Preparation, Thermal Regulation, and Energy Storage Properties of n-hexadecane@polymethyl Methacrylate Microcapsule-Cement Composite Phase Change Materials.

With the continuous growth in global energy consumption and the increase in the proportion of energy use attributed to buildings, the development of highly efficient and energy-saving building materials has become necessary for reducing energy demands and greenhouse gas emissions. Phase change materials (PCMs) exhibit great potential for enhancing the thermal inertia of buildings owing to their ability to efficiently absorb and release latent heat during phase transitions. In this study n-hexadecane@ polymethyl methacrylate (16-MMWS-K) microcapsules (where "@" denotes the core-shell encapsulation structure) with a crosslinked structure were successfully prepared via emulsion polymerization, using n-hexadecane as the core material and polymethyl methacrylate as the shell. The prepared microcapsules were incorporated into a cement matrix to fabricate a phase-change energy-storage composite material. The morphology, structure, and thermal properties of the microcapsules, as well as their effects on the thermal and mechanical performance of the cement composites, were systematically investigated. The prepared 16-MMWS-K microcapsules exhibited a well-defined core-shell structure, excellent thermal stability, and a suitable phase-change temperature. Increasing the microcapsule content significantly enhanced the thermal energy storage capacity of the cement composites, reduced thermal conductivity, improved hydrophobicity, and demonstrated effective temperature regulation in building simulation experiments. This study provides both theoretical insight and experimental evidence supporting the practical application of 16-MMWS-K microcapsules in cement composites. The 28-day compressive strength (51.7 MPa) remains acceptable despite higher porosity and slight strength reduction.