Replacing Polymer Chemistry with Biopolymer Nanomorphology: Sustainable Hierarchical Networks in Polymer Substitutes

We will discuss emerging principles of using soft matter networks in a rich variety of sustainable biopolymer structures and materials. We have introduced a process of antisolvent precipitation under shear that enables the formation of 12 classes of (bio)polymer structures, including nanoparticles, rods, nanofibers, nanoribbons, sheets, and hierarchical nanomaterials. Specifically, we will focus on the unique capabilities enabled by a new class of soft dendritic colloids (SDCs) with hierarchical morphology (Nature Materials 18:1315, 2019). The fractal branching and contact splitting phenomena enable a range of highly unusual properties of the SDCs – gelation at very low volume fractions, strong adhesion to surfaces and to each other, and ability to form new types of gels, nonwoven sheets and reinforced biocomposites. Alginate SDCs can be used in hierarchical hydrogel networks with synergistic combination of the colloidal and molecular networks (Nature Comm. 12:2834, 2021). One emerging application of the SDCs with high societal impact is active microcleaners from chitosan that capture microplastics for water remediation (Langmuir 40:5923, 2024). Finally, we report a class of high-performance multifunctional composite films made of biopolymers, where agarose matrix is reinforced with chitosan SDCs. Owing to the highly entangled hierarchical SDCs network, the reinforced biocomposites have excellent mechanical performance, high optical transmittance, hydrostability, bactericidal activity and soil biodegradability (Cell Rep. Phys. Sci. 4:101732, 2023). The results suggest a universal strategy for the design of naturally-sourced composites with hierarchical networks that can serve as substitutes for petroleum-based plastics.