bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of copolymerization systems involving multiple reaction pathways
Authors: Wood Kenneth B. , Stannett Vivian T.
Published: April 2003

A method of analysis of copolymerization systems involving multiple reaction pathways is presented. The method involves fractionation and separate analysis of the individual product populations comprising each sample. Modification of the Kelen–Tüdos linearization techniques into the form necessary to deal with high conversion copolymerizations involving multiple reaction pathways is presented. The method is applied to the ionizing radiation initiated copolymerization of styrene derivatives in dichloromethane, in which case simultaneous copolymerization via cationic and free radical mechanisms is found to occur. Reactivity ratios corresponding to each mechanism are calculated and discussed.
Catalysis of ring‐opening and vinyl polymerizations by dicobaltoctacarbonyl
Authors: Crivello James V. , Fan Mingxin
Published: April 2003

In the presence of SiH containing cocatalysts, dicobaltoctacarbonyl has been found to very efficiently catalyze the ring‐opening polymerization of cyclic ethers, especially epoxides, as well as certain vinyl monomers. The reaction conditions employed are very similar to those used in Co2(CO)8 catalyzed hydrogenation and hydrosilylation reactions. Detailed investigations have been carried out to elucidate the nature of the active species for this catalytic system. A cationic mechanism is proposed based on the experimental results of those investigations.
New coordination catalysts based on rare earth compounds for polymerization of 1‐octene
Authors: Yang Mujie , Zhang Xiaojun , Li Jianfu , Shen Zhiquan
Published: April 2003

The study of rare earth coordination catalysts for polymerization of 1‐octene has been successfully carried out for the first time. Some features and kinetic behavior of polymerization of 1‐octene by Nd(naph)3–AIEt3 catalyst system in tetrachloro‐methane are described. The overall polymerization activation energy Ea measured was 74.5 kJ/mol and the rate equation could be expressed as Rp = kp [Nd] [M] (kp = 3.21 × 10−3 L/mol s, at 50°C). The catalytic activity of various rare earth elements in Ln (naph)3 and ligands in NdL3 for the polymerization was compared. A 1‐octene oligomer with double bonds was obtained. It is either a white or pale yellow waxy semi‐solid. Its number‐average molecular weight is about 103 and the molecular weight distribution is less than 2.
Model filled polymers. V. Synthesis of crosslinked monodisperse polymethacrylate beads
Authors: Zou D. , Ma S. , Guan R. , Park M. , Sun L. , Aklonis J. J. , Salovey R.
Published: April 2003

Monodisperse polymethacrylate beads of varied size and crosslink density are prepared by emulsion copolymerization of methacrylate and divinyl monomers in the absence of emulsifiers. The sizes of polybutyl and polyethyl methacrylate beads decreased with increasing polymerization temperature, while polymethyl methacrylate beads were largely unchanged in size. The molar mass of polymer in polymethyl metnacrylate beads markedly exceeded that in polystyrene beads. The rate of polymerization increased, and bead size decreased, with increasing initiator concentration or decreasing monomer concentration. The polymethacrylate beads are used as filler particles in polymer composites.
Emulsifier‐free emulsion copolymerization of styrene and sodium styrene sulfonate
Authors: Kim J. H. , Chainey M. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

The kinetics of the emulsifier‐free emulsion copolymerization of styrene and sodium styrene sulfonate have been examined over a range of comonomer compositions. The rate of polymerization was found to increase dramatically in the presence of small amounts of sodium styrene sulfonate. This increase is attributed to the increased number of particles formed when sodium styrene sulfonate was present and to a gel effect enhanced by ion association. At low concentrations of functional comonomer, where a monodisperse product was obtained, a homogeneous nucleation mechanism of particle generation is proposed. At higher concentrations, broader and then bimodal size distributions were obtained, and this is ascribed to significant aqueous phase polymerization of sodium styrene sulfonate. The water‐soluble homopolymer is supposed to act as a locus of polymerization. The occurrence of this aqueous phase side reaction and the generation of secondary particles makes impossible the preparation of highly sulfonated polystyrene latexes by batch or seeded batch emulsion copolymerization.
Synthesis of block copolymer containing dextran and polyamide sequences
Authors: Hashimoto Kazuhiko , Imanishi Shin‐Ichiro , Okada Masahiko , Sumitomo Hiroshi
Published: April 2003

A novel AB‐type block copolymer composed of dextran and polyamide sequences was prepared through the following two approaches. One is a coupling reaction of a terminal functional group introduced in the dextran chain with that in the polyamide chain, such as the reaction of an amine group with an acyllactam group or that of a lactone group with an amine group at the corresponding chain ends. The other is an anionic polymerization of a bicyclic lactam activated with a trimethylsilylated dextran derivative having an acyllactam end group. The latter procedure was found to be more effective for the preparation of the block copolymer having a high molecular weight polyamide sequence.
Novel conjugated polymer containing aromatic ring and selenium in backbone: Addition polymerization of 1,4‐benzenediselenol to 1,4‐diethynylbenzene
Authors: Kobayashi Ellchl , Metaka Nobuki , Aoshima Sadahito , Furukawa Junji
Published: April 2003

