Room temperature ionic liquids to tailor resorcinol – Formaldehyde polymer gels

Synthesis of resorcinol – formaldehyde polymer gels was studied in various room temperature ionic liquid (RTIL) – water mixtures. Low temperature nitrogen adsorption observations reveal that the size of both the anions and of the cations influences the pore morphology of the aerogel. The 1-ethyl-3-methylimidazolium ethyl sulphate ionic liquid (IL) on its own is also able to catalyse the synthesis, yielding a totally metal free carbon aerogel precursor. The effect of water content on the gel structure is striking, thereby also offering a means of systematically adjusting the apparent surface area, the width of the pore entrance and the volume of the pores detectable by nitrogen. Here, the nature of the gel synthesis itself depends sensitively on the intrinsic pH, which is influenced by the anion of the IL. Comparison of these findings with published molecular dynamics simulations shows that the morphology of the gels is correlated with the structure of the mixed water − IL solvent, which also tunes the concentration of the IL catalyst.