Vibrational spectroscopy of self-assembled polyelectrolytes films by sum-frequency generation / Espectroscopia vibracional de filmes automontados de polieletrólitos através da geração de soma de frequências

AUTOR(ES)

Heurison de Sousa e Silva

DATA DE PUBLICAÇÃO

2007

RESUMO

In this work, Sum-Frequency Vibrational Spectroscopy, a nonlinear optical technique that is sensitive to molecular conformation at interfaces and surfaces, was used to characterize the molecular ordering of self-assembled films during all steps of self-assembly, having as model poly(allylamine hydrochloride) (PAH) / poly(styrene sulfonate) (PSS) polyelectrolyte assemble. SFG spectra showed that during immersion (in situ) of substrate in polyelectrolytes solutions, adsorption occurs but the molecules are in a disordered configuration. It was observed that the films drying by nitrogen flow are more inhomogeneous than those dried by spontaneous water evaporation. In some cases, dried films by nitrogen flow are quite disordered. Furthermore, it was observed that polyelectrolytes layers affect the ordering of the previously adsorbed layers. Based on our results, models were proposed to represent the structure of polyelectrolytes films in both: in situ and ex situ.

ASSUNTO(S)

nonlinear spectroscopy espectroscopia não-linear polyelectrolytes self-assembled fils sum-frequency generation geração de soma de frequências filmes automontados polieletrólitos

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