A novel addition polymerization of 1,4‐benzenediselenol (BDSe) to 1,4‐diethynylbenzene (DEB) was carried out by UV‐irradiation in toluene at 60°C under nitrogen atmosphere. The polymerization proceeded at such a fast rate as to give 60–70% yield for 6 min. A paleyellowish polymer (M̄n = 20000–30000) precipitated with the progress of the polymerization. In the presence of BPO, the polymerization also proceeded rapidly to give the polymer (M̄n = 18000) in 50% yield for 4 min. The polymer magnified image was insoluble in conventional organic solvents. In the IR spectrum of the polymer, the characteristic absorption bands of cis‐ and trans‐vinylene groups appeared at 1340 and 940 cm−1, respectively. The microstructures of polymers were evaluated as the cis content was 90% and the trans one was 10%, based on the model adducts of benzeneselenol and ethynylbenzene. The cis ← trans isomerization occurred with UV‐irradiation: the cis vinylene group of the polymer decreased from 90 to 40% for 18 h. The electrical conductivity of the polymer was in the order of 10−13 S/cm without dopant, but increased up to 10−5 S/cm on I2 doping. DSC and TG thermograms of the polymer indicated its decomposition point as 465°C under nitrogen atmosphere.
Synthesis and characterization of monodisperse porous polymer particles
Authors: Cheng C. M. , Micale F. J. , Vanderhoff J. W. , El‐Aasser M. S.
Published: April 2003

Monodisperse porous polymer particles in the size range of 10 μm in diameter were prepared via seeded emulsion polymerization. Linear polymer (polystyrene seed) or a mixture of linear polymer and solvent or nonsolvent were used as inert diluents. The pore diameters of these porous polymer particles were on the order of 1000 Å with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m2/g. The physical features of the porous polymer particles depended on the diluent type and the crosslinker content, as well as the molecular weight of polymer seed particles. By varying the molecular weight of the linear polymer, monodisperse porous polymer particles with different pore size distribution could be synthesized. Polymer seed with a low degree of crosslinking instead of linear polymer could also be used to prepare monodisperse porous polymer particles with smaller pore volume and pore size.
Monodisperse porous polymer particles: Formation of the porous structure
Authors: Cheng C. M. , Vanderhoff J. W. , El‐Aasser M. S.
Published: April 2003

Monodisperse porous styrene‐divinylbenzene copolymer particles were prepared via seeded emulsion polymerization using a mixture of linear polymer (polystyrene seed) and non‐solvent as inert diluent. Experimental evidence was presented to describe the mechanism of formation of porous polymer particles during the copolymerization and solvent extraction stages, in which porosity was a consequence of phase separation in the presence of diluents. Pore structure formation was investigated by changes in copolymerization kinetics, gel content, crosslinking density, particle morphology, surface area, pore volume, and pore size distribution. The process of copolymerization was presented, based on the concepts of production, agglomeration, and fixation of the interior gel microspheres of polymer particles. A portion of linear polymer used as diluent was found to participate in the network structure while the porous matrix was built‐up. The influence of the removal of the linear polymer from the matrix pores during the solvent extraction process on the porous structure was also discussed.
Photocatalytic production of hydrogen peroxide using polymer bound anthraquinone. I. Photoproducts in 2‐hydroxyethyl methacrylate hydrogels swollen with water and 2‐propanol
Authors: Foyle Victor P. , Takahashi Yoshiyuki , Guillet James E.
Published: April 2003

Photoreductions of polymer‐bound anthraquinone in degassed water‐ and 2‐propanolswollen 2‐hydroxyethyl methacrylate hydrogel films were performed at 313 and 334 nm, and in sunlight for the water‐swollen system. The quantum yield at 334 nm for production of anthrahydroquinone was 0.31 in water and 0.94 in 2‐propanol. Results at 313 nm were very similar. A reversible oxygen insensitive side product, indentified as 10‐hydroxyanthrone, was produced simultaneously to the anthrahydroquinone in water‐swollen films, but not for 2‐propanol. A small amount of irreversible side product, believed to be hydroxylated anthraquinone, was also formed in the water system. A photochemical reaction scheme is suggested to account for these observations. Hydrogen peroxide production from photoreduction‐reoxidation cycling of the hydrogels is reported.
Remote nitrogen plasma treatment of polymers: Polyethylene, nylon 6,6, poly(ethylene vinyl alcohol), and poly(ethylene terephthalate)
Authors: Foerch R. , Hunter D. H.
Published: April 2003

A remote nitrogen plasma has been used for the rapid attachment of nitrogen to linear low density polyethylene, nylon 6,6, poly(ethylene vinyl alcohol), and poly(ethylene terephthalate). Analysis was performed using X‐ray photoelectron spectroscopy to investigate the chemistry occurring on the surface. Nitrogen appeared to attach to the polymer chain at specific sites rather than uniformly over the whole chain as seen by the formation of high binding energy components and the continuously high intensity of the hydrocarbon component.
13C‐NMR Study of Anomalous Linkages in Polyurethane
Authors: Kaji Atsushi , Arimatsu Yosikazu , Murano Masao
Published: April 2003

Several kinds of model compounds for anomalous linkages in polyurethanes (branching or crosslinking; allophanate and biuret) were prepared. The phenylisocyanate (PHI) based models were identified by IR and NMR. The 13C‐NMR chemical shifts effects due to the anomalous linkages were determined. The 4,4′‐diphenylmethane diisocyanate (MDI) based models were purified incompletely but the characteristic signals of the aromatic carbons were nevertheless found in their spectra. Two types of segmented polyurethane (SPU) were prepared and the anomalous linkages were investigated by 13C‐NMR. The signals due to the allophanate (Al) and the triphenylbiuret (TB) linkages were observed in the spectra of the SPU prepared at high temperature (>80°C) or prepolymer gels yielded by abnormal reaction. A small signal due to a phenyl carbon of biuret (Bi) linkage was observed even in a normally prepared SPU (polyetherurethane‐urea). Employing the phenyl carbon signals was advantageous for the determination of anomalous linkages because of their larger intensities.
Processing studies and thermal stability of addition polymers from 1,4,5,8‐tetrahydro‐1,4;5,8‐diepoxyanthracene and Bis‐dienes
Authors: Meador Mary Ann B. , Malarik Diane C. , Olshavsky Michael A.
Published: April 2003

