The preparation of high performance Multi-functional porous sponge through a biomimic coating strategy based on polyurethane dendritic colloids

A biomimic coating strategy is proposed to firmly incorporate 30 wt% carbon nanotubes (CNTs) onto porous polyurethane (PU) sponge surface. Firstly, a non-solvent induced precipitation under turbulent method was used to prepare PU dendritic colloids, then, CNTs are absorbed onto their surface. Such branched “core–shell” structured CNT/PU dendritic colloids were coated onto porous 3D PU sponge, obtaining multi-functional sponges. Comparing with traditional methods for coating porous, PU dendritic colloids containing a layer of CNTs on their surface were firmly wrapped onto the backbone of PU sponge. Thus, local contacts between CNTs are not prohibited, leading to continuous CNTs layer on the surface of porous PU sponge. As a result, CNT/[email protected] sponges exhibit record high moisture–electric energy transformation energy density based on distilled water of 0.0792 μW·h/mm3 and thus self-powered sensing capability, excellent electromagnetic shielding ability of 22316 dB·cm2·g−1 in X-band (8 ∼ 12 GHz), strain sensitivity of 16.17 kPa−1 and resistance of 0.2 Ohm under 300 kPa, respectively. These performances are much better than [email protected] sponge treated with traditional surfactants. Moreover, CNT/[email protected] sponge demonstrates excellent multifunctional features including excellent hydrophobicity (contact angle≈134.7°), washing resistance and remarkable weather resistance. Such strategy opens a novel route to prepare high performance multifunctional porous elastic materials.