Highly transparent and self-healing films based on the dynamic Schiff base linkage

Self-healing optically transparent coatings have attracted significant attention due to their high transparency and ability to heal damages at the same time. In this study, we report an optically transparent and self-healing film via a layer by layer assembly. This film is based on chitosan (CS) and poly(ethylene glycol) functionalized by dialdehyde groups (DF-PEG). The dynamic equilibrium of Schiff base linkage between the aldehyde groups on DF-PEG and amino groups on CS resulted in the selfhealing property of the film. The CS/DF-PEG film can heal damages several times at the same location. Moreover, the Schiff base-bonded CS/DF-PEG films are highly transparent with a transmittance of up to 99.47%, and the transmittance of the film can remain at 99% after ten damage/healing processes. The combination of self-healing property and high transparency provides a new method for fabricating the optically transparent devices.