Ionic liquids based on carboxylate anions: Auto and hetero assembly with methylcellulose in diluted and semi-diluted regime

This study explores the impact of carboxylate ionic liquids (ILs) on the phase transition properties of methylcellulose (MC) in the diluted and semi-diluted regime. Conductivity measurements were used to examine the aggregation of ILs 1-decyl-3-methylimidazolium butanoate ([C₁₀MIM][BUT]), 1-decyl-3-methylimidazolium crotonate ([C₁₀MIM][CRO]), and 1-decyl-3-methylimidazolium pentanoate ([C₁₀MIM][PEN]) in the presence and absence of MC. The interaction between ILs and MC was confirmed using ¹H NMR spectroscopy. The effect of ILs on the phase transition of MC was investigated through UV–vis spectroscopy and oscillatory rheometry. Results indicated that the carboxylate ILs studied tend to interact with MC, reducing polymer-polymer interactions and the apparent viscosity of MC solutions. Furthermore, carboxylate ILs were observed to modulate the sol-gel transition temperature of MC to higher temperatures, while weakening the resulting gel compared to pure MC gels.