1,4,5,8‐Tetrahydro‐1,4;5,8‐diepoxyanthracene reacts with various anthracene end‐capped polymide oligomers to form Diels‐Alder cycloaddition copolymers. The polymers are soluble in common organic solvents, and dehydrate thermally at temperatures of 300–350°C to give thermal oxidatively stable pentiptycene units along the polymer backbone. Because of their high softening points and good thermal oxidative stability, the polymers are candidates for matrix resins for high temperature composite applications. To assess their usefulness for such applications, several parameters have been studied affecting the properties of the final polymer. These parameters include varying the formulated molecular weight of the end‐capped prepolymers, and use of meta‐substituted aromatic diamine in place of some of the para‐substituted diamine. Processability of the resins was studied using rheometric spectrometry, and a processing scheme was devised. Finally, several formulations of neat resins were compression molded into coupons, and evaluated for longterm stability in air at 315 and 371°C. The best combination of good processability and thermal oxidative stability was obtained from polymers synthesized with small amounts of meta‐diamine substitution and higher formulated molecular weight prepolymers.
Poly(methylene sebacate): Synthesis and characterization
Authors: Cimecioglu A. L. , East G. C.
Published: April 2003

The synthesis of poly(methylene sebacate) was carried out via the reaction of cesium sebacate with bromochloromethane in N‐methylpyrrolidone over a range of temperatures (55–130°C). A number of polymers having limiting viscosity numbers in the range of 0.29–0.94 dL g−1 (CHCl3; 25°C) were characterized by elemental analyses, 1H‐ and 13C‐NMR, DSC, and GPC techniques. The polymerization was found to be very rapid at 100°C, being complete in ca. 15 min. and was relatively insensitive to the stoichiometric ratio of the monomers. As high molecular weight polymers were produced without the quantitative conversion of the reactants, the polymerization is considered to be occurring by an interfacial mechanism.
Chromatography of amphiphilic graft copolymers
Authors: Wesslén Bengt , Wesslén K. Bodil
Published: April 2003

Amphiphilic comb polymers were prepared through grafting poly(ethylene glycol) methyl ether (MPEG 2000) onto acrylic and methacrylic copolymers. The graft copolymers were purified from unreacted MPEG by partition chromatography on methanol pretreated fibrous cellulose using ethyl acetate and methanol as eluents. The separation was found to depend on the water contents of the cellulose and the eluents. It is proposed that one parameter of importance for the chromatographic separation is the formation of hydrated inverted micelles. The amphiphilic comb polymers were shown by gel chromatography on Sepharose to form high molecular weight aggregates in water. On addition of sodium lauryl sulphate or inorganic salts to the eluent at low ionic strengths these aggregates dissociated and were fractionated by the gel. It was also shown that on GPC in THF solution on Styragel columns the polymers exhibited apparent molecular weights equal or smaller than those of the corresponding backbones. This effect may be a consequence of the graft copolymers having relatively small hydrodynamic volumes, and this idea is supported by the fact that their intrinsic viscosities generally were lower than those of the backbones. However, adsorption on the Styragel columns also may be of importance.
Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. IV. Properties of SiO2–TiO2 oxide fibers from polytitanosiloxane
Authors: Gunji Takahiro , Nagao Yukinori , Misono Takahisa , Abe Yoshimoto
Published: April 2003

From polytitanosiloxanes (PTS), SiO2–TiO2 oxide fibers with fairly good tensile strength were prepared, and their mechanical and thermal properties were investigated. The precursor fibers PTS‐0.5 and PTS‐1.0 were obtained by dry spinning of a highly viscous PTS solution which were formed as the reaction mixture of silicic acid (SA) with bis(2,4‐pentanedionato)titanium diisopropoxide (PTP) in the molar ratios (SA/PTP) of 0.5 and 1.0. The precursor fibers PTS‐0.5 were too brittle to measure their tensile strength, whereas PTS‐1.0 and the heat‐treated fibers were found to have tensile strength of 130 (precursor), 540 (500°C), and 450 (900°C) MPa, respectively. Heat‐treatment of the fibers PTS‐1.0 at above 1000°C forms anatase and rutile of titanium dioxide. The crystallization is resulted from the unreacted PTP which is not incorporated into the polymer network.
Nature of plasma‐induced radicals on crosslinked methacrylic polymers studied by electron spin resonance
Authors: Kuzuya Masayuki , Ishikawa Masanao , Noguchi Akihiro , Sawada Kazuhiko , Kondo Shin‐Ichi
Published: April 2003

Plasma‐induced radicals of several crosslinked methacrylic polymers such as poly(ethyleneglycol dimethacrylate) (PEDMA), poly(2‐hydroxyethylmethacrylate) (PHEMA) and polymethacrylamide (PMAAm) were studied by electron spin resonance (ESR). The observed ESR spectra did not exhibit a drastic difference in the spectral feature caused by the effect of crosslinking. All the spectral features can be represented by “nine‐line spectra” as a major spectral component similar to those of linear methacrylic polymers such as polymethacrylic acid (PMAA). A pronounced effect of crosslinking, however, has emerged on the specific formation in the radical structure and the stability of radicals formed, especially in PEDMA. The formation of fewer kinds of radical in PEDMA is apparently caused by the high degree of crosslinking which leads to a suppression of the occurrence of depolymerization on plasma irradiation.
Synthesis of aromatic polyethers by scholl reaction. VIII. On the polymerizability of 1,5‐bis(phenoxy)pentanes and 1,5‐bis(phenylthio)pentane
Authors: Percec Virgil , Wang James H. , Oishi Yoshi
Published: April 2003

