Double scaffold networks regulate edible Pickering emulsion gel for designing thermally actuated 4D printing

Abstract

3D and 4D printing of emulsion gels can be achieved by controlling the continuous phase and the interface. Edible high internal phase water-in-oil Pickering emulsion gels (PEGs) with a tunable double scaffold network structure are designed and prepared by food-grade phytosterol nanoparticles (PPs). In PEGs, PPs through hydrogen bonding enable binding of emulsion droplets to form the first scaffold network, giving PEGs high viscoelasticity for 3D printing. In the continuous oil phase, palm kernel stearin (PKST) can crystallize forming the second scaffold network of crystals to reinforce 3D printed objects of PEGs. The PEG can be used as a biocompatible template to engineer edible and rigid porous materials with adjustable strength and pore size depending on the degree of curing. 4D printing of PEGs is achieved by the thermal response of the PKST crystal network, leading to the unlimited potential of highly biocompatible PEGs in many applications.