Development of a combined ultra- and diafiltration technique for use in speciation analysis of protein-bound cadmium in plants

Summary A combination of stepwise ultrafiltration with subsequent diafiltration for application in speciation analysis of aqueous biological samples is presented which allows the determination of distribution patterns without changing the native binding forms (species). This is possible without additional buffers and, furthermore, is less time consuming than conventional ultrafiltration. It is shown that preliminary statements about binding forms can be made by an optimization of this technique for the separation of an individual sample by recording and interpreting the filtration profile. The developed filtration technique is used for the evaluation of distribution patterns of proteins and cadmium species of an extract from self-cultivated dwarf runner beans to which cadmium was offered for uptake. According to these investigations, the cadmium species are present overwhelmingly in the molecular weight range >30,000 g/mol (61% of the total cadmium content).     

Mobilisationsverhalten von Thallium und Cadmium in einem Flu?sediment

Zusammenfassung An einem kontaminierten Flußsediment wird die Mobilität von Thallium und Cadmium untersucht. Die Metalle sind sehr fest an die Sedimentmatrix gebunden und werden erst unterhalb pH 2 in relevanten Mengen freigesetzt. Die Komplexbildner NTA und HEDP besitzen keinen Einfluß auf die Mobilisierbarkeit beider Metalle. Die Bestimmungen erfolgten durch Flammen-AAS und ET-AAS.

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Mobilization behaviour of thallium and cadmium in a river sediment

Summary The mobility of thallium and cadmium was studied on a polluted river sediment. The metals are strongly bound to the sediment matrix. They are released in significant amounts beyond pH 2. The complexing agents NTA and HEDP have no influence on the mobilization behaviour of both metals. The determinations were performed by flame AAS and ET-AAS.

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Wir danken dem Fonds der Chemischen Industrie für finanzielle Unterstützung und Herrn Dr. Jakobi (Henkel & Cie. GmbH, Düsseldorf) für die Bereitstellung der Phosphonsäure.     

Determination of cadmium, lead, and thallium in materials of the environmental specimen bank using mass spectrometric isotope dilution analysis (MS-IDA)

Summary An analytical procedure for the simultaneous determination of cadmium, lead, and thallium in the mg/kg- and g/kg-range in biological materials and sewage sludge by mass spectrometric isotope dilution analysis (MS-IDA) is described.Cadmium, lead, and thallium were separated by electrolytical deposition after low temperature ashing (LTA) of the samples in oxygen plasma and dissolution of the ashes in HNO₃ or HNO₃/HF. Measurement of the isotopic ratio was carried out with a thermal ionization mass spectrometer using the silica gel technique. Cadmium contents ranging from 1.03 to 4.60 mg/kg with relative standard deviations from 0.3 to 1.3%, lead contents ranging from 75 g/kg to 25 mg/kg with relative standard deviations from 0.6 to 3.5%, and thallium contents ranging from 2.9 to 247.7 g/kg with relative standard deviations from 0.1 to 1.7% were determined in the materials of the environmental specimen bank analyzed.

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Bestimmung von Cadmium, Blei und Thallium in Materialien der Umweltprobenbank mit der massenspektrometrischen Isotopenverdünnungsanalyse

Zusammenfassung Ein Analysenverfahren zur simultanen Bestimmung von Cadmium, Blei und Thallium im mg/kg- und g/kg-Bereich in biologischen Materialien und Klärschlamm mit der massenspektrometrischen Isotopenverdünnungsanalyse (MS-IDA) wird beschrieben.Nach Niedertemperaturveraschung (LTA) der Proben im Sauerstoffplasma und Lösen der Aschen in HNO₃ oder HNO₃/HF-Gemisch werden Cadmium, Blei und Thallium durch elektrolytische Abscheidung abgetrennt. Die Isotopenverhältnismessung erfolgt mit der Silicageltechnik in einem Thermionen-Massenspektrometer. In den analysierten Probenbankmaterialien werden Cadmiumgehalte im Bereich von 1,03 bis 4,60 mg/kg mit relativen Standardabweichungen von 0,3 bis 1,3%, Bleigehalte im Bereich von 75 g/kg bis 25 mg/kg mit relativen Standardabweichungen von 0,6 bis 3,5 % und Thalliumgehalte im Bereich von 2,9 bis 247,7 g/kg mit relativen Standardabweichungen von 0,1 bis 1,7% bestimmt.

