Self-cleaning and fully polymer-based super-moisture-resistant gas barrier coating films with 2D polymers for flexible electronic devices and packaging applications

In this report, we developed fully polymer-based and completely solution-processed moisture-resistant gas-diffusion-barrier-films (GDBFs) by utilizing a 2D polymer (2DP), polydimethylsiloxane (PDMS) and self-healing elastomeric SB-PDMS (i.e., Schiff base-linked PDMS) films. Through alternate stacking of spray-coated 2DP and spin-coated PDMS on polyethylene terephthalate (PET) substrates, multiple assemblies of bi-layers (BL)_n (where n = 1, 2, 3 or 4) have been designed. Self-healing elastomeric SB-PDMS was coated on the other side of the PET substrate to introduce self-cleaning and self-healing properties to the newly fabricated GDBFs. The low BET surface area of ca. 5.16 m² g⁻¹ indicated that the stacking of 2DP materials did not align the pores or rings within the molecule. Moreover, the XRD results of spray-coated 2DP films confirmed that the molecules of 2DP with high-layer crystallinities were oriented parallel to the substrate. The water vapor transmission rate (WVTR) value was improved from 1.4 g m⁻² day⁻¹ for PET to the optimum value of 8.5 × 10⁻⁴ g m⁻² day⁻¹ for SB-PDMS/PET/(BL)₄ containing four bilayers of 2DP/PDMS films, which did not degrade even after 1000 bending cycles. Accordingly, we developed flexible GDBFs with excellent moisture barrier properties along with additional functionalities (such as self-cleaning) to enable roll-to-roll processing of large-area flexible thin films for flexible organic-electronic device applications.