Characterisation and applications of microcapsules obtained by interfacial polycondensation

Abstract

This review highlights the materials, mechanisms and applications of microencapsulation by interfacial polycondensation in different areas. This technology entraps active ingredients inside microcapsules/microspheres, having an average diameter ranging from nanosize to several 100 µ. Polycondensation reactions take place at the boundary of two phases to form the shells of microcapsules or matrix microspheres. The emulsion can be classified into three types: water-in-oil, oil-in-water and oil-in-oil. According to the hydrophilic-lipophilic property of core phase, different active substances, such as proteins, enzymes, insecticides, herbicides, vitamins, catalysts, drugs, essential oils, dyes and phase change materials, have been successfully incorporated into different microcapsules/microspheres. Based on the shell-forming materials, this technology is capable of preparing polyamine, polyurea, polyurethane, polythiourea, polyester, polyepoxide, polyacrylamide and polysiloxane microcapsules. Over the past two decades, microcapsules prepared by interfacial polycondensation have been widely used in carbonless paper, cosmetics, pharmacy, agriculture, energy storage/transfer, thermal insulation/regulation and information and magnetic recording.

Encapsulation of ionic liquid BMIm[PF6] within polyurea microspheres

“…We would like to apply these capsules in catalytic reactions, therefore the capsules should, on one hand, be permeable, in order to enable the reactants diffusion to the core. On the other hand, the shell should prevent leaching of the core [61][62]. We believe the PAPI 27:BAPIC molar ratio, 1.0:1.4 can provide these features and therefore further optimization was conducted using this ratio.…”

“…SEM images show the formation of capsules in all six ratios. Several studies demonstrated that the shell thickness is highly affected by the cross-linking monomers ratio [61][62]. This affects the permeability of the capsules and their applicability in different fields.…”

“…The amine/isocyanate type and ratio has an important role in the applicability of these capsules, since it dictates the penetrability, porosity, thickness and flexibility of the polyurea shell [61][62]. Thus, the effect of amine/isocyanate type and ratio on the formation of capsules was explored, using 4% Bu-PVP as the surfactant.…”

“…Even when an excess of HMDA was used, the C=O stretch band of the isocayanate groups was detected. This is explained by the interfacial polymerization process, in which the polymerization rate decreases with time due to inaccessibility of the monomers after the formation of the initial polymeric shell [61,64]. The free isocyanate groups within the polyurea shell of the BMIm[PF 6 ]@PU were reacted with ammonia by stirring the microcapsules at room temperature for 12 h. The capsules were then washed with water three times and a sample was taken to SEM (Supporting information, Fig.…”

Research Advances of Microencapsulation and Its Prospects in the Petroleum Industry

“…This property, along with the merits of versatile and stable mechanical and chemical properties of the membrane, as well as permeability, makes this approach a promising candidate for wide applications. Therefore, a multitude of publications have been focused on its utilization, such as self-healing [36,37] agriculture [38], cosmetics [39], and pharmaceutics [40]. Mcilroy and Blaiszik [41] developed a method for the preparation of microcapsules containing a reactive amine with potential applications in self-healing polymers.…”