Functional Cementitious Composites with MUF/n-Octadecane Microcapsules for Building Thermal Energy Storage

Amid escalating global energy challenges and rising demands for building energy efficiency, embedding phase-change microcapsules into cement matrices has emerged as a promising strategy for enhancing thermal management in building envelopes. This study presents a cementitious composite integrated with melamine–urea–formaldehyde/Tween 80-sodium dodecyl sulfate composite emulsifier (MUF/TS-SDS) microencapsulated phase-change materials (MPCMs) for effective thermal energy storage. The resulting microcapsules exhibited uniform spherical morphology, excellent dispersion, and a core–shell structure with an ∼100 nm shell thickness and 67.5% coating efficiency. The melting enthalpy (ΔHm) and crystallization enthalpy (ΔHf) of the microcapsules were 167.87 and 168.96 J/g, respectively, demonstrating excellent thermal energy storage and release capabilities. When incorporated into a cement matrix at 10–30% by weight, the phase-change latent heat of the composite material monotonically increased with increasing content. At 30% content, ΔHm and ΔHf reached 29.78 and 28.41 J/g, respectively. Simulated building experiments demonstrated that cement wall panels containing 30% microcapsules exhibit significant thermal regulation effects during heating and cooling cycles, with maximum wall temperature reductions of 13.10 °C. Although the compressive strength of the composite cement slightly decreased with increasing microcapsule content, the 28-day compressive strength at 30% content reached 49.7 MPa, meeting engineering application requirements. This study confirms the significant application potential of MUF/TS-SDS phase-change microcapsules in the field of building energy efficiency.