bluuebunny/crossref_metadata_2025 huggingface dataset:
Drug or symptom‐induced depression in men treated with alpha1‐blockers for benign prostatic hyperplasia? A nested case–control study
Authors: Clifford Gary M. , Farmer Richard D. T.
Published: August 2002

Purpose

Regulatory authorities have raised concern that α1‐blockers, prescribed predominantly for benign prostatic hyperplasia (BPH), may be associated with an increased risk of depression. The aim was to assess the risk of depression with α1‐blockers independently of that associated with symptoms being treated and concurrent illness.

Methods

Using a study population registered on the UK General Practice Research Database, and taking a prescription for an antidepressant as a proxy for clinical depression, we performed: (a) cohort analyses comparing the incidence of depression in current users of α1‐blockers versus non‐users, and in men with BPH versus those without. (b) A nested case–control analysis looking at the association between depression and α1‐blocker exposure, accounting for the presence of BPH and other illness.

Results

In the cohort analyses, risk of depression was significantly higher in men with BPH compared to those without (IRR 2.17, 2.12–2.22), but was not significantly different for men exposed to α1‐blockers versus those unexposed when adjusted for the presence of BPH. Cases of depression were more likely to have pre‐existing BPH (crude OR 2.09, 2.02–2.15) than controls. After adjusting for concurrent illness (using number of GP visits as a proxy) and the presence of BPH (adjusted OR 1.38, 1.33–1.43), there was no association with depression for exposure to any α1‐blocker (adjusted OR 1.03, 0.90–1.18).

Conclusions

This study did not suggest that the prescribing of α1‐blockers increases the risk of being depressed. The association highlighted by spontaneous reporting systems appears to be explained by confounding by concurrent disease. Copyright © 2002 John Wiley & Sons, Ltd.
Thermal properties of processable polyaniline with novel sulfonic acid dopants
Authors: Paul Raji K , Pillai C K S
Published: August 2002

Thermal properties of melt processable polyaniline (PANI) synthesized by doping with functionalised novel sulfonic acid dopants have been investigated. Doping of PANI was carried out by using the dopants derived from an inexpensive naturally existing biomonomer, cardanol: sulfonic acid of 3‐pentadecylphenol, sulfonic acid of 3‐pentadecylanisole and sulfonic acid of 3‐pentadecylphenoxyacetic acid. These dopants act as very good plasticizing cum protonating agents for PANI. Doping was carried out either by mechanical mixing of emeraldine base and the dopant or by an in situ doping emulsion polymerization of aniline. Highly conducting free‐standing flexible films of protonated PANI could be prepared by a hot pressing method at different temperatures. The thermal stability and thermal reactions of these protonated PANI were followed by conductivity measurements at different temperatures, wide angle X‐ray diffraction measurements, thermogravimetric analysis and differential scanning colorimetry analysis.

© 2001 Society of Chemical Industry
Blends of maleic‐anhydride‐grafted polyethylene with polyethylene for improved cathodic disbondment performance
Authors: Roy Debashis , Simon George P , Forsyth Maria
Published: August 2002

Buried metal structures such as pipes are usually protected by a coating, often in conjunction with cathodic protection (CP). Whilst this minimizes corrosion, it can also lead to the loss of adhesion between the protective coating and metal structure by a phenomenon called cathodic disbondment (CD). In this study, various medium‐density polyethylene (MDPE) compositions with maleic‐anhydride‐grafted‐polyethylene (MAH‐g‐PE) have been formulated to investigate the effect on CD performance, as well as both wet and dry bond strength. The results indicate an improvement in both CD performance and bond strength for all compositions. Differential scanning calorimetry (DSC) and pressure‐volume‐temperature (PVT) experiments are used to characterize the polymer formulations developed and to aid in the understanding of the reasons for such improvement. Energy dispersive X‐ray spectroscopy (EDXS) has been used to obtain surface analysis data on disbonded materials in order to evaluate the failure mode during the CD process. It is found that there may be an optimum loading of the polar functional groups in MDPE necessary for the best CD performance, and that wet adhesion strength (rather than dry) is an important parameter to assess and understand the CD performance of coatings.

© 2001 Society of Chemical Industry
Processing characteristics of poly(ethylene terephthalate): hydrolytic and thermal degradation
Authors: Al‐AbdulRazzak Sami , Jabarin Saleh A
Published: August 2002

The effects of poly(ethylene terephthalate) (PET) resin moisture content and temperature exposure have been investigated in terms of material changes resulting from the injection moulding process. Two resins with initial carboxyl contents of 10 µeq/g PET and 20 µeq/g PET have been analysed. Preforms processed at different resin moisture contents and processing temperatures of 280, 290 and 300 °C were evaluated in terms of carboxyl end‐group concentration using a titration method. Intrinsic viscosities of the performs were also measured by solution viscosity. Mathematical models describing the relationships of carboxyl end‐group concentration and intrinsic viscosity to the processing conditions were generated from the experimental data. Carboxyl end‐groups formed were compared for both resins and shown to be dependent on initial carboxyl content in the resin. Reducing the initial carboxyl content in the resin has been shown to increase its hydrolytic stability. The hydrolytic effect on the overall molecular weight drop was separated from the thermal/thermal‐oxidative degradation and shown to be dependent on both the processing temperature and the resin moisture content.

