Characterization of Chemical Heterogeneity in Polymer Systems Using Hydrolysis and Tapping-Mode Atomic Force Microscopy.
Characterization of Chemical Heterogeneity in Polymer
Systems Using Hydrolysis and Tapping-Mode Atomic Force
Raghavan, D.; Gu, X.; Nguyen, T.; VanLandingham, M. R.
Journal of Polymer Science: Part B, Polymer Physics,
Vol. 39, No. 13, 1460-1470, 2001.
atomic force microscopy; microscopy; chemical
modification; coatings; hydrolysis; heterogeneity; phase
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.