Ionic Liquid Cross-Linked Multifunctional Cationic Polymer Nanobeads via Dispersion Polymerization: Applications in Anion Exchange, Templates for Palladium, and Fluorescent Carbon Nanoparticles

Abstract

This report describes the design and synthesis of an ionic liquid by simple nucleophilic substitution reaction of 4-vinylbenzyl chloride and N-vinylimidazole. This ionic liquid is utilized as cross-linker for dispersion polymerization of acrylamide in the presence of poly(vinyl methyl ether) (PVME) stabilizer, which produces water-friendly cationic cross-linked poly(acrylamide) (CPAAm) beads. Morphology investigation reveals that these beads are nanosized and spherical and their size varies with the amount of cross-linker and PVME used. The ionic cross-linker imparts ionic nature in these beads, where anion is mobile and are eventually exchangeable. Consequently, anion exchange capacity is checked using an anionic dye Eosin B via UV–vis spectroscopy. Subsequently, the release of dye is monitored on addition of a pinch of sodium acetate. Analogous anion exchange with [PdCl4]2– results in the formation of palladium (Pd) nanoparticles (NPs) inside the cross-linked poly(acrylamide) beads due to in situ reduction by imidazolium cation present in CPAAm. The carbonization of the CPAAm nanobeads produces nitrogen-doped carbon nanoparticles of comparable morphology and sizes. The resultant carbon nanoparticles emit blue fluorescence under irradiation of UV light. Similarly, Pd NPs embedded carbon nanoparticles are easily prepared by carbonization of the Pd NPs loaded CPAAm nanobeads.