Ionic-liquid-Assisted Fabrication of Lignocellulosic Thin Films with Tunable Hydrophobicity

Thin films with enhanced water repellency and mechanical strength can be fabricated from renewable lignocellulosic feedstock as a replacement for petrochemical-derived synthetic polymers, such that it minimizes life cycle impact on the environment and human health. In this study, hybrid poplar wood, either untreated (control) or pretreated with hot water at 160 degrees C for 20 min (HWE-20), 60 min (HWE-60), and 90 min (HWE-90), was dissolved in 1-ethyl-3-methylimidazolium acetate and regenerated to fabricate thin films. The HWE-90 films were enriched in lignin by 74%, specifically on the surface, which along with hemicellulose depletion imparted hydrophobicity (108 degrees water contact angle) when compared to the control (56 degrees), HWE-20 (77 degrees), and HWE-60 (84 degrees) films. They also exhibited 86% reduced water vapor sorption hysteresis and 75% improved storage modulus compared to the control. Thus, we demonstrate how to tune the lignocellulosic film properties via a combination of hot water pretreatment and ionic liquid dissolution.

Automated summary

In this study, the properties of lignocellulosic films were successfully tuned through a combination of hot water pretreatment and ionic liquid dissolution, resulting in enhanced water repellency and mechanical strength.