Characterization of polymer coatings microstructure is critical to the fundamental understanding of corrosion of coated metals. In this paper an approach for mapping chemical heterogeneity of a polymer system using chemical modification and tapping mode atomic force microscopy (TMAFM). This approach is based on selective hydrolysis of one of the phases in a multi-phase polymer blend system and the ability of TMAFM to provide nanoscale lateral information about the different phases in the polymer system. Films made of 70:30 polyethyl acrylate/polystyrene (PEA/PS) blend were exposed to a hydrolytic acidic environment and analyzed using TMAFM. Pits were observed to form in the PEA/PS blend films and this degradation behavior was similar to that of the PEA material. Using these results, the domains in 70:30 blend were identified as the PS-rich regions and the matrix as the PEA-rich region. This conclusion is confirmed by FTIR-ATR analyses which revealed the hydrolysis of the PEA material. TMAFM phase imaging was also used to follow pit growth of the blend as a function of exposure time. The usefulness of the chemical modification/AFM imaging approach in understanding the degradation process of a coating film is discussed.
Citation: Journal of Polymer Science Part B-Polymer Physics
Issue: No. 13
Pub Type: Journals
AFM, building technology, chemical modification, coating, heterogeneity, hydrolysis, phase imaging, polymer