Sustainable Lignin-Based Coatings Doped with Titanium Dioxide Nanocomposites Exhibit Synergistic Microbicidal and UV-Blocking Performance toward Personal Protective Equipment

Lignin, a natural and nontoxic biopolymer, is an emerging material for the development of coatings, films, gels, adhesives, and adsorbents. Further, lignin holds a great potential to act as a capping, stabilizing, and reducing agent for fabricating versatile nanomaterials. In this work, both the coating material and titanium dioxide nanocomposites were developed using lignin. Initially, lignin was used as a matrix for developing titanium dioxide (TiO2) nanocomposites in a single step in a green manner. These newly developed nanocomposites exhibited excellent antioxidant, antimicrobial, and UV-blocking properties when compared with the pristine lignin or commercial TiO2 nanoparticles. Further, the lignin-based coating material was prepared using a simple, scalable, and straightforward method. The lignin coating was then doped in situ with the newly developed lignin-TiO2 nanocomposites and also with the commercial TiO2 nanoparticles (with varied quantities, 1-5% w/w) to improve the UV-blocking and antimicrobial properties of the native coating. Comparative studies were performed among all the lignin coatings (both doped and undoped) which showed that the lignin coating consisting of 5% w/w kraft lignin-based TiO2 nanocomposites exhibited the highest UV-blocking and promising antimicrobial potential. Finally, the TiO2 nanocomposite-doped lignin coating was administered on a cotton fabric which revealed a promising antimicrobial activity. This work accentuates the valorization of lignin via developing coatings and nanomaterials comprising improved multifunctional behavior for application in personal protective equipment.

Automated summary

Lignin, a natural and nontoxic biopolymer, has been developed as a material for coatings and nanocomposites, showing its potential for multifunctional behavior. It can act as a capping, stabilizing, and reducing agent for fabricating versatile nanomaterials, and exhibits excellent antioxidant, antimicrobial, and UV-blocking properties.