Formation of ag nanoparticles in CO₂-responsive microemulsion fabricated by a bio-based surfactant based on rosin

This article reports a novel CO₂ responsive W/O microemulsion stabilized by a rosin-derived surfactant MPANGG in combination with sodium dodecyl sulfate (SDS) at a mole ratio of 1:1 with n-butyl alcohol as co-surfactant. The average size of microemulsion was lower than 100 nm. This microemulsion had excellent CO₂ responsive property. The system can be rapidly switched between emulsified and demulsified states by alternating CO₂/N₂ treatment.This unique property not only facilitates the synthesis of spherical Ag nanoparticles but also, more importantly, enables the complete recovery and direct reuse of the oil phase for multiple synthesis cycles. The formation of Ag NPs was confirmed by a characteristic UV-Vis peak at 420 nm, while TEM revealed the synthesized Ag nanoparticles have an average diameter of 11.7 ± 0.5 nm, confirming a high degree of size uniformity. Furthermore, following demulsification, the upper oil phase was successfully recycled and reused for subsequent nanoparticle synthesis, demonstrating the combined economic and environmental benefits of this methodology.