Thermo-compression process-mediated in-situ cellulose microfibers phosphorylation enables high performant cellulosic paper packaging

Abstract

With the increasing demand for environmentally friendly alternatives to traditional plastic packaging, the development of sustainable cellulosic-based materials has become a strategic research topic. In this concept, a groundbreaking approach was adopted herein to produce phosphorylated cellulose microfibers (CMFs)-based paper packaging via a one-pot preparation step using a thermo-compression process (150 °C under pression for 45 min) in the presence of diammonium hydrogen phosphate ((NH4)2HPO4, denoted DAP) and urea. This process involves a chemical mechanism leading to the production of phosphorylated cellulosic paper with a very compacted structure induced by the hornification phenomenon. This phenomenon reveals the formation of additional and irreversible strong hydrogen bonds leading thus to an increase of the materials’ crystallinity up to 91%, and to an enhancement of their morphological, thermal stability, flame retardancy, hydrophobicity, water vapor permeability, and mechanical strength properties. To further enhance these properties, and thus their potential applications, the as-produced phosphorylated CMF paper samples were then coated with a thin layer (40 ± 1.11 µm) of poly[ethylene-co-(vinyl acetate)] (EVA) polymer. A comparison of collected properties with those from non-phosphorylated CMFs or from materials prepared using the conventional phosphorylation process clearly demonstrates that the proposed one-pot preparation method led to the production of advanced materials more effective for packaging applications. Overall, the findings associated to this work could be used as a proof-of-concept for the development of sustainable packaging materials, which could be made by following a more efficient and cost-effective manufacturing procedure than current benchmarks.