bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of urethane‐modified polyimides
Authors: Sendijarević Ais̆a , Sendijarević Vahid , Frisch Kurt C. , Koruga‐Lazarević Branka , Torlić Enes
Published: April 2003

The synthesis and properties of thermoplastic urethane‐modified polyimides, based on different isocyanates, with different concentrations of hard segments and different ratios of imide and urethane groups, were studied. The effect of catalysts, isocyanates, and temperature was investigated on model reactions leading to formation of monoimides, bisimides, and polyimides. A polymer based on 2,4‐TDI, poly(oxytetramethylene) glycol of 1000 molecular weight and pyromellitic dianhydride, with 75% of imide in the hard segments, retained about 50% of the original tensile strength at 120°C and about 30% at 150°C. Increasing the temperature up to 150°C had very little effect on the elongation of this copolymer. In general, increasing the imide concentration in the polymer structure provided better retention of stress‐strain properties at elevated temperatures.
Synthesis and characterization of novel 1,3,4‐oxadiazole‐ or 1,3,4‐thiadiazole‐containing wholly conjugated polyazomethines
Authors: Saegusa Yasuo , Sekiba Kazuhiro , Nakamura Shigeo
Published: April 2003

A series of thermally stable and semiconducting polyazomethines containing 1,3,4‐oxadiazole or 1,3,4‐thiadiazole ring in the polymer backbone were synthesized by the simple solution poly‐condensation of dialdehydes with the preformed nuclei with aromatic diamines under mild conditions. To elucidate the structure and also structure‐property relationships of the polymers, model compounds were prepared under the same reaction conditions. These polyazomethines having a wholly conjugated system were yellow powders and had reduced viscosities up to 0.38 dL/g in concentrated sulfuric acid and electric conductivity as high as 10−11 S cm−1 at room temperature. Thermogravimetry showed that all the polymers were heat resistant up to around 400°C, in both air and nitrogen atmospheres. Their completely black colored charge‐transfer complexes were prepared by iodine‐doping of the polymers. The room temperature conductivity of the polymers was found to be markedly increased up to the orders of 10−6–10−7 S cm−1 upon doping. The highest value attained was 4.8 x 10−6 S cm−1. Comparison of electronic spectra of the polymers with those of the model compounds indicated the π‐electrons in the polymers are extensively delocalized along the polymer main chain.
Synthesis and incorporation of 4‐triethoxysilyl‐1,2‐bis(diphenylphosphino)benzene into silica gel and solgel polymers: Preparation and utilization of recyclable catalysts for alkene hydroformylation and methanol homologation
Authors: Hardee J. R. , Tunney S. E. , Frye James , Stille J. K.
Published: April 2003

A chelating phosphine monomer, 4‐triethoxysilyl‐1,2‐bis(diphenylphosphino)benzene (9), was prepared in three steps from 2,4‐dibromoiodobenzene. Attachment of 9 to the surface of commercial silica gel, followed by chelation of rhodium, gave a catalyst which showed both undiminished activity (turnover rates of 90 atom−1 h−1) and no loss of rhodium over five recycles in the hydroformylation of styrene. Complexation of cobalt afforded a catalyst for the homologation of methanol. Monomer 9 could be incorporated into a solgel polymer produced from silicic acid in tetrahydrofuran, but low rhodium uptake and low catalytic activity suggested that few phosphine sites were available to the rhodium. The catalytically‐active species were modeled by the synthesis of cobalt and rhodium complexes containing 1,2‐bis(diphenylphosphino)benzene.
Synthesis of hydrogen‐terminated aliphatic bis(ethynyl ketone)s and aliphatic poly(enamine‐ketone)s and poly(enonesulfide)s
Authors: Wilbur J. M. , Bonner B. A.
Published: April 2003

Hydrogen‐terminated aliphatic bis(ethynyl ketone)s (H‐ABEKs): 1,9‐decadiyne‐3,8‐dione (3a) and 1,13‐tetradecadiyne‐3,12‐dione (3b) were prepared by the Friedel‐Crafts reaction of bis(trimethylsilyl) acetylene (BTMSA) with adipoyl chloride and sebacoyl chloride, followed by desilylation with an aqueous buffer solution. Aliphatic poly(enamine‐ketone)s (APEKs) and aliphatic poly(enonesulfide)s (APESs) were prepared in nearly quantitative yield by the nucleophilic addition polymerization of 3a,b with various diamines and dithiols in N,N‐dimethylformamide (DMF) and m‐cresol at room temperature during 14‐22 h. Aromatic diamines and dithiols gave polymers that were soluble only in m‐cresol. Primary diamines gave exclusively APEKs with the cis (Z) configuration. Dithiols gave APESs which contained more cis (Z) than trans (E) configurations. The inherent viscosities (ηinh) of the APEKs ranged from 0.05 to 0.73 dL/g. The APESs gave ηinh ranging from 0.36 to 2.21 dL/g.
Syntheses and properties of halato‐telechelic polyurethane‐ureas from divalent metal salts of p‐aminobenzoic acid, diamine, dialkylene glycols, and diisocyanate
Authors: Matsuda Hideaki , Takechi Shigetoshi
Published: April 2003

