Preparation and properties of wide pH range stable Pickering emulsions stabilized by a synergistic network of swollen modified microcrystalline cellulose (M-MCC) and methylcellulose (MC).

Pickering emulsions show promise in food, cosmetics, and pharmaceuticals but suffer from poor long-term stability under acidic conditions. To solve this, we designed a synergistic stabilization strategy using a composite gel matrix of lauric acid-modified microcrystalline cellulose (M-MCC) fibrous networks and methylcellulose (MC) to inhibit aggregation and coalescence via steric hindrance. Three preparation methods (M1 ~ M3) were compared. Notably, the synergistic system successfully overcame the inherent instability of cellulose-based Pickering emulsions in acidic environments. At pH 3, where electrostatic repulsion is minimal (zeta potential < -10 mV), pure M-MCC emulsions destabilized within 7 days. In contrast, all emulsions prepared via methods M1, M2, and M3 remained stable for at least 30 days without any oil separation. These results confirm that the MC-M-MCC composite gel matrix effectively compensates for the loss of electrostatic stabilization under acidic conditions. Emulsions produced by M1 and M2 exhibited high viscoelasticity and a U-shaped pH-viscosity profile. Meanwhile, those prepared by method M3 displayed smaller droplet sizes (d43 = 7.69 μm) and narrower size distributions (Span = 1.24) under alkaline conditions. This work provides a new route for high-value utilization of low-cost MCC and supports the industrial application of pH-responsive Pickering emulsions.