Energies of adsorption of poly(o-methoxyaniline) layer-by-layer films

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Abstract

The adsorption mechanisms in layer-by-layer films of poly(o-methoxyaniline) (POMA) alternated with poly(ethene sulfonic acid) (PVS) are controlled by H-bonding, even for charged POMA where electrostatic interactions were expected to predominate. This is shown here by analyzing adsorption isotherms using three analytical models for adsorption, namely, Langmuir, Frumkin, and Fillippova models, and thermally stimulated desorption results, from which energies of interaction were estimated. The adsorption free energy is ca. -35 kJ/mol, whereas the activation energy for desorption obtained from thermally stimulated desorption was +75 kJ/mol. According to the three models, adsorption is favored when the number of POMA/PVS bilayers increases, consistent with the increase in the amount of adsorbed material and film roughness. The importance of H-bonding was confirmed by FTIR measurements and adsorption experiments at high pHs where POMA is no longer doped.
Original languageEnglish
Pages (from-to)2839-2844
Number of pages6
JournalLangmuir
Volume16
Issue number6
DOIs
Publication statusPublished - 21 Mar 2000

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