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Herein we present a comprehensive study on the role of Bronsted-acidic imidazolium ionic liquids (ILs) and imidazolium salts promoting the reaction between carboxyl and epoxide groups in a controll...

This work describes the solvent-free sol–gel synthesis of epoxy-functionalized silica-based precursors in the presence of 1-butyl-3-methylimidazolium-based ionic liquids (ILs) containing different anions: chloride (Cl–) and methanesulfonate (MeSO3–). The IL-driven sol–gel mechanisms were investigated in detail using experimental characterizations (29Si NMR and ATR FTIR spectroscopy) and a theoretical computational method based on density functional theory (DFT). We observed complex IL influence on both hydrolysis and condensation steps, involving especially H-bonding and Coulomb coupling stabilization of the process intermediates. The obtained IL–silica precursors and their further xerogels were widely characterized (rheology measurements, MALDI TOF, 29Si NMR, ATR FTIR, and DFT simulation), which allowed observation of their precise silica structures and established their most energetically favorable conformations. The detected silica structures were dependent on the IL type and varied from highly condens...

Herein, we demonstrate the effect of imidazolium ionic liquids (IL) applied as additives in the in situ formation of high amorphous vinyl alcohol (HAVOH)-silica bionanocomposites, using a simple sol-gel process approach. A complementary set of alkyl-, ether-, and carboxy-functionalized IL was used, allowing silica structure control and polymer-silica interphase tuning. Consequently, hybrids with diverse morphologies, as well as improved thermo-mechanical and barrier properties, were obtained. This diversity also highlighted the systems' dependency on the IL's molecular structure, where both the cation and anion influenced the hybrids' final properties. This could be evidenced as the polar group functionalized-IL (ether- and carboxy-functionalized IL) allowed the formation of multiple hydrogen bonds at the organic-inorganic interphase, inducing a fine hybrid morphology with well-dispersed silica nanodomains. This significantly increased the storage (~50%) and tensile moduli (~20%), extensibility (up to 300%), and glass transition temperature (>20 °C) and decreased the water vapor permeability (~50%), which are desirable characteristics for potential food and medical packaging.