All-Biomass-Derived Nanocomposite Films of Pullulan/Lactate-Nanocellulose/Hydrophobic Lignin for Eco-friendly and Practical Plastic Food-Packaging Alternatives

Fully biomass-derived bioplastic packaging can potentially mitigate plastic pollution. Herein, we showed that bioplastics can be generated from pullulan, lactate-nanocellulose (laNC), or hydrophobic lignin (HBL) using simple engineering techniques. Both laNC and HBL were extracted from corn stalks with yields of 22.1% ± 0.5% and 13.7% ± 0.6%, respectively, using a recyclable, eco-friendly, lactic acid–glycine deep eutectic solvent. The fine dispersion of laNC in pullulan (20 mg/g) resulted in a bionanocomposite film (PNC20) with considerably improved tensile strength (76.6 ± 1.9 MPa) which was attributed to increased intramolecular hydrogen bonding. This film, as a food inner package, could be combined with kraft paper wrapping to preserve dry powders, biscuits, and oil. Notably, a sandwich-like film composed of two outer layers of HBL/laNC (LNC) films and a middle layer of PNC20-G300 film (glycerol content: 300 mg/g) exhibited favorable tensile strength (35.1 ± 1.2 MPa), low water vapor permeability (0.0240 ± 0.009 g·m·[m2·d·kpa]−1), and high water resistance. By variation of the numbers of LNC and PNC layers, various films which could be used as an outer packaging for foodstuffs were produced. All of the films were biosafe and readily degradable without composting or recycling, highlighting their potential in sustainability.