Thin films with enhanced water repellence and mechanical strength can be fabricated from renewable lignocellulosic feedstocks as a replacement for petrochemical-derived synthetic polymers, such that it minimizes the life cycle impact on environment and human health. In this study, hybrid poplar wood was extracted with hot water at 160 ºC for 20 min (HWE-20), 60 min (HWE-60) and 90 min (HWE-90), and then dissolved in 1-ethyl-3-methylimidazolium acetate to fabricate thin films of varying chemical composition and properties. The HWE-90 films were enriched in lignin by 74%, along with enhanced molecular entanglements during the solution casting process, which imparted hydrophobicity (108º water contact angle) as opposed to the control (56º), HWE-20 (77º), and HWE-60 (84º) films. They also exhibited 86% reduced water vapor sorption hysteresis and 75% improved storage modulus than the untreated control. Thus, we demonstrate how to tune the lignocellulosic film properties via hot water extraction.
Rajan, Kalavathy, Keonhee Kim, Thomas J. Elder, Amit K. Naskar, Nicole Labbé. Ionic-liquid-Assisted Fabrication of Lignocellulosic Thin Films with Tunable Hydrophobicity. ACS Sustainable Chemistry and Engineering,. 2022. https://doi.org/10.1021/acssuschemeng.2c01741