization of 2,5‐BOL was carried out in bulk at 12OOC or in dimethyl sulfoxide at 40, 60, and 80°C by using potassium pyrrolidonate and the N‐benzoyl derivative of 2,5‐BOL as catalyst and activator, respectively. The polymerization gave a new polyamide containing cis‐ and trans‐2,5‐linked tetrahydropyran rings in the main chain. The cis/trans ratio varied from 70/30 to 95 /5 depending on the reaction conditions. The polyamide having number average molecular weights of 3000–8000 was soluble in a variety of solvents including methanol, ethanol, dimethyl sulfoxide, dimethylformamide, chloroform, and dichloromethane. It began to decompose at 280–32OOC depending on the compositions of the cis‐ and trans‐2,5‐linked structural units. The anionic ring‐opening polymerizability of 2,5‐BOL was found to be much lower than its structural isomer, 8‐oxa‐6‐azabicyclo[ 3.2.11 octan‐7‐one (8,6‐BOL).
Preparation and properties of new photosensitive polyimides from bis(4‐aminophenyl)tetramethyldisilane and various aromatic tetracarboxylic dianhydrides
Authors: Padmanaban Munirathina , Toriumi Masaru , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew photosensitive polymides containing photosensitive disilane unit were synthesised from 1,2‐bis(4‐aminophenyl)tetramethyldisilane and various aromatic tetracarboxylic dianhydrides by the usual two‐step procedure that includes ring‐opening polyaddition to yield the precursor polyamic acids, followed by cyclodehydration giving the respective polyimides. The polymaic acids had inherent viscosities between 0.63 and 0.85 dL/g depending on the tetracarboxylic dianhydride used. Excepting the polyimide obtained from pyromellitic dianhydride, all other polyimides were soluble in N‐methyl‐2‐pyrrolidone, m‐cresol, and pyridine. While the polyimide containing diphenyl sulfone unit was amorphous, the other polyimides were semi‐crystalline polymers based on their x‐ray diffractograms. The polyimides had glass transition temperatures between 235 and 304°C. They were thermally stable up to 380°C in both air and nitrogen atmospheres. All the polyamic acids showed a drastic decrease in the inherent viscosity upon UV light irradiation, implying the inherent photosensitivity of the polymers containing the disilane moiety.
The reactivities of diarylbutadienes towards the benzoyloxy radical: the cases of 1‐(1′‐naphthyl)‐4‐phenylbuta‐l,3‐diene and 1,4‐Di (1′‐Naphthyl)buta‐1,3‐Diene
Authors: Bevington J. C. , Breuer S. W. , Huckerby T. N. , Jones Rosie F. D. , Barson C. A. 
Published: April 2003

AbstractA study has been made of end‐groups in poly(methyl methacrylate) prepared using benzoyl peroxide as initiator and either 1‐(1′‐naphthyl)4‐phenylbuta‐1,3‐diene or 1,4‐di(1′‐naphthyl)buta‐1,3‐diene as additive. At 60°C, these dienes are 500–600 times as effective as methyl methacrylate in capturing benzoyloxy radicals and more than twice as effective as 1,4‐diphenylbuta‐1,3‐diene.
Polymerization of methyl methacrylate by charge‐transfer mechanism with aliphatic primary amines and carbon tetrachloride
Authors: Dwivedi P. C. , Srivastava Archana , Rathi R. S. 
Published: April 2003

