bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of poly[arylene ether (N‐arylenebenzimidazole)]s
Authors: Smith J. G. , Connell J. W. , Hergenrother P. M. 
Published: April 2003

AbstractPoly(arylene ether)s containing N‐arylenebenzimidazole groups were prepared by the aromatic nucleophilic displacement reaction of two new bis(hydroxyphenyl‐N‐arylenebenzimidazole)s with activated aromatic difluorides in sulfolane at 200°C in the presence of anhydrous potassium carbonate. The bis(hydroxyphenyl‐N‐arylenebenzimidazole)s were prepared from bis(o‐aminoanilino) arylenes and phenyl‐4‐hydroxybenzoate. The polymers were soluble in N‐methyl‐2‐pyrrolidinone and m‐cresol and exhibited inherent viscosities from 0.37–0.86 dL/g and glass transition temperatures from 219–289°C. Thermogravimetric analyses showed 5% weight losses from 463–506°C in air and 467–522°C in nitrogen. Unoriented thin films exhibited tensile strengths, moduli, and break elongations at 23°C of 10.2–12.5 ksi, 318–365 ksi, and 4–7%, respectively, and at 177°C of 5.1–6.9 ksi, 256–296 ksi, and 1–5%, respectively. A 50 : 50 random copolymer prepared from 1,3‐bis(4‐fluorobenzoyl) benzene, 1,1'‐(4,4'‐biphenylene)‐bis[2‐(4‐hydroxyphenyl)benzimidazole], and 5,5'‐bis[2‐(4‐hydroxyphenyl)benzimidazole] exhibited higher moisture absorption and lower tensile properties than those predicted by a rule of mixtures relationship. The chemical, physical, and mechanical properties of these polymers are discussed. © 1993 John Wiley & Sons, Inc.‡
Preparation of micron‐size monodisperse polymer particles by dispersion copolymerization of styrene with poly(2‐oxazoline) macromonomer
Authors: Kobayashi Shiro , Uyama Hiroshi , Lee Seog Won , Matsumoto Yasuhiro 
Published: April 2003

AbstractThis article describes the preparation of micron‐size monodisperse polymer particles by dispersion copolymerization of styrene with a poly(2‐oxazoline) macromonomer in an aqueous ethanol solution. The macromonomer acted as a comonomer as well as a stabilizer. The diameter of the particles increased as the concentration of the macromonomer decreased. The higher the molecular weight of the macromonomer, the smaller the particle size. The copolymerization in the solvent containing higher water content gave smaller polymer particles. Under the condition giving the monodisperse particles, the particles volume increased linearly with the yield of the particles. From ESCA analysis of the particle surface, poly(2‐oxazoline) chains were enriched on the surface. © 1993 John Wiley & Sons, Inc.
Synthesis, characterization, and thermal studies of cardanol‐based polyphosphate esters
Authors: Antony Rosy 
Published: April 2003

AbstractPolyphosphate esters were synthesized from derivatives of cardanol phosphorodichloridateates and dihydric phenols by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by IR, 1H‐, 13C‐, and 31P‐NMR spectroscopy, and GPC. The thermal stability and thermal degradation kinetics of the polymers were determined by thermogravimetry. The flammability of the polymers was evaluated by limiting oxygen index values. © 1993 John Wiley & Sons, Inc.
Anionic ring‐opening polymerization of several N‐substituted diphenimides
Authors: Pyriadi Thanun M. , Ahmad Abbas F. 
Published: April 2003

AbstractFive N‐substituted diphenimides were prepared from the corresponding N‐substituted amic acids. Attempts to polymerize the prepared seven‐membered ring imides were partially successful. N‐phenyldiphenimide was relatively the best monomer that polymerized anionically using n‐butyl lithium or sodium metal as the initiater. The other N‐substituted imides were sluggish in anionic polymerization. The resistance of the seven‐membered ring imides toward ring‐opening polymerization was attributed to the stability of the rings caused by the two phenylene groups adjacent to the carbonyls. © 1993 John Wiley & Sons, Inc.
Effect of the poly(oxytetramethylene)diol spacer length on some properties of liquid crystalline polyurethanes
Authors: Szczepaniak Barbara , Frisch Kurt C. , Penczek Piotr , Mejsner Jerzy , Leszczyńska Irena , Rudnik Ewa 
Published: April 2003

