Highly Water-Tolerant TEMPO-Oxidized Cellulose Nanofiber Films Using a Maleic Anhydride/Wax Copolymer

In this article, a highly water-durable film based on (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibers (TCNFs) was prepared through a facile process using maleic anhydride/wax copolymer (MAW)/limonene solution. In the last few decades, the expansion of thermoplastic consumption has induced serious environmental issues like soil and marine pollutants and energy resource depletion. As a replacement of existing resins, the TCNF film is one of the most promising materials because it has high mechanical properties along with lightweight, good chemical and thermal stabilities under dry conditions, and cellulose as a starting material, which is the most abundant organic polymer on earth. However, the TCNF film under humid conditions shows low mechanical strength, which is not enough to use it as a commodity item. To improve the water durability of TCNF, we attempted to develop a surface modification technique with MAW/limonene solution. By immersing in MAW/limonene solution, the water contact angle of TCNF was increased from 65 degrees to 80 degrees; also, its water swelling ratio was decreased from similar to 6000% to 60%. Moreover, MAW-modified TCNF (M-TCNF) showed high mechanical strength (elastic modulus similar to 1.8 GPa and tensile strength similar to 52 MPa) in a swollen state. These results demonstrate the improvement in the water durability of the TCNF surface-modified with MAW. This contribution can help to expand the application of TCNF to various fields such as food packaging, water purification, and so on.

Automated summary

This article presents a highly water-durable film based on TEMPO-oxidized cellulose nanofibers, prepared with a facile process using MAW/limonene solution. By surface modification with MAW/limonene solution, the water durability and mechanical strength of TCNF were significantly improved, expanding its potential applications in various fields.