Scalable fabrication of biodegradable, thermally insulating, fire-proof bioplastic foams via rapid magnetic force assisted squeezing and ambient drying

Abstract

Foam materials are in great demand in modern society, which are widely used in shock absorption, packaging, heat preservation, and building insulation. However, the severe contamination of non-biodegradable plastic foam waste accumulated in the environment has increased the demand and interest in the development of degradable and multifunctional bio-sourced materials. Manufacturing of biomass foam, however, often requires long-term operation of specialized equipment under extreme conditions, making it not as environmentally friendly as claimed. Here we present an energy-efficient freeze-drying-free approach for bioplastic foam production from marine biomass waste via freeze-thawing of shear-flow-induced micro-/nano-fibrous hydrogels and rapid magnetic force-assisted squeezing and ambient drying, which differs substantially from existing inefficient and energy-consuming drying processes. The magnetic force-assisted pre-dehydration strategy prevents the collapse of the 3D network structure under capillary action during solvent evaporation, enabling a low density of 25.5–37.5 mg cm−3 and ultralow shrinkage of 9.3%-12.2%. These ambient-dried chitosan foams exhibit a high compressive modulus (366–732 kPa, supporting ∼ 4600 times its own weight), favorable thermal insulation performance (0.038 W m−1 K−1), competitive thermal stability, and fire resistance (smokeless combustion and self-extinguishing). Moreover, this bioplastic foam has been demonstrated to be recyclable and biodegradable with a substantially reduced environmental impact, as evidenced by life-cycle assessment analysis, representing a promising alternative to petroleum-based plastic foam.