bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and photogeneration properties of copolyacrylate having carbazole donor and trinitrofluorenone acceptor chromophores
Authors: Hu Chau Jin , Oshima Ryuichi , Senō Manabu
Published: April 2003

Novel copolymers containing both donor and acceptor chromophores have been synthesized by free radical polymerization of 2‐N‐carbazolylethyl acrylate and 2′‐acrylylethyl‐4,5,7‐trinitrofluorenone‐2‐carboxylate. The charge transfer complexation occurs in copolymers in a similar way to poly(2‐N‐carbazolylethyl acrylate) molecularly doped with 2,4,7‐trinitrofluorenone (TNF) and a model compound, ethyl 4,5,7‐trinitrofluorene‐2‐carboxylate (Et‐TNF). Copolymer and doped systems exhibit obvious CT bands in a 440–600 nm region, where the former shows higher absorption than the latter. Glass‐transition temperatures show positive deviations from the weight‐average values of copolymers, indicating the partial interchain interaction of copolymers in solid state. Quantum efficiency of hole photogeneration of the copolymer with the 0.05 to 1.0 molar ratio of TNF to carbazole chromophores is higher than those of the corresponding molecularly TNF‐ and Et‐TNF‐doped poly(2‐N‐carbazolylethyl acrylate), especially at lower electric fields.
The quantitative description of small molecule binding to abiotic polymers
Authors: Charton Marvin
Published: April 2003

The variation of equilibrium constants for the binding of small molecules to abiotic polymers as a function of structure is quantitatively described by the intermolecular force (IMF) equation and relationships derived from it. Structural variations in both the small molecules and in the polymers were studied. The data were taken from the literature. The results obtained suggest that the IMF equation may be generally useful for modelling the effect of structural variation on polymer properties which depend on the difference in intermolecular forces between initial and final states. They also provide a model for nonspecific binding to biopolymers.
New chemically prepared conducting “pyrrole blacks”
Authors: Walker John A. , Warren L. F. , Witucki E. F.
Published: April 2003

A series of electrically conducting pyrrole “black” polymers has been prepared by chemical oxidation of pyrrole with a variety of ferric salts. The synthesis and properties of these materials are described and compared with electrochemically‐prepared analogs. Pyrrole “blacks” with strong acid anion “dopants” exhibited the highest conductivities, up to 62 Ω cm−1 for the triflate‐doped polymer. The adjustability and ease of synthesis of the ferric‐derived polypyrroles render these particularly promising for large‐scale processing of conducting polymers.
Mechanism of thermal degradation of poly(alkyl acrylate)s using pyrolysis gas chromatography mass spectrometry
Authors: Haken J. K. , Tan (nee Gunawan) L.
Published: April 2003

The pyrolyses of homologous poly(alkyl acrylate)s is reported with identification of the major pyrolyses products. A mechanism involving random homolytic scission of the chain followed by a series of intermolecular and intramolecular transfer reactions has been proposed for poly(methyl acrylate) by Cameron and Kane and further developed by Haken, Ho, Houghton, and Gunawan. This mechanism is demonstrated to be generally applicable to the poly(n‐alkyl acrylate)s. Reaction mechanisms are postulated for the various products produced and ion fragmentation mechanisms for the mass spectra produced are shown.
Chemical release control: Schiff bases of vinylbenzaldehyde and functional amines
Authors: Kamogawa Hiroyoshi , Sakai Tsuyoshi , Sohma Hirohito
Published: April 2003

Schiff base (SB) monomers of vinylbenzaldehyde with functional amines were prepared. Copolymers of SB monomers with N‐vinyl‐2‐pyrrolidone soluble in aqueous solutions were obtained in most cases. However, p‐aminobenzenesulfonamide monomer resulted in gel formation. Thus, the reaction of vinylbenzaldehyde copolymer with the sulfonamide was used instead of the copolymerization. The hydrolytic behaviors of SB monomers and copolymers to liberate respective amines were structure dependent and, for most copolymers, the rates were lower than those of the corresponding monomers.
The crosslinking of epoxy resins at interfaces. V. Amine‐cured resins at carbon and graphite surfaces
Authors: Garton Andrew , Stevenson William T. K. , Wang S. P.
Published: April 2003

The effects of carbon blacks, chopped carbon fibers, and crushed carbon fibers on the crosslinking chemistry of a diglycidyl epoxy resin/m‐phenylenediamine system were examined by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The carbon and graphite surfaces were given oxidizing and reducing treatment to simulate the surface treatment of carbon fibers used in the manufacture of composites. The oxidized carbon surfaces initially accelerated epoxy–amine reactions but inhibited the later stages of the reaction such that the final extent of cure was reduced. The oxidized carbons also preferentially adsorbed the amine curing agent, resulting in a stoichiometric imbalance at the interface.
Characterization of poly(carboxylic acid)/poly(ethylene oxide) blends formed through hydrogen bonding by spectroscopic and calorimetric analyses
Authors: Jeon Seung Ho , Ree Taikyue
Published: April 2003

The solid state of the complex between poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO), and that between poly(methacrylic acid) (PMAA) and PEO formed via hydrogen‐bonding was studied by differential‐scanning calorimetric (DSC) and by Fourier‐transform infrared (FT–IR) spectroscopic measurements. Melting temperature Tm and the degree of the crystallinity Xc of PEO in the systems PAA (or PMAA)/PEO blends obtained from aqueous or dimethyl sulfoxide (DMSO) medium were measured in various unit mol % of PEO ([PEO]100/{[PAA(or PMAA)] + [PEO]}) where [ ] is the unit mole concentration. It was found that 50 unit mol % of PEO is a critical composition, which gives new evidence for the 1 : 1 complex formation between PAA (or PMAA) and PEO. From the FT–IR spectroscopic analysis in conjunction with DSC measurements we also found that the effects of solvent and of hydrophobic interaction (due to the α‐methyl group of PMAA) are the important factors controlling the complexation in the solution and solid systems. These factors also affect the crystallization behavior and the microstructure of the PAA (or PMAA)/PEO blend in solid state.
Reactivities of sulfur‐centered radical toward polyisoprenes and polybutadienes studied by flash photolysis method
Authors: Ito Osamu , Tamura Saburo , Matsuda Minoru , Murakami Kenkichi
Published: April 2003