AbstractPrevious studies on liquid crystalline polyurethanes prepared from 4,4′‐bis(2‐hydroxyethoxy)biphenyl (BHBP) and 2,4‐tolylene diisocyanate (TDI) were continued. In this article, a series of polyurethanes, which differ in the flexible spacer length and BHBP content is described. Poly(oxytetramethylene)diols of different molecular weights (PTMO, Mn = 250, 650, 1000, 2000) were used as flexible spacers. The polyurethanes were investigated by DSC, polarizing microscopy, x‐ray diffractometry, and IR spectroscopy. The molecular weight distribution was determined by GPC. The morphology of the polyurethanes was investigated by the SALS method. Partial replacement of BHBP by 25–75 mol % PTMO and the flexible spacer length influence the liquid crystalline properties, the phase transition temperatures, and the range of mesophase occurrence. © 1993 John Wiley & Sons, Inc.
Structural characterization of ethyl cellulose and its use for preparing polymers with viologen moieties
Authors: Liu Fu‐Tian , Yu Xian‐Da , Li Shu‐Ben 
Published: April 2003

AbstractThe characteristics of ethyl cellulose (EC) were studied by chemical reaction and the spectra method. EC was first tosylated with tosyl chloride, and then the tosylated EC (Ts‐EC) reacted with sodium iodide (NaI). By comparing the NMR spectra of EC and iodine‐substituted EC (EC‐I), a free hydroxyl group was proved to exist at the C‐6 of the D‐glucose unit of cellulose. Viologen moieties were introduced into the EC chain by the reaction of Ts‐EC with 4,4′‐bipyridine and n‐propyl bromide. The existence of viologen was confirmed by 1H‐NMR, IR, and ESR. © 1993 John Wiley & Sons, Inc.
Synthesis of monodisperse poly(divinylbenzene) microspheres
Authors: Li Kai , Stöver Harald D. H. 
Published: April 2003

AbstractHighly crosslinked monodisperse poly(divinylbenzene) microspheres were produced by precipitation polymerization with acetonitrile as solvent. The radical initiators AIBN, BPO, and ADVN were used. The process does not require stabilizers of any type, and produces monodisperse particles with diameters between 2 and 5 μm, depending on the conditions. These microspheres do not swell or dissolve in any common solvent, and have clean, stabilizer‐free surfaces. The particle formation and growth mechanism is proposed to resemble that of dispersion polymerization, except that the particles are stabilized against coagulation by their rigid, crosslinked surfaces rather than by added stabilizers. Spherical particles were formed only at effective crosslinker/monomer or divinyl/monovinyl ratios larger than 1 : 2. © 1993 John Wiley & Sons, Inc.
Functionalization of polyethylene surface using plasma‐induced graft copolymerization of acrylic acid
Authors: Hsiue Ging‐Ho , Wang Chee‐Chan 
Published: April 2003

AbstractPlasma‐induced graft copolymerization of acrylic acid onto PE films was investigated. The influence of plasma treatment power, pressure, time, graft copolymerization time, and monomer concentration on polymerization yield was determined. A chemical shift of the Cls signal of Ar plasma treated and untreated PE films was revealed by ESCA, which also verified the presence of grafted PAAc. An increase in graft polymerization yield with plasma treatment time and power was found. Both the plasma treated film and the subsequently grafted film were shown to be hydrophilic. Only the grafted film, however, shows an invariably low contact angle. The decomposition of peroxides upon heating was followed by a simple first‐order reaction. © 1993 John Wiley & Sons, Inc.
Synthesis of novel polysilylenes bearing phenol groups directly bonded to SiSi main chains for preparing Langmuir–blodgett thin films
Authors: Nakano Y. , Murai S. , Kani R. , Hayase S. 
Published: April 2003

AbstractPolysilylenes with a phenol group directly bonded to the main chain Si atom were prepared by polymerizing dichlorosilane monomers bearing phenol groups protected by t‐butyldimethylsilyl ether, followed by deprotecting the silyl ether. These amphiphilic polysilanes were applied to provide oriented thin films by the Langmuir‐Blodgett technique. Stable monolayers were not obtained for polysilylenes having only alkyl and aryl substituents. However, all the polysilylenes with phenol moieties provided monolayers on a water surface. These polysilylene monolayers were transferred to hydrophobic substrates by applying the Langmuir‐Blodgett technique. Among these polysilylenes, only poly(n‐butyl‐3‐hydroxyphenylsilylene) provided multilayers in which the SiSi main chains oriented in the dipping direction. The orientation was determined by polarized UV absorption. The orientation ratio reached 0.45. © 1993 John Wiley & Sons, Inc.
Macrothiuram disulfide for the free radical synthesis of PDMS‐vinyl triblock copolymers. I. Syntheses and polymerization kinetics
Authors: Clouet G. , Kayser D. 
Published: April 2003