Halato‐telechelic polyurethane‐ureas were synthesized from divalent metal salts of p‐aminobenzoic acid, 4,4′‐diaminodiphenylmethane (4,4′‐methylenedianiline, MDA), dialkylene glycols, and 2,4‐toluylene diisocyanate (TDI). As the divalent metal, Mg and Ca were used, and diethylene glycol and dipropylene glycol were the glycols used. The halatotelechelic polyurethane‐ureas obtained showed better solubilities in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) than previously reported halato‐telechelic polyureas from the metal salts, MDA, and TDI. The reduced viscosities of the polyurethane‐ureas in DMF and DMSO were very low at very low concentrations but increased as the concentration increased. The increase was higher in DMF having lower dielectric constant, due to lower depression of ionic association. Introducing the metal into the urethane‐urea backbone resulted in a considerable decrease in decomposition temperature. In dynamic mechanical property measurements, they exhibited no sharp decrease in relative shear modulus and no peak of tan δ, probably due to aggregation of ionic groups in the polymer main chain.
Semicontinuous seeded emulsion copolymerization of vinyl acetate and methyl acrylate
Authors: Urquiola Belen , Arzamendi Gurutze , Leiza José R. , Zamora Aranzazu , Asua José M. , Delgado Joaquín , El‐Aasser Mohamed S. , Vanderhoff John W.
Published: April 2003

The semicontinuous seeded emulsion copolymerization of vinyl acetate and methyl acrylate was investigated. The effect of type of process (starved process versus semi‐starved process), type of feed (neat monomer addition versus monomer emulsion addition), amount of seed initially charged in the reactor, and feed rate on the time evolution of the overall conversion, copolymer composition, and polymer particle size was analyzed. It was found that, in the case of the starved process, both monomers, but mainly vinyl acetate, accumulated in the reactor. The preferential accumulation of vinyle acetate resulted in a drift of the copolymer composition. Both monomers accumulation and copolymer composition drift were reduced by increasing the amount of seed initially charged in the reactor and by decreasing the feed rate. For the semi‐starved process, it was found that a vinyl aceatate rich copolymer was formed when a low methyl acrylate feed was used, whereas a methyl acrylate rich copolymer was obtained at high methyl acrylate feed rates. For both starved process and semi‐starved process, the total number of polymer particles, after an initial increase, reached a plateau value which was the same in all of the experiments carried out. These results were analyzed by means of a mathematical model developed for this system.
Polymerization of 1‐methylthio‐1‐alkynes and polymer properties
Authors: Matsumoto Tatsuhiko , Masuda Toshio , Higashimura Toshinobu
Published: April 2003

Polymerization of 1‐methylthio‐1‐alkynes (MeSCCR; R = Et, n‐Bu, n‐C6H13, and n‐C8H17) was studied by use of transition metal catalysts. A 1 : 2 mixture of MoCl5 and Ph3SiH provided polymers having M̄w over 1 × 105 in 30–50% yields from these monomers. The length of the alkyl group hardly affected the polymerization. The monomer, MeSCC‐n‐C6H13, showed low reactivity in homopolymerization, but higher reactivity than that of MeCC‐n‐C5H11 in copolymerization. Poly(1‐methylthio‐1‐alkyne)s were colorless solids, and those with long alkyl pendants (R = n‐C6H13, n‐C8H17) were soluble in various organic solvents. The present polymers were thermally more stable than poly(2‐alkyne)s, the corresponding hydrocarbon polymers.
The effect of polymer structure on the efficiency of acid generation from triarylsulfonium salts
Authors: McKean Dennis R. , Schaedeli Ulrich P. , Kasai Paul H. , Macdonald Scott A.
Published: April 2003

The irradiation of triarylsulfonium salts produces Brönsted acid along with diarylsulfide products. This photochemical conversion has been applied in several areas of polymer film technology including imaging and curing of films. This paper discusses the dependency of acid generation in polymer films on the structures of both polymer and sulfonium salt. The results suggest that the structures of both polymer and sulfonium salt. The results suggest that the efficiency of acid generation is dependent on the interaction between polymer structure and the charged sulfonium salt. Studies have been carried out for both deep‐UV and electron beam irradiation of polymer films. The variation of acid generation with sulfonium salt loading has been determined. Finally the effect of accelerating voltage on the amount of acid generation following electron beam irradiation is discussed. ESR spectroscopy has been done on films after uv irradiation to determine the nature of the radicals which are formed.
Hydrogen/liquid vapor radio frequency glow discharge plasma oxidation/hydrolysis of expanded poly(tetrafluoroethylene) (ePTFE) and poly(vinylidene fluoride) (PVDF) surfaces
Authors: Vargo Terrence G. , Gardella Joseph A. , Meyer Anne E. , Baier Robert E.
Published: April 2003

