Heat Shielding of Steel With a Polyelectrolyte Coacervate Coating

Steel used in structural and aerospace applications often needs to be protected from high temperatures for the sake of safety and to prevent structural weakening. Polyelectrolyte complex (PEC) coatings filled with clay provide a new opportunity for thermal barrier coatings (TBC) that are simple and very effective. Here, a 580 µm thick TBC prepared from a PEC coacervate, comprised of polyethylenimine, poly(sodium phosphate), and halloysite nanotube clay, reduces the backside temperature of a ∼ 3 mm steel plate exposed to prolonged flame by more than 200°C (from 346°C to 120°C). This study demonstrates the potential of clay‐filled PEC coacervate TBCs to provide long‐term protection to high thermal conductivity materials.