Several factors can lead to nanoparticle aggregation:
1. Electrostatic Interactions: Nanoparticles often carry surface charges that can lead to electrostatic attraction or repulsion. When the repulsive forces are weak, nanoparticles tend to aggregate.
2. Van der Waals Forces: These are weak intermolecular forces that can cause nanoparticles to stick together when they are in close proximity.
3. Steric Effects: The presence of bulky groups on the surface can either hinder or promote aggregation depending on their size and arrangement.
4. Environmental Conditions: Changes in pH, temperature, and ionic strength of the solution can also influence the aggregation behavior of nanoparticles.