Modification of fluorine‐containing polymers has recently received much attention due to new chemistries allowing for refunctionalization of these materials, especially their surfaces. In this article results are discussed which demonstrate various interesting modifications (including incorporations of OH and oxygen comprised functionality) to expanded poly(tetrafluoroethylene) (ePTFE) surfaces. This is effected through the use of low damage, radio frequency glow discharge (RFGD) processes. The low damage conditions, which preserve the original pore structure/morphology of these RFGD treated materials, are supported by Scanning Electron Microscopy (SEM) while the resulting atomic and molecular effects are investigated through other surface analytical methodology. All materials reported in this investigation have been subjected to intensive structural analyses utilizing Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR–FTIR), and wettability profiles obtained through contact angle measurements using a large series of liquids having varying surface tensions and surface reactive functionality. Through this multitechnique analysis of both expanded PTFE and poly(vinylidene fluoride) (PVDF) treated surfaces, a model is supported which illustrates surfaces possessing both high and low energy regions comprising both oxygen and fluorine functionality in close molecular proximity.
Synthesis and properties of multiblock copolymers based on polydimethylsiloxane and polyamides from dicarboxylic acid and diisocyanate terminated functionalities
Authors: Otsuki Toshihiro , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Polydimethylsiloxane (PDMS)–polyamide multiblock copolymers were successfully synthesized via diisocyanate route by two different procedures, i.e., the one‐step and two‐step methods, In the two‐step method, α, ω‐diisocyanate‐terminated polyamide oligomers, which were prepared in situ from a mixture of isophthalic acid (IPA) and azelaic acid (AZA) with 4,4′‐methylenedi (phenyl isocyanate) (MDI) in 1,3‐dimethyl‐2‐imidazolidone (DMI) in the presence of 3‐methyl‐1‐phenyl‐2‐phosopholene 1‐oxide catalyst, were reacted with α, ω‐bis (10‐carboxydecyl) polydimethylsiloxane (PDMS‐diacid) leading to the formation of multiblock copolymers. In the one‐step method, the reaction components, MDI, IPA, AZA, and PDMS‐diacid were reacted all together in DMI in the presence of the catalyst. These polymerizations gave multiblock copolymers having inherent viscosities in the range of 0.36–1.12 dL/g in N,N‐dimethylacetamide (DMAc). These multiblock copolymers were soluble in amide‐type solvents, and transparent (or translucent) and ductile films could be cast from the solutions in a mixture of DMAc and bis(2‐ethoxyethyl) ether. The multiblock copolymers prepared by the two‐step method had better‐defined, microphase‐separated morphology than those obtained by the one‐step method. The mechanical properties of PDMS–polyamide multiblock copolymer films were found to be highly dependent on the PDMS content; the tensile strength and modulus of the films decreased with increasing the PDMS content.
Photochromic and photomechanical ionene elastomer containing poly(tetrahydrofuran) segments and viologen units
Authors: Hashimoto Tamotsu , Kohjiya Shinzo , Yamashita Shinzo , Irie Masahiro
Published: April 2003

Elastomeric polymer consisting of poly(oxytetramethylene) segments and viologen units (PTV) was synthesized by the reaction of dicationic living poly(tetrahydrofuran) with 4,4′‐bipyridine at −70°C. The chloride or bromide ion was introduced as the counter anion into the viologen groups of PTV by the treatment of the reaction mixture with aqueous sodium chloride or bromide, respectively. The solid film of PTV having chloride inon showed photochromism, i.e., color change by light irradiation, via photoreduction of the violegen groups. In contrast. PTV of bromide counter anion required a small amount of poly(N‐vinyl‐2‐pyrrolidone) to undergo the photochromic reaction. The irradiation of light also affected the stress relaxation of the polymers, namely PTV showed photomechanical behavior. This phenomenon is considered to be induced by the decrease of total number of ionic charges of PTV by photo‐reduction of the viologen groups followed by the change of a state of ionic clustering in the polymer matrix.
Surface grafting of polymers onto inorganic ultrafine particles: Reaction of functional polymers with acid anhydride groups introduced onto inorganic ultrafine particles
Authors: Tsubokawa Norio , Kogure Akira
Published: April 2003

The surface grafting onto inorganic ultrafine particles, such as silica, titanium oxide, and ferrite, by the reaction of acid anhydride groups on the surfaces with functional polymers having hydroxyl and amino groups was examined. The introduction of acid anhydride groups onto inorganic ultrafine particle was achieved by the reaction of hydroxyl groups on these surfaces with 4‐trimethoxysilyltetrahydrophthalic anhydride in toluene. The amount of acid anhydride groups introduced onto the surface of ultrafine silica, titanium oxide, and ferrite was determined to be 0.96, 0.47, and 0.31 mmol/g, respectively, by elemental analysis. Functional polymers having terminal hydroxyl or amino groups, such as diol‐type poly(propylene glycol) (PPG), and diamine‐type polydimethylsiloxane (SDA), reacted with acid anhydride groups on these ultrafine particles to give polymer‐grafted ultrafine particles: PPG and SDA were considered to be grafted onto these surfaces with ester and amide bond, respectively. The percentage of grafting increased with increasing acid anhydride group content of the surface: the percentage of grafting of SDA (Mn = 3.9 × 103) onto silica, titanium oxide, and ferrite reaching 64.7, 33.7, and 24.1%, respectively. These polymer‐grafted ultrafine particles gave a stable colloidal dispersion in organic solvents.
Studies of photoinitiation and phototermination of free radical polymerization using dual pulsed laser techniques
Authors: Holdcroft Steven , Guillet James E.
Published: April 2003

Studies of free radical polymerization are described in which the initiation and termination events are independently controlled using two laser pulses of different wavelength. Flash photolysis of azobisisobutyronitrile (AIBN) was used to initiate the polymerization of styrene. After a predefined period the polymerization was terminated by laser photolysis of 2‐naphthylmethyl 1‐naphthylacetate (NMNA). The molecular weights of the polymer were controlled by the time interval between laser pulses. Irradiation with high intensity laser pulses in the presence of preformed polystyrene yields a fluorescent‐labelled polymer. A two‐photon process is proposed to explain the mechanism of photoaddition of naphthylmethyl groups to the polymer chain.
Synthesis, polymerization, and thermal properties of a new acetylene‐terminated schiff base
Authors: Wei Yen , Hariharan Ramakrishnan , Ray Jayanta K.
Published: April 2003

A new acetylene‐terminated Schiff base monomer, N,N′‐(1,4‐phenylenedimethylidyne)‐bis‐(4‐ethynylaniline) (PPP), was synthesized and was characterized by nuclear magnetic resonance and infrared spectroscopy. This monomer was then polymerized to yield a new polymer (PPPP) with alternating units of aromatic imine and diacetylene via an oxidative coupling polymerization of the acetylenic terminal groups. The monomer was also polymerized by thermal curing at elevated temperatures up to 400°C to afford a crosslinked polymer network without significant structural decomposition. Thermal properties and thermal reactions of the monomer and the polymers were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymers exhibit excellent thermal stabilities in an inert atmosphere. Electronic properties of the polymers are also discussed.
Biocompatible polymeric systems: Copolymerization of 4‐methacryloyloxy‐acetanilide with 2‐hydroxyethyl‐methacrylate
Authors: Román J. San , Levenfeld B. , Madruga E. L. , Vairon J. P.
Published: April 2003