The synthesis and the oxidative polymerization of 1,5‐bis(phenoxy)pentane, 1,5‐bis(phenoxy)pentane substituted with various electron‐donating groups, and 1,5‐bis(phenylthio)pentane is described. The polymers derived from methyl substituted 1,5‐bis(phenoxy)pentane monomers contain diphenyl methane, 1,2‐diphenylethane, and benzyl chloride structural units. The mechanism for the generation of these structural units is presented. It consists of the proton transfer reactions from the cation‐radical propagating species and subsequent reactions of the resulting benzyl radicals. The polymerizability of monomers with 1,5‐pentanedioxy group is lower than that of the monomers with diphenyl sulfone group. This dissimilarity was attributed to the difference between both the reactivity and the concentration of the cation‐radical propagating species resulted from these two classes of monomers.
Synthesis of multifunctional copolyamides with both cyclobutane ring and conjugated double bond in the main chain
Authors: Nishikubo Tadatomi , Iizawa Takashi , Shiozaki Yasunori , Koito Tsutomu
Published: April 2003

Copolyamides 1,9, and 10 containing both cyclobutane rings and conjugated double bonds in the main chain were synthesized by polycondensation of 1,3‐di(4‐piperidyl)propane (DPP) with β‐truxinate (β‐BNPT), with di(p‐nitrophenyl) p‐phenylenebis(acrylate) (p‐NPDA), with di(p‐nitrophenyl) p‐phenylenebis (α‐cyanoacrylate) (p‐NPDC), and with di(p‐nitrophenyl) p‐phenylenebis (α‐cyanobutadienecarboxylate) (p‐NPDCB) in aprotic polar solvents at room temperature, respectively. Reduced viscosity of copolyamide 1 was strongly affected by the reaction process, the molar ratio of two ester monomers, and reaction time. The copolyamide 1 with the highest viscosity was prepared by the reaction of DPP with 70–50 mol % of β‐BNPT for 24 h followed by the polycondensation of the resulting precursor with 30–50 mol % of p‐NPDA for 24–96 h. Although copolyamide 9 with high viscosity was not obtained by the polycondensation with β‐BNPT and p‐NPDC, copolyamide 10 with relatively high viscosity was obtained by the reaction with β‐BNPT and p‐NPDCB under the same conditions applied for the synthesis of copolyamide 1. The solubility of copolyamides 1,9, and 10 decreased gradually with increasing p‐NPDA, p‐NPDC, and p‐NPDCB units in the copolymers. Furthermore, it was found that copolyamides 1,9, and 10 crosslinked upon irradiation with 313 or 365 nm light, and these copolyamides also decomposed upon irradiation with 254 nm light. That is, the photochemical property of these copolyamides can be controlled by the selection of wavelength of the photoirradiation.
Silazane oligomers and polymers with phenylene spacing groups
Authors: Kulpinski J. , Lasocki Z.
Published: April 2003

Heating N,N′‐diphenyltetramethylcyclodisilazane with phenylenediamines in the melt at temperatures over 200°C was found to yield oligomers composed of linear and cyclic disilazane units interlinked by phenylene groups. Increasing the temperature of the reaction of meta‐ and particularly para‐phenylenediamine over 300°C promotes formation of crosslinked, infusible, and insoluble polymeric material. The succeeding steps of growth of the polymer molecules, which include cyclodisilazane ring cleavage, transaminations, and recyclizations, have been studied by elemental and spectroscopic analyses of the intermediate low molecular and oligomeric species in the distillable and nonvolatile products of the reactions.
Fast atom bombardment mass spectrometric analysis of the partial ozonolysis products of poly(isoprene) and poly(chloroprene)
Authors: Montaudo Giorgio , Scamporrino Emilio , Vitalini Daniele , Rapisardi Roberto
Published: April 2003

The low molecular weight compounds formed by partial ozonolysis of poly(isoprene) and poly(chloroprene) were analyzed by fast atom bombardment mass spectrometry (FABMS). In the poly(chloroprene) case, the ozonized mixtures were treated with piperidine before the MS analysis to transform in amide end groups the reactive acyl chlorides formed by the cleavage of double bonds along the main chain. Only one family of compounds having carboxyl and ketone or carboxyl and amide end groups were obtained from the ozonolysis of poly(isoprene) and poly(chloroprene), respectively. The assigned structures were confirmed by FAB‐MS analysis of the GPC separation fractions [poly(chloroprene)] or by FAB‐MS of the KOH‐doped ozonolysis mixtures [poly(isoprene)]. It has been also ascertained, by GPC experiments, that poly(chloroprene) decomposes more rapidly than poly(isoprene) and poly(butadiene).
Evaluation of furfurylamines as curing agents for epoxy resins
Authors: He Xiaodun , Conner Anthony H. , Koutsky James A.
Published: April 2003

Epoxy resin adhesives are widely used because of their strength, versatility, and ability to bond a variety of substrates. Furfurylamines represent a potential, new class of epoxy curing agents. Furfuryl amine (FA), tetrahydrofurfuryl amine (THFA), and 5,5′‐methylenebis‐2‐furanmethanamine (DFA) were studied as possible epoxy curing agents. The utility of FA and THFA are limited by their volatility at the temperatures needed to effect cure of diglycidyl‐ether of bisphenol A (DGEBA) based epoxy resins. DFA is a very effective epoxy curing agent with the ability to cure DGEBA at rates similar to that of standard epoxy curing agents such as liethylenetriamine.
Organoborazines. III. Homo‐ and copolymerization of p‐vinylphenylcyclotriborazines
Authors: Jackson Logan A. , Allen Christopher W.
Published: April 2003

