Lightweight, Strong, Hydrostable, Bendable, Rolled-Up, and Biodegradable Straws Enabled by Nano- and Microarchitecture Tuning of the Wood Cell Wall and Molecular Welding Strategy

Abstract

Plastic pollution has become a global environmental challenge. Specifically, plastic straws are widely discarded and do not naturally decompose. Paper straws, as alternatives, suffer from weak mechanical strength, poor water/beverage stability, and lack of bendability. Here, an all-natural plastic substitute is fabricated using a top-down approach. After lignin is selectively removed from a natural wood slice, the delignified wood is infiltrated with chitosan solution. The chitosan-infiltrated wood, in its wet state, is highly flexible, moldable, and can be rolled into desired shapes. After drying, strong hydrogen bonds form at the cellulose/chitosan interfaces, making it an all-natural plastic substitute. By enclosing two sides using a chitosan adhesive, an all-natural straw is produced with a superior mechanical strength of 242 MPa, higher than polypropylene and paper straws. After baking, the all-natural straws show high water stability and maintain high mechanical strength in water (136 MPa) and carbonated beverages (71 MPa) for >2 days. A water-moldable process also creates accordion-like joints, giving the all-natural straws superior bendability (120°) and compressibility (50%). The all-natural straws exhibit high biocompatibility, full biodegradability in 5 months, and high circularity. Overall, the eco-friendly fabrication of all-natural straws holds great potential in addressing the ongoing pollution of plastic straws.