Development and performance of multi-stimuli actuations TiO2/rGO/EVA shape memory composites

To extend the service life of shape memory ethylene-vinyl acetate (EVA), the titanium dioxide/reduced graphene oxide/EVA composites (TiO 2 -P/rGO/EVA and TiO 2 -PF/rGO/EVA) were prepared by an impregnation method and modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane and 1H, 1H, 2H, 2H-perfluorooctyltrichlorosilane as hydrophobic agents, respectively. The hydrophobic/anti-icing properties, surface durabilities, shape memory properties, and UV-aging resistance of the composites were systematically investigated. The TiO 2 /rGO/EVA composites exhibit exceptional hydrophobic and anti-icing performance. The TiO 2 -P/rGO/EVA composites and TiO 2 -PF/rGO/EVA composites displayed water contact angles of 150.7° and 152.2°, respectively, with sliding angles of 6.4° and 4.9°, and both retained these values after durability tests. Frozen droplets on the TiO 2 -P/rGO/EVA composites could melt and slide off after 36 s of NIR irradiation. The composite displayed outstanding two-way shape memory behavior with multi-stimuli responsiveness, achieving reversible deformation under either 40 V electrical stimulation or NIR irradiation. It also possessed near-complete UV shielding (≈ 100%) and remarkable UV resistance: after 14 days UV exposure, it maintains 22.10% reversible strain and 99.35% shape recovery ratio; after 28 days, relative electrical conductivity remains at 87.5%. Hydrophobicity persists for over 48 h under UV irradiation in N 2 atmosphere. Furthermore, the TiO 2 /rGO/EVA composites surface wettability can be modulated through UV irradiation-washing-recoating cycles.