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday     

Nitroxide‐mediated Living Radical Polymerization of Styrene with Fluorescent Initiator

A fluorescence method was used for determination of marked chain ends in polystyrene samples prepared by 4‐substituted TEMPO type nitroxide‐mediated living free radical polymerization of styrene. 2,2,6,6‐Tetramethyl‐1‐(1‐phenylethoxy)‐piperidin‐4‐yl‐4‐pyren‐1‐ylbutanoate (PYNOR) was prepared and used as an unimolecular initiator bearing pyrene as a fluorescence mark on mediating nitroxide fragment. The bulk polymerization of styrene at 120°C, in the presence of new unimolecular initiator, was a typical nitroxide mediated living radical polymerization. For comparison, two different molar ratios of initiator and monomer (1∶400 and 1∶1000 initiator ‐ monomer [I:M]) were used for polymerization. When I:M=1∶400, the obtained polydispersity was 1.12 and maximum molecular weight 27,000 g/mol was obtained at 62% conversion. For ratio 1∶1000, slightly higher polydispersity was obtained ?1.26 and the molecular weight was 53,000 g/mol at 70% conversion. The content of the polystyrene chains bearing mediating nitroxide fragment was determined by fluorescence spectroscopy. The intensity of pyrene fluorescence decreased as the molar mass, and the conversion increased as well. The extent of the incorporation of chromophore at propagating chain end or “livingness” of polymerization decreased despite the fact that the polydispersity did not change. The extent of side reaction leading to broadening of polydispersity is suppressed due to the high viscosity of the system at higher conversion. A low extent of “livingness” will have a very negative effect on possible preparation of block copolymers.     

Die Bestimmung von Schwermetallen in nativer Nierenmatrix mittels Feststoffanalytik und Atomabsorptionsspektrometrie

Summary Solid sample analysis by Zeeman AAS is a method which allows rapid determination of lead and cadmium in small amounts of fresh renal tissue without time consuming chemical digestion. The renal cortex is preferable to other tissues or the whole kidney to optimize standardization of sampling, homogeneity, element concentration and microsampling. The analytical quality is sufficient to detect limit concentrations of Pb and Cd in the kidney and normal levels as well.

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Teil I: Fresenius Z Anal Chem 328:370     

Determination of thallium and lead in cadmium salts by anodic stripping voltammetry with addition of surfactants to suppress the cadmium peaks

Conditions have been found which make possible the determination of thallium and/or lead in cadmium and its salts without preliminary separation. The electrochemical activity of the cadmium, which usually interferes in the determination of thallium, is inhibited by the addition of 0.01% of polyethylene glycol of M.W. 4000. Thallium is determined by electrolysis at ?0.74 V vs. SCE, in 0.1M EDTA solution: 10^?1M thallium can be determined in the presence of 0.1M cadmium, while copper and lead at 10^?2M and 10^?5M respectively do not interfere. Lead is determined in 0.1M acetic acid containing 0.1% cetyltrimethylammonium bromide (CTAB). The addition of CTAB shifts the cadmium peak, as well as the optimum deposition potential for cadmium, to more negative values, making it possible to determine lead in the presence of cadmium as long as the deposition potential lies in the range between ?0.50 and ?0.56 V vs. SCE. Lead can be determined in the presence of ten times as much thallium.     

