Impurity mediated nucleation in hexadecane-in-water emulsions

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Engineering

Background:

• Classical nucleation theory (CNT) describes liquid-to-solid transitions.
• Previous studies observed deviations from CNT in similar systems.
• Understanding nucleation kinetics is crucial for materials processing.

Purpose of the Study:

• To investigate nucleation kinetics during hexadecane freezing in emulsions.
• To identify the reasons for deviations from classical nucleation theory.
• To propose a new model explaining observed nucleation phenomena.

Main Methods:

• Utilized nearly monodisperse hexadecane-in-water emulsions.
• Performed detailed kinetic studies under isothermal and nonisothermal conditions.
• Analyzed freezing behavior and compared it with theoretical predictions.

Main Results:

• Observed significant deviations from classical nucleation theory predictions.
• Deviations were apparent when assuming a homogeneous droplet population.
• The extent of deviation suggests an underlying complexity in the system.

Conclusions:

• The assumption of homogeneous emulsion droplets is insufficient for explaining nucleation kinetics.
• Proposed a model involving dynamic generation of droplet heterogeneity via mobile impurities.
• This impurity-mediated heterogeneity model aligns well with experimental data and prior observations.