Thermal properties enhancement of coal-based solid waste derived mesoporous silica/polyethylene glycol composite phase change material: effects of pore structure and surface groups

Under the dual carbon background, the performance enhancement and application promotion of phase change materials (PCMs) hold significant practical importance. The research specifically examines the influence of pore structure and surface functional groups on structure and thermal properties of composite phase change materials (CPCMs) using coal-based solid waste-derived mesoporous silicon as carrier for polyethylene glycol (PEG) encapsulation. Complex multilevel porous silicon-based materials were synthesized through mineral phase regulation and acid etching techniques, while regular porous structures were created using cetyltrimethylammonium bromide (CTAB) as templating agent, and the pore architectures and surface functionalities were characterized and analyzed through SEM (Scanning Electron Microscopy), BET (Brunauer-Emmett-Teller), and FTIR (Fourier Transform Infrared Spectroscopy). The results demonstrate that complex porous materials exhibited enhanced thermal performance with increased pore size (1.22 nm) and volume (0.354/cm −3 ·g −1 ), whereas regular porous variants showed no thermal activity until amino-group functionalization. Post-modification, the functionalized regular porous materials achieved an enthalpy of 90.25 J·g −1 with crystallinity >90 %, confirming the co-regulatory effects of pore geometry and surface chemistry on PEG crystallization. These findings advance phase change materials (PCM) optimization strategies and coal waste valorization approaches, supporting energy storage material innovation for low-carbon development.