Flocculation of Ag nanoparticles elucidating adsorbed p-mercaptobenzoic acid by surface enhanced Raman scattering

► Flocculates of AgNPs were formed with PMBA providing enormous SERS activity. ► Electrostatic and van der Waals force play a crucial role in the flocculation of AgNPs. ► Dissociation of PMBA on AgNPs is also affected by its surface coverage. ► Different metal ions in solutions significantly varied the COO- band of PMBA.