No abstract

Most tough hydrogels are reinforced by introducing sacrificial structures that can dissipate input energy. However, because the sacrificial damage cannot rapidly recover, the toughness of these gels drops substantially during consecutive cyclic loadings. We propose a damageless reinforcement strategy for hydrogels using strain-induced crystallization. For slide-ring gels in which polyethylene glycol chains are highly oriented and mutually exposed under large deformation, crystallinity forms and melts with elongation and retraction, resulting both in almost 100% rapid recovery of extension energy and excellent toughness of 6.6 to 22 megajoules per square meter, which is one order of magnitude larger than the toughness of covalently cross-linked homogeneous gels of polyethylene glycol.

No abstract

Gels with high mechanical performance have attracted great interest because of their potential biomedical applications. Tough gels reported thus far usually contain sacrificial species to dissipate energy, thus compromising the fatigue resistance. In this study, highly stretchable and recoverable gels can be achieved by cross-linking cyclodextrin (CD)-based polyrotaxane with a low host coverage, synthesized via a one-pot enzymatic end-capping reaction with 90% yield and ∼2% CD coverage (PR02). The low coverage allows the CD cross-links to freely slip on the axis over large distance (∼2/3 of the axis length) and thus allows the PR02 slide-ring network keep intact under large deformation via the pulley effect. The PR02-hydrogel can be stretched up to ∼1600% long, withstand ∼1 MPa stress, and fully recover instantly. PR02-DMSO gels exhibit a shape memory behavior that withstood large deformation. As the first research to control the final property of the network by precisely controlling the slide distance of the cross-links, this work not only pushes the performance envelope of soft matters but also opens new opportunities for designing tough materials.

No abstract

No abstract

No abstract

A novel kind of polyrotaxane–silica hybrid aerogel is successfully prepared via one-pot sol–gel synthesis in this work. The polyrotaxane can chemically interpenetrate with Si particles homogeneously in nanoscale, so as to shorten the gelation time and construct a flexible and mechanically strong skeleton. The supramolecular effect ascribable to the sliding motion of cyclic components in polyrotaxane is introduced into the hybrid aerogel for the first time. Compared with the brittle pure silica aerogel, the obtained polyrotaxane–silica hybrid aerogels show very low density, low thermal conductivity, and more than two orders magnitude improvement in the compression strength without compromising transparency.