Proximate Composition,Antioxidant Properties,and Hepatoprotective Activity of Three Species of Shellfish of the Pacific Coast of Russia

The objective of the present study was to investigate the proximate composition, antiradical properties and hepatoprotective activity of three species of shellfish, Corbicula japonica, Spisula sachalinensis, and Anadara broughtonii, from the coastal areas of Far East Russia. Biologically active peptides such as taurine (3.74 g/100 g protein) and ornithine (2.12 g/100 g protein) have been found in the tissues of A. broughtonii. C. japonica contains a high amount of ornithine (5.57 g/100 g protein) and taurine (0.85 g/100 g protein). The maximum DPPH and ABTS radical scavenging activity (36.0 µg ascorbic acid/g protein and 0.68 µmol/Trolox equiv/g protein, respectively) was determined for the tissue of C. japonica. The protein and peptide molecular weight distribution of the shellfish tissue water extracts was investigated using HPLC. It was found that the amount of low molecular weight proteins and peptides were significantly and positively correlated with radical scavenging activity (Pearson’s correlation coefficient = 0.96), while the amount of high molecular weight proteins negatively correlated with radical scavenging activity (Pearson’s correlation coefficient = −0.86). Hepatoprotective activity, measured by the survival rate of HepG2 hepatocytes after cotreatment with t-BHP, was detected for C. japonica. The highest protection (95.3 ± 2.4%) was achieved by the cold water extract of C. japonica at the concentration of 200 mg/mL. Moreover, oral administration of hot water extract of C. japonica to rats before the treatment with CCl₄ exhibited a markedly protective effect by lowering serum levels of ALT and AST, inhibiting the changes in biochemical parameters of functional state of rat liver, including MDA, SOD, GSH and GST.     

Analyse von organosiliciumverbindungen

Zusammenfassung Bei der Analyse von technischem Hexamethyldisiloxan wurden in den höhersiedenden Destillationsanteilen eine Reihe von bisher wenig bekannten niedermolekularen Organosiliciumverbindungen mit siloxanartiger Struktur gefunden. Die Trennung und Identifizierung der Komponenten der Gemische von verzweigten Methyl- und Methylhydroxiloxanen erfolgte durch gas-chromatographische Methoden in Verbindung mit der Massenspektrometrie.

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Analysis of organosilicon compounds VII separation and identification of branched low molecular weight methyl-and methylhydrosiloxanes by GC/MS

Summary A series of unusual, low molecular weight organosilicon compounds with the siloxane structure has been found as a result of the analysis of hexamethyldisiloxane by gas chromatography. The components of the mixture of branched, low molecular weight methyl- and methylhydrosiloxanes have been identified by gas chromatography and mass spectrometry.

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VI. Mitteilung: Coll. Czech. Chem. Comm.36, 3497 (1971).     

Styrene polymerization with rare earth catalysts using a magnesium alkyl cocatalyst

A new highly active rare earth coordination catalyst composed of rare earth phosphonate, di-n-butylmagnesium (MgBu), and hexamethyl phosphoramide (HMPA) for the polymerization of styrene has been developed for the first time. High molecular weight polystyrene (M̄_ν = 50–70 × 10⁴) in 100% conversion could be prepared at following conditions: [Nd] = 6–8 × 10⁻⁴ mol/L, [St] = 3.0 mol/L, Mg/Nd = 11, and HMPA/Mg = 1–1.5 (molar ratio). The catalytic activity of this new catalyst is 3530 g PSt/g Nd. Kinetics study shows that the polymerization rate is of first order with respect to both monomer concentration and catalyst concentration, and activation energy of the polymerization is 40.1 kJ/mol. © 1996 John Wiley & Sons, Inc.     

Confined crystallization behaviors of cross-linked comb-like copolymers

Cross-linked PEG-based copolymers were obtained via synthesis of polyethylene glycol (PEG) and methoxy polyethylene glycol (MPEG) by the bridging and/or cross-linking agent of 2,4-tolylene diisocyanate (TDI) and/or hexamethylene-1,6-diisocyanate homopolymer (HDI trimer). The effects on the crystallization behaviors of the samples could be found with the changes in molecular weight of MC-PEG and molecular weight of SC-PEG in certain cross-linked density. It is revealed that the samples appear not to crystallize when the molecular weight of MC-PEG and SC-PEG are 1000 g/mol or less than that. The samples begin to crystallize when the molecular weight of either MC-PEG or SC-PEG reaches 2000 g/mol. The crystallinity of crystallized MC-PEG decreases with the increasing molecular weight of uncrystallized SC-PEG and the crystallinity of crystallized SC-PEG declines with the rise of molecular weight of uncrystallizable MC-PEG. The chains of SC-PEG (M _n = 2000 g/mol) can fold and align easilier than those of MC-PEG (M _n = 2000 g/mol), when the content of PEG is the same.     

