Preparation of polystyrene/sodium monofluorophosphate microcapsules by W/O/W solvent evaporation method

Polystyrene (PS)/sodium monofluorophosphate (MFP) microcapsules were prepared by solvent evaporation method for direct addition into concrete and the effects of wall material content, MFP content, emulsifier and protective colloid on the morphology of microcapsules were discussed. The results showed that the average diameter of microcapsule particles slightly increased with the increase of PS content and MFP contents. Span 60 was the best emulsifier comparing with sodium lauryl sulfate and Tween 80. Increasing Span 60 content could decrease the size of microcapsules and the appropriate concentration of Span 60 was 0.5%. Lower concentration of polyvinyl alcohol (PVA), as a protective colloid in the external water phase, resulted in larger particles and higher encapsulation efficiency. The optimal PVA content was approximately 2%. PS/MFP microcapsules exhibited a good sustained release in a simulated concrete solution. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.