Ostwalds' Ripenining Flashcards
What is Ostwald’s ripening in emulsions?
Ostwald’s ripening is the process where larger droplets grow at the expense of smaller ones, leading to coarsening of the emulsion over time.
How does surface tension influence droplet size in dispersions?
Surface tension causes smaller droplets to have higher internal pressure, making them less stable and more likely to shrink as molecules migrate to larger droplets.
What is the relationship between internal pressure and droplet radius?
The internal pressure (Laplace pressure) is inversely proportional to the radius; smaller droplets experience higher internal pressure.
How can the stability of emulsions be improved to extend shelf life?
Stability can be improved by adding amphiphilic molecules to lower surface tension or by increasing the continuous phase viscosity.
What role do amphiphilic molecules play in emulsions?
Amphiphilic molecules help stabilize emulsions by reducing surface tension and preventing coalescence of droplets.
Why is it important to manage kinetic barriers in dispersions?
Managing kinetic barriers helps maintain the desired structure and prevents separation until the product reaches its best-before date.
What is the effect of increasing continuous phase viscosity on droplet stability?
Increasing viscosity near the interface slows down the diffusion of soluble molecules, reducing the rate of Ostwald’s ripening.
What happens to small droplets over time due to Ostwald’s ripening?
Small droplets tend to shrink and disappear as their molecules migrate to larger droplets, which are more stable.
What is the significance of maintaining thermodynamic stability in nanodispersions?
Thermodynamic stability ensures that the dispersion remains uniform and prevents separation, which is crucial for product quality.
How does solubility of the dispersed phase relate to internal pressure?
The solubility of the dispersed phase is positively proportional to the internal pressure; higher internal pressure increases solubility.