The kinetic behavior of the thiyl radical in the solution containing polyisoprenes and polybutadienes has been studied by the flash photolysis method. For benzothiazole‐2‐thiyl radical, the addition rate constants toward these polymers and the model compounds of the polymers were evaluated. The relative reverse rate constants and equilibrium constants were also estimated. The addition rate constants decrease with an increase in the degree of polymerization; the ratio of the addition rate constant for polyisoprene (3.1 × 104M−1s−1(in monomer unit);Mv= 674,000) to that for 2‐methyl‐2‐butene (1.5 × 105M−1s−1) is about 1/5. This indicates that the polymer chain effect appears in the free‐radical addition reaction. The relative reverse rate constants for the polymers are also smaller than those for 2‐methyl‐2‐butene, suggesting a kind of polymer effects; i.e., it can be presumed that the bonded‐thiyl radicals migrate very rapidly to the neighboring double bonds in the polymer. Significant differences in the rate parameters were observed between polyisoprene and polybutadiene, betweencis‐ andtrans‐polyisoprenes, and between 1,4‐ and 1,2‐polybutadienes.
Emulsion polymerization: Theory of particle size distribution in copolymerization system
Authors: Chen Show‐An , Wu Kuo‐Wei
Published: April 2003

A mathematical model for describing the particle size distribution (PSD) in emulsion copolymerization system is developed by analogy to that in emulsion homopolymerization system as proposed by Lichti and co‐workers. By use of the appropriate combinations of the kinetic parameters of the comonomers, the complicated equations for copolymerization systems can be reduced to simpler equations identical to those of homopolymerization systems. The two calculation examples, styrene–methyl methacrylate and styrene‐butadiene systems, are given to demonstrate the applicability of the proposed theory. The conditions for producing bimodal PSD from a seeded emulsion polymerization are discussed.
Stereoregularity of poly(methyl methacrylate) prepared by aqueous polymerization and catalyzed by corundum
Authors: Moustafa A. B. , Ellatif Z. H. Abd , Amer L. I.
Published: April 2003

The aqueous polymerization of methyl methacrylate was carried out in the absence and in presence of corundum or carborundum at 25 and 80°C. In the absence of corundum and carborundum, it has been found that rising the polymerization temperature from 25 to 80°C resulted in changing the tacticity of the obtained polymers. At 25°C the isotactic triad was 26% while the heterotactic triad was 33.5% and the syndiotactic one was 40.5%. Increasing the polymerization temperature to 80°C resulted in a decrease of the isotactic structure to 0% and increased the heterotactic structure and syndiotactic structure to 48 and 52% respectively. Polymerizing at 25°C in presence of corundum (0.5 g) an increase in the syndiotactic triad took place from 40.5 to 50.7% while the isotactic triad decreased from 26 to 22.2% and the heterotactic structure decreased from 33.5 to 27%. Raising the polymerization temperature to 80°C in the presence of the same amount of corundum resulted in an increase in both the isotactic and heterotactic triads to 35 and 32.7%, respectively. Polymerizing at 80°C in presence of corundum (0.5 g) resulted in nearly an equal percentage of each triad 33%.
Polyurethane cationomers. I. Structure–properties relationships
Authors: Al‐Salah H. A. , Xiao H. X. , McLean Jr. J. A. , Frisch K. C.
Published: April 2003

Polyurethane (PU) cationomers have been synthesized by quaternizing tertiary amine‐containing linear polyurethanes using different quaternizers containing acid groups. The effect of chemical structure of PU cationomers on the physical properties was studied. The mechanical properties of PU cationomers were improved with decreasing molecular weight of poly(caprolactone) glycol, and increasing concentration of quaternary ammonium. Decreasing the carbon number in the alkyl group of the N‐alkyl diethanol‐amine chain‐extenders, and using rigid symmetrical diisocyanates, the mechanical properties of the PU cationomers were increased. The effects of these factors on the glass transition temperature of PU cationomers were also examined. The mechanical properties of the PU cationomers decreased by immersion in water and recovered after removal of the water.
New polymer syntheses. XIX. Syntheses of aromatic polyesters from phenoxyterephthalic acid
Authors: Kricheldorf Hans R. , Schwarz Gert , Ruhser Frank
Published: April 2003

The synthesis of bisphenol‐A phenoxyterephthalate was chosen as model system to find the optimum method for polycondensations of aryloxyterephthalic acids. It is demonstrated that phenoxyterephthalic acid or its acid chloride may cyclize at temperatures above 180°C yielding anthrone‐3‐carboxyclic acid which causes termination steps. The highest yield and molecular weight was obtained by interfacial polycondensation of phenoxyterephthaloylchloride.
Stereoselective substitution on PVC using phase transfer catalysts
Authors: Martíanez G. , Mijangos C. , Terroba P. , Millán J.
Published: April 2003

