Microcapsules

Microcapsules are tiny capsules in which a core material is enclosed within a protective shell. The core can be liquids, solids, or gases, and the shell is typically a polymeric, lipid, or inorganic coating that ranges from a few micrometers to hundreds of micrometers in diameter.

Shell materials include natural polymers such as gelatin, alginate, gum Arabic, and starch; proteins; synthetic polymers such as polyurethane or melamine-formaldehyde; and lipid or inorganic coatings. The choice of shell affects the stability, release profile, and compatibility with the core material and intended use.

Common production methods include coacervation or phase separation; interfacial polymerization; spray drying; spray chilling or cooling; extrusion; and emulsion-templated approaches. Each method offers different control over capsule size, shell thickness, and encapsulation efficiency, and may impose specific processing conditions.

Release from microcapsules can occur by diffusion through the shell, dissolution or rupture of the shell, erosion, or response to environmental triggers such as changes in pH, temperature, ionic strength, or enzymatic activity. This enables controlled or targeted delivery of the core material.

Applications span pharmaceuticals for controlled drug release; food and beverages to protect flavors and aromas and to mask taste; agrochemicals to improve efficacy and reduce environmental impact; cosmetics and personal care; and protective coatings and construction materials with added functionality.

Advantages include protection of sensitive actives, enhanced stability, and tailored release profiles. Limitations involve production costs, shell–core compatibility, and potential toxicity concerns for certain shell materials. Regulatory and safety considerations apply to the intended use, including material approvals and quality control.