Force Spectroscopy and Quantitative Imaging of Hard and Soft Materials

New modes of atomic force microscopy (AFM) such as Quantitative Imaging (QI) use force spectroscopy at a high rate with direct force control and allow the high-resolution topography imaging of material surfaces while collecting simultaneously high-resolution images of adhesion, stiffness, and moduli. We applied the force spectroscopy and in particular, QI mode in different systems showing its potential to reveal unprecedented information on local material properties. We mapped the local (surface) elastic modulus of engineering polymer blends and we compared it to the bulk modulus derived from macroscopic tensile testing. The results show a remarkable agreement. We also studied the interactions of natural rubber latex films with carbon black particles (attached to the AFM tip) in aqueous solutions of ultrapure water and ultrapure water with 0.7% Ammonia. We show that in the basic 0.7% ammonia ultra-pure water solution, hydrogen ions are drawn from the surfaces leading to significantly larger negative surface charges, and therefore resulting in repulsion between the carbon black and natural rubber latex films upon the tip approach. Furthermore, we have used the superior control of the applied forces (which can be very low at the range <10 pN) of the QI mode to image and interrogate mechanically biomedical phospholipid-based microbubbles. The results demonstrate the controlled collapse of the microbubbles revealing their mechanical properties and internal structure.