Fast Self‐Healing of Polyelectrolyte Multilayer Nanocoating and Restoration of Super Oxygen Barrier. Issue 10 (27th March 2017) - Song, Yixuan
Abstract : A self‐healing super oxygen gas barrier nanocoating is demonstrated for the first time. This multilayer film reduces the oxygen transmission rate (OTR) of a 179 µm poly(ethylene terephthalate) substrate by more than 1000× (OTR < 0.005 cm 3 (m −2 d −1 atm −1 )). After damaging, the oxygen barrier can be completely restored with a 10 min high‐humidity exposure. This swift and high‐efficiency self‐healing process is proven to be robust for at least ten damage–healing cycles. Abstract : A self‐healable gas barrier nanocoating, which is fabricated by alternate deposition of polyethyleneimine (PEI) and polyacrylic acid (PAA) polyelectrolytes, is demonstrated in this study. This multilayer film, with high elastic modulus, high glass transition temperature, and small free volume, has been shown to be a super oxygen gas barrier. An 8‐bilayer PEI/PAA multilayer assembly (≈700 nm thick) exhibits an oxygen transmission rate (OTR) undetectable to commercial instrumentation (<0.005 cc (m −2 d −1 atm −1 )). The barrier property of PEI/PAA nanocoating is lost after a moderate amount of stretching due to its rigidity, which is then completely restored after high humidity exposure, therefore achieving a healing efficiency of 100%. The OTR of the multilayer nanocoating remains below the detection limit after ten stretching‐healing cycles, which proves this healing process to be highly robust. The high oxygen barrier and self‐healing behavior of this polymer multilayer nanocoating makes it ideal for packaging (food, electronics, and pharmaceutical) and gas separation applications.