A healable, recyclable and thermochromic epoxy resin for thermally responsive smart windows

Traditional thermoset polymers such as epoxy resin have strong mechanical strength but are difficult to recycle, reshape and reprocess after being cured. When these materials are damaged, they can only be scrapped, resulting in a waste of resources. Introducing dynamic interactions into thermoset polymers can endow them with recyclable, reshapable and self-healing properties, thus prolonging their lifetime. In this work, we demonstrate that epoxy resin modified by coordination bonds between Ni2+ ions and imidazole/hydroxyl groups can show high mechanical strength (Young's modulus ranges from 210.4 +/- 15.7 MPa to 564.7 +/- 9.6 MPa) as well as thermoreversible behaviors (can be healed, reshaped and recovered at 80 degrees C and 0.1 MPa). More interestingly, due to the structural transformation of the Ni2+ coordination complex between the four-coordinated geometry and the six-coordinated geometry upon changing the temperature, this material shows reversible thermochromic behavior. Therefore, it has potential applications in the field of thermochromic smart windows.

Automated summary

In this study, traditional thermoset polymers were modified with dynamic interactions to make them recyclable, reshappable, and self-healing. The epoxy resin modified by coordination bonds showed high mechanical strength and thermoreversible behaviors, and exhibited reversible thermochromic behavior due to structural transformation of the coordination complex. This material has potential applications in thermochromic smart windows.