Atomic Force Microscopy Study of Biaxially-Oriented Polypropylene Films

Atomic force microscopy (AFM) uses a very sharply pointed mechanical probe to collect real-space morphological information of solid surfaces. AFM was used to image the surface morphology of a biaxially-oriented polypropylene film. The polymer film is characterized by a nanometer-scale fiber-like network structure, which reflects the drawing process used during the fabrication of the film. Polymer surface treatment to improve wettability by exposing the polymer to ozone with or without UV irradiation was studied using AFM. Surface morphology changes observed by AFM are the result of the surface oxidation induced by the treatment. Because of the topographic features of the polymer film, we have used the fiber-like structure to check the performance of the AFM tip. An AFM image is basically a mixture of the surface morphology and the shape of the AFM tip. Therefore, it is important to check the performance of a tip to ensure that the AFM image collected reflects the true surface features of the sample rather than contamination on the AFM tip.