© 2002 Society of Chemical Industry
Design optimization for higher stabilized efficiency and reduced light‐induced degradation in boron‐doped Czochralski silicon solar cells
Authors: Damiani B. , Ristow A. , Ebong A. , Rohatgi A.
Published: August 2002

Traditional boron‐doped Czochralski‐grown Si solar cells are known to suffer from light‐induced degradation (LID). By replacing B with Ga as the dopant in the Cz melt or by reducing the oxygen content by implementing the magnetic‐Cz (MCz) growth technique, not only can LID be eliminated, but also higher efficiency manufacturable screen‐printed cells can be achieved. The use of thinner wafers for cell fabrication can significantly reduce the impact of LID on conventional boron‐doped Cz cells. Knowledge of the degraded cell parameters can be used to determine the optimal thickness for the highest stabilized efficiency. A methodology is developed to maximize the stabilized efficiency after LID by using thinner wafers. A combination of device modeling and experimental data is used to demonstrate that, for traditional B‐doped Cz Si, which degraded from 75 to 20 μs, the optimum cell thickness is in the range of 150–190 μm for a back‐surface recombination velocity of ∼104cm/s. This cell design reduces the material cost and the absolute efficiency degradation from 0.75% (375 μm device) to 0.24% (157 μm device) and gives the highest stabilized Cz cell efficiency. Copyright © 2002 John Wiley & Sons, Ltd.
Spectral mismatch correction and spectrometric characterization of monolithic III–V multi‐junction solar cells
Authors: Meusel M. , Adelhelm R. , Dimroth F. , Bett A.W. , Warta W.
Published: August 2002

III–V monolithic multi‐junction (MJ) solar cells reach efficiencies exceeding 30% (AM 1.5 global) and have applications in space and in terrestrial concentrator systems. The subcells of monolithic MJ cells are not accessible separately, which presents a challenge to measurement systems and procedures. A mathematical approach is presented which enables a fast way of spectral mismatch correction for MJ cells, thereby significantly reducing the time required for calibration. Moreover, a systematic investigation of theI–Vparameters of a MJ solar cell with variation of the incident spectrum is possible, herein called ‘spectrometric characterization’. This analysis method visualizes the effects of current limitation and shifting of the operating voltage, and yields precise information about the current‐matching of the subcells. MJ cells can hereby be compared without the need to match the current of the structures to a reference spectrum in advance. Further applications of the spectrometric characterization are suggested, such as for the determination of the radiation response of the subcells of MJ space solar cells or for the prediction of the annual power output of terrestrial MJ concentrator cells. Copyright © 2002 John Wiley & Sons, Ltd.
Another look at the “C” in CBM: Does it really matter if curriculum‐based measurement reading probes are curriculum‐based?
Authors: Powell‐Smith Kelly A. , Bradley‐Klug Kathy L.
Published: August 2002

This study investigated differences between two types of reading probe material to monitor students' oral reading fluency over time. Thirty‐six second‐grade students participated in this study. Twice each week for 5 weeks, participants read two passages from each of two sources. One source was the curriculum in which the child was being instructed at school, and the second source was the “Tests of Reading Fluency,” a set of generic (curriculum‐independent) passages. Standardized curriculum‐based measurement administration and scoring procedures were used. Level and rate of improvement (slope) of oral reading fluency were the dependent measures. Level and slope data were analyzed using two, two‐tailed t‐tests. Also, readability of passages was calculated using two readability formulas. Correlational analyses were used to examine the relation between the readability and reading fluency. Correlations among readability and words read correct were not significant. Results of the analyses examining level and slope indicated that students read significantly more words correct in the generic reading passages than in the curriculum‐based passages. However, rate of progress was not significantly different. These results suggest that practitioners could use either set of passages to gauge students' reading progress over time. Implications for future research and practice are discussed. © 2001 John Wiley & Sons, Inc.
Well‐defined glycopolymer amphiphiles for liquid and supercritical carbon dioxide applications
Authors: Ye Weijun , Wells Sharon , DeSimone Joseph M.
Published: August 2002

Well‐defined D‐glucose‐containing glycopolymers, poly(3‐O‐methacryloyl‐1,2 : 5,6‐di‐O‐isopropylidene‐D‐glucofuranose) (PMAIpGlc), and diblock copolymers of PMAIpGlc with poly(1,1‐dihydroperfluorooctyl methacrylate) (PFOMA) were synthesized by living anionic polymerization in THF at −78 °C with 1,1‐diphenylhexyllithium in the presence of lithium chloride. The resulting polymers were found to possess predictable molecular weights and very narrow molecular weight distributions (MWD, Mw/Mn ≤ 1.16). Removal of the acetal protective groups from the protected glycopolymer block copolymer was carried out using 90% trifluoroacetic acid at room temperature, yielding a hydrophilic block copolymer with pendant glucose moieties. Both protected (lipophilic/CO2‐philic) and deprotected (hydrophilic/CO2‐philic) fluorocopolymers were proved to be CO2 amphiphiles. Their solubility in CO2 was heavily influenced by the amphiphilic structure, such as the copolymer compositions and the polarities of sugar block. Light‐scattering studies showed that, after removal of the protective groups, the deprotected block copolymer formed aggregate structures in liquid CO2 with an average micellar size of 27 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3841–3849, 2001
Synthesis and characterization of poly(arylene ether)s derived from 4,4′‐bishydroxybiphenyl and 4,4′‐bishydroxyterphenyl
Authors: Salunke Arun Kashinath , Madhra Mukesh Kumar , Sharma Mamta , Banerjee Susanta
Published: August 2002

