bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpolymer complex formation between helical poly(L‐proline) and random‐coil poly(methacrylic acid) through hydrogen bonding
Authors: Park Soon Moon , Jeon Seung Ho , Ree Taikyue
Published: April 2003

Interpolymer complex formation between poly(L‐proline) (PLP) with helical structure and poly(methacrylic acid) (PMAA) with random‐coil structure through hydrogen bonding in aqueous medium has been studied by several experimental techniques, e.g., viscometry, turbidimetry, potentiometry, conductometry, scanning electron microscopy, and x‐ray diffraction methods.

The decreases in reduced viscosity of the solution on addition of an increasing quantity of PLP to a constant amount of PMAA reveals the formation of a complex between PLP and PMAA. The minimum in reduced viscosity at a unit‐mole ratio [PLP]/[PMAA] = 1.0 suggests a 1 : 1 complex formation. A distinct change in the curves for turbidity, pH, and conductance versus [PLP]/[PMAA] supports this conclusion. A scanning electron micrograph for the 1 : 1 PLP–PMAA complexes shows that the PLP/PMAA complex has the shape of entangled long fibers. An x‐ray diffraction pattern for the PLP/PMAA complexes gives no diffraction patterns which appear in pure PLP, indicating the destruction of the helical structure of PLP due to the interpolymer complexation. Mixtures of PMAA with poly(γ‐hydroxy‐L‐proline) (PHLP) which has a similar conformation as PLP, but involves intra‐ or intermolecular hydrogen bonds, has also been investigated by vicometry measurements. The reduced viscosity of a solution of the mixed polymers increases with increasing [PHLP], indicating no complex formation. All the results reveal that the magnitude and the nature of the forces acting in the polymers play an important role in interpolymer complexation.
Cyclodehydration reaction of polyhydrazides. III. Influence of the sample history
Authors: Gebben B. , Rolevink E. , Mulder M. H. V. , Smolders C. A.
Published: April 2003

The influence of preparation history upon the thermal cyclodehydration reaction of polyhydrazide samples has been investigated. Solid polyhydrazide samples were prepared from DMSO solutions using the phase‐inversion technique. Significant differences in conversion rates were observed between samples prepared by nonsolvent immersion precipitation and by evaporation of solvent. It appeared that contact with the nonsolvent water during the sample preparation process has considerable influence on the conversion rate. Not only does the immersion in and washing with water lead to a better removal of the solvent also the pH of the water determines the rate of conversion. A distinct change in the conversion rate is found for washing water at a pH of 7. Basic washing solutions showing lower conversion rates than acid ones. A mechanism explaining these phenomena is proposed.
Thermoplasticization of wood. II. Cyanoethylation
Authors: Hon David N.‐S. , Luis Josefina M. San
Published: April 2003

Cyanoethylation was attempted to convert wood into thermoplastic material as a means to utilize low quality wood species as well as wood waste materials. Cyanoethylation reaction was conducted with control of the alkalinity of the reaction media, reaction temperature and time, and wood‐to‐acrylonitrile ratio. Cyanoethylated wood was purified and its nitrogen content and weight gain were determined. Fourier transform infrared (FTIR) spectroscopy was used to monitor the absorption peak of cyano group. Thermoproperties of cyanoethylated wood were analyzed by means of a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). Reaction mechanisms and chemistry influencing the thermoproperties of cyanoethylated wood were discussed.
Thermal stability and composition of the amylose–iodine complex
Authors: Fonslick Janée , Khan Arshad
Published: April 2003

Amylose–iodine blue complex (absorbance band at 615 nm) was studied at different temperatures to examine the thermal stability and composition of the complex. Our direct experiment with amylose–iodine complex for composition determination suggests that with every 2.75 glucose units of amylose helix there is an iodine unit involved. The average I—I distance in the complex is found to be 3.0 Å, which is in excellent agreement with the value obtained from x‐ray diffraction study of model compounds (3.1 Å). As the temperature increases above 15°C, the observed decrease in concentration of the complex is primarily due to dissociation of iodine from the amylose helix.
Aspects of the radiation‐induced polymerization of 2‐vinyl anthraquinone
Authors: Gradwell A. J. , Guthrie J. T. , Webber S. E.
Published: April 2003

