Development of a nature-inspired polymeric fiber (BioFiber) for advanced delivery of self-healing agents

In this study, we developed nature-inspired multi-functional polymeric fibers (called BioFiber) to deliver bio-self-healing agents into cementitious materials. BioFibers were manufactured using a load-bearing core-fiber, a sheath of endospore-laden hydrogel, and an outer damage-responsive polymeric shell layer. The innovative BioFiber integrates three key functionalities into the quasi-brittle matrix: (i) autonomous bio-self-healing, (ii) crack growth control, and (iii) damage-responsiveness. The hydrogel sheath contained endospores, as bio-agents, to establish microbially-induced calcium carbonate precipitation (MICCP) as a self-healing end-product. The core-fibers provided crack growth control functionality into quasi-brittle engineering materials. Additionally, the outer shell coating integrated a robust damage-responsive self-healing activation strategy in concrete. A comprehensive parametric study was conducted to explore material options and the influential parameters for tailoring the processing-compositions-structure properties of the developed BioFiber. The findings of this study revealed that a concentration of 8 w/v sodium-alginate crosslinked with calcium acetate provided higher solution uptake capacity required for MICCP. As for the shell, the polymer blend of polystyrene and polylactic acid (1:1 wt.%), with polymer/solvent ratio of 18 w/v-single layer coating, effectively protected BioFibers during simulated concrete casting process. Lastly, each BioFiber was able to produce 40-80 mg of calcium carbonate within the first 30 hours of activation.

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