Stiff and tough PDMS-MMT layered nanocomposites visualized by AIE luminogens.

Polydimethylsiloxane (PDMS) is a widely used soft material that exhibits excellent stability and transparency. But the difficulty of fine-tuning its Young's modulus and its low toughness significantly hinder its application in fields such as tissue engineering and flexible devices. Inspired by nacre, here we report on the development of PDMS-montmorillonite layered (PDMS-MMT-L) nanocomposites via the ice-templating technique, resulting in 23 and 12 times improvement in Young's modulus and toughness as compared with pure PDMS. Confocal fluorescence microscopy assisted by aggregation-induced emission (AIE) luminogens reveals three-dimensional reconstruction and in situ crack tracing of the nacre-inspired PDMS-MMT-L nanocomposite. The PDMS-MMT-L nanocomposite is toughened with mechanisms such as crack deflection and bridging. The AIE-assisted visualization of the crack propagation for nacre-inspired layered nanocomposites provides an advanced and universal characterization technique for organic-inorganic nanocomposites.