Microorganism inspired hydrogels: hierarchical super/macro-porous structure, rapid swelling rate and high adsorption

Abstract

Based on the production of baking bread, rolls, cake, beer or Chinese steamed bread, a novel microorganism inspired macro/super-porous hydrogel composed of specific polymers and single-celled fungi, yeast, was prepared by the production of carbon dioxide (CO₂) via a fermentation method. The appearance, porous structure, swelling behavior and adsorption properties of the resulting hydrogels were investigated by optical microscopy, scanning electron microscopy (SEM), UV/Vis spectroscopy and gravimetric methods. The resultant hydrogel presents a yellowish brown color similar to that of ale yeast, and the integration of polymeric materials and fungi has significantly improved the pore shape/size, swelling and adsorption properties of the hydrogels. Both super- and macro-pores with diameters ranging from 1 mm to 5 μm exist in the hierarchical matrix of the hydrogels. The super/macro-porous hydrogels can absorb water very rapidly and swell to an equilibrium state in less than 60 min. With increasing consumption of yeast or sugar, the adsorption capacity (Q_t) of hydrogels can be increased by 1.39–1.87 times. After adsorbing cationic dye crystal violet (CV), pores of the hydrogel matrix were blocked and a dense layer was formed. By using same fermentation method porous fibers, elastomers, ceramics and metals could be obtained, which might have potential applications in the fields of cell culture, catalytic substrates, chemical separation and battery electrodes.