Iranian Research Organization for Science and Technology Journal of Particle Science and Technology 2423-4087 11 2 2025 12 01 Effect of the smallest microwave-synthesized Cu2S nanoparticles with surfactant templates on improving the properties of engine oil 117 130 1688 10.22104/jpst.2026.7962.1286 EN Azar Bagheri Gh. Department of Chemistry, CT.C., Islamic Azad University, Tehran, Iran Forogh Nejadi Department of Chemistry, CT.C., Islamic Azad University, Tehran, Iran Melika Pejman Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran Journal Article 2025 10 26 <span lang="RU">In this study, the preparation and identification of Cu</span><sub><span lang="RU">2</span></sub><span lang="RU">S nanoparticles were carried out using the microwave method, and the effect of irradiation time, power, and surfactant on particle size was investigated</span><span lang="RU">. The sample was characterized by XRD measurements, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), and ultraviolet-visible (UV-Vis).</span> <span lang="RU">Also, the results of FE-SEM on nanoparticles prepared with four surfactants, EDTA, sorbitol, citric acid, and PEG 400, showed that nanoparticles synthesized with the PEG 400 surfactant have the smallest size. Then, the effect of microwave power on the size of Cu<sub>2</sub>S nanoparticles was investigated at three powers of 700, 500, and 900 W. The FE-SEM results showed that Cu<sub>2</sub>S nanoparticles have the smallest size at 500 W. To investigate the effect of time on the size of Cu<sub>2</sub>S nanoparticles, the experiments were repeated at times of 3, 5, and 10 min, and the FE-SEM results obtained from this stage showed that after 10 min, Cu<sub>2</sub>S nanoparticles have the smallest size.</span> <span lang="RU">Also, the effects of the prepared Cu<sub>2</sub>S nanoparticles on the thermal conductivity, density, and viscosity of engine oil were investigated. The results obtained from this research show that the increase in thermal conductivity compared to the base oil indicates that these nanoparticles improve the heat transfer ability and operation of engine oil in harsher temperature conditions</span><span lang="RU">.</span> Cu2S Nanoparticle engine oil Surfactant microwave method https://jpst.irost.ir/article_1688_ae614c557843b1df326cb29c57225459.pdf