Engineered Phytosterol-Based Pickering Emulsion Gels as Tailorable Soft Materials for 3D Printing

Developing sustainable and tailorable soft materials for advanced manufacturing remains a challenge. Here, we present a material design strategy that transforms phytosterols into functional colloidal building blocks via antisolvent precipitation. By tuning the precipitation parameters, we engineer the particles’ interfacial wettability, enabling them to serve as the effective stabilizer for constructing water-in-oil (W/O) Pickering emulsion gels. The antisolvent treatment reduced particle size from approximately 84.8 μm to 1.9–14 μm and decreased the three-phase contact angle from 145° to 115–131°, depending on the solvent/antisolvent ratio. The resulting emulsion gels exhibited tunable storage modulus ( G ′ at 1 Hz) ranging from 2.5 to 25 kPa, which is attributed to a dual mechanism: Pickering stabilization and crystalline network in the continuous oil phase. After 10 days of storage, the gels showed increased G ′ and no signs of oil or water separation, with a uniform microstructure, indicating good stability. These bioderived gels exhibit shear-thinning, yield stress, and rapid self-recovery─properties that meet the rheological requirements for 3D printing. Printing precision increased with particle concentration, reaching 90% at 9% w/v, and all gels demonstrated good printing stability. The direct printing of complex, freestanding architectures further confirms their functionality as edible inks. This work presents a strategy for designing single-component soft materials from a bioresource, highlighting the relationship between interfacial engineering, microstructure, and macroscopic performance.