Ultrahigh energy-dissipation and multifunctional auxetic polymeric foam inspired by balloon art

Herein, we report a novel strategy for making ultrahigh energy-dissipation auxetic foam inspired by balloon art. As revealed by finite element analysis of balloon deformation evolution in polymer matrix, spherical balloons will turn to reentrant shape when compressed uniaxially in polymer matrix with large Poisson's ratio. By utilizing the know-how, auxetic silicone foam (ASF) was successfully developed through a well-designed foaming-compression-curing process. ASF shows ultrahigh energy dissipation capability of similar to 2000 kJ/m(3), which is over 80 times higher than conventional auxetic polyurethane foams. Moreover, ASF has low water absorption and high chemical and temperature resistance, allowing it to be used in harsh circumstances. Additionally, ASF is a thermal-responsive material that can expand at high temperature and return to its initial state when cooling down. Our work provides routes towards multifunctional and smart auxetic foams with potential applications in protective equipment, thermal insulation, and thermally driven soft actuators.