Definition
Surface free energy is the excess energy at the surface of a material compared to the bulk. It quantifies the work required to create a unit area of surface.
Relationship with Surface Tension: Numerically equal to surface tension in liquids.
Concepts
Thermodynamics: Surface free energy arises because molecules at the surface are not completely surrounded by other molecules, leading to higher energy states.
Minimization: Systems tend to minimize surface free energy, influencing processes like droplet formation.
Importance
Wetting and Spreading: Determines how liquids interact with solid surfaces.
Particle Aggregation: High surface energy particles may aggregate to reduce total surface energy.
Applications of Surface Free Energy
Tablet Coating: Influences adhesion of coatings.
Nanoparticle Formulation: Affects stability and dispersion of nanoparticles.