Polyurea micro-/nano-capsule applications in construction industry: A review

Abstract The application of micro-/nano-capsules in construction industries has been rising over the past decade. Polyurea with tunable chemical and morphological structure are of interesting polymers to prepare micro-/nano-capsules used in construction. The structure of polyurea micro-/nano-capsule is capable to be tailored via bulk emulsion or microfluidic method. Important factors for production of micro/nano-capsules are the rate of fabrication and having control over mean size, dispersity, and wall thickness. The bulk emulsion method provides higher yield of production with less control over sizes and dispersity in comparison to microfluidic technique. The main applications of polyurea micro-/nano-capsules in construction industries are categorized as thermal energy saving, self-healing concrete, self-healing polymers, and fire retarding. Polyurea showed appropriate thermal conductivity and mechanical properties which is required for encapsulation of phase change materials. Titanium dioxide polyurea microcapsules possess energy storage efficiency of 77.3% and thermal storage capacity of 99.9%. Polyurea microcapsules with sodium silicate cargo provided self-healing abilities for oil well cement in high temperature and showed higher self-healing abilities compared to gelatin microcapsules. Graphene oxide polyurea micro-/nano-capsules demonstrated 62.5% anti-corrosive self-healing efficiency in epoxy coating, and steel coated via dendritic polyurea microcapsules embedded polyurethane remained unchanged after long time immersion in salt water.