In situ synthesis of zero-valent silver nanoparticles in polymethylmethacrylate under high temperature

► Stable zero-valent Ag nanoparticles are synthesized in PMMA by one step approach under high temperature. ► The size and shape can be controlled by reaction time. ► The competitive growth of Ag nanoparticles with the lacking of additional Ag source is discussed. ► A new mechanism of shape conversion of Ag nanoparticles is proposed.