Adsorption of poly-2-dimethylamino ethylmethacrylate-N-alkyl quaternized at the water-chloroform interfaceReportar como inadecuado




Adsorption of poly-2-dimethylamino ethylmethacrylate-N-alkyl quaternized at the water-chloroform interface - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Resumen

The interfacial properties of poly-2-dimethylamino ethyl methacrylate-N-alkyl quaternized with octyl,decyl, dodecyl and tetradecyl bromide are studied from the chloroform to the water-chloroform interface.In order to estimate the entropy of the adsorption process, the interfacial tension was measured at severaltemperatures according to the Du Noüy method. The interfacial tension decrease is highly dependent onthe hydrophilic–hydrophobic balance between the quaternary ammonium groups and the aliphatic sidechains. The shorter the polyelectrolyte side chains the higher the interfacial activity. The excess interfacialconcentrations, , are determined according to the Gibbs–Szyszkowski equation and the areas coveredby monomer unit at the interface are higher than those reported for condensed monolayers of singlelow molecular weight amphipathic molecules, such as alcohols and carboxylic acids. The free energies ofadsorption, G◦ads, reveal that the adsorption process is comparable to that occurring in small moleculessystems. The linear dependence of G◦ads with the number of carbon atoms on the side chain allowsestimating the contribution per methylene side group between +0.32 and +0.39 kJ mol−1. On the otherhand, the contribution from the polar residue to G◦ads ranges between −40.4 and −45.7 kJ mol−1. Thedependence of the interfacial tension with temperature suggests that entropy is the driving force factordetermining the adsorption process.Nota general

Artículo de publicación ISI



Autor: Ríos, Hernán E.; - González Navarrete, Javier; - Peña, María L.; - Sagredo, Claudio D.; - Urzúa Acevedo, Marcela; -

Fuente: http://repositorio.uchile.cl/



DESCARGAR PDF




Documentos relacionados