ZnO Nanoparticles Flashcards
Name one issue with ZnO during storage
The morphology can change
What is the issue with ZnO rods?
They exhibit cytotoxicity
How can ZnO NP solubility be manipulated?
By changing the pH of a ZnO NP solution
How do secondary particles form in ZnO sols?
1) Particle growth by diffusion
2) Ostwald Ripening
Explain the concept of Ostwald Ripening
Smaller particles diffuse into the solvent, and then re-crystallise and adsorb onto larger particles upon which they grow
How can ZnO NPs be synthesised?
Hydrothermal synthesis
What does electrostatic stabilisation involve?
Stabilisation of a sol through pH changes
What is steric stabilisation?
Stabilisation of a sol through the addition of long chain molecules to a particles surface
This is generally done through surfactant addition
In a surfactant, which end is lipophilic/hydrophobic?
The tail end
In a surfactant, which end is hydrophilic?
The head
What is the purpose of stabilisation?
To counteract attractive Van der Waals forces in suspensions to prevent flocculation/agglomeration
How does steric stabilisation work?
Long chain molecules adsorb a hydrophilic head to particles, with the lipophilic tail extending into the continuous liquid so that high energy tail-tail interactions prevent flocculation