A series of poly(arylene ether)s were successfully prepared by aromatic, nucleophilic substitution reactions with various perfluoroalkyl‐activated bisfluoromonomers with 4,4′‐bishydroxybiphenyl and 4,4′‐bishydroxyterphenyl. 4,4′‐Bishydroxyterphenyl was synthesized through the Grignard coupling reaction of magnesium salt of 4‐bromoanisole with dibromobenzene followed by demethylation with pyridine–hydrochloride. The products obtained by the displacement of fluorine atoms exhibited good inherent viscosity, up to 0.77 dL/g, and number‐average molecular weights up to 69,300. These poly(arylene ether)s showed very good thermal stability, up to 548 °C for 5% weight loss according to thermogravimetric analysis under synthetic air, and high glass‐transition temperatures, up to 259 °C according to differential scanning calorimetry, depending on the exact repeat unit structure. These polymers were soluble in a wide range of organic solvents, such as N‐methylpyrrolidone, dimethylformamide, tetrahydrofuran, toluene, and CHCl3, and were insoluble in dimethyl sulfoxide and acetone. Thin films of these poly(arylene ether)s showed good transparency and exhibited tensile strengths up to 132 MPa, moduli up to 3.34 GPa, and elongations at break up to 84%, depending on their exact repeating unit structures. These values are comparable to those of high‐performance thermoplastic materials such as poly(ether ether ketone) (PEEK) and Ultem poly(ether imide) (PEI). These poly(arylene ether)s exhibited low dielectric constants. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 55–69, 2002
Thermotropic liquid‐crystalline poly(oxadiazole)s with poly(methylene) spacers: Preparation and extraordinary odd–even effect
Authors: Tsai Cheng‐Jang , Chen Yun
Published: August 2002

A novel synthetic procedure for the preparation of poly(oxadiazole)s was developed with nucleophilic substitution of α,ω‐alkanediols with oxadiazole‐activated bisfluoride. Seven poly(oxadiazole)s were successfully prepared by the solution polymerization of 2,5‐bis(4‐fluorophenyl)‐1,3,4‐oxadiazole and various α,ω‐alkanediols [HO(CH2)nOH, n = 5–10 or 12] in diphenyl sulfone at temperature greater than 230 °C with K2CO3 as a catalyst. The reduced viscosities of the poly(oxadiazole)s were 0.14–0.51 dL/g, and the decomposition temperatures were greater than 350 °C and decreased from 436 to 379 °C with increasing spacer length (n). Corresponding model compounds, consisting of two terminal mesogenic 2,5‐bisphenyl‐1,3,4‐oxadiazole units and central poly(methylene) spacers, were also prepared for comparison. Both the polymers and model compounds exhibited an extraordinary odd–even effect: odd ones showed higher transition temperatures (melting and clearing temperatures). With differential scanning calorimetry, polarized optical microscopy (POM), and X‐ray diffraction, we found that the nematic mesophase was the only texture in the melts except for the polymers with longer methylene units (n = 9), in which smectic mesophases were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 293–301, 2002
Synthesis and characterization of monomers and polymers for adhesives from methyl oleate
Authors: Bunker Shana P. , Wool Richard P.
Published: August 2002

The focus of this work is to synthesize a monomer from a fatty acid methyl ester capable of forming high molecular weight polymers. The mono‐unsaturation in the starting material, methyl oleate, was first epoxidized using a peroxy acid. This intermediate material was further modified using acrylic acid. The acrylated molecule is able to participate in free‐radical polymerization reactions to form high molecular weight polymers. The rate of polymerization was low because of the long aliphatic structure of the monomer. It is hypothesized that the polymerization reaction occurred in the interface between the particle and water, thereby slowing down the reaction. After 18 h of reaction, a monomer conversion of approximately 91% was achieved. A maximum weight‐average molecular weight of approximately 106 g/mol was observed after 14 h of reaction. At early reaction times linear polymers were formed. However, as the reaction time increased, the amount of branching that occurred on the polymer molecule increased, as indicated by gel permeation chromatography and light scattering. This has been attributed to chain transfer to polymer via hydrogen abstraction from a tertiary backbone C–H bond. The resulting polymer may be of considerable interest for pressure‐sensitive adhesive applications. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 451–458, 2002; DOI 10.1002/pola.10130
Ruthenium‐catalyzed fast living radical polymerization of methyl methacrylate: The RCl/Ru(Ind)Cl(PPh3)2/n‐Bu2NH initiating system
Authors: Hamasaki Shinya , Sawauchi Chie , Kamigaito Masami , Sawamoto Mitsuo
Published: August 2002

A fast living radical polymerization of methyl methacrylate (MMA) proceeded with the (MMA)2Cl/Ru(Ind)Cl(PPh3)2 initiating system in the presence of n‐Bu2NH as an additive [where (MMA)2Cl is dimethyl 2‐chloro‐2,4,4‐trimethyl glutarate]. The polymerization reached 94% conversion in 5 h to give polymers with controlled number‐average molecular weights (Mn's) in direct proportion to the monomer conversion and narrow molecular weight distributions [MWDs; weight‐average molecular weight/number‐average molecular weight (Mw/Mn) ≤ 1.2]. A poly(methyl methacrylate) with a high molecular weight (Mn ∼ 105) and narrow MWD (Mw/Mn ≤ 1.2) was obtained with the system within 10 h. A similarly fast but slightly slower living radical polymerization was possible with n‐Bu3N, whereas n‐BuNH2 resulted in a very fast (93% conversion in 2.5 h) and uncontrolled polymerization. These added amines increased the catalytic activity through some interaction such as coordination to the ruthenium center. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 617–623, 2002; DOI 10.1002/pola.10148
Mechanism of coupling reactions of polystyryllithium with dihalomethanes
Authors: Tillman Eric S. , Hogen‐Esch Thieo E.
Published: August 2002

