Mechanochemical Synthesis of Recyclable Biohybrid Polymer Networks Using Whole Biomass

Whole-plant biomass from non-agricultural sources and waste biomass from processing agricultural products are both promising feedstocks for biopolymer production because they are abundant and do not compete with food production. However, their processing steps are notoriously tedious with the final materials often displaying inferior performance and limited scope in their properties. Here, we report a strategy to integrate whole-cell spirulina, a green-blue algae, into robust biohybrid algae-polyimine networks by leveraging a mechanochemical ball milling method. This strategy provides a greener synthetic approach to conventional solvent casting methods for polyimine synthesis; it simultaneously overcomes persistent constraints encountered in biomass processing and derivatization. The biohybrid algae-based materials retain adaptability and recyclability imparted by their underlying dynamic covalent polymer matrix and display enhanced mechanical properties compared to their all-synthetic equivalents. These advantageous properties are attributed to the unique morphology of the ball milled biohybrid materials which are facilitated by integration of the spirulina into the polymer matrix. Substituting spirulina with alternative biomass sources such as waste agricultural products also yields robust biohybrid networks, thus highlighting the broad utility of this straightforward mechanochemical synthesis to create more sustainable materials.