Supramolecular Elastomer Based Switchable Adhesives Regulated by Soft Confinement Induced Nano-Rod Crystals.

Abstract

Supramolecular adhesives enable on-demand detachment due to their dynamic nature. However, such behavior usually at the cost of limited adhesive toughness. To promote the intrinsic compromise between adhesive toughness and switchability, we propose a soft-confinement-regulated nanorod crystallization strategy to construct a supramolecular elastomer (PTA-PCL). The amphiphilic and soft poly (thioctic acid) (PTA) matrix forms a dynamically confined interface through hydrogen bonding, directing the oriented self-assembly of hydrophobic polycaprolactone glycol (PCL-OH) into nanorod crystals with an aspect ratio of 4.80 and thereby reinforcing the network. Meanwhile, thermally triggered phase transitions drive mesoscale evolution, allowing the adhesion state to be tuned by the dynamic confinement interface. Benefiting from this hierarchical structural design, the PTA-PCL film exhibited robust adhesion (1609.31 J m- 2), switchable debonding (83.7 J m- 2; switching ratio = 14.5), and high toughness (3.35 MJ m- 3). Molecular dynamics simulations indicated partial compatibility and strong interfacial interactions between PTA and PCL-OH, while the synergistic coupling between interfacial enrichment and crystallization reinforcement was confirmed by low-field solid-state NMR. Overall, this study presents a new strategy for inducing nanorod crystallization within soft networks, and the superior switchable adhesion and interfacial toughness make PTA-PCL a promising candidate for advanced adhesive materials.