bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of (o‐methylphenyl)acetylene and polymer characterization
Authors: Abe Yoshiharu , Masuda Toshio , Higashimura Toshinobu 
Published: April 2003

Abstract(o‐Methylphenyl)acetylene polymerized with high yields in the presence of W and Mo catalysts. W catalysts were more active than the corresponding Mo catalysts. The weight‐average molecular weight of the polymer formed with W(CO)6–CCl4–hv reached 8 × 105, being higher than the maximum value (ca. 2 × 105) for poly(phenylacetylene). The polymer had the structure \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} [{\rm CH} \hbox{=\hskip-1pt=} {\rm C}(o - {\rm CH}_3 {\rm C}_6 {\rm H}_4 )\rlap{--} ]_n $\end{document}. The stereochemical structure of the main chain could be determined by 13C‐NMR; the cis content varied in a range of 41–61% depending on the polymerization conditions. The present polymer was thermally more stable than poly(phenylacetylene) according to thermogravimetric analysis. Interestingly, this polymer possessed deeper color than poly(phenylacetylene), and showed a fairly strong absorption in the visible region.
The polymerization of phenylacetylene in carbon tetrachloride in the presence of light‐activated W(CO)6
Authors: Park J. S. , Serwon S. , Langner A. , Ehrlich P. 
Published: April 2003

AbstractA study of the apparent reaction rate constants of phenylacetylene polymerized in CCl4 in the presence of light‐activated W(CO)6 and of the molecular weight of the resulting polymer indicates that the propagating centers are conserved to high monomer conversions, though some chain transfer to monomer occurs, limiting molecular weights to about 100,000. Although solutions of the polymer are deep red in color, the molecular conformation is more coil‐like than rod‐like. The NMR spectra suggest that the steric purity of the polymer is limited, so that it can only be referred to as trans‐rich polyphenylacetylene, confirming other results on tungsten‐catalyzed polyphenylacetylene.
Preparation of polymandelide by reaction of α‐bromophenylacetic acid and triethylamine
Authors: Pinkus A. G. , Subramanyam Ravi , Clough Sandra L. , Lairmore Terry C. 
Published: April 2003

AbstractPolymandelide was prepared in 77% yield by reaction of α‐bromophenylacetic acid and triethylamine. The product was characterized by 1H‐ and 13C‐NMR and IR spectra and isolation and identification of mandelic acid from hydrolysis of the polymer. The NMR spectra indicate the presence of tacticity at CH in the polymer. Molecular weights were determined by GPC and viscosity measurements; n values of 12–20 are comparable to those reported for polymandelides prepared by other methods. The x‐ray powder diffraction pattern showed the product to be completely amorphous. Thermal decomposition was studied using DSC.
Synthesis and properties of an open‐chain polyimide from benzyloxyamine and terephthaloyl chloride
Authors: Kurita Keisuke , Yamakawa Masahiro , Iida Keiji , Susa Eiji , Koyama Yoshiyuki 
Published: April 2003

AbstractA procedure for synthesizing an open‐chain polyimide has been developed. O‐Substituted hydroxylamines were found to behave as difunctional nucleophiles in acylation under appropriate conditions, and thus the reaction of equimolar amounts of benzyloxyamine and terephthaloyl chloride gave rise to the corresponding novel type of polyimide, an open‐chain polyimide. The results of polymerization under various conditions indicated the reaction to proceed efficiently in N, N‐dimethylacetamide in the presence of an acid acceptor system composed of double the molar quantity of triethylamine and the molar quantity of pyridine to give the polyimide with a high molecular weight. In contrast to the conventional polyimides having cyclic imide structures, the resulting open‐chain polyimide exhibited remarkable solubility in common organic solvents and a low glass transition temperature.
Synthesis and characterization of electrically conducting polyaniline–TCNE complexes
Authors: Neoh K. G. , Kang E. T. , Khor S. H. , Tan K. L. 
Published: April 2003

AbstractPolyaniline–tetracyanoethylene (TCNE) complexes can be synthesized either from emeraldine base or emeraldine hydrochloride by a relatively simple method. The complexes demonstrate greater stability than the emeraldine hydrochloride at elevated temperatures and under high current densities. The electrical conductivity of the complexes synthesized from emeraldine base can be varied from < 10−6 to 0.2 S/cm by varying the amount of TCNE incorporated. The complexes synthesized from emeraldine hydrochloride are slightly more conductive than the starting emeraldine hydrochloride. In both types of complexes, it appears that electron transfer between the polyaniline and TCNE has occurred resulting in the formation of some positively charged polyaniline nitrogen and TCNE anions.
Copolymerization of styrene and methacrylic acid in concentrated emulsions
Authors: Ruckenstein Eli , Kim Kyu‐Jun 
Published: April 2003

