(639f) Effect of Concentration of Hydrophobic Components and Environmental Conditions on the Mechanical Properties of a Stretchable Hydrogel

Elastic biopolymers such as resilin display remarkable properties such as high stretchability and resilience, which are exploited in nature for mechanical energy storage to facilitate movement. Such properties of resilin have been attributed to the balanced combination of hydrophilic and hydrophobic segments. To obtain synthetic hydrogels mimicking the properties of resilin, we prepared a hydrogel composed of hydrophilic acrylic acid (AAc) and methacrylamide (MAM) chains and hydrophobic poly(propylene glycol diacrylate) (PPGDA) chains. The gel was prepared by free-radical polymerization in 0.8M NaCl-Sodium dodecyl sulphate (SDS) solutions using KPS as initiator. We investigated the effect of hydrophobic PPGDA concentrations on the mechanical properties of the gel. The elastic modulus of the gels, measured using tensile testing, increased with an increase in PPGDA concentration. Retraction experiments, which involve stretching of a gel sample and then releasing it, also captured an increase in retraction velocity and acceleration with an increase in PPGDA concentration. Swelling/ deswelling behavior of these gels in salt solutions with various ionic concentration was also studied, and the deswelled gels displayed an increased stretchability.