AbstractPolymerization of methyl methacrylate (MMA) with aliphatic primary amines and carbon tetrachloride has been investigated in th dimethylsulfoxide medium by employing a dilatometric technique at 60°C. The rate of polymerization (Rp) has been evaluated under the conditions, [CCl4]/[amine] < 1 and > 1. The kinetic data indicate possible participation of the charge transfer complexes formed between the amine + CCl4 and the amine + MMA in the polymerization of MMA. In the absence of CCl4 or amine, no polymerization of MMA was observed under the present experimental conditions. The polymerization of MMA was inhibited by hydroquinone, indicating a free radical initiation. The energy of activation varied from 32 to 58 kJ mol−1.
Synthesis and characterization of novel aromatic polyamides from 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylfuran and aromatic diacid chlorides
Authors: Jeong Hwa‐Jin , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractA new highly phenylated heterocyclic diamine, 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylfuran, was synthesized in three steps from 4–‐nitrodeoxybenzoin. The low temperature solution polycondensation of the diamine with various aromatic diacid chlorides afforded tetraphenylfuran‐containing aromatic polyamides with inherent viscosities of 0.2–0.8 dL/g. Copolyterephthalamides were obtained from the diamine and 4,4′‐oxydianiline. The polyamides were generally soluble in a wide range of solvents that included N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, pyridine, and m‐cresol. Glass transition temperatures of the polyamides and copolyamides ranged from 302–342°C, and 10% weight loss was observed above 480°C in nitrogen.
Allylic polymers. I. Copolymerization of allyl esters with vinyl acetate
Authors: Shigetomi Yasumasa , Kojima Takehiro , Ono Naruhito 
Published: April 2003

AbstractThe radical copolymerization of allyl esters with vinyl acetate has been studied in the range from 10 to 90 mol % allyl esters in the feed. The Kelen‐Tüdos method was employed to determine the monomer reactivity ratios. The following values were found for the reactivity ratios: allyl propionate (M1)–vinyl acetate (M2), r1 = 0.42, r2 = 1.29; allyl butyrate (M1)–vinyl acetate (M2), r1 = 0.64, r2 = 0.97; allyl isobutyrate (M1)–vinyl acetate (M2), r1 = 0.51, r2 = 1.04; allyl valerate (M1)–vinyl acetate (M2), r1 = 0.58, r2 = 1.07; allyl trimethylacetate (M1)–vinyl acetate (M2), r1 = 0.34, r2 = 1.15. The Q‐e parameters were calculated from the allyl esters (M1)–vinyl acetate (M2) reactivity ratios. The e parameters of allyl ester monomers have been found to be nicely correlated with parameters such as dissociation constants of carboxylic acids, which are constituents of allyl ester monomers, and Taft σ* constants of the alkyl group in the acids. The molecular weights of copolymers were measured by GPC and ranged from (1.0–15.0) × 104.
Preparation and characterization of fluorine‐containing aromatic condensation polymers. I. Preparation and characterization of fluorine‐containing polycarbonate and copolycarbonates by two‐phase phase‐transfer‐catalyzed polycondensation of 2,2‐bis (4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane and/or 2,2‐bis (4‐hydroxyphenyl)propane with trichloromethyl chloroformate
Authors: Saegusa Yasuo , Kuriki Minoru , Kawai Akihiro , Nakamura Shigeo 
Published: April 2003

AbstractA series of fluorine‐containing homopolycarbonate and copolycarbonates with a wide range of unit ratio were synthesized by the two‐phase phase‐transfer‐catalyzed plycondensation of 2,2‐bis (4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane (Bisphenol AF) and/or 2,2‐bis (4‐hydroxy‐phenyl) propane (Bisphenol A) with trichloromethyl chloroformate, and the effect of the fluorine substitution on the synthesis and properties of these polymers was investigated by comparing with those of Bishphenol A‐based homopolycarbonate without fluorine. Film‐forming moderate‐to high‐molecular‐weight fluorine‐containing polycarbonates with reduced viscosities up to 0.54 dL/g were obtained in high yields by using tetra‐n‐butylammonium bromide as a catalyst, sodium hydroxide as a base, and 1,2‐dichloroethane as a medium. The reduced viscosity, however, decreased markedly with increasing feed ratio of Bisphenol AF. Their solubility in common organic solvents was clearly improved by the introduction of fluorine atom. The pliability of the films also increased remarkably with increasing fluorine content. The contact angles formed by water were larger than 90°, regardless of their fluorine contents, at 25°C in air. The critical surface tension and refractive index of Bisphenol AF‐based homopolycarbonate were ca. 20 dyn/cm and 1.426, respectively. The glass transition temperatures and thermal stability increased monotonously with increasing fluorine content.
Chain‐Cleavage and hydrolysis of activated polyethylene glycol derivatives: Evidence for competitive processes
Authors: Mcmanus S. P. , Karaman R. M. , Sedaghat‐Herati M. R. , Shannon Thomas G. , Hovatter Thomas W. , Harris J. M. 
Published: April 2003

