A Fully Plant-Based\nWater- and Oil-Resistant Paper\nComposite

Disposable tableware commonly used at gatherings and\nfor takeout\nhas switched from plastic to paper due to concerns about micro- and\nnanoplastic pollution. Their water and oil resistance are typically\nachieved by using either per- and polyfluoroalkyl substances (PFAS),\nwhich are harmful and persistent in the environment, or plastic coatings,\nwhich exacerbate the plastic pollution issue. Hence, safe and ecofriendly\nwater- and oil-resistant materials are a crucial need. Emulating natural\nplant properties, we applied a seamless lignin film on paper via the\nhot-pressing method. By varying parameters such as lignin coating\nweight (10–40 g/m<sup>2</sup>), hot-pressing pressure (1–5\nMPa), temperature (120–180 °C), and moisture content (10–50\nwt %) of lignin micro and nanoparticles (LMNP) suspension before hot-pressing,\nwe determined that 40 g/m<sup>2</sup> of lignin coating weight applied\nat 3 MPa pressure, 160 °C temperature, and 30 wt % moisture content\nare the optimal condition. This yielded a lignin layer with exceptional\nwaterproofing (100 min) and oil resistance (25 min). The paper composite\nboard biodegraded within 56 days in garden soil, thereby providing\na promising eco-friendly alternative to nonbiodegradable plastics\nand PFAS.