Model Direct Analysis and Indirect Fourier Transform Analysis of Small Angle Neutron Scattering From Silica Nanoparticles

Small angle neutron scattering (SANS) patterns from spheroidal silica nanoparticles (Dave = 27.5 nm) dispersed in water at volume fractions ranging from 0.01 to 0.315 were interpreted using model direct and indirect Fourier transform methods. By analyzing the effective interparticle spacing we find that there are attractive forces between the silica nanoparticles, especially in the most dilute dispersion (0.01 v/v). The interparticle potential is similar to the two-Yukawa potential since there are also electrostatic repulsive forces that stabilize the dispersion. For weakly-interacting particles (~ 0.01 v/v) model direct analysis of SANS patterns using a polydisperse spheres form factor is simple and accurate but we calculate the pair distribution function for interacting particles more accurately using the indirect Fourier transform method.