We report here an in‐depth analysis of the reaction mechanisms involved in the formation of polymer dimers formed by the coupling of polystyryllithium (PSLi) with dichloromethane (DCM), dibromomethane (DBM), and diiodomethane (DIM) in tetrahydrofuran at −78 °C. The DBM‐mediated reactions give a high degree of coupling but generate 1,2‐diphenyl linkages in addition to the expected 1,3‐diphenyl linkages and small amounts of β‐substituted styrenic end groups that are detectable by fluorescence measurements. This is consistent with the formation of bromobenzyl end groups by lithium–bromine exchange and PSLi‐mediated elimination. The formation of α‐substituted styrenic end groups by conventional displacement and elimination is also possible. Although reactions of PSLi with DCM show no coupling at all, DIM is a much better coupling agent than DBM, significantly suppressing side reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1081–1091, 2002
Synthesis and electrical properties of polyacetylene derivatives
Authors: Jin Sung‐Ho , Jin Jung‐Ei , Moon Seong‐Bae , Lee Hyung‐Jong , Gal Yeong‐Soon , Kim Hyun‐Don , Kim Sung‐Hyun , Kim Sung‐Hoon , Koh Kwangnak
Published: August 2002

Cyclopolymerization of 1,6‐heptadiyne derivatives containing the bulky substitutents was carried out by metathesis catalyst systems. The catalytic activity of molybdenum (V) chloride (MoCl5) in homopolymerization is greater than that of the MoCl5‐cocatalyst system, and copolymerization is vice versa in catalytic activity. Newly synthesized homo‐ and copolymers were soluble in common organic solvents and could afford thin film by solution‐casting onto the indium–tin oxide coated glass substrate. The NMR, Fourier transform infrared spectroscopic, and UV–visible spectra indicated that these polymers have a linear conjugated cyclic polyene structure having a bulky substitutent as a pendant group. The number‐average molecular weight of these polymers was in the range of 2.4–6.27 × 103. The copolymers exhibited a relatively higher molecular weight than that of the homopolymers. The copolymers were stable up to 380 °C. The electrical conductivities of the I2‐doped copolymer thin film by the four‐point probe method and surface plasmon resonance spectroscopy were about 500 and 600 S/cm, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 958–964, 2002
Positron annihilation studies of poly(N‐isopropyl acrylamide) gel in mixed solvents
Authors: Acharya Anjali , Goswami A. , Pujari P. K. , Sabharwal S. , Manohar S. B.
Published: August 2002

Positron annihilation lifetime spectroscopy was used to characterize the reentrant volume‐phase‐transition behavior of poly(N‐isopropyl acrylamide) hydrogel in an ethanol/water mixed solvent. The polymer gel was synthesized with γ irradiation. The ortho‐positronium lifetime (τ3) in the gel slowly increased with an increase in the ethanol content in the mixed solvent. τ3 was not influenced by the volume phase transition. The ortho‐positronium intensity decreased with the collapse of the gel in an approximately 10% ethanol/water mixture. When swelled in pure ethanol, τ3 initially increased with the solvent amount in the gel, showing the destruction of intramolecular hydrogen bonding and the relaxation of polymer chains. The lower critical solution temperature of the gel in the 10% ethanol/water mixture was lower than that in pure water, and τ3 for various solvent contents showed behavior similar to that seen in pure solvent. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1028–1036, 2002
Synthesis and properties of organosoluble poly(amide imide imide)s based on tetraimide dicarboxylic acid condensed from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline, and trimellitic anhydride and various aromatic diamines
Authors: Yang Chin‐Ping , Chen Ruei‐Shin , Wang Ming‐Jui
Published: August 2002

A novel tetraimide dicarboxylic acid was synthesized with the ring‐opening addition of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline, and trimellitic anhydride in a 1/2/2 molar ratio in N‐methyl‐2‐pyrrolidone followed by azeotropic condensation to tetraimide dicarboxylic acid. A series of poly(amide imide imide)s (PAIIs) with inherent viscosities of 0.8–1.1 dL/g were prepared from tetraimide dicarboxylic acid with various aromatic diamines by direct polycondensation. Most of the PAIIs were readily soluble in a variety of amide polar solvents and even in less polar m‐cresol and pyridine. Solvent‐cast films had tensile strengths ranging from 99 to 106 MPa, elongations at break ranging from 8 to 13%, and initial moduli ranging from 2.0 to 2.3 GPa. The glass‐transition temperatures of these PAIIs were recorded at 244–276 °C. They had 10% weight losses at temperatures above 520 °C in air or nitrogen atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1092–1102, 2002
Emulsion copolymerization of vinyl acetate and butyl acrylate in the presence of fluorescent dyes
Authors: Oh Jung Kwon , Wu Jun , Winnik Mitchell A. , Craun Gary P. , Rademacher Jude , Farwaha Rajeev
Published: August 2002