2‐Vinyl anthraquinone has been polymerized, via radiation‐induced initiation, in dimethyl‐sulphoxide and in dichloromethane. Solvent to monomer ratios of 1 : 0.030 to 1 : 0.0167 mol have been examined for dose rates in the range 0.035 to 0.129 Gy s−1and exposure times in the range 1.44 × 104to 4.32 × 106s. Rates of polymerization were found to lie in the range from 2.4 × 10−8to 1.92 × 10−6mol L−1s−1. Values for the chain transfer constant to dimethyl‐sulphoxide and to dichloromethane have been calculated. In addition, values of the kinetic ratiok/kt, for the polymerization of 2‐vinyl anthraquinone have been estimated. The dependence ofRpon the monomer concentration and on the radiation intensity have been shown to be in broad agreement with a simplified steady‐state kinetic scheme. A value ofG(radical) for 2‐vinyl anthraquinone was obtained via electron spin resonance studies, and shown to be 0.24. ThisG(radical) value and those obtained indirectly from kinetic data are discussed in relation to the molar mass values obtained from the poly(2‐vinyl anthraquinone) products.
Synthesis of poly(dipeptide)s on the surface of functional micelle and reversed micelle
Authors: Hanabusa Kenji , Ye Xuanjing , Kurose Akio , Shirai Hirofusa , Hayakawa Tadao , Hojo Nobumasa
Published: April 2003

Amphiphilic active 4‐dodecanoyl‐2‐nitrophenyl esters of dipeptide containing β‐alanine (1–5) were prepared and their polycondensation was studied in detail. The critical micelle concentrations of the active esters 1–5 were determined in water by the dye method and the apparent mean aggregation number of reversed micelles formed by model compound 6 was determined by the osmotic method. The results of polycondensation can be explained by assuming that aggregations such as micelle and reversed micelle play an important role in polycondensation. The obtained new poly(dipeptide)s were examined by IR, 1H NMR, x‐ray diffraction, and circular dichroism spectra.
Mechanism of alternating copolymerization of 4‐hydroxy‐4′‐vinylbiphenyl with α‐chloromaleic anhydride
Authors: Inoue Kenzo , Kaku Hisanori , Hayashi Hirokazu , Tanigaki Teiichi
Published: April 2003

The copolymerization of 4‐hydroxy‐4′‐vinylbiphenyl (HVB) with α‐chloromaleic anhydride (CMAn) was investigated in THF, 1,4‐dioxane, and acetonitrile. The formation of the 1:1 charge transfer complex between HVB and CMAn was confirmed spectroscopically, and the corresponding equilibrium constant (Keq) was determined as follows: Keq = 0.19, 0.11, and 0.058 mol/L in THF, 1,4‐dioxane, and CH3CN, respectively. The copolymer composition is affected by the solvent, i.e., the content of HVB in the copolymer obtained in THF or 1,4‐dioxane is lower than 50 mol % whereas the copolymer obtained in CH3CN has excess of HVB units. The maximum rate of copolymerization was observed at a 1:1 initial comonomer mole ratio, irrespective of the solvent polarity. Plots of Rp/[HVB] vs. [HVB] gave a straight line with a slope and an intercept for the copolymerization in THF whereas a straight line in CH3CN has no slope. On the basis of these results and 13C‐NMR spectra of the copolymers, the mechanism of the predominant formation of alternating copolymers is discussed.
Two‐dimensional NMR spectra of poly(N‐vinylcarbazole)
Authors: Natansohn Almeria
Published: April 2003

