Adaptable Reversibly Interlocked Networks from Immiscible Polymers Enhanced by Hierarchy-Induced Multilevel Energy Consumption Mechanisms

Abstract

The present work proposes a novel strategy to prepare reversibly interlocked networks with enhanced mechanical properties through hierarchy-induced multilevel energy consumption mechanisms. The core issue lies in the introduction of in situ inter-macromolecular ionic interactions among the component networks regardless of their miscibility, which is hard to be implemented in other materials. Traditional small-molecule contra-ions are no longer necessary accordingly. As revealed by the proof-of-concept transparent interlocked networks composed of immiscible cross-linked styrene−butadiene rubber (SBR) and polyethylenimine (PEI), the interlocking architecture and the inter-macromolecular ionic interactions are mutually promoted. The latter pulls the immiscible polymer chains together, favoring the formation of the former, while the former prevents the neighboring chains from separation and helps the complexation among the counterpart functional groups. Eventually, multilevel energy consumption mechanisms can be triggered under the applied force and the conventionally conflicting properties including strength, toughness, and creep resistance of the interlocked networks are remarkably increased at the same time. Moreover, the moisture sensitivity that used to accompany ionic interactions disappears, which broadens the application scope of the materials in practice. Owing to the included reversible Diels−Alder bonds and Schiff base, the SBR and PEI-based interlocked networks are self-healable and reprocessable and can even be unlocked producing the original single networks. It is anticipated that a versatile and facile platform technique may thus be developed for creating new polymeric materials with advanced multifunctionality.

Repulsive segregation of fluoroalkyl side chains turns a cohesive polymer into a mechanically tough, ultrafast self-healable, nonsticky elastomer

“…PEMA4F21 exhibits 28 times higher toughness (≈17 MJ m −3 ) than chemically crosslinked PEMA. The toughening of elastomers by introducing detachable crosslinks is frequently observed 17 , 26 , 28 , 34 – 37 , 55 – 58 . In these cases, dissipation of locally concentrated stress upon detachment of physical crosslinks under deformation is expected.…”

Enhancement of intrinsic thermal conductivity of liquid crystalline epoxy through the strategy of interlocked polymer networks

“…2a and b), as a result of the unique forced miscibility of ILNs. [27][28][29][30][31][32] Besides, the equilibrium swelling degree of ILCE 0.067/0.2 -1 is the lowest in comparison with those of LCE-SchB 0.067 and LCE-DA 0.2 (Fig. 2c).…”

“…ILLCE x/y was fabricated from LCE-SchB x and LCE-DA y , referring to the method described elsewhere. [27][28][29][30][31][32] Typically, chips of LCE-SchB 0.067 (5 g) and LCE-DA 0.2 (5 g) were separately dissolved in the co-solvent DMF after heating at 80 1C for 6 h and 150 1C for 30 min, respectively. Next, the solutions were mixed at 80 1C under stirring for 30 min.…”

“…2d demonstrates that the average free volume hole sizes and fractional free volumes of ILLCE 0.067/0.2 are smaller than those of the single networks and the values expected from the additivity rule. [27][28][29][30][31] Close packing of the macromolecular chains from the single networks must have occurred, and one single network passes through the meshes of another network. The findings reflect that the ILNs have been successfully prepared.…”

“…In this context, the recently emerged interlocked polymer networks (ILNs) [27][28][29][30][31][32] may provide a useful solution. ILNs are derived from two crosslinked polymers containing orthogonal reversible covalent bonds through topological rearrangement.…”