This article describes our first experiments for preparing dye‐labeled latex particles by the emulsion copolymerization of a 4/1 (w/w) mixture of vinyl acetate‐butylacrylate (VAc‐BA). We discuss the synthesis of acrylate derivatives of phenanthrene, anthracene, and pyrene [9‐acryloxymethyl phenanthrene (7), 9‐acryloxymethyl‐10‐methyl anthracene (8), and 1‐acryloxymethyl pyrene (10)] and an allyl ether derivative of anthracene [9‐allyoxymethyl‐10‐methyl anthracene (9)]. Although the phenanthrene derivative 7 gave latex particles with high monomer conversion and good dye incorporation, the pyrene acrylate and both anthracene comonomers strongly inhibited the free‐radical reaction. To assist our search for a dye that would serve as a useful energy acceptor for phenanthrene and without suppressing VAc‐BA polymerization, we also examined batch emulsion polymerization in the presence of a variety of dye derivatives—substituted anthracenes, acridines, a coumarin, and two benzophenone derivatives. All of the anthracene derivatives, as well as acridine, strongly inhibited monomer polymerization. The coumarin dye 7‐hydroxy‐4‐methyl coumarin (22) that had only limited solubility allowed more than 90% monomer conversion. Most promising were 2‐hydroxy‐5‐methyl benzophenone (23) and 4‐N,N‐dimethylamino benzophenone (24) that at 1 mol % in the monomer mixture permitted virtually quantitative monomer conversion to latex. 4′‐Dimethylamino‐2‐acryloxy‐5‐methyl benzophenone (25) copolymerized well with the VAc‐BA mixture, yielding latex particles in high yield and with a narrow size distribution. These dyes appear to be useful acceptor dyes for energy‐transfer experiments with phenanthrene. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1594–1607, 2002
Hydrogen effects in propylene polymerization reactions with titanium‐based Ziegler–Natta catalysts. I. Chemical mechanism of catalyst activation
Authors: Kissin Yury V. , Rishina Laura A.
Published: August 2002

The hydrogen activation effect in propylene polymerization reactions with Ti‐based Ziegler–Natta catalysts is usually explained by hydrogenolysis of dormant active centers formed after secondary insertion of a propylene molecule into the growing polymer chain. This article proposes a different mechanism for the hydrogen activation effect due to hydrogenolysis of the Tiiso‐C3H7 group. This group can be formed in two reactions: (1) after secondary propylene insertion into the TiH bond (which is generated after β‐hydrogen elimination in the growing polymer chain or after chain transfer with hydrogen), and (2) in the chain transfer with propylene if a propylene molecule is coordinated to the Ti atom in the secondary orientation. The TiCH(CH3)2 species is relatively stable, possibly because of the β‐agostic interaction between the H atom of one of its CH3 groups and the Ti atom. The validity of this mechanism was demonstrated in a gas chromatography study of oligomers formed in ethylene/α‐olefin copolymerization reactions with δ‐TiCl3/AlEt3 and TiCl4/dibutyl phthalate/MgCl2–AlEt3 catalysts. A quantitative analysis of gas chromatography data for ethylene/propylene co‐oligomers showed that the probability of secondary propylene insertion into the TiH bond was only 3–4 times lower than the probability of primary insertion. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1353–1365, 2002
Synthesis of well‐defined multigraft copolymers by a two‐step living radical polymerization with nitroxyl‐functionalized poly(methyl methacrylate)
Authors: Hua F. J. , Liu B. , Hu C. P. , Yang Y. L.
Published: August 2002

Novel multigraft copolymers of poly(methyl methacrylate‐graft‐polystyrene) (PMMA‐g‐PS) in which the number of graft PS side chains was varied were prepared by a subsequent two‐step living radical copolymerization approach. A polymerizable 4‐vinylbezenyl 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) monomer (STEMPO), which functioned as both a monomer and a radical trapper, was placed in a low‐temperature atom transfer radical polymerization (60°C) process of methyl methacrylate with ethyl 2‐bromopronionate (EPNBr) as an initiator to gain ethyl pronionate‐capped prepolymers with TEMPO moieties, PMMA‐STEMPOs. The number of TEMPO moieties grafted on the PMMA backbone could be designed by varying STEMPO/EPNBr, for example, the ratios of 1/2, 2/3, or 3/4 gained one, two, or three graft TEMPO moieties, respectively. The resulting prepolymers either as a macromolecular initiator or a trapper copolymerized with styrene in the control of stable free‐radical polymerization at an elevated temperature (120 °C), producing the corresponding multigraft copolymers, PMMA‐g‐PSs. The nitroxyl‐functionalized PMMA prepolymers produced a relatively high initiation efficiency (>0.8) as a result of the stereohindrance and slow diffusion of TEMPO moieties connected on the long PMMA backbone. The polymerization kinetics in two processes showed a living radical polymerization characteristic. The molecular structures of these prepolymers and graft copolymers were well characterized by combining Fourier transform infrared spectroscopy, gel permeation chromatography, chemical element analysis, and 1H NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1876–1884, 2002
Synthesis and optical properties of new polyurethane cationomers with anchored stilbene chromophores
Authors: Buruiana Emil C. , Buruiana Tinca , Strat Georgeta , Strat Mitachi
Published: August 2002

An ionic diol bearing a one‐sided urethane‐stilbene group located on the ammonium quaternary structure was prepared and proposed as an intermediate for polyurethane ionomer synthesis. Polyurethane cationomers with stilbene ionic groups based on poly(tetramethylene oxide) diols, 4,4′‐diphenylmethane diisocyanate and the aforementioned ionic diol, were synthesized and characterized. Some aspects of the trans–cis photoisomerism and fluorescent emission of the stilbene chromophore in polyurethane cationomers were studied comparatively with the urethane‐stilbene diol. The stilbene polycations absorbed at λA = 316 nm and emitted violet‐blue light with an emission maxima at λF = 444 nm (dimethylformamide solution) and λF = 465 nm (film). These polymers are known for their elastomeric properties and are assumed to be of great interest for some future applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1918–1928, 2002
Study on side‐chain second‐order nonlinear optical polyimides based on novel chromophore‐containing diamines. II. Copolyimides possessing direct photolithographic features
Authors: Sui Yu , Lu Jiong‐Xin , Yin Jie , Liu Yan‐Gang , Zhu Zi‐Kang , Wang Zong‐Guang
Published: August 2002

