SYNOPSISThe metal-complexing properties of five different polyaziridines-poly[I-(2-aminoethyl)aziridine], poly( 1-acetylaziridine), poly[ 1-(2-hydroxyethyl)aziridine], poly[l-(2-hy-droxyethy1)aziridine-co-1-acetylaziridine], and poly[ 1-(2-aminoethyl)aziridine] oxine-were investigated in an aqueous solution with regard to the side-chain effects using membrane filtration. The results are discussed and compared with the stability constants of metal complexation of the corresponding functional moieties. Poly[ 1-(2-aminoethyl)aziridine], a poly(aziridine) with neutral nitrogen donors in the side chains, showed similar complexing properties to those of ammonia. The only exceptions are Fe(II1) and Cr(III), which cannot form complexes with ammonia but can be retained in the membrane filtration process due to the formation of Fe(II1)-colloidal species and hydroxides. The complexing properties of polyaziridines containing hydroxyl groups in the side chains (i.e., poly[l-(2-hydroxy-ethy1)aziridinel and poly[ 1 -(2-hydroxyethyl)aziridine-co-l-acetylaziridine] can be explained and described by the formation constants with the corresponding hydroxides. The introduction of a carbonyl moiety in the polyaziridine side chain, e.g., polyacetylaziridine, reduces the complexing ability for metal ions because the carbonyl group cannot form complexes with the metal ions investigated. Poly[ 1-(2-aminoethyl)aziridine]oxine showed the strongest complexing ability in the series of metal ions due to the strong complexing ligand 8-hydroxy quinoline attached to the polymer backbone.

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The metal complexation of water-soluble poly[l-(2-hydroxyethyl)aziridine-co-2methyl-2-oxazoline] with Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(II), and Sr(I1) ions was investigated in aqueous phase using Liquid-Phase Polymer-Based Retention (LPR). The study shows that all metal ions are complexed at pH 5 , except Co(I1) and Zn(I1). In contrast to Sr(II), which showed only a slight interaction over a pH range of 3 to 7, 94% of Co(I1) and 88% of Zn(I1) were retained at pH 7. At pH 3, only Cu(I1) and Cr(II1) ions interacted with the copolymer with retention values of 76% for Cu(I1) and 52% for Cr(II1). Viscosimetric measurements of the copolymer were performed in the presence of metal ions at different pH values. ZUSAMMENFASSUNG:Die Metallkomplexierung von wasserloslichem Poly[l-(2-hydroxyethyl)aziridin-co-2-methyl-2-oxazolin] mit Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(I1) und Sr(I1)-Ionen wurde in waBriger Phase mit der Methode der Liquid-Phase Polymer-Based Retention (LPR) untersucht. Die Studie zeigt, da13 alle Metallionen, auBer Co(I1) und Zn(II), bei pH 5 komplexiert wurden. Im Gegensatz zu Sr(II), das nur eine schwache Wechselwirkung in einem pH-Bereich von 3 bis 7 zeigte, wurden bei pH 7 94% Co(I1) und 88% Zn(I1) retentiert. Bei pH 3 zeigten nur Cu(I1) und Cr(II1) eine Wechselwirkung mit dem Polymeren, wobei die Retentionswerte 76% fur Cu(I1) und 52% fur Cr(II1) betrugen. Viskositatsmessungen des Copolymeren in Gegenwart von Metallionen wurden bei verschiedenen pH-Werten durchgefuhrt.

The selection of sensitive coatings is a critical task in the design and implementation of chemical sensors using coated thickness shear mode quartz crystal resonators (QCRs) for detection in liquid environments. This design or selection is performed through a study of the sorption process in terms of the partition coefficients of the analytes in the coatings. The partition coefficient, which is controlled by the chemical and physical properties of the coating materials, determines the inherent selectivity and sensitivity toward analyte molecules. The selection of the coatings is logically determined by the interactions between coating and target analyte molecules, but can also be made through a systematic variation of the coating's properties. The determination of the partition coefficients is only accurate if all contributions to the total measured frequency shifts, deltafs, of the coated QCR can be established. While mass loading is often assumed to be the dominant factor used in determining partition coefficients, viscoelastic effects may also contribute to deltafs. Both the effect of viscoelastic properties and the effect of mass loading on the sensor responses are investigated by using a network analyzer and oscillator circuit and by characterizing the total mechanical impedance of the loaded sensor. Different types of coatings including rubbery and glassy polymers are investigated, and the targeted analytes include classes of polar compounds (methanol), nonpolar compounds (toluene, xylenes), and chlorinated hydrocarbons (trichloroethylene, tetrachloroethylene, etc). It is seen that changes in viscoelastic properties due to analyte sorption may be significant enough to place the sensor in the nongravimetric regime. However, for most applications involving the detection of relatively low concentrations of organic compounds and the use of acoustically thin films, changes in the complex shear modulus of the coatings contribute less than 5% of the total shift in the series resonant frequency, depending on the coating. In that case, the measured deltafs and, hence, the calculated approximate classification and selection of the coatings for operation in a complex solution of water/analyte molecules.

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