Poly(lactic acid) hybrid nanocomposites with synergistic cellulose nanocrystal-carbon reinforcement for sustainable packaging and multifunctional applications.

Sustainable and high-performance polymer composites are needed for advanced technological applications. This study outlines the straightforward synthesis and comprehensive analysis of novel bio-nanocomposites based on poly(lactic acid) (PLA) that are reinforced in a combined way with cellulose nanocrystals (CNC) and a hybrid filler system comprising carbon nanotubes (CNTs) and reduced graphene oxide (rGO). The addition of CNTs and rGO resulted in improved crystallinity. FTIR analysis indicated changes in the local chemical environment consistent with noncovalent matrix-nanofiller interactions. Differential Scanning Calorimetry (DSC) demonstrated that 0.50 wt% rGO exhibited the most favorable thermal behavior, as well as significantly enhanced crystallinity. Thermogravimetric analysis (TGA) demonstrated that nanocomposites exhibited enhanced thermal stability by the incorporation of nanofillers. The contact angle rising from 56.2° in PLA/CNC to 82.9° in 1 wt% rGO loading showed enhancement in hydrophobicity. Lysozyme-assisted degradation tests revealed slower degradation rates in composites loaded with nanofillers, which indicates improved resistance to enzymatic breakdown. A substantial decrease in water vapor permeability (WVP) and oxygen permeability (OP) study revealed improving barrier characteristics. The Alamar blue assay was carried out to study the cytotoxicity of hMSCs (human mesenchymal stem cells). The 0.25 wt% CNT-loaded composite showed a highly significant increase in cell survival by day 7 (p < 0.001). This study demonstrates a route for developing PLA nanocomposites with tunable structural, thermal, barrier, surface, and degradation properties.