Adsorption and Structure Formation of Semi-Rigid Polyelectrolytes

Boris Mahltig,a* Manfred Stammb
a Gesellschaft zur Förderung von Medizin-, Bio- und Umwelttechnologien e.V., GMBU, Department of Functional Coatings, Postfach 520165, D-01317 Dresden, Germany, E-mail:
b Institut für Polymerforschung Dresden, Postfach 120411, D-01005 Dresden, Germany

The adsorption of a negatively charged semi-rigid sulfonated poly(para-phenylene) s-PPP on silicon oxide was studied. While the adsorption of s-PPP on native negatively charged silicon oxide is unfavourable, the switching of the substrate charge by previous adsorption of a highly positively charged, flexible polyelectrolyte enables the adsorption of s-PPP.
The amount of polymer adsorbed from aqueous solution was determined by ellipsometry. Scanning force microscopy (SFM) was used to investigate the lateral structures of the adsorbed polymer. SFM confirms the presence of wormlike structures at the interface. The length scale of these detected structures is significant larger than the persistence length of single chains in solution. Therefore the direct adsorption of whole agglomerates observed in solution can be expected.

Key words: polymer, adsorption, SFM, ellipsometry, poly-para-phenylene