Supercritical fluid foaming of nanoscale phase patterned structures: An approach to lightweight hierarchical porous foams with superior thermal insulation

Hierarchically porous (HP) design provides an effective alternative to develop lightweight thermal insulation (T-I) materials, which play an important role in efficient energy management. Unlike elaborate synthetic methods, achieving HP features via supercritical fluid (SCF) techniques is still at an early stage. In this study, a facile and effective approach is reported to develop tailored HP foams via SCF foaming of binary blends with nanoscale phase separation patterns. The resultant cyclic olefin copolymer (COC) blend foams are extremely lightweight (50 kg m(-3)) and have excellent thermal conductivity of 25.8 mW m(-1)K(-1), which is on par with the thermal conductivity of air. Through the SCF foaming process, tunable HP structures can be created from COC blends with nanoscale phase patterns (phase size from ~ 150 to 240 nm). Different from traditional T-I polystyrene foams, chemical resistant COC blend foams are good candidates for durable coatings, and a dual-mode thermal device was successfully assembled with active photothermal conversion functionality and passive T-I performance, which exhibited a temperature difference of 32 & DEG;C between the two surfaces under illumination (2.4 x 10(5) lx). This opens up a new perspective for the development of lightweight, chemically resistant and highly thermally insulating foams for thermal management applications.

Automated summary

This study reports a facile and effective approach to develop hierarchically porous (HP) foams via supercritical fluid (SCF) foaming of binary blends. The resulting COC blend foams exhibit extremely lightweight and excellent thermal conductivity, making them suitable for durable coatings and dual-mode thermal devices. This opens up a new perspective for the development of lightweight, chemically resistant and highly thermally insulating foams for thermal management applications.