Multifunctional Shape Memory Epoxy Nanocomposites Containing Carbon Dots

Recent statistics have demonstrated that the direct reuse of polymeric wastes can be considered one of the most sustainable and advantageous approaches. However, many applications require the use of products with specific shape and geometry: in this context, thermosetting wastes may be very difficult to readapt for new uses. To overcome this challenging issue, the scientific literature has witnessed the potential of shape memory epoxy thermosets. The shape recovery can be triggered by various stimuli, including pH, heat, and electricity, though the most studied is the thermally-induced shape recovery. Shape memory epoxies are employed as components in the transportation industry, where the demand for transparent and fire-resistant coatings is enormously increasing. Mostly, the flame retardancy of such coatings is improved by the chemical modification of the polymer matrix, together with the use of specific flame retardants. Unfortunately, these approaches often lead to the loss of transparency and a detrimental effect on the overall mechanical performance of the final product. In our work, we report the design and development of new multifunctional epoxy nanocomposites that exhibit photoluminescence, high hydrophobicity, fire resistance, and heat/flame-triggered shape recovery features [1]. It is worth noting that these all-in-one peculiarities can be achieved using very simple formulations, without using halogen- or phosphorus-based flame retardants, avoiding any specific modification of the polymer network, and employing carbon dots at very low loadings (namely, 0.1 and 0.3 wt.%). These latter are synthesized starting from vegetable wastes by a sustainable hydrothermal route, hence also fulfilling the circular economy concept [1].