*Article* **DPD Simulation on the Transformation and Stability of O/W and W/O Microemulsions**

**Menghua Li <sup>1</sup> , Haixia Zhang 1,\* , Zongxu Wu <sup>2</sup> , Zhenxing Zhu <sup>3</sup> and Xinlei Jia 1,\***

	- **\*** Correspondence: angle00521@163.com (H.Z.); 18436342466@163.com (X.J.)

**Abstract:** The dissipative particle dynamics simulation method is adopted to investigate the microemulsion systems prepared with surfactant (H1T1), oil (O) and water (W), which are expressed by coarse-grained models. Two topologies of O/W and W/O microemulsions are simulated with various oil and water ratios. Inverse W/O microemulsion transform to O/W microemulsion by decreasing the ratio of oil-water from 3:1 to 1:3. The stability of O/W and W/O microemulsion is controlled by shear rate, inorganic salt and the temperature, and the corresponding results are analyzed by the translucent three-dimensional structure, the mean interfacial tension and end-to-end distance of H1T1. The results show that W/O microemulsion is more stable than O/W microemulsion to resist higher inorganic salt concentration, shear rate and temperature. This investigation provides a powerful tool to predict the structure and the stability of various microemulsion systems, which is of great importance to developing new multifunctional microemulsions for multiple applications.

**Keywords:** microemulsion; interfacial tension; end to end distance; dissipative particle dynamics (DPD) simulation
