Abstract
Stereo-complexed polylactide (sc-PLA) fibers with excellent heat resistance and antibacterial properties were prepared by electrospinning. Due to poor heat resistance, common poly(L-lactide) (PLLA) fibers have poor dimensional stability at high temperatures and cannot be sterilized and recycled as a medical filter material. In this research, PLLA/poly(D-lactide) (PDLA) blends doped with silver nanoparticles (AgNPs) were electrospun to obtain the sc-PLA fibers. The effect of thermal induction temperature on the crystalline structure and thermal properties of sc-PLA fibers was investigated. Moreover, the influence of the addition amount of AgNPs on the crystal structure of sc-PLA fibers was studied, and the antibacterial properties of the sc-PLA fibers with different addition amounts of AgNPs were analyzed. The thermal induction is beneficial to the formation of stereo-complexed crystals of sc-PLA fibers, and finally completely stereo-complexed PLA fibers were obtained. The melting temperature of the completely stereo-complexed PLA fibers was 50°C higher than that of the PLLA fibers; therefore, the sc-PLA fibers have better heat resistance. The addition of AgNPs was conducive to the formation of stereo-complexed crystals of sc-PLA fibers. In addition, the antibacterial rate of sc-PLA fibers against E. coli and S. aureus was 99.99 ± 0.01% when the addition amount of AgNPs was only 0.15 wt%. The fiber membrane obtained in this experiment can be used as a reusable filter material, and the sc-PLA fiber membrane has broad application prospects in the biomedical field.
Highlights
The Fourier transform infrared spectroscopy (FTIR) test and X-ray diffractometer (XRD) were performed on the sample to characterize its crystal structure, and the antibacterial activity was studied to evaluate Stereo-complexed polylactide (sc-PLA) fibers and sc-PLA/AgNPs composite materials used in food packaging and medical applications
Morphology First, PLLA, PDLA, and sc-PLA were electrospun under the same process conditions to obtain their respective fiber membranes, and the obtained sc-PLA fiber membranes were treated at a high temperature of 120°C for 1 h
Since crystals have already existed in sc-PLA fibers before thermal induction, the crystals are prone to maintain the shape of the fibers during thermal induction (Pan et al, 2018)
Summary
Polylactide (PLA) is a kind of thermoplastic aliphatic polyester with high strength and high modulus (Amani et al, 2019; Kang et al, 2019; Hamad et al, 2020; Sanusi et al, 2020). Stereo-complexation between poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) can improve the thermal and mechanical properties of PLA. Recent studies have shown that biomedical materials prepared with PLA/AgNPs have good biocompatibility and antibacterial properties (Li et al, 2021). If AgNPs can improve the antibacterial properties of sc-PLA, even at high temperatures, sc-PLA products such as medical materials and food packaging will perform well. The Fourier transform infrared spectroscopy (FTIR) test and X-ray diffractometer (XRD) were performed on the sample to characterize its crystal structure, and the antibacterial activity was studied to evaluate sc-PLA fibers and sc-PLA/AgNPs composite materials used in food packaging and medical applications. In order to prepare fibers with antibacterial properties, 0.15wt%, FIGURE 1 | SEM of electrospun fibers: (A) PDLA, (B) PLLA, (C) sc-PLA, (D) sc-PLA 120°C, (E) sc-PLA 120°C–200°C, and (F) high magnification sc-PLA 120°C–200°C. In the formula, Y is the bacteriostatic rate of the sample (%), Wt is the viable concentration of the control sample in the flask after 18 h of shaking contact (cuf/mL), and Qt is the viable concentration of the antibacterial sample in the flask after 18 h of shaking and contact concentration of bacteria (cuf/mL)
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