AbstractCopolymerization of styrene and methacrylic acid was carried out by the concentrated emulsion polymerization method, using sodium dodecylsulfate and AIBN as emulsifier and initiator, respectively. Compared to conventional emulsion polymerization, a much smaller amount of water (5–25 vol %) is employed as the continuous phase and thus the loss of methacrylic acid, which is very soluble in water, is minimized. The concentrated emulsion, which has the appearance of a gel, was prepared at room temperature, and was polymerized at 40°C. The size of copolymer latexes is affected by the internal phase ratio, and was in the range of 0.2–0.3 μm in diameter. Potentiometric titration was used to determine the surface density of the carboxylic groups of the copolymer latexes and its dependence on the feed molar ratio of methyacrylic acid to styrene. NMR and IR spectroscopies have been employed to determined the composition of the copolymer latexes.
Acyloin condensation by polymer supported thiazolium salt: Relation between the catalytic activity and the degree of quarternization
Authors: Yamashita Keiji , Shimizu Yoshihiro , Tokuda Hiroyuki , Kuromiya Toshiaki , Tsuda Kazuichi 
Published: April 2003

AbstractThiazolium salt polymers were synthesized by the quarternization of thiazole polymers by alkyl halides. It was found that these polymers had high catalytic activities for the acyloin condensation of furfural. The catalytic activities of thiazolium salt polymers increased as the degree of quarternization decreased. This tendency was observed both in the polar solvents such as MeOH and in the nonpolar solvents such as dioxane. From the results of the acyloin condensation catalyzed by more hydrophobic polymer catalyst PTS+–St (which had styrene unit instead of free thiazole unit) and CnPTS+ (which had a long alkyl chain around the active site), it became clear that the hydrophobicity and the steric hindrance around the active site greatly affected the catalytic activity.
Cationic ring‐opening isomerization polymerization of spiro orthocarbonates initiated by carbon black
Authors: Tsubokawa Norio , Ohshima Shingo , Sone Yasuo , Endo Takeshi 
Published: April 2003

AbstractThe ring‐opening isomerization polymerization of spiro orthocarbonates (SOC), such as 2,8‐dimethyl‐1,5,7,11‐tetraoxaspiro[5.5]undecane (I), 8,10,19,20‐tetraoxaspiro[5.2.2.5.2.2]‐heneicosane‐2,4‐diene (II), and 8,10,19,20‐tetraoxaspiro[5.2.2.5.2.2]heneicosane (III), initiated by carbon black was investigated. No polymerization of SOC was initiated in the absence of carbon black. But in the presence of channel black having a carboxyl group, the polymerization of SOCs was initiated at 90–150°C to give the corresponding polyether carbonates. The initiating ability of carbon black increased with an increase in its carboxyl group content. Furnace black having no carboxyl group failed to initiate the polymerization. Based on these results, it was concluded that the carboxyl group on carbon black is capable of initiating the polymerization of SOC. During the polymerization, a part of the polymers formed was grafted onto carbon black surface via the termination of growing polymer chains. The percentage of grafting increased with an increase in conversion and reached about 55%. Furthermore, polyether carbonate‐grafted carbon black was found to produce a stable colloidal dispersion in chloroform. The mechanism of initiation and grafting were discussed.
Linear polymers for nonlinear optics. I. Polyacrylates bearing aminonitro‐stilbene and ‐azobenzene dyes
Authors: Robello Douglas R. 
Published: April 2003

AbstractThree acrylic monomers bearing 4′‐dialkylamino‐4‐nitro‐stilbene and ‐azobenzene dyes have been synthesized. The monomeric dyes were homopolymerized and copolymerized with methyl methacrylate using a free radical initiator to produce polymers useful for nonlinear optics. Comparison of the solubility and molecular weight distribution data between stilbene‐ and azobenzene‐containing polymers indicated that some crosslinking occurred during polymerization with the stilbene monomers, presumably through the internal double bond in the dye. The dye‐containing homopolymers exhibit liquid crystallinity. Some interaction among the pendant dyes was detected by visible spectroscopy.
Metallocene‐methylaluminoxane catalysts for olefin polymerization. V. Comparison of Cp2ZrCl2 and CpZrCl3
Authors: Chien James C. W. , Wang Bor‐Ping 
Published: April 2003