Polarographic determination of Cu, Cd, Pb, Bi and Tl in succinic acid

Summary Copper, cadmium, lead, bismuth, and thallium develop well defined polarograms in 0.1 M succinic acid at pH 3.0 in presence of 0.005% gelatin (except Cu which requires 0.01% gelatin). The polarograms of all these metal ions are diffusion controlled with E _1/2 at –0.07 V, –0.60 V, –0.43 V, –0.11 V, and –0.50 V vs. S.C.E., respectively. Since the half wave potentials of some of the metal ions are well separated, their simultaneous polarographic determination is possible (Cu/Pb, Bi/Pb, Pb/Zn, Cu/Cd).

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Polarographische Bestimmung von Cu, Cd, Pb, Bi und Tl in Bernsteinsäurelösung

Zusammenfassung Die genannten Metalle liefern gut ausgebildete diffusionskontrollierte Polarogramme in 0,1 M Bernsteinsäurelösung bei pH 3,0 in Gegenwart von 0,005% Gelatine (0,01% bei Cu). Die Halbstufenpotentiale betragen: –0,07 V, –0,60 V, –0,43 V, –0,11 V bzw. –0,50 V (gegen GKE). Da sie teilweise gut voneinander getrennt sind, können Bestimmungen dieser Metalle nebeneinander ausgeführt werden (Cu/Pb, Bi/Pb, Pb/Zn, Cu/Cd).

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Our sincere thanks are due to Dr. G. B. Singh, Professor and Head, Dept. of Chemistry, B. H. U., for providing the necessary facilities.     

Bestimmung der Konzentrationsverteilung von Dotierungsstoffen in Selengleichrichterschichten

Zusammenfassung Es wird über eine Methode zur Ablösung und Analyse von ca. 1 m starken Selenschichten von handelsüblichen Gleichrichterplatten berichtet. Damit ist es möglich, durch schichtweise Analyse die Verteilung der Dotierungsstoffe und der aus den angrenzenden Materialien eindiffundierenden Metalle zu ermitteln. Die Analyse erstreckt sich auf die Elemente Chlor, Jod, Cadmium, Zinn, Eisen, Nickel, Wismut, Thallium, Tellur und Gallium. An einigen Beispielen wird die Leistungsfähigkeit der Methode demonstriert. Zur Zeitraffung der zum Teil sehr aufwendigen Arbeiten erfolgt die chemische Ablösung in einer automatischen Einrichtung.

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Determination of the concentration distribution of doping substances in layers of selenium rectifiers

A method is proposed for the stripping and analysis of selenium layers ( 1 m) of commercial rectifier plates. Thus, the distribution of the doping substances and of the metals diffusing from the adjacent materials can be determined by analysis of single layers. The following elements have been determined: chlorine, iodine, cadmium, tin, iron, nickel, bismuth, thallium, tellurium and gallium. The efficiency of the method is demonstrated with some examples. The chemical stripping is accelerated by an automatic device.

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Kurzvortrag auf der Frühjahrstagung des FA Halbleiter der Deutschen Physikalischen Gesellschaft in Berlin am 21. 3. 1968.

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Herrn Dr. Schillmann danken wir für die Anregung und stetige Förderung der Arbeit.     