Two‐dimensional NMR spectra of commercially available poly(N‐vinylcarabazole) are presented and analyzed. Complete assignments for the aromatic region of the carbon spectrum are made using the edited spectrum and literature references for model compounds. The proton spectrum is assigned from its correlations with the carbon spectrum and with a J‐correlated two‐dimensional spectrum. One of the protons (number 1) is shifted to rather unusual high fields by the stacked structure of the carbazole rings, independent on the polymer tacticity. From the aliphatic carbon spectrum a meso probability of 0.45 is estimated for the commercial polymer, and another J‐correlated two‐dimensional spectrum helps assigning the triad and tetrad splittings in the aliphatic proton spectrum.
Polymerization of (o‐methylphenyl)acetylene and polymer characterization
Authors: Abe Yoshiharu , Masuda Toshio , Higashimura Toshinobu
Published: April 2003

(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

A 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

Polymandelide 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

A 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

Polyaniline–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

Copolymerization 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

Thiazolium 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

The 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

Three 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

The 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

A 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

Wholly 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

Mono‐ 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

Poly[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

Phase 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

Polyethylene 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

The 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

N‐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

The 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

Pellicular 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

CH‐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.
Radical copolymerization of 3‐tri‐n‐butylstannylstyrene with several vinyl monomers
Authors: Al‐Diab Salem S. S. , Suh Hwan‐Kyu , Mark James E. , Zimmer Hans
Published: April 2003

The free radical homopolymerization and copolymerization of 3‐tri‐n‐butylstannylstyrene (3‐BTS) with styrene (ST), ethyl acrylate (EA), methyl methacrylate (MMA), vinyl acetate (VA), and acrylonitrile (AN) were carried out using 2,2′‐azobisisobutyronitrile (AIBN) at 60°C. It was found that the yield of conversion to poly(3‐BTS) increased with the molar ratio of initiator to monomer as well as with polymerization time. The conversion at equilibrium after 50 h was about 40%. The compositions of copolymer samples were determined from elemental analyses. Monomer reactivity ratio and Q‐e values were calculated. The copolymers of 3‐BTS‐MMA and 3‐BTS‐AN were found to be alternating. The copolymers of 3‐BTS with MMA, EA and AN were not soluble in any of a large number of organic solvents tested. The insolubility is believed to be due to formation of intermolecular coordination among the tributylstannyl moiety and the carbonyl or cyano groups of the polymer. These copolymers, however, were “soluble” in trihaloacetic acid, but this solubility was due to a cleavage of the trialkyltin moiety from the phenyl groups. The glass temperatures, Tg, and melting temperatures Tm, of the various polymers were also studied.
Effect of fluorine substituents on the properties of nylon copolymers
Authors: Kiyotsukuri Tsuyoshi , Tsutsumi Naoto , Sandan Tadamasa , Nagata Minoru
Published: April 2003

Nylon 610/65F and nylon 610/65 copolymers were prepared by melt polycondensation from the diethylester of sebacic acid (10) and hexafluoroglutaric acid (5F) or glutaric acid (5) with hexamethylene diamine (6). Reduced specific viscosities of nylon 610/65F were lower than those of nylon 610/65. The crystallinity measured by WAXS and the melting point measured by DTA were depressed by the copolymerization. The melting point depression of nylon 610/65F was much larger than that of nylon 610/65. The thermal decomposition temperature measured by TG was also depressed significantly for nylon 610/65F. The residue at 600°C was increased by the fluorine substitution. The copolymers with higher fluorine content became flame retardant. The solubility was appreciably affected by the fluorine substitution. The contact angle for nylon 610/65F varied in a complicated manner with increasing 65F content and tended to be higher than the corresponding nylon 610/65.
Synthesis and properties of new polyimides containing flourinated alkoxy side chains
Authors: Ichino T. , Sasaki S. , Matsuura T. , Nishi S.
Published: April 2003