AbstractThe ethylene polymerization by Cp2ZrCl2/MAO (Cp = η5: cyclopentadienyl; MAO = methyl aluminoxane) and CpZrCl3/MAO have been studied. The MW and PD (= Mw/Mw) of polymers obtained after 2.5‐60 min are the same, which indicate short chain lifetime. The values of rate constants for Cp2ZrCl2 at 70°C are: kp = 168−1670 (M s)−1 and ktrA1 = 0.012‐0.81 s−1 depending upon [Zr] and [MAO,] ktrβ = 0.28 s−1, and ktrH = 0.2 M−1 torr−1/2 s−1. These chain transfer rate constant values are two to three orders of magnitude greater than the corresponding values found for MgCl2 supported titanium catalysts. One significant difference between the heterogeneous and homogeneous catalysts is that the former decays according to an apparent second order kinetics, whereas the latter decay is simple first order at 0°C and biphasic first order at higher temperatures. The productivity of the catalysts depends weekly on temperature while the MW decreases strongly with increase of temperature above 30°C. All the active species were formed upon mixing Cp2ZrCl2 with MAO while it took up to 20 min for the CpZnCl3/MAO system. The productivity of the former increase more strongly with the decrease of [Zr] than the latter. Otherwise, the two catalyst systems have all their kinetic parameters differing less than a factor of two.
A statistical model of free‐radical copolymerization/crosslinking reactions
Authors: Scranton Alec B. , Peppas Nikolaos A. 
Published: April 2003

AbstractA statistical model for network formation by the free‐radical copolymerization and crosslinking reaction with small crosslinker content is used to obtain expressions for structural averages as a function of reaction parameters. The analysis accounts for reaction features that are characteristic of free‐radical mechanisms and can be adapted to include cyclization, various modes of termination, and the gel effect. Profiles for structural averages such as the weight average molecular weight, the sol weight fraction, the molecular weight between crosslinks, and the number of elastically active network chains are obtained as functions of conversion.
Thermal properties of some fully aromatic thermotropic liquid crystal polyesters
Authors: Skovby Michael H. B. , Lessél Robert , Kops Jorgen 
Published: April 2003

AbstractWholly aromatic liquid crystalline main chain polyesters derived from terephthalic acid, phenyl‐ or (1‐phenylethyl)hydroquinone modified with either 3,4′‐ or 4,4′‐dicarboxydiphenylether and p‐hydroxybenzoic acid, have been prepared by acidolysis and thermally investigated. All prepared polyesters exhibit excellent thermal stability up to about 400°C, however, the (1‐phenylethyl)hydroquinone polyesters generally showed lower stability. Melting points could be decreased to around 200°C without any decrease in the thermal stability or the nematic range.
Living carbocationic polymerization. XXX. One‐pot synthesis of allyl‐terminated linear and tri‐arm star polyisobutylenes, and epoxy‐ and hydroxy‐telechelics therefrom
Authors: Iván Béla , Kennedy Joseph P. 
Published: April 2003

AbstractMono‐ and di‐ended linear and three‐arm star allyl‐telechelic polyisobutylenes, PIBA, APIBA and (where A = CH2CHCH2) have been prepared by a rapid economical one‐pot polymerization‐functionalization process. The process involves the living polymerization of isobutylene (IB) by mono‐, di‐, or tri‐functional initiating systems, specifically by allphatic and aromatic tert‐ester and ‐ether/TiCl4 combinations, followed by electrophilic functionalization of the living sites with allyl‐trimethylsilane (ATMS). Structural characterization by 1H‐NMR spectroscopy and end group titration with m‐chloroperbenzoic acid (m‐CPBA) indicate quantitative end allylation even with relatively slowly initiating systems like DiOAcTMH7/TiCl4. Detailed kinetic analysis of the latter system indicates, unexpetedly, cationation to be rate determining. Quantitative derivatizations of the allyl termini have yielded mono‐, di‐, and tri‐epoxy‐ and ‐hydroxy‐telechelic PIBs. Strong rubbery networks have been made by curing the epoxy‐telechelic PIBs with triethylene tetramine and by reacting the hydroxy‐telechelic PIBs with MDI.
Study of photopolymers. XXXIV. Etherification and esterification reactions of polymers with (o, m, or p)‐bromomethylnitrobenzene using the DBU method and the photochemical properties of the resulting polymers
Authors: Nishikubo Tadatomi , Iizawa Takashi , Takahashi Akira , Shimokawa Tsutomu 
Published: April 2003

