Highly hydrophobic and moisture barrier nanocellulose based films produced via spray deposition

Nanocellulose (NC) films are gaining popularity in recent years owing to their recyclability and biodegradability; however, the commercialization of this material is limited by environmental and moisture barrier constraints. The incorporation of carboxymethyl cellulose (CMC) with NC significantly improved the barrier performance but the resultant films were quite hydrophilic and hence completely disintegrated in water. The aim of this study is to produce hydrophobic NC/CMC films without compromising their barrier characteristics. For this purpose, the optimized content of alkyl ketene dimer (AKD) was spray-deposited on the fully and partially dried NC/CMC films and their hydrophobic, barrier and mechanical properties were assessed. The deposition of AKD has improved the hydrophobicity and flexibility while maintaining the barrier properties of the films. However, their tensile index values decreased by 26-29% as compared with the neat NC/CMC films, but the values remained in acceptable range. Additionally, the partially dried spray deposited AKD-NC/CMC films have shown superior results as they showed higher hydrophobicity (theta = 127 degrees +/- 3), while lower percentage of mass loss after immersion for 48 h in water (15%) as compared with the fully dried spray deposited AKD-NC/CMC films. [GRAPHICS] .

Automated summary

This study aims to produce hydrophobic nanocellulose/caboxymethyl cellulose films with good barrier properties. The deposition of alkyl ketene dimer (AKD) on the dried films improved their hydrophobicity and flexibility while maintaining the barrier performance. The partially dried spray deposited AKD-NC/CMC films showed higher hydrophobicity and lower mass loss percentage after immersion in water.