This paper reported the in situ fabrication of high-performance poly(ionic liquid) adsorbents by using polymeric double-ionic liquid microemulsions (PDILMs)-mediated thermosynthesis. The PDILMs were successfully formed and their pseudo-ternary phase diagram was presented. Subsequently, poly(ionic liquid)s were in situ thermosynthesized in PDILMs. The microstructure of the prepared poly(ionic liquid)s was characterized by FTIR, Tg, and DSC analyses. Besides, the influence of various parameters including the crosslinking agent amount, reaction time and adsorbent dosage on the adsorption behavior of poly(ionic liquid)s for Zn(II) was investigated in detail. The results indicated that poly(ionic liquid)s were successfully in situ polymerized within PDILMs, and designed polymers exhibited excellent adsorption property for Zn(II) from aqueous water. Adsorption kinetics and adsorption isotherms further revealed that the adsorption process followed the pseudo-second-order kinetic model, and the Freundlich adsorption isotherm models were more suitable for the description of poly(ionic liquid)s for Zn(II) adsorption. POLYM. ENG. SCI., 59:1036-1042, 2019. (c) 2019 Society of Plastics Engineers