(650h) Development of Visible-Light Responsive and Mechanically Enhanced “Smart” Ucst Interpenetrating Polymer Network Hydrogels

We will present an environmentally responsive hydrogel that exhibits the following features: enhanced mechanical property, upper critical solution temperature (UCST) swelling behavior, and responsiveness to visible-light. Poor mechanical properties are known challenges for hydrogel-based materials and hinder their applications. By forming interpenetrating polymer network (IPN) between polyacrylamide (PAAm) and poly(acrylic acid) (PAAc), the toughness of the IPN hydrogel was significantly improved compared to those made of the individual polymer network. The hydrogen bonding dissociates and re-forms between the amide group of PAAm and the carboxylic acid group of PAAc in responding to environmental temperature and facilitates a unique UCST swelling behavior of the hydrogel. By incorporating chlorophyllin into the interpenetrating network as the chromophore, the IPN hydrogel demonstrated a promising response of positive swelling to the irradiation of visible-light. The effect of chlorophyllin incorporation was also observed to reduce the average pore sizes and further enhance the mechanical properties of the hydrogel. This interpenetrating network system shows potential to serve as a new route in developing “smart” hydrogels using visible-light as a simple, inexpensive, and remotely controllable stimulus.