Super-stretchable Elastomer from Cross-linked Ring Polymers

Stretchability of polymeric materials is critical to many applications such as stretchable electronics and soft robotics, and yet the stretchability of conventional cross-linked linear polymers is often limited by the entanglements between polymers. We show using molecular dynamics simulations that cross-linked ring polymers are significantly more stretchable. Compared to cross-linked linear polymers, the degree of entanglements between ring polymers is much reduced. As a result, the stretchability of cross-linked ring polymers is determined by the maximum extension of polymer sections between cross-links, rather than the maximum extension of entanglement strands as in cross-linked linear polymers. Additionally, the more compact conformation of ring polymers before deformation also contributes to the increase in the stretchability.