Stability and durability of microencapsulated phase change materials (MePCMs) in building applications: A state of the review

Phase change materials (PCM) are widely utilized for thermal regulations in buildings owing to their high latent heat storage capacity. However, issues such as leakage, low thermal conductivity, material dispersion, and chemical instability impact the performance. Microencapsulation is a promising technique that can resolve leakage issues and interactions with the environment while also enhancing thermal conductivity. Previous reviews on microencapsulated PCM (MePCM) mainly summarize the core-shell material and structure, properties, different encapsulation methods, various heat conduction enhancement methods, and applications. Nevertheless, the present review is focused on understanding the stability and durability of MePCM in buildings. Initially, the preparation process and application scenarios of MePCM, followed by its stability and durability requirements in building applications, are reviewed in detail. Mainly, the stability and durability evaluation and their influential factors are explored and consolidated. Finally, recommended actions to enhance stability and durability at both the core and shell levels are analyzed, and the scope for future research works is briefed. It is understood that the temperatures of geothermal location and airflow in buildings are difficult to reach the onset decomposition but not in the scenario of the solar energy system, which needs to be demonstrated further. Considering the stability and durability performance, long-term experimental investigation towards life expectancy and real-time investigation of MePCM applied in buildings needs to be further explored considering the preparation process and failure mechanism. The testing standards and evaluation systems could be formulated to provide a scientific basis and technical support for the application of MePCM in buildings.