Improving the thermo-activated shape memory of thermoplastic potato starch by adding silver nanoparticles

In the last decade, shape memory has been studied in biopolymers, mainly in starches. These studies were focused on obtaining biocompatible materials for biomedical applications such as thermal sensors and prostheses. In this work, thermoplastic potato starch nanocomposites were produced by an extrusion-injection process. Silver nanoparticles were added to the matrix for reducing recovery time and improving recovery ratios of flexural shape memory. The nanocomposites were characterized by FTIR, low-field NMR, SEM and thermomechanical analysis, while the silver nanoparticles were characterized by UV–Vis spectroscopy and AFM. Recovery times decreased from seven to two minutes and the recovery ratio increased to about 100% with the increment of the nanoparticles content from 0 to 2%. The mechanical reinforcement effect of nanoparticles in the matrix was observed in the elastic modulus, while glass transition temperature of thermoplastic potato starch increased from 20 up to 31 °C because of the presence of the nanoparticles. Therefore, adding ionizable nanoparticles to thermoplastic starches represents an alternative to improve their thermomechanical properties and shape memory, leading to an activation temperature near to the body temperature (37 °C), showing a higher potential to be used in biomedical applications. Graphical abstract