Surfactant-free microemulsions (SFMEs) formed in the absence of traditional surfactants. It has been revealed that the SFMEs similar to the surfactant-based microemulsions (SBMEs), are expected to have comprehensive potential applications but the present understanding of SFMEs is very limited and many topics about SFMEs needs to be studied. Herein, we report a new SFME system consisting of methyl methacrylate (MMA) as the oil phase and 1-butanol as the amphi-solvent, to synthesis a polymerbased nanocomposite without using surfactant. For this purpose, after construction of the ternary phase diagram of the proposed system, the microstructures and structural transition of the SFME were investigated by measuring electrical conductivity and surface tension. The microenvironment polarity and salt solubility of water domains in the microemulsion region were also investigated. In the phase diagram three different microregions of water-in-MMA, bicontinuous and MMA-in-water regions were identified and compared with SBME system based on the Tween 80 surfactant. The size of the microemulsion droplets were characterized by dynamic light scattering technique. Finally, Ag nanoparticles were synthesized in the polymerizable systems of SFME and SBME to obtain stable colloids and consequently Ag/ PMMA nanocomposites, after polymerization process. Transmission electron microscope and energydispersive X-ray analysis were used to characterize the synthesized nanocomposites in SFME and SBME systems. The antibacterial activity of the nanocomposites showed the similar results for the samples prepared in SFME and SBME systems. The approach established in current work can potentially be used as a viable and practical method for making numerous other uniforms and morphologically well-defined nanocomposites free of surfactants.