Soluble copolymers of 4‐methacryloyloxy‐acetanilide (M), an acrylic derivative of paracetamol, with 2‐hydroxyethyl‐methacrylate (H) were prepared by free radical polymerization in DMF solution at 50°C, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The reactivity ratios of both monomers were determined by the application of conventional linearization methods suggested by Fineman‐Ross and Kelen‐Tudos. The results obtained make clear that this system copolymerizes at random with the reactivity ratios rm = 2.15 ± 0.05 and rH = 0.90 ± 0.10. The microstructure of copolymer chains is described on the basis of the first order Markov statistics. The copolymer glass transition temperatures were determined calorimetrically and the variation of Tg with the copolymer composition is discussed according to modern methods, considering the sequence distribution of monomeric units along the copolymer chains. Also the Tg of the corresponding homopolymers were determined giving the values of Tg(M) = 471 K and Tg(H) = 358 K.
Interpenetrating polymer networks of poly(carbonate‐urethane) and polymethyl methacrylate
Authors: Frisch Harry L. , Zhou Peiguang , Frisch K. C. , Xiao X. H. , Huang Misty Weiyu , Ghiradella H.
Published: April 2003

We report the synthesis and characterization of interpentrating polymer networks (IPN's), pseudo INPN's, and blends of urethane‐containing aliphatic polycarbonates (PCU) and polymethyl methacrylate (PMMA). The simultaneous full IPN's of PCU's and PMMA over the whole composition range have only one Tg, as determined by DSC and DMA which, together with transmission electron microscopy observations, suggest a single phase morphology even though the linear chain blends are completely immiscible. The full IPN's exhibit a maximum tensile strength at a certain composition, and superior solvent and heat resistance as compared to the pseudo IPN's, linear blends, and the pure crosslinked PCU's and PMMA.
Reactions in aminosilane‐epoxy prepolymer systems. II. Reactions of alkoxysilane groups with or without the presence of water
Authors: Serier A. , Pascault J. P. , Lam Thanh My
Published: April 2003

The hydrolysis and reactions of alkoxy silane groups have been studied on a model compound (TA) prepared from 2 mol of phenyl glycidyl ether and 1 mol of aminopropyl triethoxy silane. At low (40°C) and high (140°C) temperatures, the monomer conversion and the evolution of the molecular mass are followed by size exclusion chromatography (SEC). During the same reaction time, the evolution of the functional groups, hydroxyl CHOH, ethoxy OC2H5, and siloxane SiOSi, is observed by FTIR spectroscopy. Without the presence of water, reactions between hydroxyl and ethoxy silane lead to gelation at the end of the reaction. A by‐product, probably a cyclic tetramer is also formed. After the hydrolysis, the reaction of the model compound is quite different. The product of reaction is always soluble, even after a treatment at high temperatures, and the evolution of the molecular mass versus the reaction time seems to correspond to the condensation giving a dead cyclic tetramer. From this study it is evident that the curing cycle has a great influence on the properties of the interface of a composite based on a epoxy matrix.
Syntheses and polymerization of (meth)acrylates containing spiro ortho ester moieties
Authors: Kitamura Naoya , Takata Toshikazu , Endo Takeshi , Nishikubo Tadatomi
Published: April 2003

Acrylates and methacrylates bearing pendant spiro ortho ester groups (3) were prepared by the reaction of (meth)acrylic acid with bromomethyl spiro ortho esters (2) in the presence of 1,8‐diazabicyclo [5.4.0] undec‐7‐ene (DBU). These monomers were copolymerized with styrene (St) at 60°C in the presence of α,α'‐azobisisobutyronitrile (AIBN) to give the corresponding copolymers with M̄n 6000‐17000 and their compositions were in proportion to the feed ratios. Similarly, the copolymerization of 3 with acrylonitrile (AN) was carried out at 60°C to obtain the corresponding copolymers with the similar compositions to the feed ratios. Two kinds of 3‐St copolymers with different compositions were treated with BF3OEt2 in refluxing methylene dichloride affording the crosslinked polymers quantitatively. Slight expansion in volume was observed during the crosslinking.
Interfacial polycondensation and characterization of polyphosphates and polyphosphonates
Authors: Richards M. , Dahiyat B. I. , Arm D. M. , Lin S. , Leong K. W.
Published: April 2003

The synthesis of four bisphenol A‐based polyphosphates and phosphonates was accomplished. The polymerization involved a condensation between bisphenol A and a phosphorodichloridate. The heterophasic polycondensation technique was used with the aid of a phase transfer catalyst to yield molecular weights in the range of 20,000–40,000. The polymers were characterized by FT‐IR, FT‐NMR, and DSC. Systematic studies on the interfacial polymerization indicated that a more concentrated organic phase and a slight excess of diol favored the production of high molecular weight polymers. An optimum concentration of 5–10 mol % was observed for three different phase transfer catalysts. Kinetic studies showed that the polymerization was complete within the first 10 min. The degree of agitation was shown to be important, as the overhead mechanical stirrer was not as effective as the blender. In addition, crosslinking with pentaerythritol yielded significant increases in the molecular weights of these polymers.
Ziegler–Natta catalysts on silica for ethylene polymerization
Authors: Nowlin T. E. , Mink R. I. , Lo F. Y. , Kumar T.
Published: April 2003

