We will report a new class of biopolymer composite films, which are envisioned as sustainable high-performance packaging material. These films are based on the recently discovered soft dendritic colloids (SDCs) in our group. The SDCs are highly branched polymeric particles surrounded by a nanofibrillar corona that result from polymer precipitation in a turbulently sheared non solvent medium. The biocomposite films that we developed are based on an agarose (AG) polysaccharide matrix reinforced with chitosan (CS) SDCs. The composite films are prepared through a solvent mixing and subsequent solution casting. The hierarchically branched CS reinforcement network endow superior properties to the films such as mechanical toughness and hydrophobicity. The ductility and toughness modulus of films containing 15 w/w% of CS SDCs increase 3-fold compared to their unreinforced counterpart. Due to a dense network formation and dispersive and electrostatic intermolecular interactions between the SDCs and the matrix, the films become hydrophobic, which may overcome the most common limitation to biodegradable packaging materials. The swelling of the films and their oxygen and water vapor permeability showed synergistic effects due to the SDCs inclusion. The composite films remain optically clear with high transmittance in the visible light range. Due to the abundance of polar functional groups along both AG and CS molecules, which can form intermolecular hydrogen bonds, chemical interactions are characterized using infrared spectrum analysis (FT-IR). Morphological analysis showed that SDCs are well incorporated in the AG matrix with no obvious signs of agglomeration in the composite films. These films can find application as sustainable food packaging materials with comparable or superior properties to the commercial petroleum-based films.

A new class of biodegradable, tough, and clear polysaccharide films reinforced with nanofibrillated chitosan

ACS Spring Meeting 2021

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