Self‐Healing and Recycling Properties of Networked Polydithiourethanes With Reversible Crosslinked Moieties via Hydrogen and Dynamic Covalent Bonding

ABSTRACT In this study, eight types of networked Polydithiourethanes (PDTUs) were synthesized with the combinations of various dithioisocyanates, dithiols, and tetrafunctional thiols, and the self‐healing behaviors of the networked PDTUs were observed. In particular, the networked PDTUs with an ether structure in the main chain (ET/ET/PE) exhibited a healing efficiency, which was estimated by the ratio of initial and healed toughness values, of up to 77% at 25°C for 24 h. Moreover, the healing efficiency of ET/ET/PE reached almost 100% under the healing conditions at 50°C for 24 h or at 25°C for 48 h. However, after four repetitions of the self‐healing operation at 25°C for 24 h, the healing efficiency of ET/ET/PE decreased from 77% to 16%. Herein, the damaged ET/ET/PE was depolymerized at 150°C for 1 h, followed by repolymerization at room temperature, and the damaged ET/ET/PE was chemically recycled as the polymer that exhibited the same toughness and healing efficiency as the initial value. Since PDTUs exhibit a high refractive index and transparency, it is expected to develop applications as a self‐healable and chemically recyclable optical resin.