A series of new polyimides containing fluorinated alkoxy side chains are prepared from novel fluorinated alkoxy diamines. The dieletric constant at 1 kHz in the fluorinated polyimides decreases from 3.3 to 2.6 as fluorine content increases. The refractive index also changes from 1.58 to 1.48, dependent on the fluorine content. In addition, the fluorinated polyimides exhibit lower water absorption than the reference polyimides prepared from m‐phenylenediamine.
Gel permeation chromatographic analysis of polyurethane prepolymer synthesis kinetics. I. The effect of catalyst
Authors: Thompson Corley M. , Taylor Sue G. , Mcgee William W.
Published: April 2003

Polyurethane prepolymers are a complex mixture of oligomers. The proportion of the various species in this mixture determines the handling properties of the prepolymer as well as the physical properties of the final polyurethane. An analytical method has been developed that gives a clear and sensitive picture of both the reaction kinetics and the concentrations of the oligomeric species in the prepolymer mixture. The analytical method is applied to the polypropylene glycol/tolylene diisocyanate/catalyst system. The expected changes in reaction rates and in the formation of higher oligomers in the prepolymer were observed when catalyst was added at three different polyol molecular weights. An alternative equation for predicting the number average degree of polymerization is developed for the cases where reactant ratios are significantly less than one. An empirical equation is derived that permits expressing the reaction kinetic data in a linear plot. This equation is used to express the results of this work.
Studies of reactions with polymers. V. The reaction mechanism and resultant structure of PVA with PAN in DMSO without any catalyst
Authors: Hu Chun‐Min , Chiang Wen‐Yen
Published: April 2003

The reaction of polyacrylonitrile with poly(vinyl alcohol) in dimethyl sulfoxide without any catalyst was studied, and it showed that the adjacent nitrile groups on polyacrylonitrile could be linked up to form conjugated carbon‐nitrogen sequence by the presence of poly(vinyl alcohol). However, no such reaction occurred when poly(vinyl alcohol) was replaced by i‐propanol or poly(vinyl alcohol) graft copolymers. The structure of the resulting polymers were proposed by means of IR, UV, 1H, and 13C‐NMR spectroscopies. On the basis of the results, the effect of polymer feed and polymerization condition on this reaction were discussed. The compositions were determined by elemental analysis. The viscosity and thermal analysis of the products were also determined. At feed weight ratios of poly(vinyl alcohol) to polyacrylonitrile above one‐half, gels were obtained.
Preparation and characterization of wet poly(vinyl chloride)‐polypyrolle composite film
Authors: Uosaki Kohei , Okazaki Kentaro , Kita Hideaki
Published: April 2003

Wet poly(vinyl chloride) (wPVC) coated glassy carbon (GC) electrode was prepared by casting a DMF solution of poly(vinyl chloride) on glassy carbon and immersing it in methanol, and then in water. The wPVC coated GC (wPVC/GC) electrode showed electrochemical activity in aqueous solution; therefore, it was possible to obtain a wPVC/polypyrolle (PPy) composite by electropolymerization from aqueous solution of pyrolle (Py) into the wPVC matrix on the electrode. PPy segregated in wPVC matrix and the mechanical properties of PPy was improved by forming a composite without changing the electrochemical properties of PPy. The PPy/wPVC ratio can be controlled by controlling the concentration of PVC in DMF solution.
Emulsion polymerization of vinyl acetate initiated by potassium persulfate‐cyclohexanone sodium bisulfite redox pair system
Authors: Badran A. S. , Moustafa A. B. , Yehia A. A. , Shendy S. M. M.
Published: April 2003

The emulsion polymerization of vinyl acetate using potassium persulfate and cyclohexanone sodium bisulfite as redox pair initiation system was studied. The rate of polymerization, maximum conversion, and the number of polymer particles produced were found to change with redox initiator, monomer and emulsifier concentrations, and temperature variation. The rate of polymerization was found to be dependent on the initiator, the monomer, and the emulsifier concentrations to the 0.88, 0.22, and 0.20 powers, respectively. The K2S2O8–NaHSO3 redox system was found to decrease maximum conversion and doesn't form a stable emulsion. The apparent arrhenius activation energy (Ea) estimated for the polymerization system was 65.6 kJ/mol. The viscosity average molecular weights for some obtained poly(vinyl acetate) were determined.
Mechanistic studies of the electrochemical polymerization of pyrrole: Deuterium isotope effects and radical trapping studies
Authors: Lowen Stephen V. , Van Dyke John D.
Published: April 2003