AbstractPDMS‐based macrothiuram disulfides of different molecular weights capable of being used as macro‐thermal iniferters towards deriving PDMS‐containing triblock copolymers were synthesized and characterized. The synthesis of ω‐(secondary amine)‐terminated PDMS were accomplished by the hydrosilylation reaction of silyl hydride terminated PDMS with allyl‐N‐methylamine. Macroamines were eventually transformed to macroiniferters by the thiocarbamylation reaction and oxidative coupling. Kinetics of polymerization studied in the case of MMA and styrene in bulk, and as in toluene solution in case of MMA, revealed that the macroiniferters are as efficient as their microanalogues from the point of view of their initiating and chain‐terminating properties. The different kinetic parameters were determined and discussed. © 1993 John Wiley & Sons, Inc.
A kinetic study on grafting of maleic anhydride onto a thermoplastic elastomer
Authors: Wu Chung‐Jen , Chen Chuh‐Yung , Woo Eamor , Kuo Jen‐Feng 
Published: April 2003

AbstractMaleation of a thermoplastic elastomer, styrene‐[ethylene‐butylene]‐styrene (SEBS) triblock copolymer, was carried out by a solution grafting reaction with maleic anhydride initiated by dicumyl peroxide. The reaction products from the graft reaction in xylene, commonly chosen as the solvent for maleation graft reactions, were identified using liquid chromatograph (LC), IR, and 13C‐NMR. Side products from the graft reaction were identified by the LC analysis and, it was concluded that xylene affected the graft reaction through its active methyl groups. Reaction mechanisms were investigated by performing free radical kinetics analysis. The reaction orders and the apparent rate constant were estimated. It was concluded that a proper choice of the solvent might favor better graft efficiency. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new block copolymers based on polydimethylsiloxane and tetraphenylethylene‐containing polyimide
Authors: Nakata Shoichi , Kawata Masatoshi , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew polydimethylsiloxane (PDMS)‐polyimide block copolymers were synthesized by the solution polycondensation of aminopropyl‐terminated polydimethylsiloxane, 1,1‐bis(4‐aminophenyl)‐2,2‐diphenylethylene, and 3,3′,4,4′‐benzophenonetetracarboxylic dithioanhydride in pyridine. New 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane (BADS)‐based random copolyimides were also prepared. The inherent viscosities of all the random and block copolyimides were in the range of 0.13–0.90 dL/g in N‐methyl‐2‐pyrrolidone. These copolymers were soluble in N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, and m‐cresol. All the BADS‐based random copolymers and PDMS‐containing copolymers with PDMS content above 42 wt % were soluble in tetrahydrofuran and chloroform. Transparent or somewhat cpaque films were prepared by casting from the reaction solutions. The BADS‐based random copolyimides had one glass transition temperature (Tg) in the whole composition ranges, which showed single phase nature of the copolymers. On the other hand, the PDMS‐polyimide block copolymers had double TgS, indicating phase‐separated morphology. The block copolymers containing PDMS content above 73 wt % behaved like a high temperature elastomer. © 1993 John Wiley & Sons, Inc.
Perfluorocyclobutane aromatic ether polymers
Authors: Babb David A. , Ezzell Bob R. , Clement Katherine S. , Richey W. Frank , Kennedy Alvin P. 
Published: April 2003

AbstractNovel polymers containing alternating perfluorocyclobutane and aromatic ether subunits are prepared from aryl poly(trifluorovinyl ether) monomers via the thermal [2π + 2π] dimerization of the trifluorovinyl ether functionality. A model study is described, which probes the nature of the perfluorocyclobutane rings formed during the polymerization reaction. The bifunctional monomer 4,4′‐bis(trifluorovinyloxy) biphenyl and the trifunctional monomer 1,1,1‐tris(4‐trifluorovinyloxyphenyl)ethane are prepared and polymerized to provide thermoplastic and thermoset polymers, respectively. Characterization of the mechanical and dielectric properties of these new polymers is presented. © 1993 John Wiley & Sons, Inc.
PCILO and CNDO calculations on the specific interaction in two model analogs of BPA‐polycarbonate and a linear aliphatic polyster
Authors: Mora M. A. , Rubio M. , Cruz‐Ramos C. A. 
Published: April 2003

