Effect of atomic force microscope tip geometry on the evaluation of the crystal size of semicrystalline polymers

The objective of this study is the evaluation of the effect of the tip geometry on imaging the structure of semicrystalline polymers at the nanometer scale by atomic force microscopy. The size and habit of crystals in model-like samples of isotactic polypropylene were analyzed using a standard silicon tip and a high-resolution tip with approximate front curvatures of the tip apexes of 1 and 10 nm, respectively. The experimental data demonstrate that the true size of typical polymer crystals, within the investigated range between 5 and 25 nm, can accurately only be evaluated by using the high-resolution tip. The tip of a larger front curvature of 10 nm yielded apparent crystal sizes which were about 5–10 nm larger than that obtained on using the sharper tip. (technical design note)