Water resistance and antimicrobial properties of poly(vinyl alcohol) composite films containing surface-modified tetrapod zinc oxide whiskers

Tetrapod zinc oxide whiskers (TZnO-W) were successfully synthesized via a thermal oxidation method and surface-modified TZnO-W (STZnO-W) were prepared using a silane coupling agent to ensure good dispersion interaction in a poly(vinyl alcohol) (PVA) matrix. Their chemical structure, morphology, and antimicrobial properties were investigated. Additionally, five different PVA/STZnO-W composite films were prepared with different STZnO-W content. Compared with pure PVA, the thermal properties and moisture barrier properties of the PVA/STZnO-W composite films were enhanced as STZnO-W, which may be the result of the strong interfacial interactions of the -OH groups of PVA and -NH2 of STZnO-W in the composite films. Furthermore, the addition of STZnO-W with a high surface to volume ratio and hydrophobicity may act as an excellent moisture barrier and form a tortuous path to adsorb and diffuse water molecules in the PVA matrix. The PVA/STZnO-W composite films showed remarkably enhanced antimicrobial activity against gram-negative micro-organisms such as Escherichia coli (E. coli) and Vibrio vulnificus (V. vulnificus) compared with gram-positive micro-organisms, such as Staphylococcus aureus (S. aureus). The enhanced thermal, moisture and antimicrobial properties achieved by incorporating STZnO-W can be advantageous in various packaging applications, though the antimicrobial properties around gram-positive micro-organisms require further research.[Figure not available: see fulltext.]