The nucleophilic substitution with sodium benzenethiolate in aqueous suspension in the presence of a phase‐transfer catalyst has been studied for two samples of PVC of different tacticities. The kinetics shows two well‐defined periods: one period is very fast and involves low conversions that are greater as the isotactic content of PVC increases, while another steady period is slow and its slope seems to depend on physical features, e.g., molecular weight and crystallinity, which would affect the accessibility of nucleophile. The evolution of unreacted syndio, iso, and heterotactic triad contents with degree of substitution has been followed by 13C‐NMR spectroscopy. Since the content of syndiotactic triads does remain unreacted at the end of the reaction and that of isotactic and heterotactic triad decreases, but at a different rate, the reaction is proved to proceed by a stereospecifically controlled mechanism. The influence of degree of substitution on both the thermal degradation rate and the evolution of UV–Visible spectra of equally degraded samples has been also studied; the highest stability in terms of degradation rate and content of short polyenes is obtained when a specific fraction of isotactic triads has reacted. From the correlation between the results of this work and those previously obtained in solution, some enlightening conclusions about the reaction mechanism are drawn.
Synthesis and characterization of polyazo(amine‐imide)s
Authors: Thanuja J. , Srinivasan M.
Published: April 2003

Aromatic polyamine‐imides were synthesized from N,N′‐bismethylolazobenzenetetracarboxylic diimide and various diamines. Polycondensations were carried out in DMAc containing 1% water. The linear polyamine‐imides obtained varied in color and had inherent viscosities in the 0.25–0.35 dL/g range. These polymers were characterized by physical and thermal methods.
Preparation and properties of polyamides from 2,8‐phenoxathiin‐bis‐(γ‐ketobutyric acid), 2,7‐thianthrene‐bis(γ‐ketobutyric acid), and aromatic diamines
Authors: Reddy T. Ashok , Srinivasan M.
Published: April 2003

Aromatic‐aliphatic polyamides containing phenoxathiin and thianthrene heterocyclic units were prepared by the direct polycondensation of 2,8‐phenoxathiin‐bis(γ‐ketobutyric acid) (I) or 2,7‐thianthrene‐bis(γ‐ketobutyric acid) (II) with various aromatic diamines in a triphenylphosphite‐pyridine system. Prior to polymer synthesis two model diamides were prepared by condensing γ‐keto acid I or II with p‐toluidine. The model diamides and polyamides were characterized by spectral methods and elemental analysis. The polyamides, obtained in 56–90% yields, had inherent viscosities in the 0.82–1.1 dL/g range in concentrated H2SO4 at 30°C. The effect of heterocyclic units on polymer properties, such as solubility, crystallinity, and thermal stability has been discussed.
Hydrogen bonding on accessible surfaces of cellulose from various sources and relationship to order within crystalline regions
Authors: Rowland Stanley P. , Howley Phyllis S.
Published: April 2003

Celluloses from a variety of common sources were analyzed for availabilities of O(2)H, O(3)H, and O(6)H in order to estimate the extent of hydrogen bonding on accessible fibrillar surfaces. Celluloses from flax, ramie, sisal, and wood (both cellulose I and II from wood) together with liquid NH3‐swollen cotton and NaOH‐swollen cotton (cellulose II) had relative availabilities similar to those of native cotton. Celluloses from Valonia centricosa and in rayon samples stood apart from each other and from the “cotton family.” The difference between Valonia and cotton celluloses appears to result, in addition to the accepted smaller, less perfect crystallites in cotton, from an O(2)H hydrogen bond which is likely the intramolecular bond between O(2)H and O(6′)H that is present in Valonia and absent in cotton. Rayon samples also showed evidence of similar bonds involving O(2)H on accessible surfaces. Since the regenerated rayons had relative availabilities different from those of mercerized cotton and wood cellulose samples, it is proposed that chain packing arrangements are not the same in these two types of cellulose II.
Benzocyclobutene in polymer synthesis. I. Homopolymerization of bisbenzocyclobutene aromatic imides to form high‐temperature resistant thermosetting resins
Authors: Tan Loon‐Seng , Arnold Fred E.
Published: April 2003

A series of new bisbenzocyclobutene‐terminated aromatic imide monomers has been synthesized from the condensation reaction of 4‐aminobenzocyclobutene and the perspective dianhydride in refluxing acetic acid/toluene. The differential scanning calorimetric studies of the foregoing monomers indicated that polymerization exotherms began at 229–250°C and reached their maxima at 258–263°C. The cured samples (250–254°C; N2; 8 h) were surprisingly stable toward thermo‐oxidative degradation; only 7–10% weight loss was observed after 200 h (in air) at 314°C (600°F). At higher temperatures (650 and 700°F), the most rigid structure was the most thermo‐oxidatively stable. An approach to enhance both the final glass‐transition temperature (Tg cure) and the thermo‐oxidative stability of the bisbenzocyclobutene system was to dilute the cure‐site density since the cure‐site structure is the weakest part of the polymeric structure. Therefore, a series of bisbenzocyclobutene‐terminated aromatic imide oligomers were prepared, using various aromatic amines as the chain‐extending agents. Meta‐phenylenediamine was apparently the most effective in the advancement of both the Tg (cure) and thermo‐oxidative stability.
Emulsion polymerizations. I. A novel approach to the evaluation of the molecular weight distributions
Authors: Giannetti Enzo , Storti Giuseppe , Morbidelli Massimo
Published: April 2003

A simple, probabilistic approach describing the number distribution of the molecular weight (MWD) of polymers formed by emulsion polymerization is presented. The radical populations of the reacting system are formally split into infinite, quickly convergent series of particularly tagged radical populations. These populations are characterized by the nature and the number of the state transitions of the associated latex particles. For each kind of single radical or radical pairs a distribution function is then defined. These functions can be specified on the basis of αi and Qi, the growth probabilities, within a latex particle in state i, of a single radical and a radical pair respectively. The overall MWDs are then given by summation over all the distributions of the radical populations and over all the allowed states. Only one set of ordinary differential equations (the Smith–Ewart equations) are involved in the mathematical formulation, single distribution functions being obtained by solving simple exponential‐type integrals. In this paper, analytic solutions are presented for the zero‐one, zero‐one‐two and general systems. Analogies and differences between our approach and previously reported treatments are critically discussed.
Characterization of polyethylene terephthalate by gel permeation chromatography (GPC)
Authors: Weisskopf Klaus
Published: April 2003