The polymerization and copolymerization with styrene of a series of unsymmetrically B‐p‐vinylphenyl‐N‐methyl and N‐phenyl borazines [R3(R2)2B3N3(R1)3; R1 = methyl, phenyl, R2 = methyl phenyl, R3 = p‐vinylphenyl] has been studied. The polymerization of these monomers yielded both tractable and crosslinked materials. The polymers obtained were characterized by 1H‐ and 13C‐NMR spectroscopy, elemental analysis, gel permeation chromatography, and thermogravimeteric analysis. The reactivity ratios for the copolymerization reaction were calculated by the Mortimer‐Tidwell method.
Laser‐Initiated copolymerization ofN‐vinylpyrrolidone with maleic anhydride and maleimide
Authors: Sadhir R. K. , Smith J. D. B.
Published: April 2003

This article describes the laser‐initiated copolymerization ofN‐vinylpyrrolidone with maleic anhydride and maleimide via charge transfer complexes. The dependence of copolymer yield on the molar ratios of the monomers in the feed and on the irradiation time is described. Based on the ultraviolet and infrared spectroscopy, and chemical analysis results, a tentative mechanism of polymerization is suggested. The rates of polymerization of several monomer systems are compared. TheN‐vinylpyrrolidone and maleimide system shows the highest rate of polymerization.
Preparation of sulfonyl aromatic polyamides and copolyamides by means of di‐ or triphenyl phosphite
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Huang Ching‐Jung
Published: April 2003

High molecular‐weight aromatic polyamides were obtained by the direct polycondensation reaction of 4,4′‐sulfonyldibenzoic acid (SDA) with various aromatic diamines, by means of di‐ (DPP) or triphenyl phosphite (TPP) in N‐methyl‐2‐pyrrolidone (NMP)‐pyridine solution containing metal salts such as LiCl and CaCl2. The factors affecting the phosphorylation reaction were investigated, in particular for the reaction of SDA and 4,4′‐oxydianiline (ODA). For the polymerization by means of TPP, the optimum conditions are: molar ratio of TPP to diacid, higher than 2.3; concentration of metal salts, 8 wt % LiCl or 6 wt % CaCl2; reaction temperature, 100°C; and monomer concentration, 0.4 mol/L. For the polymerization by means of DPP, the optimum conditions are: molar ratio of DPP to diacid, higher than 3.8; concentration of metal salts of 8 wt % LiCl or 10 wt % CaCl2; reaction temperature, 110°C; and monomer concentration, 0.4 mol/L. Copolyamides were also prepared from the reaction of ODA with the mixed diacids of SDA and other dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6‐naphthalene dicarboxylic acid by using TPP and DPP as the condensing agents.
Accessibility of the gel phase in macroporous network polymers: A comparison of the fluorescence probe and inverse steric exclusion chromatography techniques
Authors: Jerábek K. , Shea K. J. , Sasaki D. Y. , Stoddard G. J.
Published: April 2003

Two independent methods of analysis were employed to evaluate accessibility of the gel phase in macroporous network polymers. Fluorescence probes, covalented incorporated into the gel during polymerization, can provide a qualitative assessment of accessible surface area from an analysis of the solvatochromic shift of fluorescence emission. These findings are corroborated by inverse steric exclusion chromatography (ISEC). The data permits quantification of the polymers surface character in the solvated state. The results call attention to the inadequacy of dry surface area technique (e.g., BET analysis) in providing information of this type.
Catalytic aminolysis of acrylic copolymers in solution and in the melt. I. Mechanism and kinetics
Authors: Hu G. H. , Holl Y. , Lambla M.
Published: April 2003

The aminolysis of poly(styrene‐co‐methyl acrylate) (SMA) by octadecylamine was studied in solution and in the melt at temperatures around 200°C. This reaction is rather slow, so several types of catalysts were tested to accelerate it. The most efficient is 2‐pyridone, a compound in tautomeric equilibrium with 2‐hydroxypyridine. A mechanism of the catalytic reaction is proposed whereby the tautomeric nature of the catalyst plays a key role in a very important step of the reaction, namely the proton transfer. This mechanism is confirmed by the kinetic data determined in a 1,2,4‐trichlorobenzene solution and in the melt. In addition, it was found that the kinetic data obtained in both media are very close, indicating no significant difference of local polarity in the two reaction media. Data also show only a minor effect due to difference in viscosity. Finally, the question of the homogeneity of the molten medium is discussed.
Catalytic aminolysis of acrylic copolymers in solution and in the melt. II. Comparison between styrenic and ethylenic copolymers
Authors: Hu G. H. , Lorek S. , Holl Y. , Lambla M.
Published: April 2003

The aminolysis of poly(styrene‐co‐methyl acrylate) (SMA) by octadecylamine in solution and in the melt has been reported in Part I. We now have studied the aminolysis of poly(ethylene‐co‐methyl acrylate) (EMA) with the same amine in the melt and compared the two sets of data in this paper. With EMA, the data confirmed and precised the catalytic mechanism proposed in Part I. The best tautomeric catalysts are the ones which form an eight‐atom ring structure with the ester and amine groups. With EMA aminolysis is faster than with SMA because of the steric hindrance of phenyl groups in SMA. But EMA aminolysis remains a rather slow reaction. In a corotating twin‐screw extruder the conversion was only around 4% at 220°C with a mean residence time of 150 s. It was also shown that the EMA/octadecylamine/catalyst system, like the SMA system, is homogeneous in the molten state at temperatures around 200°C.
Poly(N‐acylethylenimine) copolymers containing pendant pentamethyldisiloxanyl groups. I. Synthesis
Authors: Cai Gangfeng , Litt Morton H.
Published: April 2003