AbstractPrevious investigations have given evidence of the existence of specific chemical interactions between poly(bisphenol‐A carbonate) (PC) and a number of linear aliphatic polyesters, with the consequent formation of compatible polymer alloys. Here we address the particular kind of specific interaction that takes place in these systems by performing a quantum‐mechanical study of the apparently most reasonable types of molecular interactions occurring in model compounds of the above polymers. Complete neglect of diffential overlap, (CNDO), in its CNDMEX version, and perturbative configuration using localized orbitals (PCILO) were the calculation schemes used on diphenyl carbonate (DPC) and dimethyl succinate (DMS), selected as models. It was found that, on a one‐to‐one basis, the DPC‐DMS system is energetically more stable than the individual separate molecules; on examination of the possible interaction sites for the two chemical species, the interaction between the ester group oxygen in one DMS molecule with one of the phenyl rings in DPC appears to be the most favorable type of molecular interrelation, even though hydrogen bond formation is also possible between the oxygen atoms in DPC and the methylene hydrogens in DMS. (The former interaction decreases the total energy of the system by 0.12 kcal/mol, more than the latter.)
Rutherford backscattering spectrometry studies of iodine diffusion in polyimide
Authors: Romanelli J. F. , Mayer J. W. , Kramer E. J. , Russell T. P. 
Published: April 2003

AbstractRutherford backscattering spectrometry with a 2.1‐meV He2+ion beam is used to measure the diffusion of iodine into polyamic acid and polyimide films. The iodine diffusion coefficient D decreases from its initial value of about 2X10−13cm2/s in polyamic acid to approximately 1.4 × 10−15cm2/s in partially cured polyimide, but then increases to a value of nearly 1.5 × 10−14 cm2/s in fully cured polyimide. This dramatic increase in D cannot be attributed to the “in‐plane” biaxial orientation of the polyimide molecules since indential D's were found with isotropic specimens. Microvoids less than 2 nm in size caused by water and carbon dioxide formation during imidization may, however, give rise to the observed behavior. The results demonstrate that Rutherford backscattering spectrometry with its excellent depth resolution (better than 30 nm) and good sensitivity (50 ppm iodine can be detected) is very useful for measuring the diffusion of slowly diffusing species in glassy polymers.
Light‐scattering studies on the sol–gel transition in aqueous solutions of poly(vinyl alcohol)
Authors: Komatsu Motoko , Inoue Takashi , Miyasaka Keizo 
Published: April 2003

AbstractThe dynamics of the sol–gel transition in aqueous solutions of poly(vinyl alcohol) was investigated by light scattering. The dynamical studies confirmed that this system has an upper critical solution temperature. In the phase diagram, the spinodal curve crosses the sol–gel transition curve. Essentially this is nothing but the situation predicted by Coniglio et al. as a result of the site‐bond correlated‐percolation problem. The gelation takes place both above and below the spinodal curve, suggesting two modes of gelation: one is accompanied by a spinodal decomposition and the other takes place without liquid–liquid phase separation. In the former case, the dynamics of phase separation at an early stage of gelation is well described within the framework of Cahn's linearized spinodal decomposition theory. The wavelength of the concentration fluctuation at the highest rate of phase separation is about 300 nm.
A dielectric study of poly(ethylene‐co‐vinyl acetate)–poly(vinyl chloride) blends. II. Loss curve broadening and correlation parameters
Authors: Rellick G. S. , Runt J. 
Published: April 2003

AbstractNormalized dielectric loss curves for blends of PVC with an EVA copolymer containing 70% vinyl acetate showed significant broadening with increasing PVC content. In conjunction with phase separation studies it was concluded that increasing loss curve broadness correlated with increasing tendency toward phase separation. Calculation of correlation parameters for the blends revealed differences in intermolecular correlations with blend composition.
Influence of static strain on dynamic mechanical behavior of amorphous networks prepared from aromatic polyesters
Authors: Diaz‐Calleja R. , Riande E. , Guzman J. 
Published: April 2003

AbstractDynamic mechanical experiments were performed between −140 and 50°C on both poly(diethylene glycol isophthalate) and poly(triethylene glycol terephthalate) networks. Plots of loss tangent versus temperature show a well‐defined α peak, associated with the transition from glasslike to rubberlike consistency, and two overlapping peaks (β1 and β2) in the glassy region. Dynamic deformations of small amplitude were superimposed on large static deformations. It was found that the position of the β1 and β2 peaks as well as their intensities are independent of the static elongation ratio. However, the intensity of the loss tangent associated with the glass–rubber transition tends to decrease with increasing static deformation. Moreover, the position of the maximum of the α peaks shifts to lower temperatures as the elongation ratio increases. This behavior suggests that for both networks the volume effects (shifting the α peaks to lower temperatures with increasing elongation ratio) overcome the entropic effects (shifting the α peaks to higher temperatures with decreasing entropy).
Axial force fluctuations in long‐chain molecules
Authors: Weiner J. H. , Berman D. H. 
Published: April 2003

