Robust microencapsulated phase change materials in concrete mixes for sustainable buildings

For passive building applications, phase change materials (PCMs) are microencapsulated to avoid leakage of PCM from concrete structure. The primary challenge of using microencapsulated PCM (MPCM) is its weak shell structure. New MPCMs with different shell compositions to prevent breakage during mixing in fresh concrete are needed. In this study, free radical polymerization method to microencapsulate capric acid-myristic acid mixture as PCM with two different methyl methacrylate co-polymers is proposed to produce robust MPCMs for building applications. Two new microcapsules (MPCM-1 and MPCM-2) having latent heats of 91.9 and 97.3 J/g were synthesized. SEM analyses showed the size of microcapsules being in the range of 400-850 nm for MPCM-1 and 250-475 nm for MPCM-2. Analyses also reveal that the shells of MPCMs were not harmed, as they were added into concrete mixes. The microsphere's geometry was preserved, and distribution was homogeneous. The MPCMs were also studied under thermal tests of 1000 heating/cooling cycles. No significant changes in thermal properties were observed after thermal cycling tests. Copyright (C) 2016 John Wiley & Sons, Ltd.