Recent Advances in Pickering Emulsions: Stabilizers, Applications and Future Directions

Pickering emulsions are a type of dispersion in which solid particles stabilize the interface between oil and water, often offering greater stability than traditional emulsions that rely on surfactants. This review thoroughly examines the main factors that affect the performance and stability of Pickering emulsions, such as the particles' wettability, dimensions, morphology, and how densely they cover the interface. A crucial factor, particle wettability, is typically measured by the contact angle formed at the interface of the three phases. Crucial for effective emulsion stabilization, with particles exhibiting intermediate wettability (θ ≈ 90°) offering optimal stability. Particle size plays a complex role, with smaller particles enhancing stability by forming dense interfacial layers and resisting sedimentation. Non-spherical particles, such as rods, ellipsoids, and Janus particles, exhibit unique stabilization mechanisms due to their high aspect ratios and deformability at the interface. Surface coverage and electrostatic interactions also significantly impact emulsion stability. The review discusses the pickering emulsions offer several benefits compared to traditional surfactant-based emulsions. These advantages include enhanced stability due to the irreversible adsorption of solid particles at the interface, reduced reliance on synthetic surfactants, and improved biocompatibility and environmental friendliness, reduced toxicity and suitability for various applications. The preparation methods and characterization techniques for Pickering emulsions are summarized, along with their diverse applications in pharmaceuticals, biomedicine, cosmetics, and functional foods. Recent advances and future directions are explored, emphasizing the potential of engineered colloidal particles, multiparticle stabilization, and microencapsulation techniques for enhancing stability and functionality. This comprehensive review provides valuable insights into the fundamental principles and practical applications of Pickering emulsions, guiding future research and development in this promising field.