Second‐order nonlinear optical copolyimides were prepared from a novel chromophore‐containing diamine, 4‐nitro‐4′‐[N‐(4,6‐di‐4‐aminophenylamino)‐1,3,5‐triazin‐2‐yl]aminoazobenzene, a codiamine, 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane, and benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride by a traditional two‐step process, which includes a solution polycondensation followed by a chemical imidization. Some of the polyimides (PIs) obtained possessed direct photolithographic features, and good photolithographic patterns were easily obtained. All PIs exhibited high‐glass transition temperatures (235–246 °C) and high thermal‐decomposition temperatures. They were also soluble in strong polar aprotic solvents such as N‐methyl‐2‐pyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and γ‐butyrolactone. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1419–1425, 2001
Segmented polyethylene oxides: A new class of polyethers prepared via melt transetherification
Authors: Jayakannan M. , Ramakrishnan S.
Published: August 2002

Several segmented polyethylene oxides (SPEOs) were prepared by a melt‐transetherification process using 1,4‐bis(methoxymethyl)‐2,3,5,6‐tetramethylbenzene and polyethylene glycols (PEGs) of different molecular weights (di‐, tri‐, and tetraethylene glycols and PEGs of molecular weights 300, 600, 1000, 1500, and 3400) as the monomers. The effect of polymerization temperature (185 and 150 °C) on the molecular weight of SPEOs was studied, and it was shown that the molecular weight is larger at a higher polymerization temperature. The reversal of the polycondensation (transetherification) equilibrium by treatment of the polyethers with excess methanol transformed them completely into the starting monomers. The analysis of the degraded products by mass and NMR spectroscopies revealed that side reactions, such as the self‐condensation of diols, are insignificant. The polymers containing shorter PEG spacers are amorphous, whereas the ones with longer PEG spacers are semicrystalline. The glass‐transition temperature (Tg) of the SPEOs decreased with increases in the spacer length and attained the value of PEO at PEG‐600, whereas the melting transition (Tm), crystallization temperature (Tc), and their enthalpies of transition, (ΔHm) and (ΔHc), increased with increases in the spacer length. The introduction of “molecular kinks” into SPEOs by the use of another monomer, 1,3‐bis(methoxymethyl)‐2,4,5,6‐tetramethylbenzene, surprisingly, showed little effect on their thermal properties. A “branched‐PEO” analogue, containing pendant oligoethyleneoxy units, was also prepared, and its thermal properties were compared with its linear analogue. Preliminary ionic conductance measurements showed that some of these SPEOs could serve as potential candidates for solid polymer–electrolyte applications. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1615–1628, 2001
Quantitative analysis of the temperature effect on the radiation crosslinking and scission of polyethylene macromolecules
Authors: Shyichuk Alexander , Shyichuk Irena , Wu Guozhong , Katsumura Yosuke
Published: August 2002

The γ‐radiation‐induced crosslinking of low‐density polyethylene over a wide temperature range was studied with a new log–logarithmic scale method for sol–gel analysis. A straight line was always obtained for the plotting of log (sol fraction) against log (dose). Gel points were accurately obtained from the plot intersects, and scission/crosslinking ratios were obtained from the plot slopes via computer simulations with GelSim6 software. The crosslinking and scission yields were determined to be 0.17 and 0.078 mmol/kJ, respectively, at 30 °C, and they increased to 2.3 and 4.4 mmol/kJ, respectively, at 300 °C. The observed regularities are explained by the fact that enhanced macromolecular motion decreases the cage effect on recombination reactions in the polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1656–1661, 2001
Effect of the solvent polarity on the living ligated anionic polymerization of tert‐butyl methacrylate and copolymerization with methyl methacrylate
Authors: Zune C. , Archambeau C. , Dubois Ph. , Jérôme R.
Published: August 2002

An anionic polymerization of t‐butyl methacrylate and a copolymerization with methyl methacrylate were initiated with an organolithium ligated with 10 equiv of LiCl. As a rule, the complexation of the active species by LiCl masked the effect that the polarity of the solvent might have on the molecular structure of the chains. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1774–1785, 2001
Water‐soluble acrylamide copolymers. VIII. Preparation and characterization of polyacrylamide‐co‐N‐t‐butylacrylamide
Authors: Hocking Martin B. , Klimchuk Keith A. , Lowen Stephen
Published: August 2002

The preparation of a series of copolymers of N‐t‐butylacrylamide (NTBAM) with acrylamide (AM) is reported. The insolubility of NTBAM in water led to the testing of methanol, t‐butanol, and mixtures of these solvents with water to obtain effective copolymerization. Several of these polymerizations produced nonhomogeneous product mixtures. Samples of the components were separated and characterized by photoacoustic Fourier transform infrared spectroscopy and 13C NMR spectroscopy. Hydrodynamic volumes of the products were obtained from solution‐viscosity measurements, gel permeation chromatography, and multi‐angle laser light scattering methods. The NTBAM‐co‐AM copolymers had degrees of polymerization and molecular weights in the 4.1–5.9 × 104 monomer units and 3.25–4.5 × 106 g/mol range, respectively. They contained from 15 to 36 mol % NTBAM. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 1960–1977, 2001
Soluble fluorinated polyimides derived from 1,4‐ (4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl)benzene and aromatic dianhydrides
Authors: Zhou Hongwei , Liu Jingang , Qian Zhiguo , Zhang Shuying , Yang Shiyong
Published: August 2002

