Facile preparation of eco-friendly plastic from rosin modified microcrystalline cellulose for food packaging

The development of packaging materials from renewable resources presents a viable solution for tackling the environmental issues stemming from the extensive production of non-biodegradable plastic packaging films derived from petroleum. Herein, a series of fully forestry sourced rosin modified microcrystalline cellulose (MCC-HDA) films, in which the rigid rosin moieties and cellulose chains were chemically linked by the flexible hexanediol, were successfully prepared via green, facile and efficient hydroxyl-yne click chemistry method. With the increase of rosin content, the modified films exhibited improved UV shielding with high transparency and improved hydrophobic properties. The introduction of the designed flexible hexanediol and rigid rosin segment lead to a denser microstructure of MCC-HDA films. Therefore, both the strength and toughness of the MCC-HDA film were effectively improved: the tensile strength, Young's modulus and toughness have been observed to reach up to 80±2.4 MPa, 5.5±0.3 GPa and 5.8±0.65 MJ/m 3 , respectively, which are 1.6, 2.6 and 1.4 times higher than those of pure MCC films. In addition, the denser structure also leads to a significant decrease in the oxygen and water vapor barrier layers of the MCC-HDA film, achieving the lowest transmission rates of 295 cm 2 /m 2 /24 h for oxygen and 793 g/m 2 /day for water vapor. Compared to commercial Polyethylene (PE) film, these films demonstrated not only high biodegradability (fully degrading in approximately 50 days), but also showed better fruit preservation performance (greatly reduced the oxidation of fruits). Given these significant characteristics, rosin-grafted cellulose films are anticipated to displace conventional non-biodegradable polymers and have prospective uses in the food packaging industry.