Authors Spange, St. ; Reuter, A. ; Prause, S. ; Bellmann, C.
Title Electrokinetic and Solvatochromic Studies of Functionalized Silica Particles
Date 27.01.2000
Abstract Zeta potential plots, Kamlet-Taft's &#945; (hydrogen bond-donating, HBD), &#946; (hydrogen bond-accepting, HBA), and &#960;* (dipolarity/polarizability) parameters as well as Gutmann's <I>DN</I> (donor numbers) are presented for 12 differently functionalized (i.e. alkyl, cyanoalkyl, aminoalkyl, and imidazolidine) silica particles. The pH-dependent zeta potential plots were measured in aqueous solution, whereas the solvatochromic studies were performed in 1,2-dichloroethane and cyclohexane as solvents using a special UV/visible spectroscopic technique. For the determination of the solvatochromic polarity parameters, a set of carefully characterized polarity indicators was employed: Cu(tmen)(acac)<SUP>+</SUP>B(C<SUB>6</SUB>H<SUB>5</SUB>)<SUB>4</SUB><SUP>-</SUP> for &#946; and <I>DN</I>; dicyano-bis(1,10-phenanthroline)iron(II) for &#945;; 4,4&#8242;-bis(N,N-dimethylamino)benzophenone for &#960;*; and an aminobenzofuranone derivative {3-(4-amino-3-methylphenyl)-7-phenyl-benzo[1,2b : 4,5b&#8242;]difuran-2,6-dione} (ABF) for &#945;, &#946;, and &#960;*. The calculation of the polarity parameters was carried out via linear solvation energy (LSE) correlation equations using the Kamlet-Taft solvent parameters as a reference system. A linear correlation between the electrokinetically determined value of the isoelectric point and the &#946; parameter of the functionalized silicas is demonstrated.
Journal Journal of Adhesion Science and Technology 14 (2000) 399-414

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