The mechanism of the electrochemical polymerization of pyrrole and pyrrole‐d4 has been studied by an examination of the kinetic deuterium isotope effect. The kinetic rate constants of the reaction were measured by cyclic voltammetry, UV/visible specrophotometric analysis of polymer growth, and quantitative gas chromatographic analysis of monomer uptake. All three techniques demonstrated no primary isotope effect, from which it is concluded that proton loss or abstraction is not involved in the rate‐determining step of the polymerization. Furthermore no consistent secondary effect could be observed, suggesting that the rate‐determining step is free of hybridization changes or hyperconjugative effects in the transition state. A radical trap experiment revealed that polymer formation is completely inhibited by the presence of a radical trap and thus a reaction with the scavenger is more favorable than coupling with another radical cation or a neutral monomer molecule. Previously proposed mechanisms are examined and compared in light of the present study. Oxidative coupling is favored as the mechanism for electrochemical polymerization of pyrrole and related compounds. For this mechanism the rate‐limiting step must be either oxidation of monomer or radical cation coupling.
Synthesis of difunctional initiator via the Peterson reaction
Authors: Lee Day‐Chyuan , Chung T. C.
Published: April 2003

This paper presents an improved method to prepare divinylphenyl compounds which are a useful class of precursors in preparing difunctional organolithium initiators. In the past, most of the divinylphenyl compounds reported were prepared from reactions of phosphorus‐substituted carbanions with aldehydes and ketones (Wittig reaction). The phosphorus by‐product of the Witting reaction was difficult to be completely removed from the final products. In this paper, we apply the Peterson reaction (silane substituted carbanions) to the synthesis of divinylphenyl compounds. This reaction appears to be operationally simpler and cleaner than the Wittig reaction since the by‐product of silane is easily removed by silica Gel chromatography. The syn‐elimination of β‐hydroxylsilane is complete and clean under NaH condition with no detectable isomers in the final product. The reaction of the divinylphenyl compound with S‐butylithium forms a difunctional organolithium initiator which is used to prepare triblock copolymers with the desirable microstructure in each block.
Alternating copolymerization of 2,4‐dicyano‐but‐1‐ene and isoprene. II. Mechanism of copolymerization
Authors: Cowie J. M. G. , Cree S. H. , Ferguson R.
Published: April 2003

A careful compositional analysis of copolymers formed during the reaction of 2,4‐dicyano‐but‐1‐ene with isoprene has shown that the products are highly alternating over a broad feed range. The mechanism of alternation has been explored using four models, the terminal, complex‐participation, penultimate, and restricted penultimate. Nonlinear least‐squares analysis of the data for each model, followed by a statistical test to gauge the improvement of data fitting by each compared with the terminal model has been carried out. The statistical analysis is based on calculating the probability that one model has been carried out. The statistical analysis is based on calculating the probability that one model is significantly better than another, from the incomplete β‐function. This indicates that the restricted penultimate model gives the best description of the data and that significant charge‐transfer complex participation can be discounted.
Preparation and polymerization of the two isomeric (chloromethyl)oxetanes
Authors: Wicks Douglas A. , Tirrell David A.
Published: April 2003

2‐(Chloromethyl)oxetane was prepared in 8% overall yield from 2‐propen‐1‐ol by protection of the alcohol with dihydropyran, epoxidation, ring expansion with dimethylsulfoxonium methylide, acid deprotection, and chlorination with triphenylphosphine in CCl4. 3‐(Chloromethyl)oxetane was prepared in 22% overall yield by hydroboration‐oxidation of 3‐chloro‐2‐chloromethyl‐1‐propene followed by base‐catalyzed cyclization. Each of the oxetanes was converted to the corresponding elastomeric homopolymer by treatment with a triethylaluminum–acetylacetone–water mixture. Poly[2‐(chloromethyl)oxetane] was found to be similar to polyepichlorophydrin in reactivity toward benzoate ion, whereas poly[3‐(chloromethyl)oxetane] is more reactive by a factor of 2.
The synthesis and morphology of semi‐interpenetrating polymer networks based on polyurethane–polydimethylsiloxane system
Authors: Xiao H. , Ping Z. H. , Xie J. W. , Yu T. Y.
Published: April 2003

