Fabrication of Two‐Dimensional‐Oriented Microporous Poly(L‐Lactic Acid) With Enhanced Antibacterial Characteristics

ABSTRACT In this work, a two‐dimensional (2D)‐oriented microporous structure was introduced into poly ( L ‐lactic acid) (PLLA) by efficient biaxial orientation technology combined with eco‐friendly supercritical carbon dioxide (SC‐CO 2 ) foaming technology. Meanwhile, poly‐dimethylsiloxane terminated with monofunctional glycidyl ether (e‐PDMS) was introduced to enhance melt properties and assist PLLA ultrathin film to uniformly foam. This e‐PDMS‐chain‐extended PLLA 2D‐oriented microporous film material exhibited good strength and toughness; the strength and the elongation at break reached 150.5 MPa and 71.3%, respectively. The density also decreased from 1.34 to 0.48 g/cm 3 . Due to this e‐PDMS‐ chain‐extended 2D‐oriented microporous structure, the interaction force with water and oil was greatly declined, which is beneficial to reducing the inner package loss of oil ester packaging materials. It is worth mentioning that the modified PLLA also showed excellent and lasting antibacterial properties, and the interaction force with bacteria decreased from 30.5 to 2.8 mN/m. After 10 days of coculture with staphylococcus aureus and bacillus aeruginosa, there was almost no bacterial growth on the surface of the material. This work provides a strategy for the design and manufacture of PLLA packaging films with good antibacterial properties.