INTERACTION BETWEEN WATER-SOLUBLE POLYMERS AND AZO DYES CONTAINING FLUORINE-ATOMS - PART 4 - COMPARISON WITH AZO DYES HAVING DIFFERENT CHAIN-LENGTH OF ALKYL-GROUPS

The interaction between sulphonated monoazo dyes having different chai n length of alkyl groups and poly(vinylpyrrolidone) was investigated b y means of visible absorption spectrum measurements, and compared with the results for sulphonated monoazo dyes containing fluorine atoms. T he first binding constants increased with an increase in the alkyl cha in length induced into the dyes. The first binding constants for dyes carrying branched chains were affected only by the carbon number in th eir main chains. The thermodynamic parameters for the binding processe s changed with the alkyl chain length in an opposite manner to those r eported for Methyl Orange derivatives. This is explained in terms of t he accessibility of the alkyl groups in the dyes to the polymer chains . (C) 1998 Elsevier Science Ltd. All rights reserved.