Nanocellulose-silica nanoparticles Pickering foams as leakage-free multifunctional phase change composites for energy management

In this study, leakage-free, multifunctional foams were prepared by incorporating polyethylene glycol (PEG) with different molecular weights (2000, 4000, 6000, 8000) into cellulose nanofiber (CNF)–silica Pickering foams. The resulting constructs combined latent heat storage with robust structural integrity, thermal insulation, and acoustic damping. The control foam (PEG-free) exhibited ultrahigh porosity (∼99.8%) and low density (∼21.8 kg m⁻³), while increasing PEG content reduced porosity, most markedly with PEG 8000 (86–87%). All foams showed cellular-solid stress–strain responses, with the control reaching 97.9 ± 1.2 kPa at 80% strain and 170 ± 5.2 kPa modulus, whereas PEG 6000 formulations exhibited enhanced compressive strength (up to 336 kPa). PEG-loaded foams showed thermal stability correlating positively with PEG fraction. Thermal conductivity remained within 33–42 mW m⁻¹ K⁻¹, confirming the insulating capacity of our foams. Differential scanning calorimetry demonstrated latent heats up to ∼111 J g⁻¹ for P2k-80, with excellent cycling stability over 100 cycles and leakage-free performance; preliminary observations suggest similar trends for higher molecular weight PEG foams, though further testing is recommended. Infrared imaging of miniaturized model houses confirmed reduced and delayed surface heating compared to styrofoam, while acoustic tests revealed high absorption coefficients (0.8–1) in the 1–6 kHz range. These findings establish CNF–silica–PEG foams as lightweight, renewable composites that integrate latent heat storage with thermal and acoustic management for sustainable insulation applications.