Thioctic Acid-Enabled Melt Processing of Cyclodextrin-Based Polyrotaxane into Functional Supramolecular Networks for...

Cyclodextrin-based polyrotaxanes (CD-PRs), a class of mechanically interlocked materials (MIMs), have attracted attention for their low-cost raw materials, good biocompatibility, mechanical resilience, and dynamic adaptability. However, the extreme insolubility of the unmodified CD-PRs has long prevented scalable fabrication. Herein, a deep-eutectic-solvent (DES)-assisted melt processing strategy is reported in which natural thioctic acid (TA) both dissolves CD-PRs and co-polymerizes into poly(thioctic acid) (PTA) elastomers, forming robust pseudo-sliding-ring networks. By simply tuning the CD-PR loading, two distinct regimes of network reinforcement are demonstrated. Specifically, at low loadings, CD-PRs act as discrete toughening agents, enhancing elastomer toughness and fracture strain with minimal change in elastic modulus, whereas at higher loadings, they contribute as continuous crosslinks, improving both tensile strength and elastic modulus. The versatility of the resultant supramolecular networks is further showcased as two applications: (1) hot-melt adhesives, where the incorporation of CD-PRs enhances adhesion strength by 432% via enhanced cohesive energy, and (2) an ionically conductive elastomer (ICE), which enhances both elastic modulus and toughness to enable reliable underwater/air amphibious Morse Code transmission. This work overcomes the longstanding solubility challenge of cyclodextrin-based polyrotaxanes, reveals their concentration-dependent mechanistic roles, and provides a generalizable, green pathway for processing supramolecular networks from mechanically interlocked polymers.