(262g) Impact of Sol Molecular Weight and Network Architecture On the Strain Rate-Dependent Mechanical Properties and Fracture Behavior of Elastomeric Polysiloxanes

Polymer gels have the potential to be utilized in a wide variety of applications including coatings, robotics, and sensors. However, widespread implementation of polymer gels has been limited due to their relatively poor mechanical performance and toughness. In this report, we investigate the impact of the solvent molecular weight and network architecture on the mechanical properties and fracture behavior of model polydimethylsiloxane gels. When the solvent molecular weight is increased above the molecular weight of entanglement (MW_ENT) the resulting gels exhibited a decreased impact on the modulus relative to a low molecular weight solvent.  The decreased impact on the modulus is attributed to the solvent entangling with the polymer network and contributing to the stiffness.  In addition, gels containing solvents above MW_ENT exhibited enhanced strain rate dependent mechanical properties on timescales consistent with the solvent reptation time. Gels containing solvent above MW_ENT have also exhibited higher energy release rates during tear testing.  We are now coupling the solvent molecular weight with the network architecture to further enhance the mechanical response and toughness.