Even microencapsulated self-healing agent has proven applications in designing of self-healing polymer coatings. Techniques of microcapsule manufacture Physicochemical methods Ionotropic gelation Ionotropic gelation occurs when units of uric acid in the chains of the polymer alginate, crosslink with multivalent cations. These may include, calcium, zinc, iron and aluminium. Coacervation-phase separation Coacervation-phase separation consists of three steps carried out under continuous agitation. Formation of three immiscible chemical phases: liquid manufacturing vehicle phase, core material phase and coating material phase. Deposition of coating: core material is dispersed in the coating polymer solution. Coating polymer material coated around core. Deposition of liquid polymer coating around core by polymer adsorbed at the interface formed between core material and vehicle phase. Rigidization of coating: coating material is immiscible in vehicle phase and is made rigid. This is done by thermal, cross-linking, or dissolution techniques. Chemical methods Interfacial polycondensation In interfacial polycondensation, the two reactants in a polycondensation meet at an interface and react rapidly. The basis of this method is the classical Schotten-Baumann reaction between an acid chloride and a compound containing an active hydrogen atom, such as an amine or alcohol, polyesters, polyurea, polyurethane. Under the right conditions, thin flexible walls form rapidly at the interface. A solution of the pesticide and a diacid chloride are emulsified in water and an aqueous solution containing an amine and a polyfunctional isocyanate is added. Base is present to neutralize the acid formed during the reaction. Condensed polymer walls form instantaneously at the interface of the emulsion droplets. Interfacial cross-linking Interfacial cross-linking is derived from interfacial polycondensation, and was developed to avoid the use of toxic diamines, for pharmaceutical or cosmetic applications. In this method, the small bifunctional monomer containing active hydrogen atoms is replaced by a biosourced polymer, like a protein. When the reaction is performed at the interface of an emulsion, the acid chloride reacts with the various functional groups of the protein, leading to the formation of a membrane. The method is very versatile, and the properties of the microcapsules (size, porosity, degradability, mechanical resistance) can be customized. Flow of artificial microcapsules in microfluidic channels: In situ polymerization In a few microencapsulation processes, the direct polymerization of a single monomer is carried out on the particle surface. In one process, e.g. cellulose fibers are encapsulated in polyethylene while immersed in dry toluene. Usual deposition rates are about 0.5μm/min. Coating thickness ranges . The coating