The amount of dibutylmagnesium (DBM) or triethylaluminum (TEAL) that reacted with silica at 55–60°C depended on the silica calcining temperature. Lower silica calcining temperatures resulted in more Mg or Al fixed to the silica surface, indicating greater amounts of DBM or TEAL reacting with the silica. The amount of the metal alkyls butyl(octyl) magnesium ethoxide, ethylaluminum dichloride, tri‐n‐hexylaluminum, and diethyl(ethyldimethylsilanolato) aluminum that reacted with 600°C calcined silica was also determined. The metal alkyl can react with the silica at two sites, a surface hydroxyl group and a siloxane group. The silica surface hydroxyl groups can be chemically converted to trimethylsilyl groups so that only the siloxane groups are available for attack. After the metal alkyl was reacted with silica, the resulting intermediate was treated with titanium tetrachloride to yield an ethylene polymerization catalyst in the presence of TEAL. When no metal alkyl was employed, titanium tetrachloride reacted only with the silica surface hydroxyl groups to yield a weakly active ethylene polymerization catalyst.
Emulsion copolymerization of styrene and methyl methacrylate. II. Molecular weights
Authors: Forcada Jacqueline , Asua José M.
Published: April 2003

A mathematical model for the time evolution of both number‐average molecular weight and weight‐average molecular weight is described. The model results in a set of ordinary differential equations and its application is not limited by the maximum number of radicals per particle. The model was used to analyze the effect of the monomer molar ratio in the initial charge on the weight‐average molecular weight during the emulsion copolymerization of styrene and methyl methacrylate in a batch reactor.
The preparation, characterization, and application of cellulose–MMA graft copolymers. I. The aqueous‐based preparation of cellulose–MMA graft copolymers
Authors: Guthrie J. T. , Tune P. D.
Published: April 2003

Cellulose‐MMA graft copolymers have been produced using aqueous‐based, Ce(IV)‐initiated and periodate‐initiated systems and also photochemical initiation. The reaction variables studied include the effect on grafting of varying the MMA monomer concentration, the initiator type and concentration, and also the reaction time. Of the three initiator types examined, the Ce (IV)‐initiated and the photochemically‐initiated systems are comparable in their effects on graft copolymer formation. Concurrent homopolymer formation was in the region of 50% by weight. Periodate‐initiation leads to less efficient grafting of MMA onto cellulose, although homopolymer formation is also lower (typically <20% by weight). The characterization of the copolymeric products through their properties as solids and, as their carbanilated derivatives, through their solution properties has been undertaken. Values of the activation onergy of decomposition (EA) of the cellulose‐MMA graft copolymers decrease with increasing MMA content, ranging between 227 and 155kJ mol−1. There is also a dependence on initiator type and grafting reaction conditions used (EA (cellulose wood pulp) = 239 kJ mol−1; EA (PMMA) = 115 kJ mol−1). Quantitative zeta‐potential (ζ) determinations for cellulose‐MMA graft copolymer samples produce negative surface charge density (σ) values. At a comparable MMA grafting level of 70–80%, values are of the order: photochemical (−730 esu/cm2) > periodate (−470 esu/cm2) > Ce (IV)‐initiation (−351 esu/cm2). Characterization of carbanilate solutions (by rheological examination) and of dry, carbanilate films (by study of surface wetting behavior) highlighted differences in the physical conformation of copolymers prepared by the different initiation routes. The highly degradative effect on cellulose of a periodate initiator, in comparison with the Ce (IV)‐initiation system, is reflected in significantly reduced molar mass values (typically, Mn 65,000 as opposed to 130,000 for Ce (IV)‐initiated graft copolymer carbanilates).
Synthesis of poly(benzylidene phthalide)s: A new class of polymers
Authors: Cassidy Patrick E. , Johnson C. Greg , Neef Charles J. , Jhingree Isaac , Aminabhavi Tejraj M.
Published: April 2003

Pyromellitic dianhydride (PMDA) was condensed with different aromatic diacetic acids via a Perkin reaction to produce new polymers containing the benzylidenephthalide group in the backbone. Yields ranged from 50 to 90% with inherent viscosities ranging from 0.07 to 0.37 dL/g. Polymerizations at 275°C for 4 h using p‐phenylenediacetic acid and PMDA gave the polymer with highest inherent viscosity. However, polymerization under identical conditions of p,p′‐diphenyl ether diacetic acid, each with PMDA, yielded poor results. For these two monomers the best polymerization conditions were 250°C for 8 h. In general, the most thermally stable polymer was derived from the diphenyl ether diacetic acid monomer (308°C). This polymer was obtained in highest yields and gave the greatest amount of pyrolytic residue in argon (67%).
Synthesis and NMR study of amide and imide derivatives of PMR‐15 monomeric units
Authors: Milhourat‐Hammadi A. , Chayrigues H. , Levoy R. , Merienne C. , Gaudemer A.
Published: April 2003

Variations in PMR‐15 composite properties could be due to by‐products formed during the polymerization cycle. In order to identify these compounds, various condensation products derived from the three monomeric constituents of the resin: NE, BTDE, and MDA, have been synthesized and fully characterized by spectroscopic methods, mainly by 1H‐ and 13C‐NMR. In these products, one or two MDA amino groups are replaced by amido or imido groups, leading to mono‐ and di‐substituted MDA derivatives. Monosubstituted derivatives were obtained by first protecting one MDA amino group with a terbutoxycarbonyl group (Boc). The MDA's CH2 bridge of these molecules gives rise, in their 1H NMR spectra, to a characteristic resonance singlet, the position of which can be correlated to the nature of the amino substituents through 1H chemical shift increments. The latter provide a useful tool to predict the CH2, shifts in other compounds. Similar substituent increments are proposed for the chemical shifts of the MDA aromatic protons and carbon atoms.
Synthesis of organotin polymers from diallylidenepentaerithritol (DAPE) and organotin monohydrides having an alkenyl substituent
Authors: Moriya Osamu , Urata Yoshikiyo , Endo Takeshi
Published: April 2003