Functional polyisobutylenes via electrophilic cleavage/alkylation

Lewis‐acid catalyzed degradation of poly(isobutylene‐co‐isoprene) (butyl rubber) in the presence of an alkoxybenzene compound was studied as a new route toward low molecular weight multifunctional polyisobutylenes. Simultaneous cleavage and functionalization of butyl rubber was conducted at ?70 °C and ?40 °C under TiCl₄ or AlCl₃ catalysis in 60/40 hexane/methylene chloride cosolvents in the presence of (3‐bromopropoxy)benzene (BPB) for various times up to 24 h. The butyl rubber (EXXON? Butyl 365) possessed M _n = 1.91 × 10⁵ g/mol, PDI = 1.66 (GPC/MALLS), and 2.30 mol % isoprene units (nearly exclusively trans ?1,4). At ?70 °C with TiCl₄, molecular weight was reduced to various values within the range 7 to 11 × 10³ g/mol depending on conditions; lower BPB concentration produced lower molecular weight. However, the ratio of isobutylene repeat units to BPB units (IB/Q ) remained constant at about 43:1, which is approximately the same as the ratio of isobutylene to isoprene repeat units (IB/IP) in the starting butyl rubber (42.5:1). At ?40 °C with TiCl₄, molecular weight was reduced to about 5 × 10³ g/mol, and IB/Q was reduced below IB/IP, indicating nearly a difunctional telechelic structure. AlCl₃ was a more active catalyst and produced results similar to TiCl₄ at ?40 °C, even when used at seven times lower concentration. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1991–1997     

1-(2-Pyridyl-azo)-2-naphthol (PAN) als photometrisches Reagens

Zusammenfassung Es wird ein Verfahren zur photometrischen Bestimmung von Zink- und Cadmiumverunreinigungen in Reinkupfer beschrieben, sowie einige Erfahrungen bei der Verwendung von Chloroform zur Extraktionsanalyse mitgeteilt.Bei 2 g Einwaage lassen sich mit PAN als Reagens noch wenige ppm Zink und Cadmium mit einer Genauigkeit von einigen Prozent erfassen. Das Chloroform zur Extraktion muß vorgeprüft und gegebenenfalls von Oxydationsprodukten usw. nach einem einfachen alkalischen Waschverfahren befreit werden, um vorzeitige Farbstoffzersetzung zu vermeiden.

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Summary A method is described for the photometric determination of impurities of zinc and cadmium in pure copper and some experiences are mentioned concerning the application of chloroform to analytical extraction methods.A few ppm of zinc and cadmium can be detected with an accuracy of some per cents from a sample weight of 2 g using PAN as reagent. The chloroform for the extraction has to be pretested. If necessary oxidation products have to be removed by a simple alkaline washing procedure in order to prevent decomposition of the dye.

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I. Mitteilung: Berger, W., u. H. Elvers: diese Z. 171, 255 (1959/60).     

微波消解–电感耦合等离子体质谱法测定酱卤肉中铬、砷、镉、铊、铅

建立微波消解–电感耦合等离子体质谱法测定酱卤肉中铬、砷、镉、铊、铅5种元素含量的检测方法。采用微波消解法处理酱卤肉样品,对预处理条件和仪器工作参数进行了优化,以内标校正法降低基体影响。结果表明,铬、砷、镉、铊、铅5种元素的质量浓度在0.1~50.0 μg/L范围内与质谱响应值具有良好的线性关系,相关系数均大于0.999,方法检出限为0.2~6.2 μg/kg。在3种加标浓度水平下平均回收率为72.4%~113.5%,测定结果的相对标准偏差为3.1%~7.7%(n=6)。该方法简便,快速,高效,准确,可为酱卤肉中铬、砷、镉、铊、铅的测定提供技术支持。     

Die mikromaßanalytische und polarographische Bestimmung von Thalliumspuren

Zusammenfassung Die Möglichkeiten zur Isolierung von Thalliumspuren werden kritisch betrachtet. Die Ätherextraktion aus salzsaurer, bromwasserstoffsaurer und jodwasserstoffsaurer Phase wird untersucht. Thallium kann in Anwesenheit größerer Mengen von Eisen, Kupfer, Zink und anderen Dithizonmetallen sowie Alkalien und Erdalkalien aus 3-n Bromwasserstoffsäure mit Isopropyläther quantitativ isoliert werden. Die isolierten Thalliumspuren von 1 bis 1000 g werden mikrojodometrisch oder polarographisch bestimmt. Die polarographische Bestimmung erfolgt in 6-n Ammoniak als Grundlösung. Das angegebene Anreicherungsverfahren ermöglicht die Bestimmung von Thallium in fast allen organischen oder anorganischen Materialien spezifisch und sehr empfindlich.

