Effects of Functionalization on Photo-Actuatable Octa(dimethylsiloxy)silsesquioxane-Azobenzene Network Gels and their Substance Loading and Unloading Efficiencies

Abstract

The synthesis, characterization, analysis, and effect on solvent uptake of styrene, alcohol, amino, and perfluoro functionalized silsesquioxane-azobenzene hybrid gels are discussed. 4,4′-Diallyloxyazobenzene and octa(dimethylsiloxy)silsesquioxane (Q₈M₈^H) gels are generated using hydrosilylation chemistry. These gels were modified through two routes: in situ and postsynthesis modification, depending on the compatibility of the modifiers. The dynamic gel systems react to visible and UV light to expand and contract, giving them sponge-like properties. The general characteristics of each gel are illustrated through UV–vis, ATR-FTIR, TGA, NMR, and SEM imaging. Effects on their solvent uptake load and preference for various solvents/pollutants are detailed below, and notable findings include preferences of the styrene material for aromatics, perfluoro for THF, and alcohol for acetone. This is accompanied by a low affinity for water, enabling them to remove organic solvents and particulates from water. We find that selectivity for certain substances can be obtained but at the cost of the total absorptivity of the gel systems.