The use of the solvent mixture chloroform/hexafluoroisopropanol (98 : 2 vol %) in the GPC‐analysis of polyethylene terephthalate (PET) is described. PET‐samples of different molecular weight have been prepared and characterized by light scattering, viscometry, and improved techniques of osmometry and end group titration. These well characterized samples were used in calibrating the GPC. The calibration with polydisperse standards was found superior to the universal calibration procedure in the solvent system chosen.
Polyarylates. V. The influence of phase transfer agents on the interfacial polycondensation
Authors: Lee Yu‐Der , Tsai Hong‐Bing , Jeng Jaw‐Tarng
Published: April 2003

The effect of various phase transfer agents on the interfacial polycondensation of bisphenol A with isophthaloyl chloride was investigated. It was found that the transfer rate of bisphenolate and, thus, the reaction rate of polycondensation were increased with an increasing lipophilicity of the phase transfer agent, i.e. TBAC > TEBAC > TEAC, whereas the equilibrium of bisphenolate between the organic phase and the aqueous phase was hardly affected. Moreover, experimental evidence indicated that a phase transfer agent of high lipophilicity reduced the hydrolysis of the acid chloride, an important aspect in interfacial polycondensation.
Radical cyclopolymerizations of diallylsilanes and triallylsilanes
Authors: Saigo Kazuhide , Tateishi Kazuo , Adachi Hiroshi
Published: April 2003

The radical polymerizations of diallylsilanes such as diallyldimethylsilane (1) and diallylmethylphenylsilane (2) have been conducted. Both poly(diallyldimethylsilane) (3) and poly(diallylmethylphenylsilane) (4) are soluble in benzene, methyl ethyl keton (MEK), and chloroform, slightly soluble in acetone, and insoluble in methanol and ethanol. No insoluble fraction of either polymer was obtained. Very little evidence of vinyl protons in the 1H‐NMR spectra can indicate that both polymerizations predominantly proceed with intramolecular cyclization. In order to study the ring size of cyclic structure in the repeating unit of the polymers, a model compound, allyl(2‐chloropropyl)dimethylsilane (5), was synthesized and cyclized with Bu3SnH in the presence of azobisisobutyronitrile (AIBN) in benzene, under similar condition of those for the cyclopolymerizations. The product was analyzed with GC–MS which showed that the five‐membered ring compound, 1,1,3,4‐tetramethylsilacyclopentane, was not formed. From the result of the cyclization of the model compound, it can be suggested that the polymerizations undergo with only h–t intramolecular cyclization to form a six‐membered ring in the repeated unit. The 13C‐NMR spectra of 3 and 4 were measured to study the ring size and the configuration of the cyclic structures. The two peaks at −1.6 and −3.4 ppm of the spectrum of 3 show that there are two kinds of methyl carbons in the repeating unit. From consideration of the model reaction and the number of the peaks of the NMR spectrum, it can be considered that the polymer main chain is assembled with the six‐membered ring in cis‐form, and the two signals are assigned to equatorial and axial methyl carbons, respectively. The two peaks at ‐1.5 and ‐5.1 ppm of the 13C‐NMR spectrum of 4 can be assigned similarly. The radical cyclopolymerizations of triallylsilanes such as methyltriallylsilane (6) and phenyltriallylsilane (7) were conducted. The 1H‐NMR spectra of poly(methyltriallylsilane) (8) and poly(phenyltriallylsilane) (9) show broad peak around 5 ppm for vinyl protons and around 2 ppm for alkyl protons. Comparisons of the relative intensities of the peaks indicate that both polymerizations undergo with single ring closure to form a polymer with monocyclic structure moiety, cyclosilahexane, and an allyl group in a repeating unit of 8 and 9.
Surface modification of polymers. I. Vapour phase photografting with acrylic acid
Authors: Allméar K. , Hult A. , Rårnby B.
Published: April 2003

Surfaces of low density polyethylene, high density polyethylene, and polystyrene have been modified by grafting with acrylic acid. Benzophenone and acrylic acid in the vapor phase were UV‐irradiated in the presence of a polymer substrate. Grafting with acrylic acid took place in a thin layer on the surface, thus increasing the wettability of the polymer. After 5 min of irradiation, the contact angle against water had decreased to 20° for polystyrene and 50° for the polyethylene samples. ESCA measurements on samples irradiated for 5 min showed a 90% poly(acrylic acid) coverage of the surface for polystyrene, 63% for low density polyethylene, and 56% for high density polyethylene. Acetone or ethanol were used as carriers of monomer and initiator. Acetone was able to initiate grafting and was found to promote and direct grafting to the surface. The stability of the acrylic acid grafted surfaces was studied by contact angle measurements and ESCA. At room temperature, the grafted layer is confined to the surface, but when the material was heated in air the surface was reshaped into a hydrophobic one. The process was reversible. In aqueous surroundings at elevated temperatures the hydrophilic character of the surface was restored.
Synthesis and characterization of BTDA‐based polyamide‐imides
Authors: Dezern James F.
Published: April 2003

