AN INNOVATIVE MULTI-LAYER SYSTEM FOR THERMALLY ACTIVATED SWITCHING ACTIONS

Smart and shape-changing materials are entering a wide range of disciplines including the autonomous activation of devices. Here, a novel thermally driven multifunctional material that works as switch that independently reconfigures itself to trigger an electrical circuit, is presented. The material consists of multiple polymeric layers that are capable to spontaneously adapt their shape, as a system, when exposed to specific thermal gradients. The multi-layer system hosts in itself an electrically conductive layer. In particular, the film is flat at low temperature and is curved at higher temperature. In this case study the rolled configuration corresponds to the closed circuit (current flow) while the flat configuration corresponds to the opened circuit. The shape changing capability of the film is given by its unique structure which comprises multiple layers (PE and PET) characterized by specific and indeed opposite glass transition temperatures. A key feature of this design is that the material can be "educated" to reach both the desired shape at a specific set temperature, the desired degree and speed of shape change. Moreover, and most importantly, such morphing actions are cyclic without the need of re-educating the material. The study highlights the possibility to fine-tune with repeatability and precision, the shape of the film as a function of temperature.