Stability of self-assembled polymer films investigated by optical laser reflectometry.

Langmuir

University of Franche-Comté, UTINAM Institut, Equipe Matériaux et Surfaces Structurés, CNRS-UMR 6312, 25030 Besançon Cedex, France.

Published: April 2008

AI Article Synopsis

  • The study investigated how rinsing affects the stability of self-assembled polyelectrolyte films made from poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS).
  • Rinsing at a pH of 9 (same as the film buildup) kept the films stable, whereas rinsing at higher pH levels caused significant polymer release, leaving only a PAH monolayer.
  • Thicker films (4+ bilayers) remained stable at lower pH, but stability of thinner films varied; films with PSS on top stayed stable, while those with PAH released more material.

Article Abstract

We studied the influence of post-treatment rinsing after the formation of self-assembled polyelectrolyte films made with the weak base poly(allylamine hydrochloride) (PAH) and the strong acid poly(styrene sulfonate) (PSS). The stability of the film was studied using optical fixed-angle laser reflectometry to measure the release of polymeric material and AFM experiments to reveal the change of morphology and thickness. We found that the polymer films were stable upon rinsing when the pH was the same in the solution as that used in the buildup (pH 9). The films released most of the polymeric material when rinsed at higher pH values, but a layer remained that corresponded to a PAH monolayer directly bound with the silica surface. Films containing at least four bilayers were stable upon rinsing at lower pH values, but the stability of thinner films depended on the type of the last polymer deposited. They were stable in the case of PSS as an outermost deposit, but they released a large part of their material in the case of PAH. The stability results were determined using a simple model of the step-by-step assembly of the polymer film described formerly.

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Source
http://dx.doi.org/10.1021/la703307fDOI Listing

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