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Characterization of Chemical Heterogeneity in Polymer Systems Using Hydrolysis and Tapping-Mode Atomic Force Microscopy.


pdf icon Characterization of Chemical Heterogeneity in Polymer Systems Using Hydrolysis and Tapping-Mode Atomic Force Microscopy. (372 K)
Raghavan, D.; Gu, X.; Nguyen, T.; VanLandingham, M. R.

Journal of Polymer Science: Part B, Polymer Physics, Vol. 39, No. 13, 1460-1470, 2001.

Keywords:

atomic force microscopy; microscopy; chemical modification; coatings; hydrolysis; heterogeneity; phase imaging; polymers

Abstract:

Characterization of polymer coatings microstructure is critical to the fundamental understanding of corrosion of coated metals. 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 multiphase 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 Fourier transform infrared-attenuated total reflection analyses that 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.