10‐(Pentamethyl disiloxanyl) decyl oxazoline (Si) was synthesized. It was copolymerized with either undecyl (U) or nonyl (N) oxazolines using methyl 4‐nitrobenzenesulfonate as initiator. Two series of random poly(N‐acylethylenimine) copolymers, U/Si and N/Si, were synthesized over the whole composition range of Si monomer with a total degree of polymerization of about 100. Narrow molecular weight distributions were obtained. At a monomer to initator ratio of about 1060, the final degree of polymerization was 374 with a polydispersity index of 1.93. This shows the effect of chain transfer in this system.
Poly(N‐acylethylenimine) copolymers containing pendant pentamethyldisiloxanyl groups. II. Thermal behavior and x‐ray diffraction study
Authors: Cai Gangfeng , Litt Morton H.
Published: April 2003

Two series of random copolymers of 10‐(pentamethyl disiloxanyl) decyl oxazoline (Si) with undecyl (U) (four copolymer compositions) and nonyl (N) (eight copolymer compositions) oxazolines over the whole composition range, with a total degree of polymerization of about 100, were studied by DSC and wide angle X‐ray diffraction. All the polymers are crystalline. For the N/Si copolymers, the melting points, normalized ΔH and ΔS of fusion are almost constant in a broad range of copolymer composition from 10 to 65 mol % of Si. The rationale for this behavior is that the copolymers crystallize two dimensionally, with the crystalline polymethylene plates separated by the bulky flexible pentamethyl disiloxanyl (P) groups. In this range, increasing Si only increases the distance between the plates. With more than 65 mol % Si, the bulky P groups interfere with the packing of the alkyl chains and change the crystallization behavior; the polymers show disordered packing as demonstrated by their X‐ray patterns and extremely low ΔH. In the U/Si copolymers, since the undecyl side chain has one more carbon than the decyl group to which the P group is attached, the P groups interfere much more strongly with the packing of the side chains than in the N/Si polymers. The copolymer melting points uniformly decrease as the concentration of Si increases. The plateau on the plot of normalized ΔH versus polymer composition is only from 10 to 50 mol % of Si. The average long spacings of the annealed polymers increase linearly from 24 Å (N/Si polymers) or 28 Å (U/Si polymers) to 34.1 Å with the increase of Si up to 50%. With more than 50% Si, the polymers have an identical lamellar thicknesses of 34 Å, within the experimental error. Copolymers with less than 75 mol % of Si can crystallize from hexadecane solutions forming gels down to polymer concentrations of 2‐3 wt %. The long spacings of the gels are almost identical with those of the pure crystalline polymers and independent of the polymer/solvent ratios. When hexamethyl disiloxane is added to the solutions, it can intercalate and the resulting crystalline gels have long spacings larger than those found in the absence of siloxane.
Polymerization of vinylcyclohexane with ziegler–natta catalyst
Authors: Endo Kiyoshi , Otsu Takayuki
Published: April 2003

Polymerization of vinylcyclohexane (VCHA) with TiCl3–aluminum alkyl catalysts was investigated. The polymerization rate of VCHA was low due to the branch at the position adjacent to the reacting double bond. The effects of aluminum alkyl on the polymerization and monomer‐isomerization were observed; the polymer yield decreased in the following order: (CH3)3Al > (i–C4H9)3Al > (C2H5)3Al. Isomerization of VCHA was observed with the TiCl3–(i–C4H9)3Al and the TiCl3–(C2H5)3Al catalysts during the polymerization, while with the TiCl3–(CH3)3Al catalyst such isomerization was not observed. Monomer‐isomerization copolymerization of VCHA and trans‐2‐butene took place to give copolymers consisting of VCHA and 1‐butene units.
Particle nucleation and monomer partitioning in styrene O/W microemulsion polymerization
Authors: Guo J. S. , Sudol E. D. , Vanderhoff J. W. , El‐Aasser M. S.
Published: April 2003

Particle nucleation in the polymerization of styrene microemulsions was found to take place throughout the polymerization as indicated by measurements of the particle number as a function of conversion. A mechanism based on the nucleation in the microemulsion droplets was proposed to explain the experimental findings although homogeneous nucleation and coagulation during polymerization were not completely ruled out. A thermodynamic model was developed to simulate the partitioning of monomer in the different phases during polymerization. The model predicts that the oil cores of the microemulsion droplets were depleted early in the polymerization (4% conversion). Due to the high monomer/polymer swelling ratio of the polymer particles, most of the monomer resides in the polymer particles during polymerization. The termination of chain growth inside the polymer particles was attributed to the chain transfer reaction to monomer. The low n̄ (less than 0.5) of the microemulsion system was attributed to the fast exit of monomeric radicals.
Synthesis and characterization of bismaleimides from epoxy resins
Authors: Park Jung O. , Jang Sung H.
Published: April 2003

Novel bismaleimides (BMIs) were prepared from functional monomaleimides and diglycidyl ether of bisphenol A (DGEBA) and some of them were shown to have good processibility and improved water resistance while retaining characteristic thermal stability of polyimide. Functional monomaleimides were synthesized via the condensation reaction of maleic anhydride with either aminobenzoic acid or aminophenol. Crosslinking reaction of thus obtained BMIs was carried out with or without catalyst at the temperature range of 100–250°C. The type of the functional group species and their position in monomaleimides significantly affected the crosslinking behavior of the resulting BMIs and the thermal property of their crosslinked products. BMIs with meta linkage, obtained from meta monomaleimides, exhibited much faster thermal crosslinking behavior than corresponding para BMIs. When the molecular weight of BMI was larger, the crosslinking density became smaller and Tg was lower as expected, while the viscosity started to increase at a higher temperature. Glass transition temperatures of the crosslinked resins were in the range of 160–250°C and these resins showed excellent thermal stability up to 370°C.
Molecular weight distribution in emulsion polymerization. II. The copolymer case
Authors: Storti Giuseppe , Polotti Gianmarco , Canu Paolo , Morbidelli Massimo
Published: April 2003

