Design and synthesis of multifunctional microencapsulated phase change materials with silver/silica double-layered shell for thermal energy storage, electrical conduction and antimicrobial effectiveness

We have synthesized a novel type of multifunctional microcapsules based on an n-eicosane phase-change material (PCM) core and a silver/silica double-layered shell through interfacial poly condensation followed by sliver reduction. The resultant microcapsules showed the regular spheres with a well-defined core-shell structure and a silver outer layer. The characterization of chemical composition and crystalline structure indicated that the microcapsules had a perfect silver outer layer when the reaction time for reduction and deposit of silver ions was set to 20 h. The analysis of differential scanning calorimetry indicated that the microcapsules contained about 67 wt % of n-eicosane core under the encapsulation of 33 wt % shell materials. The microcapsules also achieved high latent-heat storage and release efficiency and a good thermal regulating capability. Most of all, the microcapsules achieved a high electrical conductivity of 130 Omega.m. These microcapsules were also found to have a high antibacterial activity, especially against Staphylococcus aureus and Bacillus subtilis, and they exhibited good antimicrobial effectiveness with a sterilization rate of above 95% at the contact time of 4 h. With such a multifunctional feature, the microcapsules designed by this study show potential applications in microelectronic and biomedical fields. (C) 2016 Elsevier Ltd. All rights reserved.