Pressurizing the mixtures of two ionic liquids: Crystallization versus vetrification

A series of mixtures prepared with different content of the ionic liquids N‐trimethyl‐N‐propylammonium bis(trifluoromethylsulfonyl)imide (TMPA‐TFSI) and N‐trimethyl‐N‐hexylammonium bis(trifluoromethylsulfonyl)imide (TMHA‐TFSI), namely, (TMPA‐TFSI) 100− x (TMHA‐TFSI) x , is investigated by means of Raman spectroscopy as a function of pressure at room temperature. Both pure TMPA‐TFSI and the x  = 2 mixture crystallize under an applied pressure lower than 1 GPa. On the contrary, for x  > 7, none of the investigated mixtures crystallize, but they undergo a glass transition over the 1–2 GPa pressure range. We suggest that the disorder induced by the high number of possible configurations for the longer alkyl chain of TMHA‐TFSI in a compressed environment is a key factor in the suppression of the crystallization process.