Flexible and resilient photothermal polyurethane film from polydopamine-coated phase change microcapsules

A major barrier to widespread use of solar energy remains: the need for storage to correct the mismatch between supply and demand. Herein, this paper prepared a flexible and resilient polyurethane film (m-Mn/PU) that could convert and store solar energy by compositing photothermal phase change microcapsules (microPCMs) coated with polydopamine (PDA) and waterborne polyurethane. The modified microPCMs (>225 J/g) were obtained via the surface deposition with PDA, and the m-Mn/PU films displayed desirable photothermal storage efficiency from 49.1% to 66.8%. It was found that incorporation of PDA improved the elongation at break of 50-Mn/PU films (>110 J/g) from 163% to 442% due to the favorable interaction of PDA-coated microPCMs with PU. The films also demonstrated the excellent thermal durability, photothermal cyclability and flexibility. The simple PDA deposition strategy could be adopted in making varieties of photothermal composites suitable for thermal energy management and solar energy collector system. •The microPCMs loading 1.2 wt% PDA had the photothermal property.•Photothermal PDA-coated microPCMs@PU films had the excellent flexibility.•The composite films had melting enthalpy over 110 J/g and thermal durability.•The composite films also had excellent photothermal cyclability.