A series of thermally‐stable, tough, linear polyimides containing amide linkages were prepared. These materials have potential as high temperature films and coatings as well as matrix resins in graphite reinforced structures. The new polyamide‐imides were prepared by reacting a group of isomers of diaminobenzanilide (DABA) with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) to form the polyamide‐acid with subsequent thermal conversion to the polyamide‐imide (PAI). Four polymers were synthesized from unsubstituted amide diamines and two others from N‐substituted amide diamines. The properties of these polyamide‐imides were compared to those of the polyimide of benzophenonetetracarboxylic dianhydride/3,3′‐diaminobenzophenone (LARC–TPI) because their structures are similar, except for the presence of the more flexible amide linkages. These polymers exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films which showed good thermal stability and good resistance to organic solvents. Mechanical properties of the PAI films were better than those of LARC–TPI. Films of the 4,4′‐isomer polyamide‐imide exhibited an exceptionally high modulus and toughness during impact evaluation.
Thermotropic copolyesters. II. Synthesis and characterization of copolyesters containing the bicyclo[2.2.2]oct‐2‐ene mesogenic unit
Authors: Harruna Issifu I. , Polk Malcolm B.
Published: April 2003

Random copolyesters based on 1,4‐benzenedimethanol, trans‐1,4‐cyclohexanedimethanol, and 1,4‐bicyclo[2.2.2]octanedimethanol as spacers in ratios of 2 : 3 of the mesogenic group, bicyclo[2.2.2]oct‐2‐ene‐1,4‐diol were prepared and characterized. The copolyesters containing the 1,4‐benzenedimethanol moiety formed a more brightly colored birefringent fluid in the melt.
Synthesis and properties of aramids and polyarylates having perfluoro‐substituents on the benzene ring
Authors: Kiyotsukuri Tsuyoshi , Tsutsumi Naoto , Okada Kazuya , Asai Kunihiko , Nagata Minoru
Published: April 2003

A new series of 16 aramids and 16 polyarylates having perfluoro‐substituents on the benzene ring was prepared by a low temperature solution or an interfacial polycondensation. The effects of fluorine substituents on the structure and properties of polymers were examined. Fluorinated aramids exhibited higher crystallinity, while fluorinated polyarylates show lower crystallinity. The melting point (Tm) of aramids decreased with fluorine substitution, whereas Tm of polyarylates from fluorinated aromatic diols was higher than that of those from unfluorinated ones. The temperature of 10% weight loss and the residue at 900°C decreased with fluorine substitution except for the aramids from fluorinated diamines. Solubility and contact angle also increased with fluorine substitution. Some polyarylates were found to exhibit an optical anisotropy.
Polymer‐supported bases. IX. Synthesis and catalytic activity of polymer‐bound 4‐(1‐pyrrolidino)pyridine moieties
Authors: Tomoi Masao , Ishigaki Satoru , Arita Yasushi , Kakiuchi Hiroshi
Published: April 2003

Polystyrene‐bound 4‐(1‐pyrrolidino)pyridine moieties were prepared by the reaction of chloromethylated polystyrene resins with pyrrolidinopyridine derivatives containing hydroxyl groups. The supported amines were effective catalysts for acylations of tert‐alcohols or enols, acylrearrangements, and diester synthesis from epoxides and anhydrides. Some of the low ring‐substituted (8–15%) catalysts exhibited high activity comparable to that of 4‐(N,N‐dimethylamino)pyridine, though the activity was a little lower than that of 4‐(1‐pyrrolidino)pyridine. The recovered catalysts can be re‐used, except for acyl rearrangements, without significant decrease in activity.
Photostabilizing effect of 5‐hydroxy‐3‐phenyl‐amino‐1‐phenyl‐ 3 : 5‐dihydrobenzene derivatives in polychloroprene
Authors: Abdel‐Razik E. A.
Published: April 2003

The photostabilization of polychloroprene in the presence of four derivatives of 5‐hydroxy‐3‐phenylamino‐1‐phenyl‐ 3:5‐dihydrobenzene was studied. The inhibitory activity of the added compounds is proportional to their extinction coefficient values. The addition of singlet oxygen quenchers such as β‐carotene reduces the rate of degradation of polymer solutions. This means that singlet oxygen may involve the photooxidation process. The influence of the most effective stabilizer was also examined using Differential Scanning Calorimeter (DSC) technique; the obtained results indicates the photostabilizing effect of it.
Synthesis and photoinduced memory effect of poly[2‐N‐carbazolylethyl acrylate‐co‐2‐(3,5‐dinitrobenzoyloxy) ethyl methacrylate]
Authors: Hu Chau Jin , Oshima Ryuichi , Arai Yuji , Senō Manabu
Published: April 2003

Copolymers containing an intramolecular electron donor‐acceptor (EDA) complex were synthesized by free radical copolymerization of 2‐N‐carbazolylethyl acrylate and 2‐(3,5‐dinitrobenzoyloxy)ethyl methacrylate. Glass transition temperatures show a positive deviation from the weight‐average values of copolymers, indicating the presence of the specific EDA interaction in copolymers in the solid state. Photoinduced “memory effect,” which is defined as the percentage of the difference of the surface potential given by corona charging before and after irradiation of light on polymer films, was 30% for the copolymer with 5 mol% of acceptor content. Memory effect increased to 70% for a 8 μm film by doping with 2 wt% of trichloroacetic acid (TCAA), and leveled off at 5 wt% of TCAA content. Memory effect was also enhanced by increasing the thickness of polymer films and irradiation time. The largest value of memory effect (85%) was obtained from the film of the copolymer with 5 mol% acceptor content doped with 1 wt% TCAA and with thickness larger than 14 μm.
Polymers from nitriles. VII. Polymerization of fumaronitrile with triethylamine as initiator
Authors: Wöuhrle Dieter , Knothe Gerhard
Published: April 2003

The reaction of fumaronitrile with triethylamine in bulk at 295–353 K gives in high yields dark‐colored polymers. The polymerization occurs at one of the two nitrile groups and not at the (CC) double bond. The kinetics of the reaction were investigated and the polymers characterized analytically.
Grafting behavior of copolymers of styrene and ortho‐vinylbenzaldehyde
Authors: Van Ballegooie Peter , Rudin Alfred
Published: April 2003

