Biodegradable Poly(butylene adipate-co-terephthalate) Antibacterial Nanocomposites Reinforced with MgO Nanoparticles

Antibacterial packaging materials can reduce the microbial contamination of food surfaces. In this study, magnesium oxide (MgO) nanoparticles were synthesized and then coated with cetrimonium bromide (CTAB). CTAB-modified MgO (MgO@CTAB) was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis. Then, different loadings of MgO@CTAB were mixed with poly(butylene adipate-co-terephthalate) (PBAT) by melt compounding. The results showed that the addition of MgO@CTAB deteriorated the thermal stability of PBAT due to MgO serving as a catalyst to promote the thermal degradation of PBAT. In addition, MgO@CTAB could serve as a nucleating agent to improve the crystallinity of PBAT. With the optimal 3 wt% of MgO@CTAB, the tensile strength of PBAT/MgO@CTAB increased from 26.66 to 29.90 MPa, with a slight enhancement in elongation at break. SEM observations and dynamical rheological measurements revealed that aggregation occurred when the content of MgO@CTAB exceeded 5 wt%. The presence of MgO@CTAB endowed PBAT with antibacterial properties. The bacterial inhibition zone increased with the increasing content of MgO@CTAB. In addition, MgO@CTAB had a better antibacterial efficiency against Gram-positive bacterial S. aureus than Gram-negative bacterial E. coli.

Automated summary

Magnesium oxide nanoparticles modified with cetrimonium bromide can be used as an additive in antibacterial packaging materials to improve thermal stability and tensile strength. However, high loading of MgO@CTAB may lead to aggregation, affecting the material performance.