Glutaraldehyde crosslinked ternary carboxymethylcellulose/polyvinyl alcohol/polyethyleneimine film with enhanced mechanical properties, water resistance, antibacterial activity, and UV-shielding ability without any UV absorbents
Zhihao Shan, Jiayi Huang, Yuling Huang, Yuping Zhou, Yiqun Li
Abstract
Despite the plethora of methods reported for fabricating ultraviolet (UV) shielding films using various UV absorbers to date, it remains a major challenge for the development of novel UV shielding films that simultaneously exhibit excellent transparency. In this work, a novel composite film (GA-x-CMC/PVA/PEI) is fabricated by integrating anionic carboxymethylcellulose (CMC), cationic polyethyleneimine (PEI), and polyvinyl alcohol (PVA) via electrostatic and hydrogen bond interactions and further cross-linking with glutaraldehyde (GA). Herein, PVA expands hydrogen bonding networks, reduces film haze, and enhances its mechanical strength. GA acts as a crosslinker in producing Schiff bases with PEI and acetals with CMC and PVA. The synthesized GA-x-CMC/PVA/PEI composite film possesses a notable amount of unsaturated -CH=N- bonds of Schiff base, resulting from the condensation of PEI and GA, which exhibit superior shielding efficiency against both UV-A and UV-B rays while maintaining exceptional transparency, visibility, and simultaneously enhancing mechanical properties and thermal stability. Notably, increasing the content of PEI leads to almost complete shielding of the entire UV spectrum (<400 nm) due to the increasing of the number of -CH=N- unsaturated bonds. Furthermore, the obtained film without any UV-shielding additives has exceptional mechanical properties, hydrophobicity, and antibacterial properties, rendering it a wide application prospect.