Aluminate-activated nano-SiO2 for enhancing water vapor barrier properties in polymers films: A safe and effective strategy

Abstract

In this work, a series of nanocomposite films composed of polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT), polybutylene succinate (PBS), nano-SiO₂ activated by aluminate for different times were developed to enhance water vapor barrier properties. The physiochemical and thermal properties of the films were characterized. In addition, total and aluminum migration from the films was monitored, and non-targeted screening was performed to evaluate the potential safety of the composite films. Fourier Transform infrared spectroscopy analysis indicated that the nano-SiO₂ was successfully activated by aluminate. Differential scanning calorimetry analysis indicated that incorporation of the activated nano-SiO₂ slightly reduced the glass transition temperature (from 54 to 51 °C) and increased the crystallinity degree (from 6.9 % to 11.1 %) of PLA. Incorporation of 0.4 % nanofillers was found to give the highest crystallinity. Thermogravimetric analysis showed that the thermal stability of the PLA/PBAT/PBS films did not change significantly after adding the activated-nano-SiO₂. However, the incorporation of these nanofillers did increase the interfacial roughness and crystallinity degree of the films, thereby reducing the water vapor permeability by around 30 %. Erucamide was detected in the composite films after exposure to food simulants, however, the films containing the nanofillers still met European Union safety standards. In summary, the nanofiller-loaded polymer films developed in this study were shown to be safe and have high water barrier properties, which means they may be suitable for application in the food, cosmetic, personal care, pharmaceutical, and agrochemical industries.