Versatile crosslinked poly(ionic liquid) gel nanocomposites for environmental remediation, sustainable energy generation and antibacterial applications

A series of PIL gel-based nanocomposites were obtained, characterized and evaluated for relevant applications such as environmental remediation, sustainable energy generation and antibacterial applications. The materials consisted of poly(4-vinyl pyridine) crosslinked by dibrominated PEG or PCL, leaving IL-like moieties that act as crosslinking nodes within the gel network. Afterwards, the materials were employed as supports for the synthesis of Au and Pt nanoparticles (NPs) via an adsorption/reduction approach. The hybrid materials were characterized by FT-IR, TGA, DSC, NMR and HRTEM techniques. The selection of the crosslinker showed a considerable effect on the swelling and adsorption properties of the materials. Compared with the PIL-PCL gels, the PIL-PEG systems presented higher swelling ratios and faster metal uptake because of the hydrophilicity of PEG. AuNPs/PIL-based materials can remove 4NP from water sources, via adsorption and conversion into 4-aminophenol, a reaction used as an environmental remediation model. The process took place with yields above 82 % in successive runs, also exhibiting a remarkable recyclability, with no desorption of catalytic entities from the support. On the other hand, nanocomposites bearing PtNPs were capable of hydrolysing ammonia borane into hydrogen, as a model reaction for the generation of energy vector molecules, conserving the properties revealed during 4NP removal, like high effectiveness (conversion into hydrogen above 95 %), proper reusability and stability during three reaction cycles. Finally, the presence of ionizable units in the gel endows the material with antimicrobial properties, allowing a significant reduction in bacterial viability, enhancing system durability in the environments where it may be applied.