Self‐healing and reprocess of crosslinked polyurethane based on dynamic oxime‐carbamate bond

Abstract

Abstract Polymer materials containing oxime‐carbamate bonds show superior self‐healing ability under certain conditions. In this study, a series of dynamic oxime‐carbamate based PU‐D‐x (Polyurethane‐Dimethylglyoxime‐x) with different crosslinking degrees (x indicates the content of crosslinker based on the weight of solid content) were prepared, and the self‐healing together with the reprocessing characteristic was investigated. In situ variable temperature FTIR spectroscopy shows that the dissociation of oxime‐carbamate bonds occurred at 80°C and can be accelerated by the increasing temperature. With relatively lower cross‐linking degrees, these types of PU can be healed at low temperature and in a short time, for example, PU‐D‐0.3 can be completely healed at 80°C in 6 h, and PU‐D‐0.45 can be almost completely healed at 80°C in 9 h. With the increase of cross‐linking degree, the self‐repair of this kind of PU needs to be carried out at higher temperature and needs an extension of time. However, when the temperature increased to 100°C, the self‐healing time is greatly reduced to 3–5 h. Most interestingly, these types of crosslinked PUs showed expected reusing and reprocessing characteristics, even the PU‐D‐1.2 sample with the highest crosslinking degree can be completely reshaped and reprocessed under 120°C and 10 MPa pressure.