Fig. 2: Mechanical, photothermal and photomechanical properties of PULM nanocomposites.

a Tensile stress strain curve of PULM nanocomposites under a strain rate of 100 mm min⁻¹. b Elastic modulus and mechanical toughness of PULM nanocomposites. c Hysteresis area when PULM nanocomposites are pulled to 100, 500, and 1000% strain after the first cycle of cyclic stress–strain measurements. Inset shows the hysteresis area at 100% strain. d Recovered hysteresis area of PULM nanocomposite cyclic stress–strain curves after a 1 min and 180 min delay at 100% strain. e Arrhenius fittings (dashed lines) of ln(t) versus scaled inverse temperature. t refers to the relaxation time. Slope of Arrhenius fittings represents the relaxation activation energies. f Temperature change profile of PULM0 and PULM15. NIR light was turned on for 150 s at 0.2 W cm⁻² or 0.8 W cm⁻² and subsequently turned off for films to cool down. g IR images of PULM0 and PULM15 illuminated at different NIR light intensity for 150 s. h Change in storage modulus (ΔE’) of PULM0 and PULM15 after 10 s of NIR light illumination as a function of NIR light intensity. i Change in storage modulus (ΔE’) of PULM15 as a function of time after turning on and off the NIR light for 10 cycles at a frequency of 0.05 Hz followed by cooling for 100 s. All error bars are the standard deviation of three independent samples.