(79a) Biopolymer-Based Solid Polyelectrolyte Complexes for Fully Recyclable Packaging Materials

Of the more than 260 million tons of plastic waste generated annually, packaging materials are the largest contributor due to the growth of single-use plastics and recycled at the lowest rate. In recent years, only 5% of plastic waste was recycled in any form, and even then, current mechanical recycling practices of mechanical grinding, melt filtration, and pelletization result in lower molecular weight polymers compared to virgin feedstocks, limiting reusability in subsequent generations of plastics. Polyelectrolyte complexes (PECs) are a promising sustainable alternative to petroleum-based plastics that would enable closed-loop recycling. In particular, PECs form from the self-assembly of polyelectrolytes via electrostatic attraction. After mixing, polyelectrolytes can phase separate into liquid and solid phases, of which the solid phase is the PEC. The electrostatic interactions that stabilize PECs are reversible via the addition of salt, enabling dissolution of the solid material, while extraction of salt ions leads to reformation of solid PECs. Furthermore, PECs made from biopolymers extracted from renewable resources, such as keratin and alginate, would decrease our reliance on non-renewable feedstock and incorporate naturally biodegradable linkages.