Microencapsulation of octadecane as a phase-change material by interfacial polymerization in an emulsion system

 Microcapsules containing phase-change material for thermal adaptable fiber application were synthesized and characterized. The microcapsules of about 1 μm in diameter were prepared using an interfacial polycondensation method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Octadecane was used as a phase-change material and NP-10 which is nonionic surfactant, was used as an emulsifier. To investigate the reaction ratio of monomers, microcapsules were synthesized with 3 g TDI and 0–4 g DETA. Polyurea microcapsules were formed not only by reaction with TDI and DETA, but also by reaction of TDI with hydrolyzed TDI at the interface. TDI was reacted with DETA in the weight ratio of 3:1. NP-10 was reacted with TDI to form urethane. The microcapsules containing octadecane showed a phase change of octadecane at 29–30 °C. The core content measured using the heat of fusion of octadecane was less than that calculated. The efficiency of octadecane encapsulation increased as the core content decreased.