Design and Optimization of PLA-Based Nanocomposites: Enhancing Performance through Nanofillers and Solvent Systems

The transition from conventional fossil-based polymers to biopolymers is essential to promote sustainability and mitigate the environmental impact of persistent thermoplastic waste.Among bio-based alternatives, polylactide (PLA) has emerged as a leading candidate due to its derivation from renewable resources, biodegradability, and favorable mechanical and barrier properties.PLA holds significant promise in fields such as food packaging, biomedical devices, filtration, and technical textiles.However, its brittleness, low melt strength, and slow crystallization hinder its broader applicability.One of the most preferred and economical method to overcome the limitations of PLA is the incorporation of nanofillers to develop PLA-based nanocomposites.A variety of nanofillers-including nanoclay, nanosilica, graphene, carbon nanotubes, and cellulose nanocrystals (CNCs)-have been employed for this purpose.Among these, CNCs-renewable, biodegradable polysaccharide nanoparticles-stand out due to their low density, high specific surface area, and excellent mechanical characteristics.These attributes position CNCs as attractive candidates for the development of environmentally sustainable nanocomposite materials.Owing to their multifunctionality, CNCs have demonstrated significant potential across a broad range of applications, including mechanical reinforcement, barrier films, biomedical devices, drug delivery systems, electrospun nanofibers, and technical textiles.Despite their promise, CNCs tend to aggregate in hydrophobic polymer matrices due to surface hydroxyl groups and sulphate half-esters introduced during acid hydrolysis.Factors such as PLA molecular weight and crystallization behavior significantly influence CNC dispersion and final nanocomposite properties.Moreover, the solution casting method provides superior dispersion compared to melt processing, where CNC agglomeration is often observed.To further enhance CNC dispersion in solution-based systems, approaches such as use of surfactants, surface modification, and selection of highly polar solvents have been revealed.This review aims to explore the enhancement of material properties through the incorporation of different types of nanofillers into the polylactide matrix and to assess the key conditions necessary for achieving uniform dispersion of nanoparticles, especially cellulose nanocrystals, within PLAbased polymer systems.