Multifunctional Thermoplastic Paper Enabled by Plant‐Cell‐Derived Additives: A Paradigm of Paper‐Based “Modern Alchemy”

Papermaking, an ancient yet remarkable invention, hinges on the formation of a network of plant cells. With the growing demand for bio-derived alternatives to non-renewable resources and difficult-to-degrade plastics, enhancing the functional attributes of cellulosic paper is essential to broaden its applications. Here, a facile approach is introduced to upgrade conventional cellulosic paper into an advanced thermoplastic biomaterial, endowed with ductility, wet-strength, gas and liquid barrier functionalities, and antistatic properties. The concept is grounded in the specialized area of papermaking wet-end chemistry and chemical additives and employs plant-cell-derived cellulosic additives, prepared via ring-opening-based heterogenous chemical engineering of paper-grade pulp with microstructurally porous cell walls comprising fibrils, which are then formed upon dissolution in an aqueous "non-derivatizing" solvent, for engineering the paper through a process that somehow mimics the industrial surface sizing. The utilization of additives initiates a form of paper-based "modern alchemy", which involves the encapsulation of fibers with ring-opening-engineered cellulosic structures, solvent-induced fiber annealing, bridging of interfiber gaps, film-forming, porosity reduction, structural densification, enhanced internal bonding, paper surface smoothening, etc. The engineered paper can be facilely reshaped through hot-pressing for 3D forming and recyclable applications. Additionally, their dissolution in a cellulosic solution yields functional additives for diverse applications, offering another avenue for recycling. This work offers insights into designing paper-based thermoplastic materials using sustainable additives.