# Surface-Treated MDI-Compatibilized PPC-P/PPC-ECH Film with PVA/Tannic Acid Complex for High-Gas-Barrier Application

## TL;DR

A new low-cost film with improved mechanical and gas barrier properties was developed using a compatibilizer and a PVA/tannic acid coating for advanced packaging.

## Contribution

A novel PPC-ECH polymer and a PVA/tannic acid coating were combined to create a high-performance, low-cost packaging film with excellent gas barrier properties.

## Key findings

- Adding 2 phr MDI increased elongation at break from 71% to 502% while maintaining tensile strength and light transmittance.
- The PVA/tannic acid coating reduced oxygen permeability to an ultra-low 0.1 cm3·mm/(m2·day).
- The film shows strong potential for advanced packaging due to its mechanical and gas barrier properties.

## Abstract

A novel low-cost poly(propylene carbonate-co-epichlorohydrin) (PPC-ECH) with mechanical properties similar to those of poly (butylene adipate-co-terephthalate) (PBAT) was developed and incorporated into a poly(propylene carbonate-co-phthalate) (PPC-P) matrix. Meanwhile, 4, 4′-diphenylmethane diisocyanate (MDI) was employed as a reactive compatibilizer and mixed with PPC-P and PPC-ECH to create a variety of PPC-P/PPC-ECH/MDI blends. The effects of PPC-ECH and MDI content on the mechanical, optical, thermal, morphological, and gas barrier properties of the blends were systematically investigated. Results demonstrated that MDI reacts with both PPC-P and PPC-ECH, forming a chemically bonded interface that significantly improves their compatibility. Notably, when 2 phr of MDI was incorporated, the elongation at break of the PPC-P/PPC-ECH/2MDI blend increased dramatically from 71% to 502%, while maintaining good tensile strength (~23 MPa) and light transmittance (~80%). To further enhance the gas barrier performance, a high-oxygen-barrier poly(vinyl alcohol) (PVA)/tannic acid (TA) complex coating was applied to the surface of the PPC-P/PPC-ECH/2MDI film. This coating synergistically leveraged the abundant hydroxyl groups in PVA and TA to form a dense hydrogen-bonded network, reducing oxygen permeability to an ultra-low value of 0.1 cm3·mm/(m2·day). This outstanding performance highlights the strong potential of PPC-P/PPC-ECH-based films for advanced packaging applications.