Preparation of silica microspheres encapsulating phase-change material by sol-gel method in O/W emulsion

Abstract

Spherical silica microcapsules containing phase-change material (PCM) were prepared by the sol-gel method in O/W emulsion. This is the first time that inorganic encapsulation of PCM with core/shell structure has been studied. The results of this synthesis revealed that micron size (4 - 8 microm) silica microspheres encapsulating n-pentadecane can be successfully created from acidic solutions ([H+] > or = 1.44 N) by using cationic surfactants as the emulsifiers. The identification of the mechanisms for the formation of silica shell at the oil-water interface indicates that it should be the charge-controlled mechanism through S+X-I+ (positively charged surfactant-halide ion-positively charged silica species) electrostatic interactions or the reaction rates-controlled mechanism working on cationic emulsifiers.

Development of bifunctional microencapsulated phase change materials with crystalline titanium dioxide shell for latent-heat storage and photocatalytic effectiveness

“…There are a few publications concerning the inorganic silica as a wall material for encapsulation of PCMs. Wang et al [19] first reported the encapsulation method of PCMs into silica through the in-situ polycondensation in an oil-in-water emulsion and also discussed the formation mechanism. Chang et al [20] studied the synthetic technology of microencapsulated noctadecane PCMs with PMMA network-silica hybrid shell via the sol-gel process.…”

Design and fabrication of dual-functional microcapsules containing phase change material core and zirconium oxide shell with fluorescent characteristics

“…As mentioned in many articles, the inorganic silica was most employed as a wall material for the encapsulation of PCMs. Wang et al [20] first reported the encapsulation method and mechanism of PCMs with silica through in-situ polycondensation in an oil-in-water emulsion. Li et al [21] and Fang et al [22] reported the synthetic method of the silica/paraffin phase-change composites through interfacial polycondensation of tetraethyl orthosilicate in the sol-gel process and found that these phasechange composites exhibited a good heat-storage performance and also had a form-stable feature.…”

Review of solid–liquid phase change materials and their encapsulation technologies

“…Figure 11: Schematic formation of a sol-gel process [71] Other researchers have also fabricated MEPCMs using the sol-gel method but with silicon as a shell material. Wang et al [72] were the first to encapsulate PCMs with silicon and to investigate the formation mechanism which established that the use of cationic surfactants (i.e. cetyltrimethylammonium chloride, dodecyltrimethyl-ammonium chloride and dodecyltrimethylammonium bromide) as emulsifiers are suitable for the production of MEPCMs.…”