AbstractStudies have been carried out with the tosylate of the monomethyl ether of polyethylene glycol (MeO–PEG–OTs) and with low molecular weight models to assess whether the neighboring oxygen at position 3 or 6 provides the driving force for hydrolytic cleavage of these activated derivatives. Our results reveal that MeO–PEG–OTs undergoes hydrolysis by competitive pathways. Water directly displaces the tosylate group to give the original PEG alcohol and the oxygen at position 6 nucleophilically displaces the tosylate group to give a cyclic oxonium ion as an intermediate. This intermediate can react by three pathways. First, it can lead to the production of the original PEG alcohol by attack of water on a ring carbon; second, dioxane and a lower molecular weight PEG alcohol is produced by water attack at the nonring carbon next to the charged oxygen; and third dioxane can be displaced by the oxygen atom at position 6 in the chain.
Synthesis and characterization of polyimides based on novel tricyclo[6,2,2,02,7] dianhydride
Authors: Su Ching‐Yie , Lee Yu‐Der 
Published: April 2003

Abstract3‐Phenyl‐tricyclo [6,2,2,02,7]dodeca‐2,11‐ene‐5,6,9,10‐tetracarboxylic dianhydride was prepared from 1,1‐diphenyl ethylene and maleic anhydride in 1 : 2 mole ratio by [4 + 2]π Diels‐Alder cycloaddition. The structure of the dianhydride was determined by mass spectroscopy, IR, 1H‐NMR, elemental analyses, and single crystal x‐ray diffraction. The monomer was condensed with several diamines in N‐methyl pyrrolidone or m‐cresol. The polyamic acids and the polyimides synthesized had inherent viscosities in the range of 0.19–0.31 and 0.17–0.25 dL/g, respectively, measured in N‐methyl pyrrolidone at 30°C. Both the polyamic acids and the polyimides were found to be soluble in m‐cresol, N‐methyl pyrrolidone, dimethylacetamide, dimethyl formamide, and dimethyl sulfoxide. The polymides showed a low degree of crystallinity from wide angle x‐ray diffraction. Thermal analysis of these polyimides revealed that their glass transition temperatures (Tg) were in the 215–237°C range and they decomposed in two stages. The first‐stage decomposition temperatures were almost the same in O2 or N2 atmospheres, but the polymers showed a better thermal stability in O2 rather than in N2 in the second stage. The mechanism of thermal degradation is discussed.
Membrane of epoxidized styrene–butadiene–styrene block copolymer complexing with (N,N′‐disalicylideneethylenediamine) cobalt (II) and use for oxygen permeation
Authors: Hsiue Ging‐Ho , Yang Jen‐Ming , Lee Pao‐Shun , Liaw Chin‐Yih 
Published: April 2003

AbstractThe complex formation reaction of epoxidized styrene‐butadiene‐styrene triblock copolymer (ESBS) with (N,N‐disalicylideneethylenediamine) cobalt(II) (CoS) in chloroform solution is studied. The coordination number and formation constant are determined by the Miller method. The membranes of ESBS complexing with CoS (ESBS–CoS) are made by solution casting method. The kinetics of oxygen binding to ESBS–CoS membrane is studied and the equilibrium constant, association, and dissociation constant are determined. The membrane of ESBS–CoS has the affinity to absorb oxygen with reversibility and that is confirmed by the studies of DSC. Due to the reversible absorption of oxygen to ESBS–CoS, the permeation of oxygen through ESBS–CoS membrane can be explained by dual mode.
The effect of power on the plasma‐assisted deposition of fluorinated monomers
Authors: d'Agostino R. , Favia P. , Fracassi F. , Illuzzi F. 
Published: April 2003

