Directly Converting Agricultural Straw into All-Biomass Nanocomposite Films Reinforced with Additional in Situ-Retained Cellulose Nanocrystals

It is attractive and meaningful to effectively utilize agricultural straws for preparing high value-added materials. In this work, we employ corn husk as a model substance for agricultural straws. By using microcrystalline cellulose (MCC) as an adhesive and reinforcing phase, direct utilization of corn husk is achieved, and consequently, corn husk/MCC films are fabricated in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). Corn husk is dissolved completely in AmimCl; then, MCC is added and partially dissolved by controlling the dissolution conditions. The undissolved nanocrystals from MCC are used as the reinforcing phase, and the dissolved MCC is used as the adhesive and part of the matrix. As a result, homogeneous, transparent, beige-colored corn husk/MCC nanocomposite films are obtained. The resultant nanocomposite films with the content of corn husk in a range of 50-71 wt % exhibit high tensile properties. The tensile strength and elastic modulus of nanocomposite films containing 50 wt % corn husk have reached 67 MPa and 4.4 GPa, respectively. Thus, this work provides a simple, economical, and effective method for converting sustainable biomass resources into valuable materials.