Force spectrum of a few chains grafted on an AFM tip: Comparison of the experiment to a self-consistent mean field theory simulation

A simulation model based on self-consistent mean field theory (SCMFT) has been developed to inspect the approaching process of the polymer chain grafted AFM tip to a substrate. The effects of various controlling parameters, such as grafting position, chain number, chain length, as well as solvent- and substrate-chain interactions, on the force curve were investigated. Real force spectroscopy of AFM tips modified by poly(ethylene glycol) (PEG) chains interacting with the fresh mica has been recorded, and several typical types of the force curves that correspond to the different states of the grafting chain were assorted. The simulations fit the experimental results well, providing a strong support to the model.