New fluorinated aromatic polyimides were prepared from 1,4‐(4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl)benzene and aromatic dianhydrides via the polycondensation of one‐step high‐temperature and two‐step thermal or chemical imidization methods. Experimental results indicated that some of the polyimides were soluble both in strong dipolar solvents (N‐methyl‐2‐pyrrolidone or N,N‐dimethylacetamide) and in common organic solvents such as tetrahydrofuran, CHCl3, and acetone. The polyimides showed exceptional thermal and thermooxidative stability and good mechanical properties. No weight loss was detected before a temperature of 520 °C in nitrogen, and the glass‐transition temperatures ranged from 208 to 251 °C. Low dielectric constants (2.55–2.71 at 1 MHz), low refractive indices, and low water absorption were also observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2404–2413, 2001
Synthesis of chromophore‐embedded polyurethanes for electrooptical materials
Authors: Xin Zhong , Sanda Fumio , Endo Takeshi
Published: August 2002

We carried out the polyaddition of dye‐embedded diols with diisocyanates to obtain novel nonlinear optical (NLO) polyurethanes, where the NLO units were embedded in the polymer backbone. The obtained polymers showed high glass‐transition temperatures (138–184 °C) and thermal stability (temperature of 10% weight loss under nitrogen = 227–287 °C). The λ maximum of the polymers was 521–556 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2620–2624, 2001
Synthesis of high refractive‐index melt‐stable aromatic polyphosphonates
Authors: Shobha H. K. , Johnson H. , Sankarapandian M. , Kim Y. S. , Rangarajan P. , Baird D. G. , McGrath J. E.
Published: August 2002

The synthesis of aromatic polyphosphonates based on the step polymerization of various bisphenols and dichlorophenyl phosphine oxide was investigated. The effect of catalyst, type, concentration, and polymerization time were systematically varied to obtain high molecular weight polymers. Very high molecular weight tough, ductile materials with a high degree of optical clarity were synthesized. In contrast with the aromatic polycarbonates, the refractive index was increased from 1.58 to 1.60 (for the bisphenol A‐based system) and 1.64 for a biphenol‐based system. The latter was still an amorphous soluble polymer as a result of the non‐coplanar nature of the phenyl phosphine oxide bond, unlike the analogous polycarbonate. Hydrolytically stable melt‐processable cumyl phenol end‐capped polyphosphonates were successfully achieved for the first time. Rheological studies show that these end‐capped systems are melt‐stable at 200 °C, whereas the systems of initially higher molecular weight but without any well‐defined end capping clearly degraded quickly probably as a result of an acid‐catalyzed hydrolysis process. Extensive high char yields were produced upon pyrolysis in either nitrogen or air, suggesting good fire resistance. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2904–2910, 2001
Synthesis of amino‐functionalized latex particles by a multistep method
Authors: Miraballes‐Martínez Iris , Martín‐Molina A. , Galisteo‐González F. , Forcada Jacqueline
Published: August 2002

Cationic latex particles with surface amino groups were prepared by a multistep batch emulsion polymerization. In the first one or two steps, monodisperse cationic latex particles to be used as the seed were synthesized, and in the third step, two different amino‐functionalized monomers [aminoethylmethacrylate hydrochloride (AEMH) and vinylbenzylamine hydrochloride (VBAH)] were used to synthesize the final functionalized latex particles. 2,2′‐Azobisisobutyramidine dihydrochloride was used as the initiator, and different concentrations of two quaternary ammonium emulsifiers with hydrophobic chains of different lengths were examined. To characterize the final latexes yields were obtained gravimetrically, and particle size distributions and average particle diameters were determined by transmission electron microscopy and photon correlation spectroscopy. The amount of amino groups was determined by fluorimetry. The effect of the amino‐functional monomer used on the final latexes and the colloidal behavior of the system were studied. The influence of the different conditions utilized to synthesize the latexes on the colloidal stability of the particles was evaluated in terms of the Fuchs stability ratio and electrophoretic mobility. High yields of the amino‐functional monomers were obtained. Surface amino, amidine, and quaternary ammonium groups provided the cationic character. The colloidal stability behavior of the products obtained was compatible with their cationic character. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2929–2936, 2001
Living tert‐butyllithium initiated anionic polymerization of 2‐vinylnaphthalene in toluene‐tetrahydrofuran mixtures
Authors: Nossarev Gennadi G. , Hogen‐Esch Thieo E.
Published: August 2002

The tert‐butyllithium (t‐BuLi) initiated polymerization of carefully purified 2‐vinylnaphthalene in toluene containing small amounts of tetrahydrofuran with respect to t‐BuLi proceeds on a timescale of several hours without significant deactivation and allows the synthesis of very narrow molecular weight distribution poly‐(2‐vinylnaphthalene) (P2VN) (polydispersities as low as 1.04) and molecular weights between 1000 and 20,000. The absence of P2VN‐Li deactivation at these conditions is also indicated by high degrees of trimethylsilyl end functionalization (>95%) and coupling with dibromoxylene. The respective polymerizations of conventionally purified monomer reveal a complex polymerization profile consistent with deactivation by 2‐acetylnaphthalene during the early stages of the reaction. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3034–3041, 2001
Reactions of polystyryllithiums and model lithium carbanions with 9,10‐bis(halomethyl)anthracenes
Authors: Tillman Eric S. , Nossarev Gennadi G. , Hogen‐Esch Thieo E.
Published: August 2002

