Preparation and Optimization of Graphene-Doped TiO2 Shell Microencapsulated Phase Change Materials for High-Stability Cold Storage

The development of phase change materials (PCMs) with high energy storage density and enhanced thermal conductivity is crucial for improving energy efficiency and t 0emperature control precision in low-temperature cold storage and cold chain transportation. To address this challenge, this work fabricated composite microencapsulated phase change materials (MEPCMs) using n-tetradecane, titanium dioxide and graphene as the core, shell and thermal conductive filler, respectively. The effects of key synthesis factors on the performance of MEPCMs were evaluated through systematic single-factor experiments. Furthermore, response surface methodology (RSM) was employed to establish predictive models and identify the optimal synthesis conditions. Physicochemical characterization indicates that the as-prepared MEPCMs exhibited a regular spherical morphology along with excellent physical compatibility and chemical stability. The incorporation of graphene significantly enhanced the thermal conductivity to 0.6320 W/m·K, representing an 85.39% increase over the graphene-free sample. The MEPCMs demonstrated a high melting enthalpy of 159.5 J/g and maintained 97.62% of this enthalpy after 500 thermal cycles, underscoring their outstanding cold storage capability and cycling reliability. These results indicate that MEPCMs possess significant application potential in precision temperature control systems for cold chain logistics.