A model for evaluating instantaneous degree of polymerization distribution and the chain composition distribution of copolymers produced in emulsion is developed. The approach adopted is based on the mathematics of Markov processes and represents an extension of the one developed for homopolymers in Part I. As in the homopolymer case, the main aspect of the theoretical treatment is the definition of the proper one step transition probability matrix through the so called subprocess‐main process procedure. The model accounts for monomolecular and bimolecular termination (both by combination and disproportionation) and, in principle, it can be applied to any number of reacting monomer species as well as to any number of active chains per particle. However, only the 0–1–2 and 0–1–2–3 emulsion copolymerization systems are discussed in detail. In the case of the chain composition distribution, the model allows the calculation of its moments only, through the method of the Generating Function associated with the probability density function. The expression obtained for the instantaneous probability density functions, as well as for the corresponding cumulative distributions, are all in explicit form and involve only algebraic operations among matrices. Efficient numerical procedure for their application are reported in the Appendix. Illustrative calculations are reported for a 0–1–2–3 copolymerization system, simulating the copolymer styrene–methylmethacrylate. The effect of the various termination mechanisms on the distribution of degrees of polymerization and on the first two moments of the chain composition distribution is discussed in detail. Finally, the three dimensional overall distribution function of both chain length and composition is shown under the assumption of Gaussian type chain composition distribution.
Template polymerization of N‐vinylimidazole along poly(methacrylic acid) in water. VI. Crosslinked PMAA as template
Authors: Van De Grampel H. T. , Santing A. G. M. , Tan Y. Y. , Challa G.
Published: April 2003

The effect of crosslinked poly(methacrylic acid) (c‐PMAA) on the polymerization of N‐vinylimidazole in aqueous solution was studied using UV, calorimetry, SEM, and TEM. It was established that synthetic lightly crosslinked PMAA samples behaved intermediate between rigid crosslinked PMAA particles functioning as microreactors, and linear conventional PMAA, where template and conventional polymerization in the surrounding solution are integrated. A modified calorimetric technique was used to measure monomer conversion, and to correct for the rapid adsorption process. Rate enhancements up to a factor of 4 were obtained for the c‐PMAA's, which were lower than those obtained for linear conventional PMAA, and which slightly decreased with increasing crosslink density of the samples. Template complexes possessed a platelet‐like morphology similar to template complexes obtained for linear PMAA.
Selective vinyl polymerization of 4‐vinyl‐1‐cyclohexene with ziegler–natta catalyst
Authors: Endo Kiyoshi , Fujii Kazuyoshi , Otsu Takayuki
Published: April 2003

The polymerization of 4‐vinyl‐1‐cyclohexene (4VCHE) with Ziegler–Natta catalysts was studied. The polymerization of 4VCHE by the vinyl group took place with TiCl3–aluminum alkyls catalysts, while vinylene group of 4VCHE did not participate in the reaction, but it affected the polymerization rate of 4VCHE. The effects of aluminum alkyl and type of TiCl3 on the polymerization were examined. The overall activation energy for the polymerization was estimated to be 41.9kJ/mol. Monomer‐isomerization copolymerization of 4VCHE and trans‐2‐butene occurred with the TiCl3‐(i‐C4H9)3Al catalyst to give copolymers consisting of 4VCHE and 1‐butene units.
Flame‐retardant modification of UV‐curable resins with monomers containing bromine and phosphorus
Authors: Guo Wenjeng
Published: April 2003

UV‐curable urethane acrylate resin and oligoester acrylate resin have been effectively flame retarded with vinyl‐type flame‐retardant monomers containing both bromine and phosphorus atoms. Thermogravimetric analysis indicates that the decomposition temperature of flame‐retardant monomer is more closely matched to the decomposition temperature of cured oligoester acrylate resin than to that of cured urethane acrylate resin. The efficiency of each flame‐retardant monomer in oligoester acrylate resin is higher than in urethane acrylate resin by a factor of ∼ 2.2. The individual and the combined effects of tribromophenyl acrylate and triphenyl phosphate on the oxygen index of UV curable urethane acrylate resin have been studied. The bromine phosphorus synergistic action of the two flame‐retardant components is evaluated quantitatively, and a maximum intermolecular bromine phosphorus synergism was observed in a flame‐retarded formulation containing a Br/P atom ratio of 2. In the three acrylic monomers containing both bromine and phosphorus atoms, the optimum intramolecular bromine phosphorus synergism was observed at a monomer also containing a Br/P atom ratio of 2.
Interpenetrating polymer networks of poly(carbonate‐urethane) and polyvinyl pyridine
Authors: Zhou Peiguang , Frisch Harry L. , Ghiradella H.
Published: April 2003

Simultaneous interpenetrating polymer networks (IPN's), pseudo IPN's, and liner blends of aliphatic poly(carbonate‐urethane) (PCU) and polyvinyl pyridine (PVP) have been prepared and characterized by DSC, DMA, and TEM. The full IPN's of PCU and PVP had a single phase morphology only above 50 wt % PCU, as determined by both DSC and DMA and confirmed by transmission electron microscopy (TEM). However, in both pseudo IPN's of PCU and PVP and in their linear blends there exist multiple glass transitions and melting points seen by DSC and DMA indicating phase incompatibility. The full IPN's exhibited superior ultimate mechanical properties and solvent resistance as compared to the pseudo IPN's, liner blends, and the pure crosslinked PCU and PVP networks.
Consistent values of rate parameters in free radical polymerization systems. II. Outstanding dilemmas and recommendations
Authors: Buback M. , Gilbert R. G. , Russell G. T. , Hill D. J. T. , Moad G. , O'Driscoll K. F. , Shen J. , Winnik M. A.
Published: April 2003