Statistical copolymers of styrene and ortho‐vinylbenzaldehyde (o‐VBA) have been prepared by free radical solution polymerization using azodiisobutyronitrile initiator. Subsequent “grafting from” reactions could be induced through photolytic excitation of the pendant aldehyde carbonyl functionality in the presence of methyl methacrylate monomer; however, actual grafting of polymethylmethacrylate (PMMA) to the copolymer backbone was shown to be quite low (< 6% graft‐on). Another more promising route involved abstraction of labile benzylic hydrogens of the copolymer by chemical methods [e.g., dibenzoyl peroxide or α,α′‐di‐(t‐butylperoxy)diisopropylbenzene] to produce potential graft sites. Graft copolymers prepared by this procedure had PMMA content ranging up to about 30% (by weight), depending upon polymerization conditions. Higher grafting levels were generally observed with increasing reaction temperature and prolonged reaction times. While some grafting evidently originated from the copolymer backbone, the presence of the o‐VBA moiety significantly enhanced the ultimate percent grafting. The resulting multicomponent polymer systems displayed substantial miscibility as evidenced by the transparency of their cast films as well as by their glass transition behavior.
Thermally stable polymers by condensation of diphenols with glyoxal
Authors: Maravigna Pietro
Published: April 2003

Polycondensation of bisphenol A, hydroquinone, or dihydroxynaphthalenes with glyoxal using methane sulphonic acid as condensing agent leads to polymeric materials having linear and ladder structure and high thermal stability. These polymers were characterized by NMR and TG. Oligomers (from dimer to tetramer) were isolated by GPC and their structures characterized.
Low surface energy polymers and surface‐active block polymers. III. Adamantyl‐containing polymers
Authors: Hsieh Bing R. , Litt Morton H.
Published: April 2003

Two adamantyl‐containing oxazoline monomers. 2‐(1‐adamantyl)‐2‐oxazoline, A, and 2‐(1‐adamantylmethyl)‐2‐oxazoline, B, were synthesized, and polymerized in 1,2‐dichlorobenzene to give polymers PA and PB respectively. Both polymers are highly crystalline and showed very high Tm's (269°C for PA and 320°C for PB) and little solubility in common organic solvents. Annealed PA showed a critical surface tension of 23.6 dyne/cm. PB was not soluble in the many organic solvents tested at room temperature. Due to its high Tm and insolubility, contact angle measurements on PB were impossible. Diblock copolymers based on different weight ratios of A and 2‐ethyl‐2‐oxazoline, E, showed relatively narrow molecular weight distribution (MWD) when methyl p‐nitrobenzenesulfonate, I, was used as initiator. After annealing, diblock polymers with B/I = 7, 10, or 12 showed Tm's (200–281°C); after quenching the same samples showed Tc's (160–171°C), which were lower than that of pure PB, 215°C. The quenched diblocks showed single Tg's (63–82°C) which implies that these short blocks are compatible. Diblock polymer with B/I = 5 and E/I = 20 was amorphous and displayed inverse emulsifying ability in styrene + water emulsion polymerization. BEB type triblock polymers prepared using ethylene glycol dinosylate as initiator had broader MWD and higher Tm's compared to their diblock counterparts with the same B/E wt% and B/I ratios. These triblock polymers were not completely soluble in styrene and/or water and therefore could not be used as emulsifying agents.
Oligomerization of vinyl monomers. XXI. Characterization of model carbanions of living poly(2‐vinylpyridine) in THF by 7Li‐NMR and conductance: Evidence for the occurrence and nature of triple ion formation
Authors: Khan Ishrat M. , Hogen‐Esch Thieo E.
Published: April 2003

The formation of triple anions is demonstrated by 7Li‐NMR in THF solutions of 1‐lithio‐1‐(2‐pyridyl)ethane, 1‐lithio‐1(3‐methyl‐2‐pyridyl)ethane, and 1‐lithio‐1,3‐di(2‐pyridyl) butane. Good agreement with conductance data was demonstrated in the case of 1. Triple anion formation in the case of 2 was found to be about twice as high as in 1 possibly as a result of the greater charge density on the carbanion in the case of 2.
Spectroscopic studies on the initial stages of thermal degradation of polychloroprene
Authors: Miyata Yoshiaki , Atsumi Masao
Published: April 2003

Thermal degradation of polychloroprene under nitrogen, especially at the initial stages, has been studied by using 1H‐NMR, 13C‐NMR and FT–IR spectroscopy. A model polymer of low molecular weight (Mn = 6300) was prepared to avoid gelation during degradation. None of isomerized 1,2 unit has been found in the original polymer. Allylic rearrangement of 1,2 unit was the first‐stage reaction, which was finished within 30 min at 150°C. The extent of HCl loss was proportional to the decrease of isomerized 1,2 unit. It has been suggested that the next‐stage reaction is dehydrochlorination of the isomerized 1,2 unit. The presence of terminal vinyl group and the increased amount of olefinic proton were not found in the degraded polymer. The back‐biting mechanism involving a six‐membered cyclization process is proposed for the dehydrochlorination. The thermal racemization has been also found to take place in the 3,4 unit.
Modified cellulose acetate flat membranes for desalination
Authors: Wen‐E Yan , Pu‐Chen Yang , Yi‐Kuan Wang
Published: April 2003

In this article, the radiation grafting of acrylamide on to cellulose acetate flat membranes using UV‐irradiation on the initiator is described. The modified membranes thus obtained have been characterized by IR, DSC, and TGA. Their transport properties have been studied. The modified membranes exhibit higher salt rejection with slightly reduced water flux as compared with cellulose acetate membrane. The work is further extended to study the thermal stability of these modified membranes in a dry state. These modified membranes up to 330°C are stable.
Cationic grafting from carbon black. VIII. Cationic ring‐opening polymerization and copolymerization of oxepane initiated by acylium perchlorate groups on carbon black
Authors: Tsubokawa Norio , Jian Yu , Sone Yasuo
Published: April 2003

