(Mercaptopropyl)Methylsiloxane Homopolymer

Jourdain, Antoine, Anatoli Serghei, and Eric Drockenmuller. ACS Macro Letters 5.11 (2016): 1283-1286.

1,2,3-Triazolium-based polysiloxane ionic liquids (PSILs) were synthesized via UV-triggered thiol-ene linkage between (mercaptopropyl)methylsiloxane homopolymer and tailor-made vinyl-functionalized triethylene glycol based 1,2,3-triazole ionic liquids. The quantitative nature of the thiol-ene coupling was demonstrated by 1H and 13C NMR, while the properties of this novel PSIL were discussed based on solubility, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy measurements. In addition to having a low glass transition temperature (T = -62 °C) and high thermal stability (T = 284 °C), this novel poly(1,2,3-triazole) exhibits the highest bulk anhydrous ionic conductivity value reported so far for PILs (σ = 7 × 10S cmat 30 °C).
Further UV-triggered thiol-ene ligation between the vinyl-functionalized TIL and (mercaptopropyl)methylsiloxane homopolymer afforded the 1,2,3-triazolium-based PSIL 7 as a light orange viscous liquid in 64.7% yield. Photo- or thermally initiated thiol-ene ligation has been previously used for the efficient functionalization of vinyl- or thiol-functionalized polysiloxanes, but this example is the first application of thiol-ene reactions to the synthesis of PSILs.