Polylactic acid (PLA) is one of the most widely used biopolymers, and it has demonstrated a huge potential for replacing some of the conventional plastics in certain application fields. However, due to a lack of other attributes such as antimicrobial properties and slow degradation rates, it is often blended with other polymers to impart these properties. Chitosan has desirable features including antimicrobial and antioxidant properties, biodegradability and biocompatibility, and environmental friendliness. Thus, it is widely blended with PLA to generate materials that can be applied in various fields. In recent years, PLA/chitosan blend composites and nanocomposites have been produced to develop sustainable and ecofriendly materials that can be suitable in active food packaging, water treatment, air filtration, and biomedical applications. This review provides an overview of the recent advancements in the development of PLA/chitosan blend composites and nanocomposites for various applications. The processing strategies, mechanical and thermal properties, together with utilization in biomedical, air filtration, water treatment, and packaging applications, are provided.

The growing need for sustainable materials has stimulated research into eco-friendly composites, with biochar emerging as an important reinforcement in polymer matrices. Biochar is a carbon-rich material produced by pyrolyzing organic biomass, offering various benefits over traditional fillers, including sustainability, waste reduction, and carbon sequestration. This study explores the effects of bamboo biochar as a hybrid reinforcement on the properties of polylactic acid (PLA)-rice husk composites. The present hybrid composites are prepared by varying the bamboo biochar from 5–25% and have better mechanical properties than PLA and its composite reinforced with a rice husk filler. The tensile, flexural, and compressive strengths of 51.5, 166.0, and 77.5 MPa are measured for the biochar percentage of 10%, representing increases of 73.1, 150.0, and 58.2% compared to PLA, and 158.2, 98.6, and 31% compared to the PLA composite with rice husk. Higher tensile and flexural moduli of 1.46 and 7.34 GPa are observed for 10 and 15%, respectively. However, the impact strength decreases with higher biochar content due to increased rigidity. The material’s hardness increases at higher biochar content due to enhanced stiffness. Thermal transition and degradation points rise due to increased crystallinity from the biochar reinforcement’s nucleation effect. Additionally, the hydrophobic biochar reinforcement reduces water absorption of PLA composite from 3.2 to 1.6%.

In this study, a new plastic film with antiviral and antibacterial properties was developed using modified cassava starch with glycidyltrimethylammonium chloride (GTMAC) and reinforced by crystalline nanocellulose (CNC), called Q-CS/CNC. For comparison, a control film (Q-CS) was produced without the addition of CNC. Elemental analysis revealed a degree of substitution (DS) of 0.552, indicating the replacement of the OH groups of starch by the NR₄⁺ groups of GTMAC during the quaternization reaction. The addition of CNC resulted in significant increases (p < 0.05) of 38.9, 38.2, and 43.1% in thickness, opacity, and water vapor permeability measurements, respectively, compared to Q-CS. Incorporating CNC also contributed to an increase of 43.6% in tensile strength and 109% in stiffness but slightly decreased thermal stability. The Q-CS/CNC film demonstrated efficacy by inactivating 99% of the coronavirus in 1 min and inhibiting the growth of Staphylococcus aureus and Escherichia coli. This action is attributed to the electrostatic interaction of quaternary amino groups, grafted onto starch, with the phospholipid membrane of microorganisms, resulting in the inactivation of these microorganisms. Therefore, these results highlight the potential use of Q-CS/CNC film as antimicrobial packaging, especially against coronavirus.

This study demonstrated, for the first time, the successful formation of porous paramylon esters, which were made from euglenoid polysaccharide known as paramylon and short-chain fatty acids, through supercritical CO₂ processing. By maintaining a constant ester functional group attached to the paramylon and varying its proportion, distinct porous structures were selectively produced. Solubility parameter estimations indicated that changes in esterification had no significant effect on the solubility of the paramylon esters used in the experiment. Thus, these structural differences are likely attributed to variations in the viscoelastic properties of paramylon esters under supercritical CO₂ conditions. Furthermore, thermal conductivity measurements revealed reductions of up to 20%. Intriguingly, substantial decreases in thermal conductivity were observed even at low foaming ratios, achieved through precise control of the porous structure.

The environmental and ecological concerns drive researchers to synthesize functional materials using components from natural resources. Nanocellulose (NC), derived from plants, marine animals, or microorganisms, is a green material attracting attention due to its abundance, biocompatibility, and biodegradability. NC’s interstice properties enable the synthesis of functional nanocomposites in forms like aerogels, foams, paper, sheets, or hollow filaments. This review briefly describes NC classification and production while comprehensively presenting its mechanical, rheological, optical, and electrical properties, offering foundational knowledge for future research. Additionally, it highlights recent developments in NC-based products across fields such as papermaking, water treatment, civil engineering, electronics, cosmetics, food, and medicine. For the first time, this paper explores recent advances in NC molecular simulation, providing insights into structure, arrangement, and interactions through molecular dynamic simulation. Finally, future prospects for NC-based applications are discussed to encourage studies addressing current challenges.