The cationic ring‐opening polymerization of oxepane was found to be initiated by carbon black having acylium perchlorate (CO+CIO) groups, which were introduced by the reaction of acyl chloride groups with silver perchlorate. It was confirmed that polyoxepane, i.e., poly(oxyhexamethylene), was propagated from CO+CIO groups on carbon black and effectively grafted on the surface. The rate of the polymerization and the percentage of grafting of poly(oxyhexamethylene) remarkably increased by the addition of epichlorohydrin (ECH) as a promoter: the percentage of grafting in the presence of ECH increased to about 100% with an increase in conversion. Furthermore, CO+CIO groups on carbon black have an ability to initiate the cationic ring‐opening copolymerization of oxepane with ECH to give poly(oxepane‐co‐ECH) with various composition. The ring‐opening copolymerization of oxepane with phthalic anhydride was also initiated by CO+CIO groups to give polyether ester, i.e., poly(hexamethylene phthalate) containing poly(oxyhexamethylene) sequence. In the copolymerization, polyether or polyether ester was effectively grafted from carbon black based on the propagation of these polymers from CO+CIO groups.
The liquid crystalline state of polyimide precursors
Authors: Whang W. T. , Wu S. C.
Published: April 2003

The polyimide precursor poly(4,4′‐methylenediphenylene pyromellitamic acid) (PMDPAA) in N‐methyl pyrrolidone (NMP) was a lyotropic liquid crystal as evidenced by a DSC thermogram and x‐ray spectrum on its gel, and optical properties by the existence of the critical concentration on the solution viscosity. The configuration of PMDPAA as shown by wide angle x‐ray diffraction pattern was composed of regular meta pyromellitamic acid units. These units together with the rigid character of CH2 linkage between two phenyl rings, and the hydrogen bonding of the intermesogenic units were surmised to be the driving force for liquid crystal formation. The liquid crystalline characters were dependent on molecular weight, solid content, temperature, and the extent of mechanical shearing flow. Data from rheometrics mechanical spectrometer (RMS) indicated that the elastic character of the melt of PMDPAA gel at room temperature shifted to lower frequency on standing and the complex dynamic viscosity increased with time.
Synthesis and characterization of silicon‐containing phenylated soluble aramids
Authors: Mohite S. S. , Maldar N. N. , Marvel C. S.
Published: April 2003

New high molecular weight (inherent viscosities, 1.21–0.50 dL/g) aramids having silicon and pendant phenyl groups were synthesized by low temperature interfacial polycondensation technique involving the reaction of acid chlorides: bis(4‐chlorocarbonylphenyl)dimethylsilane and bis(3‐chlorocarbonylphenyl)dimethylsilane with diamines: 2,5‐bis(4‐aminophenyl)‐3,4‐diphenyl‐thiophene and bis(4‐aminophenyl)ether. Copolyamides were obtained by using different proportions of these diamines. All the polymers were completely soluble in organic solvents such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, and N,N‐dimethylformamide. Thermal properties were evaluated by thermogravimetry which showed no weight loss below 325°C in both air and nitrogen atmospheres.
Study of photopolymers. XXXIII. Chemical modification of poly(epichlorohydrin) and its application as photosensitive polymers
Authors: Nishikubo Tadatomi , Shimokawa Tsutomu , Fujii Takeshi , Iizawa Takashi , Harita Yoshiyuki , Koshiba Mitsunobu
Published: April 2003

High Tg. polymers containing both vinyloxy moiety and pendant phthalyl, 2‐thiobenzoxazole or 2‐thiobenzothiazole groups were synthesized by elimination reaction of poly(epichlorohydrin) with potassium hydroxide followed by substitution reaction of the obtained polymer with potassium phthalimide, potassium 2‐thiobenzoxazole or potassium 2‐thiobenzothiazole using tetrabutylammonium bromide as a phase transfer catalyst. The polymers containing vinyloxy moiety and pendant phthalyl or 2‐thiobenzothiazole groups showed high photochemical reactivity and excellent practical photosensitivity as a positive type resist with photo‐generated cationic catalyst such as 2,5‐dibutoxy‐4‐morpholinobenzene diazonium hexafluoroanthimonate. On the other hand, the polymers had high practical photosensitivity and good resolution as a negative type resist with 2,6‐di‐(4′‐azobenzal)‐4‐methylcyclohexanone as a photosensitizer.
Preparation and properties of aromatic polyamides and copolyamides from phenylindanedicarboxylic acid and aromatic diamines
Authors: Yoneyama Masaru , Kuruppu K. D. Athula , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Aromatic polyamides (aramids) having inherent viscosities of 0.5–1.10 dL/g were prepared by the direct polycondensation of 1,1,3‐trimethyl‐3‐(4‐carboxyphenyl)indane‐5‐carboxylic acid with various aromatic diamines using triphenyl phosphite and pyridine as the condensing agents. Copolyamides were also prepared by a similar procedure from a mixture of the phenylindane diacid, terephthalic acid, and p‐phenylenediamine. Almost all of the aramids were soluble in a variety of solvents such as N‐methyl‐2‐pyrrolidone, pyridine, and m‐cresol, and afforded transparent and tough films by the solution casting. These aramids and copolyamides had glass transition temperatures in the range of 290–355°C, and started to lose weight at 340°C in air.
Parylene C at subambient temperatures
Authors: Sharma Ashok K.
Published: April 2003