AbstractPoly[4‐(4‐nitrobenzyloxy)styrene] was synthesized with a high degree of etherification by the reaction of poly(4‐hydroxystyrene) (PHST) with p‐bromomethylnitrobenzene (p‐BMNB) using 1,8‐diazabicyclo‐[5,4,0]‐7‐undecene (DBU) in hexamethylphosphoramide (HMPA). Poly[4‐(3‐nitrobenzyloxy)styrene] and poly[4‐(2‐nitrobenzyloxy)styrene] were also prepared with a high degree of etherification by the corresponding reaction with m‐ or o‐BMNBs. However, the degrees of etherification of PHST with these BMNBs were relatively low when the reactions were carried out in other aprotic polar solvents such as DMF, DMSO, and N‐methyl‐2‐pyrrolidone. On the other hand, poly(4‐introbenzyl methacrylate) (PPNBMA), poly(3‐nitrobenzyl methacrylate) (PMNBMA), and poly(2‐nitrobenzyl methacrylate) (PONBMA) were synthesized with a high degree of esterification by the reaction of poly(methacrylic acid) with the corresponding BMNBs using DBU in DMSO at 30°C. The photochemical properties of the resulting poly(nitrobenzyl methacrylate)s were examined, and it was found that the rates of photodecomposition of PPNBMA and PMNBMA were promoted by the addition of tributylamine and trifluoromethanesulfonic acid, respectively. However, the rate of photodecomposition of PONBMA was not affected by addition of the base or the acid.
Halato‐telechelic polymers. XV. Ionic cross‐interactions of immiscible telechelic polymers: A reversible pathway to block copolymer‐type materials
Authors: Horrion J. , Jérôme R. , Teyssié Ph. 
Published: April 2003

AbstractPhase separation of two immiscible polymer blends can be controlled by ionic cross‐interactions of the end‐groups as promoted by proton transfer from acid end‐groups of polymer PA to aliphatic tert‐amine end‐groups of PB. IR spectroscopy supports the occurrence of proton transfer with formation of ammonium carboxylate ion pairs that influences the solution behavior of the blends. Optical microscopy illustrates the opportunity to get finely dispersed blends at a scale of ca. 0.2 μm depending on nature, molecular weight, and functionality of the immiscible polymers and strength of the ion pairs. Tg measurements are in agreement with the general pattern reported for multiphase block polymers, and give consistency to an analogy between finely phase separated blends of acid and tert‐amine telechelic polymers and related block polymers.
Surface modification of polymers. V. Biomaterial applications
Authors: Allmér Klas , Hilborn J. , Larsson Per H. , Hult A. , Rånby B. 
Published: April 2003

AbstractPolyethylene films were surface grafted with glycidyl methacrylate (GMA) by UV irradiating the film for 5 min together with benzophenone. Poly(ethylene glycol) (PEG) was attached to the grafted surface through reaction with the epoxy groups. This yielded a surface which consisted of 95% PEG as measured with ESCA. The adsorption of human transferrin onto this film was significantly reduced as compared with a pure polyethylene film. Heparin was also reacted with a GMA grafted PE surface. ESCA showed that heparin was grafted to the surface, and in vitro blood clotting tests on the heparinized PE surface showed a reduced thrombus formation. GMA grafted polystyrene wells were reacted with carbohydrazide, to the formed carbohydrazide surface a rabbit antibody raised against mouse urinary protein (RaMUP) was covalently coupled. The RaMUP coupled surfaces was used in the detection of mouse urinary protein (MUP) at low concentrations (ca. 1 ng/mL) with an ELISA technique.
Oxidation of polyethylene surfaces by remote plasma discharge: A comparison study with alternative oxidation methods
Authors: Foerch Renate , McIntyre N. S. , Hunter D. H. 
Published: April 2003

AbstractThe reaction rates and products of remote oxygen plasma treatment, corona discharge, and ozone treatment of high and low density polyethylenes have been examined using x‐ray photoelectron spectroscopy. The oxygen uptake by remote plasma treatment was faster than that of other surface treatments using excited oxygen species. A steady state concentration of 18 ± 1% oxygen can be attained within 1 s of exposure in the remote plasma.
Preparation of a thermally phase‐separating copolymer, poly(N‐isopropylacrylamide‐co‐N‐acryloxysuccinimide), with a controlled number of active esters per polymer chain
Authors: Yang Heung Joon , Cole Carole‐Ann , Monji Nobuo , Hoffman Allan S. 
Published: April 2003

