Fabrication of the sandwich-like artificial muscles

RM257 (11.5 g; 19.54 mmol) and toluene (3.565 g) were mixed in a beaker and heated in an oven at 85°C for around 20 min. Then, the HHMP photoinitiator (0.074 g; 0.33 mmol) was added to the beaker. Subsequently, PETMP (0.83 g; 1.69 mmol) and EDDET (2.477 g; 13.59 mmol) were added to the mixture. The DPA catalyst (0.036 g; 0.36 mmol) was later poured into the same beaker. After the DPA dissolved, 0.08 g of the MWCNT powder was also poured into the solution. Then, the solution was stirred for 3 min, degassed for 5 min, and then poured onto a 1-mm-thick low-melting-point alloy die with a through-hole array. Next, the molds were placed in a dark environment for 24 hours to let the materials chemically react. Subsequently, the cured LCE-MWCNT–based composite was placed in an oven at 60°C to melt the alloy die, and, then, the solvent was evaporated in the oven at 85°C for 12 hours. Once the LCE-MWCNT–based composite cooled down to room temperature, the sandwich-like artificial muscle was obtained by stretching the polydomain LCE-MWCNT–based composite to specified multiples of its original thickness and simultaneously irradiated under 365-nm ultraviolet (UV) (10 mW cm⁻²) for 1 hour (figs. S34 and S35) (56).