Dependence of Parylene C deposition rate on dimer sublimation temperature, inert gas pressure, substrate temperature, and mass of dimer has been investigated. It was found that Parylene C deposition proceeds best at ambient temperature and produces film of optimum performance. Opacity in the film results from its rough morphology and not from the incorporation of the dimer in the film as is normally thought. This was evidenced from scanning electron microscopy and from an estimation of the volatile contents of the Parylene C films. Deposition of Parylene C at liquid nitrogen temperature proceeds via trapping of active monomer species followed by spontaneous polymerization. A quantitative study of the monomer to polymer transition by ESR spectroscopy is presented.
Synthesis and liquid crystalline properties of thermotropic homo‐ and copolycarbonates
Authors: Sato Moriyuki , Kurosawa Katsuya , Nakatsuchi Kazuyasu , Ohkatsu Yasukazu
Published: April 2003

Nondirect‐type thermotropic homo‐ and copolycarbonates which have flexible spacers between mesogens and carbonate linkages (‐mesogenic unit‐flexible spacer‐carbonate link‐flexible spacer‐) were derived from dihydroxyalkyleneoxy derivatives containing biphenyl, i.e., 4,4′‐bis (ω‐hydroxyalkyleneoxy)biphenyl (Ia and Ib), as mesogens and the structure‐liquid crystallinity relationships were evaluated by thermal analysis and with polarizing microscope.

Homopolycarbonates with high molecular weight
magnified image
were prepared from (Ia) and (Ib), and alkylene diphenyl dicarbonates (II) by melt polycondensation. The polymers form mesomorphic phases and exhibit linear decrease of phase‐transition temperatures with increment of alkylene spacer lengths without displaying odd‐even number fluctuations. They show lower phase‐transition temperatures and narrower mesomorphic temperature ranges than analogous direct‐type (‐mesogenic unit‐functional group‐flexible spacer‐) biphenyl‐containing polycarbonates \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm OMOC}({\rm O}){\rm O}({\rm CH}_2)_m {\rm OC}({\rm O})\rlap{--})_x $\end{document} and polyesters \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm OMOC}({\rm O})({\rm CH}_2)_m {\rm C}({\rm O})\rlap{--})_x $\end{document}, but have wider temperature ranges than nondirect‐type (‐mesogenic unit‐flexible spacer‐functional group‐flexible spacer‐) biphenyl‐containing polyesters \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm O}({\rm CH}_2)_n {\rm OMO}({\rm CH}_2)_n {\rm OC}({\rm O})({\rm CH}_2)_m {\rm C}({\rm O})\rlap{--})_x $\end{document}. These results indicate that by the incorporation of alkylene segments between mesogens and carbonate linkages the polymers having reasonable phase‐transition temperatures and wider mesophasic temperature ranges can be obtained. Copolycarbonates
magnified image
were prepared from mixtures of (Ib) and 1,4‐bis(2‐hydroxyethyleneoxy)benzene (IV), nonmesogenic moiety, taken in definite molar ratio in feed and (II) (m = 2 and 4). These copolymers except polymers having only nonmesogenic moiety show liquid crystalline mesophases and have wider phase‐transition temperature ranges than the homopolymers. Maximum temperature ranges are observed in the copolymers of composition ratio of 1 : 1. Stable mesophases can be obtained over the entire range of compositions, even though the copolymers contain nonmesogenic units in the backbones.
Kinetic study of the reaction between a hydroxylated polybutadiene and isocyanates in chlorobenzene, III. Reaction with dimer diacid diisocyanate (DDI)
Authors: Coutinho Fernanda M. B. , Rocha Marisa G.
Published: April 2003

A kinetic study of the reaction of hydroxylated liquid polybutadiene (M̄n = 2400) R‐45M and dimer diacid diisocyanate (DDI) was carried out in chlorobenzene solution. The kinetic data were compared with the data obtained in a previous work using toluene as solvent. This reaction presented an apparent second order rate law, and was faster in chlorobenzene than in toluene. The accelerating effect of chlorobenzene was higher at higher temperatures.
Polymerization of fluorinated diacetylenes
Authors: Baum Kurt , Cheng Paul G. , Hunadi Ronald J. , Bedford Clifford D.
Published: April 2003

Perfluoroalkylene diacetylenes, HCC(CF2)nCCH, underwent thermal polymerization at 250–350°C to give glassy polymers stable to 450°C. Partial polymerization of the volatile monomers gave oligomers that are processable at atmospheric pressure. Polymers with similar thermal stability were obtained by transition‐metal‐catalyzed polymerization of the monomers at moderate temperatures.
Synthesis and characterization of acrylated phosphonates and their polymers having 1,3‐dioxolane and 1,3‐dioxane moieties derived from brominated cyclic acetals of polyols through the Arbuzov reaction. II
Authors: Sahni Suresh K. , Cabasso Israel
Published: April 2003

Glycerol, D‐mannitol, and D‐sorbitol were converted into their mono‐ and di‐O‐1,3‐dioxolane and 1,3‐dioxane bromoethylidene derivatives through a transacetalation reaction with bormoacetaldehyde diethyl acetal under controlled conditions. These brominated dioxolane or dioxane derivatives were subsequently phosphonylated through the Arbuzov reaction. The phosphonylated cyclic acetals were used as precursors for the synthesis of acrylated phosphonate monomers. All these compounds have been characterized by elemental analysis and spectroscopic (IR, 1H‐,13C‐, 31P‐NMR and mass) methods. A mixture of 1,3‐dioxane and 1,3‐dioxolane derivatives was obtained with D‐sorbitol, whereas the reaction products with glycerol and D‐mannitol yielded primarily the 1,3‐dioxolane derivatives. The acrylated phosphonates of glycerol and mannitol have been polymerized and studied on the basis of gel permeation chromatography and their spectral and thermal properties. The acrylated phosphonates, monomers, and polymers, were shown to have a large capacity to solvate and dissolve heavy metal salts. This results in a dramatic increase (> 100°C) of the glass transition temperature of these polymers.