AbstractThe effect of power variation on the polymerization kinetics and on the polymer structure is reported for RF glow discharges fed with C2F6–H2 mixtures. Both deposition rate and polymer structure trends can be correlated to the variations of gas‐phase species density (atoms, radicals, and charged species) and can be explained by considering the competition of the deposition and etching process.
Rigid rod molecules as liquid crystal thermosets. II. Rigid rod esters
Authors: Hoyt Andrea E. , Benicewicz Brian C. 
Published: April 2003

AbstractNine rigid rod ester monomers endcapped with maleimide, nadimide, and methylnadimide groups were prepared and studied by DSC and hot stage polarized light microscopy. All of the monomers showed thermotropic nematic liquid crystalline phases and could be thermally crosslinked in the nematic phase. The nematic texture was maintained in the crosslinked solid state. The nematic phase range was enlarged by B‐staging the monomeric compounds. Heating the monomers for a short period of time in the nematic phase lowered the crystal to nematic transition temperatures and increased the nematic to isotropic transition temperatures. A nonequilibrium phase diagram was proposed to explain the melting behavior of these reactive liquid crystal thermoset materials.
Chemical structure of networks resulting from curing of N,N‐diglycidylaniline‐type resins with aromatic amines. IV. Characterization of TGDDM/DDS and TGDDM/DDM networks by high‐resolution solid‐state 13C‐NMR
Authors: Attias A. J. , Bloch B. , Laupretre F. 
Published: April 2003

AbstractCured N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM) based epoxy resins were investigated by high‐resolution solid‐state 13C‐NMR spectroscopy. Associated hardeners were the most commonly used low reactivity 4,4‐‐diaminodiphenylsulphone (DDS), as well as, for comparisons reasons, the higher reactivity 4,4′‐diaminodiphenylmethane (DDM) with, in each case, a1 to 1 or 1 to 0.6 epoxy/NH ratio. In order to interpret the spectra, the poorly resolved aliphatic region was decomposed into elementary lines, the structural assignments of which were made using solution 13C‐NMR data resulting from a previous model compound study. The main structural feature of all investigated systems is the predominance of small cyclic units resulting from intramolecular reactions of N,N‐diglycidylaniline groups. The resins are therefore far less crosslinked that it could be anticipated from the functionality of the reactants. Using the low reactivity DDS still increases this effect, due to a higher proportion of residual non reacted secondary amines. Reducing the initial ratio of hardener could on the contrary lead to a higher proportion of reacted amine function, and thus to a higher crosslinking degree. A qualitative picture of such networks is given at the end.
Synthesis, spectral, thermal, and flammability studies of phenolphthalein polyphosphate esters
Authors: Kishore K. , Kannan P. 
Published: April 2003

AbstractPolyphosphate esters were synthesized from phenolphthalein and aryl phosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by IR, 1H‐, 13C‐, and 31P‐NMR spectroscopy. The molecular weights were calculated by end group analysis using 31P‐NMR spectral data. The thermal stability of the polymers was studied by thermogravimetry and the flammability was investigated by measuring limiting oxygen index values.
A novel synthetic procedure of vinylacetamide and its free radical polymerization
Authors: Akashi Mitsuru , Yashima Eiji , Yamashita Takanori , Miyauchi Noriyuki , Sugita Shuichi , Marumo Kuniomi 
Published: April 2003

AbstractThe pyrolysis of N‐(α‐methoxyethyl) acetamide, which was obtained by one‐step reaction of acetamide, acetaldehyde, and methanol, gave N‐vinylacetamide (NVA) in a good yield. The polymerizability and copolymerizability of NVA were studied. Free radical polymerization was carried out in the presence of radical initiator or by γ‐ray irradiation. The monomer reactivity ratios of NVA were estimated in the copolymerization with acrylamide, vinyl acetate, and methyl methacrylate. The solvents were found to influence the monomer reactivity ratio. NVA showed a typical copolymerizability as nonconjugated vinyl monomer, and Q and e values were obtained in DMF as 0.16 and −1.57, respectively.
Synthesis of soluble polymeric photosensitizers with the 4‐nitro‐1‐naphthyl‐carbamoyl as pendant group
Authors: Diaz F. R. , Tagle L. H. , Garcia F. , Sastre R. , Conde M. , Mateo J. L. , Catalina F. 
Published: April 2003

