Hydrophobic bio-based foam with improved mechanical strength and antibacterial activity via rosin coating

Pulp fiber foam (PFF) exhibits potential as substitute for traditional plastic foam in packaging fields due to renewability and degradability. However, the hydrophilic nature limits its application. Inspired by the hydrophobic and antibacterial properties of natural polymer rosin, hydrophobic PFF (r-PFF) was prepared in an environmentally friendly and simple way. The prepared r-PFF has low density (30.79 kg/m3) and high hydrophobicity with the water connect angle reaching 125 °. Moreover, the rosin coating enhanced the mechanical properties of r-PFF at different humidity. Compared with PFF, the stress at 50 % strain of r-PFF increased by 71.3 % at 90 % RH. In addition, a static compression constitutive model of r-PFF was established to predict the mechanical properties of r-PFF at varying RH. Water and moisture barrier was enhanced and stability in water for the foam was improved. Furthermore, r-PFF displayed good antibacterial properties due to the introduction of rosin. This study provided an environmentally friendly and simple route for construction of light bio-based materials with good hydrophobicity and antibacterial activity.