Bispillar[5]arene-Based Slide-Ring Polyrotaxanation Enables Enhanced Toughness, Recyclability, Impact, and Puncture Resistance of Polyisoprene Elastomers

A series of slide-ring polyrotaxanes (SRPs) have been constructed by the solvent-free blending of a ditopic pillar[5]arene (<b>DP5A</b>) and polyisoprene (PIP) after thermal annealing. Solid-state ¹³C NMR experiments supported the fact that the pillar[5]arene rings of <b>DP5A</b> were threaded by PIP chains to afford physically interlocked networks. Tensile tests revealed that 1% of <b>DP5A</b> can improve the elongation at break from 50 to 239%, the tensile modulus from 2.1 to 3.9 MPa, and the toughness from 0.35 to 4.5 MJ/m³. Impact and puncture resistance experiments show that the <b>DP5A</b>-doped materials exhibit remarkable enhancement of protective and impalement-resistant performance. The samples can be also recycled repeatedly due to their physical crosslinking nature. The important stress delocalization effects have been attributed to the pulley effect of <b>DP5A</b> in the SRP materials, which represents a supramolecular approach for improving the performance of PIP elastomers.