PBAT-based biodegradable nanocomposite coating films with ultra-high oxygen barrier and balanced mechanical properties

Poly(butylene adipate-co-terephthalate) (PBAT) nanocomposite films (NCFs) with high loading of highly exfoliated and orientated montmorillonite (MMT) have superior gas barrier performance and high stiffness but often lack satisfactory toughness. In this study, novel nanocomposite coating films (NCCFs) composed of PBAT substrate and thin sulfonated PBAT/MMT nanocomposite coating (NCC) layer were prepared by coating nanocomposite dispersion (NCD) containing nano-sized sulfonated PBAT (sPBAT) particles and exfoliated Na-MMT onto PBAT substrate films pretreated with plasma. MMT morphology, gas permeability and mechanical properties of the NCCFs were investigated. The NCC layer endows the NCCFs with superior oxygen barrier and highly improved stiffness, and the PBAT substrate mainly contribute to the tensile strength and toughness. The NCCFs with about 12% thickness NCC layer containing 28-70 vol% MMT in it exhibited oxygen permeability (0.0057-0.0016 barrer) over two orders of magnitude lower than PBAT, a modulus comparable to polyethylene (150-480 MPa) and toughness comparable to PBAT (elongation at break 620-730%). The ultra-high oxygen barrier and balanced mechanical properties provide potential of the NCCFs for high-end packaging applications.

Automated summary

Novel nanocomposite coating films (NCCFs) composed of PBAT substrate and thin sulfonated PBAT/MMT nanocomposite coating (NCC) layer were prepared. The NCC layer endows the NCCFs with superior oxygen barrier and highly improved stiffness, while the PBAT substrate mainly contributes to the tensile strength and toughness.