A series of semi‐interpenetrating polymer networks (semi‐IPNs) based on polyurethane and polydimethylsiloxane were prepared. They are formed by crosslinking the polydimethylsiloxane prepolymer with 3‐aminopropyltriethoxysilane in the presence of linear polyurethane. Investigations were carried out by swelling measurement, dynamic mechanical analysis, Fourier transform infrared experiments, and scanning electron microscopy. It is concluded that the crosslinking of the polydimethylsiloxane network is restricted by the presence of the polyurethane, and the grafting level between the two components is low. The system is phase separated, and there is dual phase continuity in the midrange composition.
Polymerizable viscoelastic fluids
Authors: Peiffer D. G.
Published: April 2003

Rheological, elongational flow, and scanning electron microscopy measurements have been performed on cationic monomers associated with specific counterions. The monomers are formed through the reaction of allyl bromide and a variety of dimethylalkylamine derivatives. The results show that above a specific monomer–counterion concentration, highly elongated structures are formed in solution. These structures are adequately described as polymerizable rod‐like micelles. The physical properties of these fluids are interpreted in terms of a micellar sphere to rod transition which gradually occurs over a specific concentration range (>1g/dL, in general). At higher concentrations, these rod‐like entities are capable of interacting with each other. Therefore, even though the forces holding the structures together are certainly weaker than a chemical bond, polymeric‐like properties are observed in these polymerizable viscoelastic fluids.
Phase separation in polystyrene latex interpenetrating polymer networks
Authors: Sheu H. R. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

Polystyrene/polystyrene latex interpenetrating polymer networks (IPNs) were prepared by seeded emulsion polymerzation of styrene–divinylbenzene mixtures in crosslinked monodisperse polystyrene seed latexes. The resulting latexes comprised uniform nonspherical particles, which were formed by separation of the second‐stage monomer from the crosslinked seed network during swelling and polymerization. The kinetics of phase separation were investigated by examining the changes in particle morphology using optical microscopy, which revealed that the phase separation was induced by the relaxation of the polymer chains before polymerization began and was enhanced by increased conversion. The thermodynamics of phase separation were investigated by analysis of the free‐energy changes during swelling and polymerization, and the phase separation was described by a nucleation‐and‐growth mechanism. The results of this study have been applied to the design and synthesis of a series of uniform nonspherical particles of different morphology.
Uniform nonspherical latex particles as model interpenetrating polymer networks
Authors: Sheu H. R. , El‐Aasser M. S. , Vanderhoff J. W.
Published: April 2003

Polystyrene/polystyrene latex interpenetrating polymer networks (IPNs) were prepared by seeded emulsion polymerization of styrene–divinylbenzene mixtures in crosslinked monodisperse polystyrene particles. The resulting latexes comprised uniform nonspherical particles, e.g., ellipsodal and egg‐like singlets, symmetry and asymmetric doublets, and ice cream cone‐like and popcorn‐like multiplets. The nonspherical particles, which were formed by separation of the second‐stage monomer from the crosslinked seed network during swelling and polymerization, are excellent models for studying phase separation in IPN's. The degree of phase separation increased with increasing degree of crosslinking of the seed particles, monomer/polymer swelling ratio, polymerization temperature, and seed particle size, and with decreasing divinylbenzene concentration in the swelling monomer. The results were consistent with a thermodynamic analysis based on the elastic‐retractile force of the polymer network, the monomer/polymer mixing force, and interfacial tension force.