The direct and nearly quantitative incorporation of 9,10‐anthracenylidene (AN) chromophores into polystyrene occurred via the reaction of polystyryllithium (PSLi) with 9,10‐bis(chloromethyl)anthracene (BCMA) at −78 °C in tetrahydrofuran (THF)/ hexane containing between 30 and 40 vol % hexane. Although the reaction of PSLi and BCMA or 9,10‐bis(bromomethyl)anthracene (BBMA) in THF at −78 °C gave nearly quantitative coupling, typically only 30–50% AN incorporation was observed, as determined by ultraviolet–visible spectrometry. Model coupling reactions of 3,3‐dimethyl‐1,1‐diphenyl‐1‐lithiobutane, (1,1,2,2‐tetramethyl)propylcyclopentadienyllithium, 9‐methylfluorenyllithium, and triphenylmethyllithium with BCMA or BBMA at −78 °C in THF in nearly all cases gave several AN‐containing coupling products. This was consistent with lithium–halogen exchange leading to the linking of multiple AN groups. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3121–3129, 2001
Synthesis and characterization of fully aromatic thermotropic liquid‐crystalline copolyesters containing m‐hydroxybenzoic acid units
Authors: Yerli̇kaya Zekeri̇ya , Aksoy Serpi̇l , Bayramli Erdal
Published: August 2002

A series of fully aromatic copolyesters based on p‐acetoxybenzoic acid (p‐ABA), hydroquinone diacetate (HQDA), terephthalic acid (TPA), and m‐acetoxybenzoic acid (m‐ABA) were prepared by a modified melt‐polycondensation reaction. The copolyesters were characterized by DSC, thermogravimetric analysis, 1H NMR, polarized optical microscopy, X‐ray diffraction, and intrinsic viscosity measurements. The copolyesters exhibited nematic liquid‐crystalline phases in a broad temperature range of about 150 °C, when the content of linear (p‐ABA, HQDA, and TPA) units was over 67 mol %. DSC analysis of the anisotropic copolyesters revealed broad endotherms associated with the nematic phases, and the melting or flow temperatures were found to be in the processable region. The flow temperatures and crystal‐to‐nematic and nematic‐to‐isotropic transitions depend on the type of linear monomer units, and these transitions increased as the content of the p‐ABA units increased, as compared to the HQDA/TPA units. When the content of the p‐ABA units increased, as compared to other linear units (HQDA and TPA), the intrinsic viscosity and degree of crystallinity of the copolyesters also increased, implying a higher reactivity for p‐ABA in the p‐ABA/HQDA/TPA/m‐ABA polymer system. The aromatic region in the 1H NMR spectra of the copolyesters containing equal molar compositions of p‐ABA, HQDA, and TPA units were sensitive to the sequence distribution of aromatic rings. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3263–3277, 2001
Viscoelastic diffusion
Authors: Vrentas J. S. , Vrentas C. M.
Published: August 2002

A constitutive equation is proposed for the viscoelastic diffusion flux, and this equation is used to calculate sorption curves for differential step‐change sorption experiments. The predictions of the theory are shown to be consistent with eight experimental observations that report a wide range of diffusional behaviors for polymer–solvent systems. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1529–1547, 2001
Superdrawing of polytetrafluoroethylene virgin powder above the static melting temperature
Authors: Endo Ryokei , Kanamoto Tetsuo
Published: August 2002

A new two‐stage draw technique was successfully applied to the superdrawing of polytetrafluoroethylene (PTFE) virgin powder. A film, compression‐molded from powder below the melting temperature (Tm = 335 °C), was initially solid‐state coextruded to an extrusion draw ratio (EDR) of 6–20 at 325 °C, about 10 °C below the Tm. These extrudates from the first‐stage draw were further drawn by a second‐stage pin draw in the temperature (Td) range of 300–370 °C that covers the static Tm. The maximum achievable total draw ratio was ∼60 at a Td = 300 °C and increased rapidly with increasing Td, reaching a maximum of 100–160 at a temperature window between 340 and 360 °C, depending on the initial EDRs. At yet higher Td's, the ductility was lost as a result of melting. The high ductility of the PTFE extrudates at such high temperatures was ascribed to the improvement of interfacial adhesion and bonding between the deformed powder particles upon the first‐stage extrusion combined with the rapid heating of only a portion of the extrudate followed by the elongation at a high rate. The highly drawn fibers were highly crystalline (χc ≤ 87%) and showed high chain orientation (fc ≤ 0.997) and a large crystallite size along the chain axis (D0015 ≤ 160 nm). The molecular draw ratio, estimated from the entropic shrinkage above the Tm, was close to the macroscopic deformation ratio independently of the initial EDRs. These results indicate that the draw was highly efficient in terms of chain extension, orientation, and crystallization. Thus, the maximum tensile modulus and strength achieved in this work were 102 ± 5 and 1.4 ± 0.2 GPa, respectively, at 24 °C. These tensile properties are among the highest ever reported on oriented PTFE. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1995–2004, 2001
Spinodal decomposition in N‐isopropylacrylamide gel
Authors: Hu Zhibing , Wang Changjie , Chen Yuanye , Zhang Xiaomin , Li Yong
Published: August 2002

Spinodal decomposition in a chemically crosslinked N‐isopropylacrylamide (NIPA) polymer gel was investigated using turbidity and ultrasonic techniques. The turbidity of the quenched NIPA gel was measured over five orders of magnitude of timescales. With an increase of time, the gel transfers from a transparent and swollen gel to a cloudy and inhomogeneous gel, and eventually to a transparent and collapsed gel. The first transformation is a rapid process that only involves local arrangement of the polymer network and solvent into dilute and dense domains. The second transformation is a very slow process that involves global arrangement of the polymer network and solvent. The characteristic time for disappearance of the turbidity is proportional to the linear size squared at a constant temperature above Tc and increases exponentially as a function of the quenching depth of T − Tc. By probing the movement of domains, a possible time‐dependent gel structure in the spinodal decomposition region is presented. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2168–2174, 2001