Mechanically robust, stretchable, recyclable, and biodegradable ionogels reinforced by polylactide stereocomplex nanocrystals

Abstract

Spider silk possesses the combined properties of high strength, great toughness, and good elasticity due to the unique two-phase structures, in which the β-sheet nanocrystals consisting of hydrogen-bonded polypeptide chains are connected by the flexible chains. The spider-silk-like structures provide novel avenues to create functional materials. Herein, a novel yet simple strategy has been developed for the fabrication of spider-silk-like ionogels. The scaffolds of ionogels, polyurethane (scPLA-PEG), were prepared from poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and poly(ethylene glycol) (PEG). The stereocomplex nanocrystallites (sc) could be formed through the multiple hydrogen-bonds on the enantiomeric PLLA and PDLA chains, thus the as-prepared scPLA-PEG possesses the spider-silk-like two-phase structures, in which the stereocomplex nanocrystallites are cross-linked by the amorphous PEG phases. As compared, the scPLA-PEG exhibit much higher mechanical properties than the pristine PLA counterparts. The scPLA-PEG ionogels also display good mechanical properties, extremely temperature-tolerant flexibility that endures twisting at low temperature (−30 °C) and stretching at high temperature (70 °C). Furthermore, the scPLA-PEG ionogels can be easily recycled owning to the reversible properties of scPLA. The results would present a new insight into designing novel functional ionogels with distinguished mechanical properties, tractable recyclability, and biodegradability, which will promote the sustainable flexible electronics.