AbstractThe fluctuations Δf in the axial force f acting on a long‐chain molecule whose end‐to‐end displacement r is fixed are computed for a freely jointed model in which the covalent bonds are represented by stiff linear springs. It is found that the relative fluctuation Δf/f remains large regardless of the length of the chain. A time‐dependent computer simulation of the model serves both to verify the theoretical calculation of Delta;f and to provide physical insight. The result helps to clarify the difference in behavior of the strain ensemble (r is fixed and f fluctuates) and the stress ensemble (f is fixed and r fluctuates) for which, in the absence of excluded volume, the strain ensemble predicts that f = 0 for r = 0, while for the stress ensemble with f = 0 it is found that 〈r2〉0 > 0.
Solute and penetrant diffusion in swellable polymers. I. Mathematical modeling
Authors: Korsmeyer Richard W. , Lustig Steven R. , Peppas Nikolaos A. 
Published: April 2003

AbstractA mathematical model was developed to describe diffusion of a penetrant and a solute in a swellable polymer slab. The model was applied to the case of a hydrophilic polymer loaded with a soluble bioactive agent, in which the penetrant (water) is sorbed and solute is desorbed. The model allows the incorporation of any appropriate form of the diffusion coefficients. A Fujita‐type exponential dependence on penetrant concentration was chosen and shown to be adequate for prediction of a range of transport behavior. Dimensional changes in the sample were predicted by allowing each spatial increment to expand according to the amount of penetrant sorbed. During the initial period of release, the swelling was restricted to one dimension by the glassy core of the sample. At a later point in the process, the center of the sample had sorbed enough penetrant to plasticize it, and the sample relaxed to an isotropically swollen state; thereafter swelling was three‐dimensional.
Concurrent chain extension and crosslinking of hydroxyl‐terminated poly(dimethyl siloxane): Possible formation of catenate structures
Authors: Rigbi Z. , Mark J. E. 
Published: April 2003

AbstractDifunctional and tetrafunctional ethoxysilanes in varying proportions were used to simultaneously chain‐extend and crosslink dihydroxyl‐terminated poly(dimethyl siloxane). When only dimethyl deithoxysilane was used an insoluble product, possibly a catenate, was formed. Its swelling behavior was equivalent to that of a tetrafunctional network obtained by end‐linking chains approximately twice as long as those actually used.
Studies on the β‐crystalline form of isotactic polypropylene
Authors: Jacoby P. , Bersted B. H. , Kissel W. J. , Smith C. E. 
Published: April 2003

AbstractA study has been made of the mechanical, thermal, and morpholigical characteristics of melt‐crystallized isotactic polypropylene containing high levels of the β or pseudohexagonal crystalline form. Different levels of β‐form crystallinity were produced in the polymer by blending in low levels of quinacridone dye nucleating agent. Microscopical studies of the crystallization process revealed that both α‐form (monoclinic), and β‐form spherulites nucleated on the dye particles, with α‐spherulite growth commencing at a higher temperature. These observations were able to qualitatively explain the dependence of β‐form level on both the nucleant concentration and its state of dispersion in the polymer. Improving the dispersion of the nucleant was found to reduce the level of β‐form crystallinity if the nucleant concentration exceeded an optimum level. A new procedure for quantifying the volume fraction of β spherulites in a sample was developed which utilized the technique of selective solvent extraction. From volume‐fraction, x‐ray, and density data, the pure α and β crystal densities were obtained. Dynamic mechanical measurements‐obtained on unoriented specimens containing varying levels of β‐form crystallinity showed an increase in the magnitude of the damping in the post‐Tg region with increasing β content. High levels of the β form lead to lower values of the modulus and yield stress, and higher values of the elongation at break and impact strength.
On the theory of dilute polyelectrolyte solutions: Extensions, refinements, and experimental tests
Authors: Davis R. M. , Russel W. B. 
Published: April 2003

AbstractWe synthesize a quantitative theory for the radius of gyration, second virial coefficient, intrinsic viscosity, and friction coefficient for polyelectroytes in dilute solution from existing treatments of electrostatic and hydrodynamic interactions within and among wormlike chains. Comparison with data for K‐PSS demonstrates the importance of accounting for nonlinearities in the electrostatics and the finite diameter of the polymer backbone.