Sulfonated Poly(butylene Adipate-co-terephthalate)/Sodium Montmorillonite Nanocomposite Films with an Ultra-High Oxygen Barrier

Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable polymer very suitable for film applications. However, its low oxygen and water vapor barrier performance limit its applications in some high-demanding fields. Herein, we report PBAT-based nanocomposite films with an ultra-high oxygen barrier prepared by exfoliating a large amount of Na-montmorillonite (MMT) in a water-dispersible sulfonated PBAT copolyester matrix. At a MMT volume percentage (phi;m) of 9-22 vol %, the MMT was highly oriented and the volume fraction dependence of oxygen permeability (PO2) of the films can be well described by the Bharadwaj model. At higher MMT loadings of 28-32 vol %, a network-like MMT morphology was formed and the PO2 value was even lower than that predicted by the model. The nanocomposite film (NCF) with 32 vol % MMT exhibited a PO2 value of 7.5 x 10-16 cm(-3) cm cm(-2) s(-1) Pa(-1 )and a water vapor permeability of 1.57 x 10-11 g m m(-2) s(-1) Pa-1. Compared to PBAT, the oxygen barrier was improved by 2 orders of magnitude.

Automated summary

PBAT-based nanocomposite films with ultra-high oxygen barrier were prepared by exfoliating Na-montmorillonite in a sulfonated PBAT copolyester matrix. The films showed highly oriented MMT at certain MMT volume percentage and network-like MMT morphology at higher MMT loadings. The nanocomposite film with 32 vol% MMT exhibited significantly improved oxygen barrier compared to PBAT.