Fabrication of antibacterial casein-based ZnO nanocomposite for flexible coatings

•Antibacterial casein-based composite was designed by introducing ZnO nanoparticles.•The incorporation of ZnO was beneficial for obtaining a compact and continuous hybrid film.•Flexible caprolactam-casein/ZnO film presented flowerlike ZnO aggregation.

Flexible hybrid caprolactam-casein/ZnO nanocomposite (CCZ) was prepared by in-situ polymerization method. The micro morphology and structure were characterized using DLS, TEM, SEM and FT-IR. The influence of ZnO dosage on the appearance, hand feeling, mechanical property as well as antibacterial activity of as-prepared composite films was explored separately. TEM measurements revealed that ZnO NPs were trapped in the inner layer by casein micelles. SEM indicated that part of ZnO was deposited on both surface and inside of CCZ film in film-forming process. Moreover, the films displayed expected mechanical properties and excellent antibacterial activities against Staphylococcus aureus and Escherichia coli. This work provided a feasible pathway for fabricating natural polymer-based nanocomposite antibacterial coating which will has great potential use in several fields, such as textile, leather, packaging, paper making and indoor wall coating.

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