Q-Silsesquioxane Photoactuatable Sponges for Substance Uptake and Release

Recent work in the Furgal Laboratory at BGSU has focused on the development of photoactive silicon-based materials with high porosity, phototriggered formation of siloxane bonds, and the recycling of preformed polymeric systems such as silicones. We have developed a set of photoswitchable Q-silsesquioxane based hybrid 3D polymeric smart sponges with azobenzene actuation units. Reversible UV triggered actuation of up to 18.3% has been achieved, with excellent recovery using visible light to the native state. These smart materials also offer reversible modulus switching from 160 kPa in the swollen state to 500 kPa in the UV activated state. Various substances were tested for uptake and release capabilities with polarity and size having the greatest impact on performance.[1] This photo-triggered behavior gives these materials high potential for use as reusable environmental remediators (i.e. PFAS), soft robotics, and biomedical applications. We have extended this work to incorporate functional groups within the network to adjust the internal polarities of the sponges to improve overall selectivity.[2] We have also been able to increase the overall photo-induced shrinkage of the materials to ~55% of their initial size by using asymmetric push-pull azobenzenes which give better isomerization to the cis form, greatly increasing their potential in controlled release applications. This presentation will discuss our development towards these photoresponsive systems.