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Determination of degree of ionization of poly(allylamine hydrochloride) (PAH) and poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2- ethanediyl, sodium salt] (PAZO) in layer-by-layer films using vacuum photoabsorption spectroscopy

Ferreira, Q., Gomes, P.J., Ribeiro, P.A., Jones, N.C., Hoffmann, S.V., Mason, Nigel, Oliveira, O.N., Raposo, M. (2013) Determination of degree of ionization of poly(allylamine hydrochloride) (PAH) and poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2- ethanediyl, sodium salt] (PAZO) in layer-by-layer films using vacuum photoabsorption spectroscopy. Langmuir, 29 (1). pp. 448-455. (doi:10.1021/la304036h) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
https://doi.org/10.1021/la304036h

Abstract

Electrostatic and hydrophobic interactions govern most of the properties of supramolecular systems, which is the reason determining the degree of ionization of macromolecules has become crucial for many applications. In this paper, we show that high-resolution ultraviolet spectroscopy (VUV) can be used to determine the degree of ionization and its effect on the electronic excitation energies of layer-by-layer (LbL) films of poly(allylamine hydrochloride) (PAH) and poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO). A full assignment of the VUV peaks of these polyelectrolytes in solution and in cast or LbL films could be made, with their pH dependence allowing us to determine the pKa using the Henderson-Hasselbach equation. The pKa for PAZO increased from ca. 6 in solution to ca. 7.3 in LbL films owing to the charge transfer from PAH. Significantly, even using solutions at a fixed pH for PAH, the amount adsorbed on the LbL films still varied with the pH of the PAZO solutions due to these molecular-level interactions. Therefore, the procedure based on a comparison of VUV spectra from solutions and films obtained under distinct conditions is useful to determine the degree of dissociation of macromolecules, in addition to permitting interrogation of interface effects in multilayer films.

Item Type: Article
DOI/Identification number: 10.1021/la304036h
Uncontrolled keywords: Benzene, Charge transfer, Hydrophobicity, Interfaces (materials), Ionization, Macromolecules, Polyelectrolytes, Salts, Sodium, Ultraviolet spectroscopy, Degree of dissociation, Electronic excitation energy, Hydrophobic interactions, Layer-by-layer films, Molecular level interactions, Photoabsorption spectroscopy, Poly(allylamine hydrochloride), Supramolecular systems, Multilayer films
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Nigel Mason
Date Deposited: 16 Jul 2019 10:26 UTC
Last Modified: 16 Jul 2019 10:26 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/74723 (The current URI for this page, for reference purposes)
Mason, Nigel: https://orcid.org/0000-0002-4468-8324
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