SiO₂-TiO₂-PBC nanocomposite film morphology, solvent swelling, estimated χ parameter, and liquid transport

Tetraethylorthosilicate (TEOS), titanium isopropoxide (TIP), and poly [t-butylstyrene -b- ethylene -alt- propylene -b- sulfonated styrene -b- ethylene -alt- propylene -b- t-butylstyrene] or Pentablock Copolymer (PBC) were used to create a series of nanocomposite inorganic-organic materials. Sol-gel chemistry provided a route to maximize the interactions between an inorganic network and organic polymer chains. The inorganic materials presence affected film morphology, swelling behavior, and liquid transport properties. PBC morphology was disrupted by TIP, which is attributed to enhanced interactions between inorganic and organic domains. This caused micro-phase separation that was observed as a morphology change from ordered to random. These dynamic interfacial interactions perturbed the chain's packing efficiency, which caused a decrease in the estimated polymer density within nanocomposites from 1.036 g/mL to 0.879 g/mL. Inorganic concentration within PBC caused a significant increase in alcohol uptake from around 200 wt% to more than 300 wt%, and a decrease in THF uptake from around 400 wt% to 20 wt%. Nanocomposite film swelling was modeled using the Flory-Rehner Equation. Modeling predicted that increasing inorganic content shifted the material to a more polar system. This led to a decrease in χ with alcohols and water, and an increase in χ with THF. Alcohol and fructose transport through an inorganic-organic film increased four times without sacrificing selectivity.