AbstractN‐isopropylacrylamide and N‐acryloxysuccinimide have been copolymerized in various mixtures of terrahydrofuran and toluene using azobisisobutyronitrile as initiator. Polymerization has been conducted for 24 h at 50°C under a slightly positive pressure of nitrogen. The copolymers were assayed for active ester content by measuring the UV absorbance (259 nm) of N‐hydroxysuccinimide anion, generated by reacting the copolymers with N‐isopropylamine in dimethylformamide and dissolving the resulting mixture in 0.1M HEPES buffer, pH 7.5. The molecular weight and its distribution have been estimated by gel permeation chromatography. The active ester content was found to be equivalent to the comonomer feed ratio, and the major factor controlling the molecular weight was the ratio of tetrahydrofuran to toluene. Thus, the number of active esters per polymer chain could be controlled by adjustment of the comonomer feed ratio and the ratio of tetrahydrofuran to toluene. Monomer reactivity ratios for copolymerization of N‐isopropylacrylamide with N‐acryloxysuccinimide were also estimated. These copolymers are useful for immobilizing binding ligands such as antibodies for subsequent thermally induced precipitation immunoassays and bioseparation processes.
Thermal decomposition of poly(2‐vinylpyridine): Effect of complexation with copper chloride
Authors: Lyons A. M. , Pearce E. M. , Mujsce A. M. 
Published: April 2003

AbstractThe thermal decomposition of complexes between poly(2‐vinylpyridine) (P2VPy) and copper chloride was investigated by several techniques, including thermogravimetric analysis and mass spectrometry. P2VPy was selected as the host polymer for two reasons: its ability to form complexes with copper compounds which are soluble in high concentrations, and because it forms essentially no char upon pyrolysis.The decomposition mechanism of P2VPy changes significantly upon complexation with copper compounds. P2VPy was initially thought to be an ideal ligand for the pyrolytic formation of pure copper owing to its low carbon yield upon thermal decomposition. The presence of copper chloride during polymer decomposition alters the decomposition mechanism of the polymer and accounts for significant yields of carbonaceous char. The magnitude of this effect is dependent upon the quantity of copper present. Polymer char yields as high as 41 wt% have been obtained when each pyridine moiety is complexed by CuCl2. Studies based on the model compound Cu(2‐picoline)2Cl2 indicate that the diffusion length of released volatiles plays a significant role in the observed decomposition mechanisms.
New pellicular ion exchangers by grafting onto polypropylene beads. I. Synthesis and characterization
Authors: Polednick C. , Widdecke H. , Bodrero S. , Revillon A. , Guyot A. 
Published: April 2003

AbstractPellicular ion exchangers are obtained by grafting styrene or vinyl benzyl chloride onto commercial polypropylene (PP) beads (280 μm) previously peroxidized by an air‐ozone mixture. Appropriate chemical modification of the grafted homopolymer follows to provide supported sulfonic acids of improved accessibility. The amount of grafted monomers has been varied from 0.3 to 30 wt %. Ion exchange capacities up to 2 meq H+/g were obtained. The thickness of the sulfonated grafted shell onto the polypropylene beads after swelling in water can exceed 200 μm.
Superactive and stereospecific catalysts. IV. Influence of structure of esters on MgCl2 supported olefin polymerization catalysts
Authors: Chien James C. W. , Hu Youliang , Vizzini James C. 
Published: April 2003

AbstractCH‐type catalysts were prepared by reacting MgCl2 · ROH, where ROH is 2‐ethyl hexanol (EH), (R)‐2‐octanol (R‐20), and (S)‐2‐octanol (S‐20), with TiCl4 in the presence of di‐i‐butyl phthalate (BP), di‐i‐butyl terephthalate (BT), (‐)‐dimenthyl phthalate (MP), or (‐)‐dimenthyl terephthalate (MT). The MT catalysts were found to incorporate 8.9 to 13% Ti whereas the BP catalysts contain only 1.9 to 2.6% Ti. Comparison of the CH(EH, BP) and CH(EH, MT) catalysts showed that they have about equal number of isospecific active sites per gram of catalyst and the same rate constants of propagation for their nonspecific sites, however, the isospecific sites in the latter are less active by comparison. Consequently, the CH(EH, BP) catalysts is five times more active than the CH(EH, MT) catalysts and produces polypropylene which is 97% isotactic (reflux n‐heptane insoluble) as compared to 84.7% for the latter. The catalysts derived from 2‐octanols are much less active than the corresponding catalysts prepared with 2‐ethyl hexanol due to lack of reactivity with phthalic anhydride which permits excessive incorporation of TiCl4 to form nonstereospecific catalytic sites as well as inactive Ti species.