Halloysite based geopolymers filled with wax microparticles as sustainable building materials with enhanced thermo-mechanical performances

This work proposes a novel protocol for the fabrication of halloysite based geopolymers filled with beeswax microparticles obtained from Pickering emulsions. The actual filling of the microwax into the geopolymers has been demonstrated by using several techniques, including thermal analyses, spectroscopies, microscopies and contact angle experiments. According to the morphological and structural investigations, microwax spherical particles (diameter ranging between ca. 3 and 5 mu m) have been homogeneously dispersed within the geo-polymeric network conferring excellent properties to the hybrid geopolymers in terms of mechanical perfor-mances and heat storage capacity although their low content in the hybrid material. For comparison, we have prepared and characterized hybrid geopolymers obtained by the loading of variable amounts of beeswax within the geopolymeric matrix. Reliable enhancements of the flexural characteristics and heat absorption capacity have been achieved only with a large content of beeswax. Moreover, the removal of microvax and wax from the hybrid geopolymers has been obtained by rinsing with ethanol. The washed geopolymers have been characterized by wettability and water vapour permeability experiments, which have been proved that the beeswax has been removed and the porosity of the materials can be controlled by the initial composition of the hybrid geopolymers.In conclusion, this paper puts forward an easy strategy to fabricate composite geopolymers with heat storage capacity due to presence of phase change materials (microwax particles) confined in the geopolymeric network. Their enhanced flexural performances make the hybrid geoppolymers suitable as building materials.