8th International Conference on Self Healing Materials – ICSHM 2022, Milan, Italy, 20 - 22 June 2022, pp.1
Materials with recycling and self-healing properties have gained growing attention in recent years due to their potential to improve the damage tolerance and sustainability aspects of materials and components made thereof. However, producing materials with both high self- healing efficiency and recyclability is still a challenge. In this study we will show the potential use of metal-coordination to develop healable and recyclable PDMS elastomers with overall good mechanical behavior. To this aim, healable and recyclable PDMS elastomers were prepared from aminopropyl terminated PDMS and 2, 5-thiophene dicarboxaldehyde via Schiff base formation. Iron and zinc ionic salts were used to induce reversible physical crosslinking through metal-ligand complexation with the PDMS. Bond energies of the metal- ligand complexes were calculated through density functional theory (DFT) at the B3LYP/6-311G(d,p) level. Bond energies were used for investigate the effect of coordination bond energy and bond dynamics on the mechanical properties, recyclability and self-healing efficiency of PDMS elastomers. Mechanical properties of the elastomers short after synthesis, after healing of cut-through damages and after polymer reprocessing were determined using universal testing machine with dog bone shaped samples. It was found that, unlike for iron-thiophene complexes, zinc-thiophene metal-ligand complexation provides fast healing ability (up to 96%) and high degrees of recyclability. The relationship between the bond energy and the healing and recycling abilities will be discussed.