Synthesis of silica microcapsules encapsulating different organic compounds for addition in the cement paste

Abstract

ABSTRACT In this work, the addition of silica microcapsules encapsulating different organic compounds into the cement paste is presented as a first step to provide to the cementitious material of two new different functionalities, on one hand, the self-healing capability and on the other hand, latent heat thermal energy storing capacity. The synthesis route used for obtaining the microcapsules is a combination of sol-gel chemistry and emulsion technology. Combining both methods, silica core-shell microcapsules encapsulating specific organic compounds are obtained. The organic materials chosen for this work vary from epoxy resins, for the self-healing application, to the phase change materials for the latent heat thermal energy storing functionalisation. Furthermore, several studies such as, changing the pH of the reaction during the hydrolysis step, varying the method used to obtain the emulsion (by mechanical stirring or by a combination with sonication) as well as modifying the mechanical stirrer speed during emulsion step, have been carried out to observe the effects on the synthesised microcapsules. Scanning electron microscopy, transmission electron microscopy, particle size distribution studies and thermogravimetrical studies have been carried out to characterise the microcapsules. Addition of the encapsulated organic compounds to the cement paste has been performed and different characterisations such as, scanning electron microscopy, mechanical tests and differential scanning calorimetry have been carried out to prove the suitability of the proposed strategy.