Increasing energy autonomy and lowering dependence on lithium-based batteries are more and more appealing to meet our current and future needs of energy-demanding applications such as data acquisition, storage, and communication. In this respect, energy harvesting solutions from ambient sources represent a relevant solution by unravelling these challenges and giving access to an unlimited source of portable/renewable energy. Despite more than five decades of intensive study, most of these energy harvesting solutions are exclusively designed from ferroelectric ceramics such as Pb(Zr,Ti)O 3 and/or ferroelectric polymers such as polyvinylidene fluoride and its related copolymers, but the large implementation of these piezoelectric materials into these technologies is environmentally problematic, related with elevated toxicity and poor recyclability. In this work, we reveal that fully biobased non-isocyanate polyurethane-based materials could afford a sustainable platform to produce piezoelectric materials of high interest. Interestingly, these non-isocyanate polyurethanes (NIPUs) with ferroelectric properties could be successfully synthesized using a solvent-free reactive extrusion process on the basis of an aminolysis reaction between resorcinol bis-carbonate and different diamine extension agents. Structure–property relationships were established, indicating that the ferroelectric behavior of these NIPUs depends on the nanophase separation inside these materials. These promising results indicate a significant potential for fulfilling the requirements of basic connected sensors equipped with low-power communication technologies.

The effect of the post-annealing process on different properties of poly (L-lactic acid) (PLLA) nanofibers has been investigated in view of their use in energy-harvesting devices. Polymeric PLLA nanofibers were prepared by using electrospinning and then were thermally treated above their glass transition. A detailed comparison between as-spun (amorphous) and annealed (semi-crystalline) samples was performed in terms of the crystallinity, morphology and mechanical as well as piezoelectric properties using a multi-technique approach combining DSC, XRD, FTIR, and AFM measurements. A significant increase in the crystallinity of PLLA nanofibers has been observed after the post-annealing process, together with a major improvement of the mechanical and piezoelectric properties.