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Summary A critical review of the possibilities of isolating traces of thallium is given. A study was made of the ether extraction from the hydrochloric, hydrobromic, and hydriodic acid phase. Thallium can be quantitatively isolated by means of isopropyl ether from 3N hydrobromic acid in the presence of considerable amounts of iron, copper, zinc, and other dithizone metals as well as alkalis and alkaline earths. The isolated traces of thallium, from 1 to 1000 g are determined microiodometrically or polarographically. The polarographic determination employs 6N ammonia as fundamental solution. The stated accumulation procedure permits the determination of thallium in practically all organic or inorganic materials specifically and with high sensitivity.

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Résumé Considération critique des possibilités d'isolement de traces de thallium. Recherches sur l'extraction par l'ether des phases chlorhydrique, bromhydrique et iodhydrique. Il est possible de séparer quantitativement le thallium par extraction par l'éther isopropylique d'une solution 3 N d'acide bromhydrique en présence de quantités élevées de fer, de cuivre, de zinc et d'autres métaux réagissant avec la dithizone ainsi que des métaux alcalins et alcalino-terreux. Les traces de thallium en quantités comprises entre 1 et 1000 g sont déterminées après leur isolement par microiodométrie ou polarographie. Le dosage polarographique est effectué dans une solution d'ammoniaque 6 N. La technique d'enrichissement décrite permet de doser le thallium avec spécificité et grande sensibilité dans la plupart des milieux organiques ou minéraux.

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Herrn Prof. Dr.Hans Lieb zum 70. Geburtstag ergebenst gewidmet.

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Die Verfasser danken FrauleinI. Polewacz und HernW. Bonsels für die sorgfältige Ausführung der Verschue.     

Zur Analytik von Elementbindungsformen in Bodenl?sungen mit Gel-Chromatographie und chemischen Reaktionsdetektoren

Zusammenfassung Durch die Kopplung von Gel-Chromatographie mit photometrischen Messungen in chemischen Reaktionsdetektoren werden Verteilungsmuster für organisch gebundene Elementgehalte (Al, Fe, Zn) in einer Gleichgewichtsbodenlösung im Hinblick auf UV-detektierbare Substanzen unterschiedlicher Molgrößenbereiche und auf phenolische OH-Gruppen ermittelt. Mittels Gel-Chromatographie wurden die Auftrennungen organischer Stoffe an 17 im Handel erhältlichen Gelen verglichen. Die Molgrößenverteilung an Sephadex G-25 wird anhand von Ultrafiltrationen überprüft. Die Anwendung weiterer Analysentechniken (photometrische Continuous-Flow-Analyse, AAS) läßt eine Differenzierung in freie Metallspezies, kinetisch labile und stabile Komplexe zu. Die ersten Ergebnisse zeigen, daß kinetisch labile Metallspezies vorwiegend an nieder- und mittelmolekularen organischen Molekülen (Zn) bzw. an niedermolekularen Stoffen (Al, Fe) gebunden sind. Die Verteilungsmuster für Al und Fe korrelieren mit der Verteilung phenolischer OH-Gruppen.

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Element species analysis in soil solutions by gel chromatography and chemical reaction detectors

Summary By coupling gel chromatography with photometric measurements in chemical reaction detectors, distribution patterns were found for organically bound element contents (Al, Fe, Zn) in a soil equilibrium solution by means of u.v. detectable substances of different molecular weight ranges and by means of phenolic OH-groups. The resolutions of organic matter by 17 commercially available gels were compared by gel chromatography. The molecular weight distribution on Sephadex G-25 is rechecked by ultrafiltration technique. A differentiation of free metal species, kinetically labile and stabile complexes is possible due to the application of further analytical techniques (photometrically continuous-flow-analysis, AAS). First results show that kinetically labile metal species are predominantly bound to low and medium molecular organic molecules (Zn) or to low molecular matter (Al, Fe), respectively. The distribution patterns of Al and Fe correlate with the distribution of phenolic OH-groups.

