Abstract:

Objective This study presents an novel technological approach for preparing antimicrobial fibers by integrating oligomers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with a supercritical fluid. The objective is to develop antimicrobial fibers that exhibit both high antimicrobial rate and wash resistance. Through this integration, the fibers maintain their functional properties even after repeated washing, thereby enhancing their durability and practical applicability.

Method The molecular structures and functional groups of both PHBV and its derived oligomers (OPHB) were characterized using nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FT-IR) spectroscopy. In accordance with the Disinfection Technical Specification (2002 edition), the minimum inhibitory concentration and safety profile of OPHB were systematically evaluated. Antimicrobial fiber was processed by supercritical fluid technology, and its antimicrobial function comes from OPHB. The physical properties of the fibers were assessed both before and after the processing. Subsequently, the processed fibers were subjected to 50 washing cycles in compliance with the Chinese textile standard FZ/T 73023—2006. The antimicrobial rate of the processed fibers was quantitatively determined before and after washing, in accordance with the testing protocol specified in GB/T 20944.3—2008.

Results The structural characteristics of OPHB were investigated using FT-IR spectroscopy and NMR spectroscopy. The analytical results confirmed that OPHB is an oligomeric derivative of PHBV. OPHB demonstrated minimum inhibitory concentration of 5 000 mg/L against both E. coli (a gram-negative bacterium) and S. aureus (a gram-positive bacterium) through antimicrobial susceptibility testing. This comparable efficacy across bacterial classes underscores its broad-spectrum antimicrobial activity. Comprehensive safety evaluations further demonstrated that OPHB is non-toxic, non-irritating to skin, and non-mutagenic. Antimicrobial fibers were fabricated by applying the supercritical fluid technology and OPHB to a range of common textile substrates, including cotton, viscose, Modal, and polyester. At an OPHB content of 0.5%, all treated fibers achieved antimicrobial rates exceeding 90%. Increasing the OPHB concentration to 1% further enhanced performance, yielding near-complete inhibition rate (approaching 100%). Notably, after undergoing 50 standardized washing cycles in accordance with FZ/T 73023—2006, the antimicrobial rate of the treated fibers remained above 90%, thereby demonstrating exceptional wash durability and long-term functional stability. Mechanical integrity assessments confirmed that the processing technology did not adversely affect physical and mechanical properties of the fiber. Specifically, no statistically significant changes were observed in linear density, tensile strength, or elongation at break, indicating that the structural integrity of the fibers was fully preserved during processing. Furthermore, leaching of antimicrobial components was evaluated by the inhibition zone test. All treated fibers exhibited negligible inhibition zones (D<1), confirming a non-leaching mechanism of action. Finally, textile fabrics produced through standard industrial processes, including spinning, weaving, and dyeing of fibers, maintained high antimicrobial performance. These fabrics exhibited antimicrobial rates of approximately 90% against three distinct bacterial strains, both before and after repeated washing, highlighting the robustness and practical applicability of the developed technology.

Conclusion As an oligomer derived from PHBV, OPHB combines safety with high antimicrobial rate, demonstrating excellent antimicrobial activity even at low concentrations. The supercritical fluid technology for OPHB loading is applicable to diverse fiber substrates, yielding antimicrobial fibers with outstanding long-lasting washing resistance while maintaining mechanical properties nearly identical to untreated fibers. OPHB-based antimicrobial fibers function via a non-leaching mechanism, minimizing potential risks to human skin and making them suitable for intimate apparel and similar textiles. Fabrics produced from OPHB antimicrobial fibers through full-process operations, including spinning, weaving, and dyeing, retain superior antimicrobial performance and washing resistance.

Key words: antimicrobial fiber, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), supercritical fluid technology, washing resistance, non-leaching antimicrobial, functional fiber