The rapid agglomeration of SiO2 nanoparticles suspended in organic solvents, where the interactions between the PMMA chains and SiO2 are very weak and may be ignored, is, therefore, concluded to be "entanglement agglomeration mechanism" triggered by strong mutual entanglement effects occurring when the polymer chains come into contact, overlap, and mutually intrude each other at higher polymer concentrations, providing the driving force for particle agglomeration.