In‐line monitoring of UV photopolymerization with a quartz crystal resonator

An in‐line monitoring device using a quartz crystal resonator for thin film polymerization was proposed, and its performance has been evaluated by implementing in the UV polymerization of 2‐hydroxyethyl methacrylate with a photoinitiator of 1‐chloroanthraquinone. Because the variation of resonant resistance of the resonator is proportional to the square root of viscosity change that is closely related to the polymerization degree, the resistance can be used as a measure of the polymerization degree. The resistance measurements were compared with the outcome of instrumental analyses of polymerization degree using an FTIR spectrometer and a gel permeation chromatograph. The experimental results showed that the resistance measurements were consistent with the experimental outcome of the instrumental analyses, and this indicates the effectiveness of the proposed device. Owing to the simplicity and availability of the resonator system, its wide utilization in the monitoring of a variety of film polymerization processes, including photoresistor application, is expected. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2428–2439, 2006     

Lithographic design of photosensitive polyarylates based on reaction development patterning

The factors affecting pattern‐forming properties in reaction development patterning were examined with polyarylates with various bisphenol moieties. The developability of the photosensitive polyarylates was dependent on the properties of the subtituent (R) in the bisphenol moieties. The development time decreased in the following order: R?C(CH₃)₂ > fluorenyl unit ? phenolphthalein unit > C(CF₃)₂ > SO₂. This order agreed with that of the reactivity between the polyarylates and ethanolamine, and these orders can be explained by pK_a of the bisphenol used to prepare the polyarylates. The development with NH₂? R′? OH resulted in successful positive‐tone pattern formation. However, pattern formation with the developers containing NH₂? R′? OCH₃ was unsuccessful. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2694–2706, 2006     

The response of microstructure to processing in a series of poly(siloxaneimide) copolymers

Poly(siloxaneimide) (PSI) segmented copolymers exhibit organized microdomains if the blocks are sufficiently incompatible. As with neat diblock and triblock copolymers, the processing route employed to prepare films of PSI materials is expected to influence the dimensions and/or morphology of the resultant microstructure. In this work, small-angle neutron scattering (SANS) is utilized to characterize the disordered microstructure found in films of a series of PSI copolymers which are subjected to solvent casting and various thermal treatments. Microstructural dimensions such as the periodicity and correlation length are deduced from the Teubner-Strey (TS) model for disordered microemulsions. The scattering intensity of each copolymer up to q = 5.0 nm^?1, where q is the scattering vector, is found to scale as q^?2.8+?0.1. Results indicate that processing the materials as cast films or as melt-pressed films allowed to cool slowly has a small, but discernible, effect on microstructural characteristics. SANS profiles of films quenched from elevated temperatures reveal a clear transition in microdomain periodicity, which correlates well with the glass transition temperature of the imide microphase in these and other materials of similar chemical structure. © 1993 John Wiley & Sons, Inc.     

Chemiluminescent determination of reactive hydrocarbons

Summary Chemiluminescent reactions of ozone with several classes of compounds at different temperatures are described. In a reaction chamber in front of a photomultiplier ozone is mixed with the compounds studied such as alkanes, olefins, alcohols, aromatics, C₂H₂, NO, vinyl chloride or H₂S. The chemiluminescent emission is proportional to the concentration of the compound involved. At room temperature only olefinic hydrocarbons respond but at temperatures above 150°C also a response for alkanes, alcohols, CO etc. is obtained. It is suggested that next to the ozonide-excited formaldehyde mechanism the CO-CO ₂ ^* mechanism is responsible for the chemiluminescent emission at high temperature. A detection limit of a few ppb is achieved. Possible applications are a selective gas-chromatographic detector, an air pollution monitor for instance for CO, and a photochemical reactivity monitor.