AbstractSeveral models of monomers, homopolymers, and copolymers containing a photosensitizer group, 4‐nitro‐1‐naphthyl‐carbamoyl (NNC), have been synthesized. Synthetic methods are described, in addition to two routes for copolymers preparation. First, the radical copolymerization between monomers with the photosensitizer group built‐in and comercial monomers such as styrene and methyl acrylate and, second, polymer modification by nucleophilic reaction between carbonyl group polymer supported and nitro‐naphthyl amine. All products were characterized and one of the resulting soluble polymeric photosensitizer and its model compound, were tested as triplet energy donors against trans‐ stilbene and their Stern–Volmer constants were determined. Results show that the sensitizer efficiency is closer to that of the well known benzophenone sensitizer and higher than that of the acetophenone, while the sensitizer efficiency disminished when the chromophore is bonded to the polymer.
The preparation, characterization, and selected charge transfer properties of some anthracene functionalized polyesters
Authors: Gorda K. R. , Peiffer D. G. , Denney D. B. 
Published: April 2003

AbstractNovel anthracene backboned polyesters were successfully prepared by the melt condensation polymerization of anthracene 9,10‐diacetic acid dimethyl ester using titanium (IV) n‐butoxide as catalyst. Monomer and polymer structures were identified by a variety of methods. The melt polymerizations were carefully controlled to give low molecular weight polyesters soluble in chloroform. 1H‐NMR was used to determine the degree of polymerization
$ \[ {\rm (}\overline {{\rm DP}} ) \] $
and number‐average molecular weight
$ \[ {\rm (}\overline {\rm M} _n ) \] $ for each of the polyesters. Analysis of the 3‐5 ppm spectral region contained the necessary resonances for the interpretation. Spectral results show
$ \[ \overline {\rm M} _n = 7,000 - 10,000{g \mathord{\left/ {\vphantom {g {mol}}} \right. \kern-\nulldelimiterspace} {mol}} \] $.
Higher molecular weight polymers can also be prepared but chloroform solubility is lost. Thermal studies reveal the Tg of these materials varies from 50–60°C depending upon the aliphatic segment of the polymer. Decomposition temperatures in the range of 400–500°C were observed. Charge transfer complexes of these polymers were also studied. Ultraviolet absorption spectroscopy indicates these polyesters are good electron donating systems. Complexation with tetrachloro‐1,4‐benzoquinone (chloranil) have absorption maxima at approximately 662 nm. Absorption studies also reveal perturbations do exist in the polymer complexes suggesting the possibility of polymer effects. The emission spectra of these materials also confirms that fact.
Some aspects of stabilization and degradation of nigerian natural rubber. I. Photostabilization of natural rubber with bound di‐tert‐butyl‐4‐hydroxybenzyl thioglycollate (dbhbt)
Authors: Ebi Godwin Chukwu , Singh A. 
Published: April 2003

Abstract3,5‐Di‐tert‐butyl‐4‐hydroxybenzyl thioglycollate (DBHBT) has been reacted with Nigerian Natural rubber latex at 65 ± 1°C using 4,4‐azobiscyanovaleric (AZBN) acid‐ferrous sulfate redox system to obtain a binding efficiency of 13%. The bound DBHBT was investigated as a UV stabilizer in unprocessed and unvulcanized rubber using spectroscopic method. With respect to the CO index, the masterbatch diluted to 56% gave the optimum activity and higher concentrations showed significant pro‐oxidant activity. The CC bonds in particular, showed greater stability which is a function of DBHBT concentration. The methylenic and the allylic hydrogen atoms, the most susceptible, and probably the sites of the primary attack, were not protected by DBHBT.