Measuring the Interfacial Thickness of Immiscible Polymer Blends by Nano-probing of Atomic Force Microscopy

Immiscible polymer blends are an important family of polymer materials. The interfacial thickness between different phases is a very important parameter that dictates, to a great extent, the morphology and properties of such a blend. This work explores and optimizes an up-to-date atomic force microscopy (AFM) of type NanoIR2 (TM) system in order to quantitatively measure the interfacial thickness of immiscible polymer blends. This system is equipped with two nano-probes capable of detecting the response of a material to an infrared pulse called AFM-infrared spectroscopy mode (AFM-IR) or conducting resonance called AFM-Lorentz Contact Resonance mode (AFM-LCR), respectively. Its potential for quantitatively measuring the interfacial thickness of immiscible polymer blends is evaluated using blends composed of polyamide 6 (PA6) and polyolefin elastomer (POE) in the presence or absence of a POE containing maleic anhydride (POE-g-MAH) as a compatibilizer. Surface roughness affects adversely the signal intensity and consequently an accurate measurement of the interfacial thickness. Optimum sample surface preparation procedures are proposed.