Thermogelation-regulated Pickering emulsion templating for fabricating efficient bio-based closed-cell foams

The development of sustainable and cost-effective thermal insulation materials is essential for improving energy efficiency and reducing dependence on petroleum-derived foams. Herein, a simple heating curing strategy was developed to fabricate bio-based closed-cell foams through hydroxypropyl methylcellulose (HPMC)-regulated Pickering emulsion templating. In this process, acrylated epoxidized soybean oil (AESO)-based emulsions were directly cured by heating, while the thermogelation and film-forming behavior of HPMC regulated the evolution of the porous structure. Increasing the HPMC concentration significantly enhanced the rheological stability of the emulsions, with the storage modulus increasing and the thermal gelation temperature decreasing from 66.1 °C to 40.3 °C. The foams exhibited low thermal conductivity of 0.042 − 0.058 W/m·K and exhibited pronounced thermal insulation in infrared thermography analysis. Meanwhile, the Young’s modulus increased from 2.64 MPa to 4.72 MPa, indicating improved mechanical properties. Micro-CT and SEM analyses revealed that the pore structure could be regulated by HPMC, with the average pore diameter increasing from 0.27 ± 0.13 mm to 1.26 ± 0.25 mm and the macropore volume fraction within the reconstructed region of interest decreasing from 84.4 % to 58.8 %. These findings provide a scalable and sustainable strategy for designing candidate bio-based thermal insulation foams, with potential relevance to energy-saving applications such as building-related insulation fillers, cold-chain logistics, and protective packaging.