Tri‐n‐butyltin hydride (Bu3SnH) and modified organotin monohydrides which had an allylic ether group were employed for polymerizations of diallylidenpentaerithritol (DAPE) to prepare crosslinked polymers containing both organotin and acetal groups. The use of the latter monohydrides having a terminal unsaturated bond was particularly effective for introduction of various contents of the organotin moieties into the polymers, althought they did not undergo homopolymerizations.
Olefin copolymerization with metallocene catalysts. I. Comparison of catalysts
Authors: Chien James C. W. , He Dewei
Published: April 2003

A number of metallocene/methylaluminoxane (MAO) catalysts have been compared for ethylene/propylene copolymerizations to find relationship between the polymerization activities, copolymer structures, and copolymerization reactivity ratio with the catalyst structures. Stereorigid racemic ethylene bis (indenyl) zirconium dichloride and the tetrahydro derivative exhibit very high activity of 10 7 g (mol Zr h bar)−1, giving copolymers having comonomer compositions about the same as the feed compositions, molecular weights increasing with the increase of ethylene in the feed, random incorporation of comonomers, and narrow molecular weight distribution indicative of a single catalytic species. Nonbridged bis (indenyl) zirconium behaved differently, favoring the incorporation of ethylene over propylene, producing copolymers whose molecular weight decreases with the increase of ethylene in the feed, broad molecular weight distribution, and a methanol soluble fraction. This catalyst system contains two or more active species. Simple methallocene catalysts have much lower polymerization activities. CpTiCl2/MAO produced copolymers with tendency toward alternation, whereas Cp2HfCl2/MAO gave copolymer containing short blocks of monomers.
Olefin copolymerization with metallocene catalysts. IV. Metallocene/methylaluminoxane catalyzed olefin teropolymerization
Authors: Chien James C. W. , He Dawei
Published: April 2003

Ethylene, propylene, and ethylidene norbornene (D) were terpolymerized by Et [Ind]2ZrCl2/MAO in solution and supported on silica. The presence of D decreases the rate of polymerization. EPDM containing between 3 and 22 wt % of D were synthesized which have narrow MW distribution. The supported catalyst produces EPDM with E/P ratio which are similar to the ratio in the feed.
Free‐radical distributions in emulsion polymerization which employs oil‐soluble radical generators
Authors: Brooks Brian W.
Published: April 2003

The use of oil‐soluble radical generators for emulsion polymerization is considered. When radicals are formed in pairs within particles of a seed latex, the occurrence of radical desorption leads to complex kinetics. Use of radical balances and realistic simplifications produce a method for a relatively simple calculation of radical populations in the particles. Examples are restricted, for illustration purposes, to cases where the average number of radicals per particle, n, is less than one. Very low rates of radical desorption cause a substantial increase in n. As the desorption rate increases, the value of n decreases. n increases slowly with radical generation rate. Large decreases in the chain termination rate coefficient (which may accompany a gel effect) can have a negligible effect on the value of n. Radical distributions obtained from oil‐soluble initiators can be slightly broader than those expected from the use of water‐soluble initiators. The kinetics of emulsion polymerization will be similar for the two types of radical generator when radicals from oil‐soluble generators can desorb from the polymer particles.
Novel benzyl sulfonium salt having an aromatic group on sulfur atom as a latent thermal initiator
Authors: Hamazu Fumio , Akashi Sumio , Koizumi Tatsuya , Takata Toshikazu , Endo Takeshi
Published: April 2003

Three benzyl p‐hydroxyphenyl methylsulfonium salts with different counter anions were synthesized as novel latent thermal initiators. Syntheses of the sulfonium salts (2) were performed by the reaction of p‐hydroxyphenyl methyl sulfide with benzyl chloride followed by exchange of the counter anion (Cl−) with SbF−6 (2a), PF−6 (2b), or BF−4 (2c). In the bulk polymerization of glycidyl phenyl ether (PGE) with 2, initiator activity of the sulfonium salts was evaluated by comparison with that of benzyl tetramethylenesulfonium hexafluoroantimonate (1, R = H). Among the initiators, 2a showed the highest activity, and was much more active than 1 (R = H). Since the polymerization of PGE with 2a proceeded efficiently at more than 80°C but not at all at less than 60°C, 2a was suggested to be a good latent thermal initiator.
Characterization of plasma polymerized hydrocarbons using CP–MAS 13C‐NMR
Authors: Gambogi Robert J. , Cho D. L. , Yasuda H. , Blum Frank D.
Published: April 2003

Plasma polymerized hydrocarbons made from ethane and methane were produced under different reactor conditions and probed by solid‐state carbon‐13 nuclear magnetic resonance (13C‐NMR) with cross‐polarization and magic‐angle sample spinning. NMR experiments provided structural information about the plasma polymers. The conditions of low power, high hydrocarbon gas flow rate, and no added hydrogen gas appeared to give the highest amount of nonprotonated sp3 hybridized carbons in the films for the reactor design used. The use of methane or ethane as reactor gas did not affect plasma polymer structure significantly.
Synthesis and activity of aryl benzyl methyl sulfonium salts as cationic initiators: Effect of substituent on aryl group
Authors: Hamazu Fumio , Akashi Sumio , Koizumi Tatsuya , Takata Toshikazu , Endo Takeshi
Published: April 2003

