Colloid in water and in ionic water
Physics description
Fig. 1: Two C240 in periodic box of size 4*4*6 nm
The colloid particles in the water can interact with each others in means of many possible forces, including van der Waals force, Coulomb interaction, hydrogen bond interaction…etc. The surrounding solute also plays a role on influencing the interaction potential. To understand the potential dependence with solute and without solute, and attraction or repulsion relations between colloid particles, the potential of mean force (PMF) along with separated distance is the key factor we want to investigate. By holding particles with respect to different relative distance, we can get the idea of potential tendency of depletion force of colloids.
Fig.2 Schematic of Pulling of C240 and measuring forces at different position
One can use GROMACS to see the influence of different ions and of their concentrations on the depletion force of colloid particles.
The colloid particles investigated in this simulation research are C240, a hollow sphere like particle. The solute ions in the simulation are ammonium (NH4+) and nitrate (NO3–) with concentration 1 M. The simulations are run under condition of constant volume (4*4*6 nm3) and under temperature 300 K.