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Herrn Prof. Dr. W. Fresenius zum 70. Geburtstag gewidmet

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Die Arbeiten wurden aus Mitteln des Niedersächsischen Ministers für Wissenschaft und Kunst im Rahmen eines Forschungsvorhabens unterstützt.

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Vortragender     

Cationic cyclopolymerization of new divinyl ethers: The effect of ether and ester neighboring functional groups on their cyclopolymerization tendency

The cationic polymerization of two new divinyl ethers, 1‐(2‐vinyloxyethoxy)‐2‐[(2‐vinyloxyethoxy)carbonyl]benzene ( 2 ) and 1,2‐bis[(2‐vinyloxyethoxy)carbonyl]benzene ( 3 ), as well as 1,2‐bis(2‐vinyloxyethoxy)benzene ( 1 ), with BF₃OEt₂ in CH₂Cl₂ at 0 °C at low initial monomer concentrations ([M]₀ = 0.15 and 0.075 M) gave soluble polymers with relatively high molecular weights and broad molecular weight distributions (MWDs), whereas reactions with the HCl/ZnCl₂ initiating system yielded soluble polymers with relatively narrow MWDs (weight‐average molecular weight/number‐average molecular weight ? 1.6) under similar reaction conditions. An NMR structural analysis of the HCl/ZnCl₂‐mediated polymers from the divinyl ethers showed that poly( 1 ) had virtually no unreacted vinyl ether groups throughout the polymerization (monomer conversion = 28–98%), whereas poly( 2 ) and poly( 3 ) possessed some amount of unreacted vinyl ether groups in the initial stage of the polymerization; the content of the vinyl groups of poly( 2 ) was 18 mol % at a 15% monomer conversion, and the content of the vinyl groups of poly( 3 ) was 31 mol % at an 18% monomer conversion. Therefore, divinyl ether 1 underwent cyclopolymerization exclusively to give almost completely cyclized polymers [degree of cyclization (DC) ～ 100%], whereas divinyl ethers 2 and 3 exhibited a lower cyclopolymerization tendency [DC for poly( 2 ) = 82%; DC for poly( 3 ) = 69%]. The differences in the cyclopolymerization tendencies among the divinyl ethers can be explained by the differences in the solvation powers of the neighboring functional groups adjacent to the vinyl ether moiety with the active center: the ether oxygen of the ether neighboring group solvates intramolecularly with the active center to accelerate the intramolecular propagation, but such an interaction is less effective with the more electron‐deficient oxygen attached to the carbonyl group of the ester neighboring group. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 281–292, 2003     

Aliphatic-aromatic poly(ether amide)s containing oxyethylene units. Synthesis and characterization

The synthesis and characterization of aromatic polyamides containing oxyethylene units is reported, and the differences observed in polycondensation yields, molecular weights, and molecular weight distributions, as a function of the method of synthesis, are discussed. Four diamines containing oxyethylene units and aromatic rings, meta and para oriented, and their corresponding hydrochlorides were prepared as condensation monomers to be combined with isophthaloyl chloride (IPC) and terephthaloyl chloride (TPC). High molecular weight polyamides were obtained by interfacial and low-temperature solution methods. Values of (OVERLINE)M(/OVERLINE)_n up to 6 × 10⁴ g/mol and (OVERLINE)M(/OVERLINE)_w up to 2 × 10⁵ g/mol could be measured by gel permeation chromatography using aromatic polyamide standards, and values of (OVERLINE)M(/OVERLINE)_n up to 2 × 10⁵ g/mol and (OVERLINE)M(/OVERLINE)_w up to 5 × 10⁵ g/mol by using polystyrene standards. © 1996 John Wiley & Sons, Inc.