Benzyl o‐, m‐, and p‐substituted phenyl methyl sulfonium salts (2b–2g) were synthesized and their activities as cationic initiators were evaluated in the bulk polymerization of phenyl glycidyl ether (PGE). Especially, their activities were estimated with respect to the effect of substituents on the aryl groups. In the polymerizations of PGE with a series of benzyl p‐substituted phenyl methyl sulfonium salts, the order of their activities was found to be 2c (CH3OCOO) > 2b (CH3COO) > 2d (CH3O) ∼ 2a (HO). In particular, 2c was the most active initiator of all, capable of initiating the polymerization of PGE even at room temperature. In the polymerizations with 2a, 2e (m‐Cl), 2f (o‐CH3), and 2g (m‐CH3), the activity of 2e was the highest of all while those of 2a, 2f, and 2g were almost the same. These results strongly suggested that the electron‐withdrawing group placed on the aryl group undoubtedly enhanced the activity of the sulfonium salts as the cationic initiators.
Addition curing thermosets endcapped with 4‐amino [2.2] paracyclophane
Authors: Waters John F. , Sutter James K. , Meador Mary Ann B. , Baldwin Larry J. , Meador Michael A.
Published: April 2003

A new family of addition curing polyimides were prepared that contained 4‐amino [2.2]‐paracyclophane as the endcap. An improved synthesis of the endcap 4‐amino‐[2.2] cyclophane was accomplished increasing the yield to 60% and simplifying the procedure. DSC and rheological analysis of endcapped polyimide oligomers confirmed that the onset for polymerization of the ethylene bridge was 250°C. 13C CP/MAS NMR was used to determine the structural changes of the oligomers after thermal treatment. The cyclophane capped polyimides were successfully compression molded to from void free neat resin specimens. T'gs as high as 353°C were obtained by thermomechanical analysis for postcured samples. Preliminary thermal stability studies (TGA) suggest that these resins have a high onset of decomposition ranging from 549 to 567°C.
Synthesis and properties of aromatic polyamide‐benzoxazoles from trimethylsilyl‐substituted 2,4‐diaminophenol and aromatic dicarboxylic acid chlorides
Authors: Tanaka Yuji , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Aromatic poly(o‐hydroxy amide)s having inherent viscosities of 0.6–2.2 dL/g were readily synthesized by the low‐temperature solution polycondensation of N,N′,O‐tris(trimethylsilyl)‐substituted 2,4‐diaminophenol with aromatic dicarboxylic acid chlorides in various organic solvents. The viscosity values were much higher than those of the polymers obtained by a conventional method using parent 2,4‐diaminophenol. Subsequent thermal cyclodehydration of the poly(o‐hydroxy amide)s at 280°C under vacuum afforded the corresponding aromatic polyamide‐benzoxazoles. Most of the poly(o‐hydroxy amide)s dissolved readily in amide‐type solvents, whereas the polyamide‐benzoxazoles were quite insoluble in organic solvents. The polyamide‐benzoxazoles, which gave yellow, transparent, and tough films, had glass transition temperatures of 260–300°C and were stable up to 400°C in air.
Synthesis of halogenated monodispersed telechelic oligomers. III. Bistelomerization of allyl acetate with telogens which exhibit α, ω‐di(trichloromethyled) end groups
Authors: Améduri Bruno , Boutevin Bernard , Lecrom Christophe , Garnier Laurent
Published: April 2003

The redox bistelomerization of allyl acetate with telogens which exhibit α, ω‐di(trichloromethyled) end groups catalyzed by copper, iron salts, or a ruthenium complex led to monoadducts and telechelic oligomers. These diacetates were quantitatively changed into diols. Such compounds have been characterized by both 1H‐ and 13C‐NMR. A reactivity series has been determined and shows that both end groups must be activated to obtain the expected telechelic products in satisfactory yields.
Synthesis of poly(alkylene phosphate)s bearing uracil moiety in the main chain
Authors: Łapienis Grzegorz
Published: April 2003

Poly(alkylene phosphate)s bearing regularly distributed uracil moiety in the main chain have been obtained. The synthetic procedure consists of condensation of bis(diethylamino)‐methoxyphosphine with N1,N3‐bis(2′‐hydroxyethyl) uracil followed by oxidation, dealkylation, and transformation to the resulting sodium polysalt. The final polymer (\documentclass{article}\pagestyle{empty}\begin{document}$\bar M_n \approx 10^4 $\end{document}) as well as the intermediate products were characterized by 1H‐, 13C‐, and 31P‐NMR spectroscopy.
Facilitated transport of molecular oxygen in cobaltporphyrin/poly(1‐trimethylsilyl‐1‐propyne) membrane
Authors: Nishide H. , Kawakami H. , Sasame Y. , Ishiwata K. , Tsuchida* E.
Published: April 2003

The combination membrane of poly(1‐trimethylsilyl‐1‐propyne) with enormously high permeability and poly(vinylimidazole)‐bound porphinatocobalt with selective oxygenbinding ability was prepared. Oxygen transport through the membrane was facilitated in terms of oxygen transport via the latter domain as a fixed oxygen‐carrier, and this oxygen permeability maintained for a month.
Synthesis and diels–alder polymerization of furfurylidene and furfuryl‐substituted maleamic acids
Authors: Mikroyannidis John A.
Published: April 2003

