3D printing

A commercial desktop DLP printer (Miicraft Plus) was used for all the 3D printing experiments. The setup of the 3D printer is shown in Supplementary Fig. ¹⁷. The printer is based on a LED projector (405 nm) with an intensity of 1.0 mW cm⁻² at the vat and a resolution of 450 ppi (∼56 μm). The build area is 43 mm × 27 mm × 180 mm and the layer thickness is adjustable from 5 to 200 μm.

Before printing, the ink (~10 mL) was poured into the resin tank. The 3D printing started by irradiating the ink with a pre-determined cure time for a given layer thickness (Supplementary Note ¹). After printing, the 3D printed objects were carefully separated from the build platform and then immersed in acetone for 24 h to remove unreacted monomers and porogens. The volume change of the 3D printed nanoporous polymers in acetone was almost negligible (Supplementary Fig. ¹⁸), ensuring the structural fidelity of the 3D printed objects.

For drying of 3D printed objects, supercritical drying was used to avoid the collapse of the nanoporous structures. The printed objects immersed in acetone were first transferred to the chamber of the supercritical apparatus (Leica EM CPD030), followed by exchanging the solvent with CO₂ at 10 °C five times (each exchange took ~1 min), reaching a pressure of 50 bar. Then, the chamber temperature and pressure were increased to 35 °C and 90 bar in 15 min to maintain the CO₂ in supercritical condition. Finally, the chamber pressure was gradually dropped to atmospheric pressure for releasing the CO₂.