Abstract:

Significance Facemasks serve as essential personal protective equipment, playing a crucial role in preventing the spread of infectious diseases and safeguarding environmental health. The COVID-19 pandemic has significantly increased global demand and consumption of facemasks, leading to concerns on the environmental impact due to excessive plastic waste. Conventional facemasks are predominantly made of petroleum-based polypropylene (PP), a non-degradable polymer that contributes to persistent environmental pollution and exacerbates the global plastic waste crisis. As a result, there is an urgent need to develop sustainable alternatives that maintain high-performance filtration efficiency while minimizing environmental harm. Polylactic acid (PLA) has emerged as a promising candidate for next-generation facemask filter materials due to its bio-based origin, biodegradability, and excellent processability. Derived from renewable resources such as corn starch and sugarcane, PLA offers a viable solution to reducing reliance on fossil fuels while minimizing environmental impact. Despite these advantages, PLA-based materials face inherent limitations, including brittleness, low elongation at break, and slow degradation rates under ambient conditions. Addressing these challenges is critical to advancing the practical application of PLA-based facemasks. This review provides a comprehensive analysis of PLA-based facemask filter materials, emphasizing their advantages, limitations, and modification strategies to address existing challenges.

Progress Significant research efforts have been devoted to improving the mechanical properties and biodegradability of PLA-based facemask materials to meet the requirements of protective applications. Among the various strategies, modification of PLA through polymer blending has been an effective method for enhancing toughness and accelerating degradation. The blends of PLA with other biodegradable polymers, such as polycaprolactone (PCL), polybutylene succinate (PBS), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), have demonstrated marked improvements in flexibility and biodegradability. These blends not only retain the biocompatibility and renewability of PLA but also help overcome its inherent brittleness. However, critical challenges remain, particularly in achieving homogeneous dispersion of the secondary polymer phase, minimizing phase separation, and reducing the overall production cost—factors that significantly hinder the scalability and industrial adoption of such materials. In addition to the polymer blends, plasticization has gained considerable attention as a means of enhancing the ductility, flexibility, and processability of PLA. Bio-based small-molecule plasticizers, such as citrate esters, triglycerides, and oligomeric lactic acid, have shown great potential in improving PLA's mechanical properties and promoting faster degradation. These plasticizers, derived from renewable sources, provide an environmentally friendly and cost-effective solution to enhancing PLA's flexibility, which align well with the principles of green chemistry and sustainable materials development. Nevertheless, issues related to high plasticizer content and migration tendencies pose concerns regarding long-term stability and material integrity. Current research is increasingly focused on the development of high-performance plasticizers with reduced migration tendencies, as well as the use of reactive compatibilization and advanced processing techniques (e.g., electrospinning, melt blending) to ensure stable and effective modification of PLA-based facemask materials.

Conclusion and Prospect PLA-based fibrous materials show considerable promise as sustainable alternatives for facemask production due to their biodegradability and potential for functional modification. Current research has yielded encouraging results, particularly in enhancing mechanical properties and degradability through polymer blending and plasticization. However, several challenges remain. These include maintaining long-term structural integrity, ensuring uniform dispersion of additives, controlling plasticizer migration, reducing the production cost, and achieving performance comparable to PP-based masks. From a forward-looking perspective, the development of next-generation PLA-based facemasks should focus on multifunctionality and reusability. Integrating bio-based antibacterial and antiviral agents, self-cleaning coatings, and even real-time sensing functionalities can significantly expand the applicability of PLA in protective equipment. Furthermore, optimization of spinning and membrane-forming technologies, such as electrospinning or melt-blown processes, is crucial for producing highly efficient filtration media with enhanced comfort and breathability. The shift from single-use to reusable PLA-based facemasks not only aligns with global sustainability goals but also offers a viable solution to plastic pollution caused by disposable PP masks. To achieve this, interdisciplinary efforts combining materials science, environmental engineering, and health technology are essential. Ultimately, the evolution of PLA-based facemasks from disposable consumables to high-performance, sustainable protective equipment will contribute significantly to the advancement of green protective materials.

Key words: polylactic acid, bio-based plasticizer, biodegradable polymer, air filtration, facemask, biodegradable facemask, filtration material