Highly flexible, healable and degradable polyurethane phase change materials with exceptional mechanical properties for thermal regulation

Materials with multifunctionality, especially polymers based on dynamic covalent bonds, have attracted considerable interest due to their technological innovation. Nowadays, phase change materials (PCMs) are widely used in various cutting-edge fields, while strategies for simultaneous realization of their flexibility, self-healing, high mechanical properties and degradability are still highly anticipated. In this work, we have designed and constructed a multifunctional polyurethane phase change material (PU-PCM) by the incorporation of isocyanate-hydroxy coupling reaction, where the soft phase polyethylene glycol (PEG6K) serves as latent heat storage sectors, and triple boron-urethane bonds (t-BUBs) as dynamic cross-linkers in the hard segment provide healable ability, excellent mechanical properties, and degradability through the cooperative effect of ordered H-bonding interactions. As a result, the well-designed PU-PCM exhibits high flexibility, superior tensile strength (∼39.0 MPa), tensile strain (∼1425%), and toughness (∼324.0 MJ/m3), as well as excellent healable efficiency (∼90% at room temperature), and degradability in a mildly acidic solution. Also, the h-BN enhanced PU-PCM composite film can be used to cool the working CPU as the PEG6K chains embedded in the soft segments can work as a smart thermal-regulator to harvest the undesired heat from the surroundings.