Templating of ethyl(hydroxyethyl)cellulose on graphite by surfactant-polymer interactions

Ordered, templated, thin films of ethyl(hydroxyethyl)cellulose (EHEC) were produced on a freshly cleaved crystalline graphite surface by exploiting the nature of sodium dodecyl sulfate adsorption (SDS) and its interaction with EHEC. The films were prepared by exposing the graphite surface to a dilute aqueous solution containing EHEC-SDS mixtures, followed by rinsing to remove the SDS and drying. The structure of the remaining EHEC film at the graphite-air interface was investigated by atomic force microscopy and compared with images of SDS and EHEC polymer on adsorbed graphite obtained in separate experiments. The results showed that polymer networks were formed from the EHEC-SDS mixture (after rinsing out the SDS), which were predominately aligned in one of three preferential directions separated by 60, presumably as a result of templating by coadsorbed SDS. In addition, the alignment of the EHEC polymer and spacing between the polymer strands was found to be a function of surfactant concentration. Films formed from a solution containing EHEC (10 ppm) and SDS solution (5 mM) after removal of the SDS by washing formed "tight", highly aligned networks. At the same EHEC concentration and 20 mM SDS, a more "open" structure was formed. The results provide valuable insights into the interaction and organization of SDS and EHEC at a crystalline hydrophobic surface.