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Bestimmung reaktiver Kohlenwasserstoffe durch Chemiluminescenz

Zusammenfassung Chemiluminescenzreaktionen von Ozon mit verschiedenen Verbindungsgruppen (hauptsächlich Kohlenwasserstoffe) bei unterschiedlichen Temperaturen werden beschrieben. In einer Reaktionskammer werden die Verbindungen vor einem Photomultiplier mit Ozon vermischt. Es handelt sich u. a. um folgende Verbindungstypen: Alkane, Olefine, Alkohole, Aromaten, C₂H₂, NO, Vinylchlorid, H₂S. Die Emissionsintensität ist proportional der Konzentration. Bei Raumtemperatur sprechen nur Olefine an, die übrigen Verbindungen erst über 150°C. Die Emission bei höherer Temperatur wird neben der Bildung von Formaldehyd auf die Reaktion CO-CO ₂ ^* zurückgeführt. Die Nachweisgrenze beträgt wenige ppb. Als mögliche Anwendungsgebiete werden ein selektiver GC-Detektor, ein Monitor für Luftverunreinigungen (z.B. für CO) sowie ein Monitor zur Messung photochemischer Reaktivität der Luft genannt.

Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria.     

R?ntgenspektrometrische Elementbestimmung in Abwasser: Probenvorbereitung und Matrixkorrekturverfahren

Zusammenfassung Für Elementbestimmungen in Abwasser wird ein Röntgenfluorescenzverfahren beschrieben. Zur Probenvorbereitung werden die Elemente durch Gefriertrocknung auf einem inerten Träger angereichert. Diese Anreicherung ist nicht selektiv und erfaßt praktisch alle in Abwasser gelösten und suspendierten Verunreinigungen. Für die Berechnung der Elementkonzentrationen aus den gemessenen Fluorescenzintensitäten wird ein Matrixkorrekturverfahren angegeben, welches dem unterschiedlichen Absorptionsverhalten der Probenmatrix Rechnung trägt. Die Massenabsorptionskoeffizienten werden durch Messung der diffus gestreuten Bremsstrahlung bzw. der Comptonstreustrahlung ermittelt. Die Selbstabsorption des zu bestimmenden Elementes wird rechnerisch berücksichtigt. Das Korrekturverfahren kann auf alle mit Röntgenfluorescenzanalyse bestimmbaren Elemente angewendet werden.

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Determination of elements in waste water by x-ray fluorescence analysis: Sample preparation and matrix correction method

Summary For sample preparation the elements are enriched upon an inert carrier by freeze-drying. This enriching procedure is not selective and collects all dissolved and suspended contaminations from the waste water. In order to calculate the element concentrations from the measured fluorescence intensities a matrix correction method is given which considers the different absorption behaviour of the matrix. The mass absorption coefficients are obtained by measuring the scattered X-ray tube spectrum or a Compton scattered X-ray tube line, respectively. The self-absorption of the element to be determined is taken into account. The correction method is applicable to all elements detectable by X-ray fluorescence.

Herrn Dr. H. Wagner danken wir für das stete Interesse, die zahlreichen konstruktiven Diskussionen und die Hilfe beim Abfassen des Manuskripts.     

Vergleichende Untersuchung der Bestimmung von Apolipoprotein B

Ohne Zusammenfassung

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Comparative investigation of the determination of apolipoprotein B

     

Enthalpimetric and thermometric determination of some nitrogen containing bases and some physiologically active alkaloids

Summary The enthalpimetric determination of a series of bases by using the reaction of the bases and sodium tetraphenylboron is described. The accuracy of the method is analytically acceptable, over the range 3×10^–5 moles to 7.5×10^–4 moles. The upper limit is determined by the bulk of the precipitate.Dosage forms of some physiologically active alkaloids contain more than the upper limit of analyte. Yet, preliminary investigations using silicotungstic acid indicate that this is suitable for thermometric titrations.

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Enthalpimetrische und thermometrische Bestimmung stickstoffhaltiger Basen und physiologisch aktiver Alkaloide

Zusammenfassung Die enthalpimetrische Bestimmung einiger N-haltiger Basen erfolgte aufgrund der Reaktion mit Natriumtetraphenyloborat. Die Genauigkeit ist im Bereich von 3 · 10^–5-7,5 · 10^–4 Mol befriedigend. Eine obere Grenze der Anwendbarkeit ergibt sich aus der Menge des anfallenden Niederschlags. Diese wird bei der Bestimmung von Formulierungen einiger physiologisch aktiver Alkaloide überschritten. Jedoch ist in diesem Fall eine thermometrische Titration mit Hilfe von Silicowolframsäure möglich.

Lecture presented at Euroanalysis I Conference, 28. 8.–1. 9. 1972 in Heidelberg, Germany.