The problems of determining reliable, well‐characterized values of kinetic parameters in free‐radical polymerizations are discussed. The origins of the fact that experimental determinations of rate coefficients of ostensibly identical systems often result in quite different values being reported can be ascribed to subtle mechanistic assumptions made in data interpretation, which are considered in detail. A series of recommendations to assist in overcoming these problems, and to highlight their origins, are presented, with emphasis placed on new techniques including those employing laser photolysis and EPR.
The mechanism of core–shell inversion in two‐stage latexes
Authors: Lee Sharon , Rudin Alfred
Published: April 2003

In two‐stage latexes where the first polymer is more hydrophilic than the second, inversion of the core and shell can occur. The mechanism of core–shell inversion during the initial and final intervals of the second‐stage polymerization was investigated using model PMMA/PS systems. The phase behavior of polymer solutions intended to model the two‐stage system during the initial interval of the second stage polymerization has yielded some insight into the thermodynamics of phase inversion. If the second stage monomer dissolves first stage polymer, the latter will tend to precipitate at the water/monomer interface, particularly in the presence of surfactant. The energy of the oil/water interface is thereby reduced. In the final interval, when much of the second monomer has polymerized, phase mobility is crucial to the inversion process.
Effect of degradation on thermotropic cholesteric optical properties of (2‐hydroxypropyl) cellulose (HPC) esters
Authors: Rusig I. , Dedier J. , Filliatre C. , Godhino M. H. , Varichon L. , Sixou P.
Published: April 2003

Some esters of (2‐hydroxypropyl) cellulose have been prepared and studied. Their cholesteric properties change with ageing and may disappear. Accelerated aging has been performed in order to analyze degradation processes which are relevant to the scission of the polymeric main chain and to the hydrolysis of the ester bonds which are mainly due to traces of water. The necessity of carefully elaborate purification is highlighted.
Mechanistic studies of the oxidative coupling polymerization of phenols. VI. Comparison of reactivities of DMP, PPO‐dimer, and ‐trimer in the copper‐catalyzed oxidative coupling polymerization
Authors: Viersen F. J. , Renkema J. , Challa G. , Reedijk J.
Published: April 2003

In the oxidative coupling polymerization, catalyzed by copper‐amine complexes, the oxidation rates of 2,6‐dimethylphenol (DMP) and its CO‐coupled dimer [4‐(2′,6′‐dimethylphenoxy)‐2,6‐dimethylphenol] and trimer [4‐(‐4′‐(2″,6″‐dimethylphenoxy)‐2′,6′‐dimethylphenoxy))‐2,6‐dimethylphenol] have been determined. The DMP concentration dependence shows a Michaelis–Menten‐type behavior. On the other hand, the dimer and trimer showed a first‐order rate‐dependence in the respective phenol concentrations. This indicates that the slow reaction step, following an equilibrium complex formation between DMP and copper complex, is relatively fast for both the dimer and the trimer. Therefore, coordination of dimer or trimer to the copper complex appears to be rate‐determining. Furthermore, the dimer and trimer gave overall reaction rates approximately eight times higher than found for DMP. Following the Flory principle of equal reactivity for functional groups of oligomers in polycondensations, all PPO oligomers can be assumed to have equally high oxidation rates as the dimer and trimer. The yield of undesired DPQ side product is strongly reduced when starting with the dimer (0.18%), or trimer (0.17%), compared to 3.3% for DMP. This is not unexpected, since DPQ can only be formed from two monomeric DMP residues. In fact, using a 1/10 molar mixture of dimer/DMP already results in a DPQ yield of only 1.7%. Furthermore, when starting from DMP, it has been observed that DPQ was predominantly formed during the first 30% conversion. Starting from dimer (or trimer) DPQ was formed at an almost constant very low rate during the whole course of the reaction. From these experiments it can be concluded that the most important polymerization reaction involves oxidation of copper‐coordinated DMP anion to its corresponding cations, followed by coupling with a copper coordinated PPO chain.
Poly(1,3‐cyclohexadiene‐alt‐α‐fluoroacrylonitrile): Synthesis and structural analysis of a new alternating copolymer
Authors: Panchalingam V. , Reynolds John R.
Published: April 2003

Poly(1,3‐cyclohexadiene‐alt‐α‐fluoroacrylonitrile) [poly(1,3‐CHD/α‐FAN)], an alternating copolymer of α‐fluoroacrylonitrile and 1,3‐cyclohexadiene has been prepared in bulk using varied monomer feed ratios and AIBN as initiator at 65°C. Elemental and 1H‐NMR analyses indicate that the copolymer contains an equimolar composition of α‐FAN and 1,3‐CHD as observed for alternating copolymers with donor‐acceptor polymerizations. A 2‐D 1H‐COSY NMR experiment indicates that the copolymer contains 1,4‐linkages across the cyclohexene unit while more reliable 13C‐NMR spectra suggests the copolymer to contain both 1,2‐ and 1,4‐linkages. Poly(1,3‐CHD/α‐FAN) exhibits improved thermal stability relative to the alternating copolymer of 1,3‐CHD and α‐chloroacrylonitrile due to a higher resistance to HF elimination relative to HCl elimination.