Self-healing and recyclable photonic elastomers based on a water soluble supramolecular polymer†
Inspired by the color shifting capability of chameleon skin, photonic elastomers (PEs) that can change their color with mechanical deformation have been attracting growing attention because of their potential applications in sensing and optical materials. However, it remains challenging to develop facile and environment-friendly methods for the preparation of PEs with desirable optical and mechanical properties for practical applications. Here, water-soluble supramolecular polymer-based PEs with angle-independent structural color, self-healing, and recyclable properties are reported. The PEs are prepared by incorporating isotropically arranged SiO2 nanoparticles (SiO2 NPs) into a water-soluble ureidopyrimidinone (UPy) cross-linked poly(ethylene glycol) (PEG) polymeric matrix. The stable angle-independent structural color and mechanical properties could be tuned by incorporating SiO2 NPs with different sizes and contents. The resulting flexible PEs demonstrate a fast response to mechanical strain and can be used as a visual strain sensor for monitoring finger bending motions. More importantly, the resultant elastomers exhibit improved self-healing properties due to the introduced dynamic quadruple hydrogen bonding arising from the UPy–UPy dimers and could be readily recycled via a redissolving–casting or hot-press remolding process with negligible change in the structural color and mechanical properties. This study provides an eco-friendly and sustainable strategy for the preparation of PEs with improved self-healing and recycling capabilities, potentially useful in visual sensors.