Here, we take the next step in understanding such systems' dynamics and present an investigation of interaction in interfacial nanoparticulate systems and modulation of forces in the system. We report the impact of the ionic strength of the subphase on PSiFe films at the airwater interface. We found that PNIPAM-modified particles at the interface behave very differently than in colloidal suspension. Humphreys et al. studied the effect of ionic strength and salt identity on PNIPAM brush-modified colloidal silica particles. They found that the addition of salt causes the aggregation of particles. Our experiments described in this work further revealed the complex nature of the interactions' mix that is observable at the interface.