High Amorphous Vinyl Alcohol-Silica Bionanocomposites: Tuning Interface Interactions with Ionic Liquids

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.