The reactions of monomaleamic acid derived from an aromatic diamine with furfural afforded a novel class of furfurylidene‐substituted maleamic acids 2a–2d. The latter were cyclodehydrated to yield maleimides 3a–3d which are AB‐monomers for a Diels–Alder polymerization. In addition, N‐furfurylmaleamic acid (4) was synthesized by reacting furfurylamine with maleic anhydride at ambient temperature. Cyclodehydration of 4 afforded N‐furfurylmaleimide (5). The polymer precursors were characterized by IR and 1H‐NMR spectroscopy. Their curing behavior was investigated by DTA and correlated with chemical structures. Diels–Alder polymerization of monomers occurred at the temperature range of 113–210°C. Thermal stability of monomers was evaluated by TGA and isothermal gravimetric analysis (IGA). It was shown that thermal stability of the polymer derived from maleamic acid 4 was dramatically improved upon curing at high temperatures due to the formation by dehydration of a stable aromatic structure.
Synthesis, characterization, and blends of high temperature poly(arylether sulfone)s
Authors: Andrews S. M.
Published: April 2003

The preparation of poly(4‐oxy‐1,4‐phenylenesulfonyl‐4,4′‐biphenylene‐4‐sulfonylphenylene) (PBP) has been accomplished by the base mediated, polycondensation reaction between two biphenyl containing monomers. The bisphenol, 4,4′‐bis[(4‐hydroxyphenyl) sulfonyl]biphenyl (HSB), was reacted with 4,4′‐bis[(4‐chlorophenyl)sulfonyl]‐biphenyl (CSB) in tetramethylene sulfone solvent. The highest mechanical properties and glass transition temperature was observed for polymer PBP with a reduced viscosity around 1.0 dL/g. Consequently, the current synthesis route provides polymer with higher properties than other historical preparative routes. Blends of PBP with a different poly(ether sulfone) were miscible based on the observance of a single glass transition temperature. The Tgs of the polymer blends exhibited an unusual positive deviation from the weighted linear averages of the components.
Solid‐State polymerization of the binary mixture of methacrylate and liquid‐crystalline compound by electron beam
Authors: Shindo Tadafumi , Uryu Toshiyuki
Published: April 2003

Solid‐state polymerization of a binary mixture of nonliquid‐crystalline monomer and liquidcrystalline compound was carried out using electron beam. The monomers were benzoic acid containing 4‐[ω‐(meth)acryloyloxyalkyloxy] benzoic acids, in which the alkylene spacer was ethylene, hexamethylene, or undecamethylene. The conversion yield of monomer to polymer to a large extent increased with increasing content of a liquid‐crystalline compound with a terminal carboxylic group, such as 4‐n‐alkyloxybenzoic acid, while the addition of a liquid‐crystalline compound without terminal carboxylic group did not affect polymerization of the monomer. Phase diagrams of the mixture of monomer and liquid‐crystalline compound were examined using cross‐polarizing microscopy and differential scanning calorimetry (DSC). All mixtures of monomer and 4‐n‐alkyloxybenzoic acid or liquid‐crystalline compound without terminal carboxylic group showed liquid‐crystallinity in a broad composition range. It was concluded that liquid‐crystalline compounds with terminal carboxylic acid may form hydrogen bondings with methacrylate or acrylate monomer having terminal carboxylic acid which enhance polymerizability of the mixture. The stereoregularity of polymers determined by NMR depended on increasing irradiation dose and temperature rather than the content of the added liquid‐crystalline 4‐n‐decanoxybenzoic acid.
Modification of polyolefin surfaces with iron cluster oxidants
Authors: Bergbreiter David E. , White Nicole , Zhou Jing
Published: April 2003

Modification of polyethylene and polypropylene film and powder surfaces with oxygen and hydrogen peroxide is promoted by nonporphyrinic, nonfree radical based iron reagents such as Fe3O(OCOCH3)6(C6H5N)3.5 and FeCl3 • 6H2O/picolinic acid. These oxidation systems introduced small amounts of carbonyl groups onto the surface of these hydrocarbon polymers. The most visible manifestation of this reaction was increased polyolefin wettability toward water. IR spectroscopy, XPS spectroscopy, and chemical derivatization all were used to verify that the reaction had occurred and that a chemically derivatizable surface had been prepared. The overall process produced a fraction of the density of functional groups introduced by conventional etching chemistry.
Plasma polymerization using pulsed microwave power
Authors: Hwu Wen‐hwa , Zurawsky W. P.
Published: April 2003

Pulsed microwave power was used to polymerize a variety of monomers containing different functional groups. We examined the effects of pulse frequency and duty cycle on the deposition rates and the composition of the polymers. For monomers that do not contain oxygen we find that there is an increase in deposition rate with increasing pulse frequency and that the pulsed deposition rate is always less than the continuous power deposition rate. For monomers that contain oxygen, or for co‐depositions of hydrocarbon monomers with O2 or CO, we find that there is a decrease in deposition rate with increasing frequency, however the deposition rate using pulsed power is greater than the rate using continuous power. This result is shown to be related to the amount of etching that takes place during the deposition process. Infrared studies reveal that pulsed power can alter the composition of plasma polymers of some oxygen‐containing monomers. The presence or absence of vinyl unsaturation, nitrile groups, or a cyclic structure have no effect on the polymerization process.
Spectroscopic studies of new model compounds for poly[N,N′‐bis(phenoxyphenyl)pyromellitimide]
Authors: Saini Ajay K. , Carlin Clifford M. , Patterson Howard H.
Published: April 2003

New model compounds for poly[N,N′‐bis(phenoxyphenyl)pyromellitimide] have been synthesized in order to investigate the formation of imine bonds which are proposed to form during the curing process and lead to crosslinking in the bulk polymer. Raman studies show that terminal amines can react with imide carbonyls during curing to form CN bonds. The Raman band due to CN appears at 1656 cm−1 and the band due to CO closest to the imine bond is observed at 1742 cm−1. These results are in agreement with previously published results on vapor deposited polyimide films.