Effects of Composition and Cure Parameters on the Mechanical and Optical Properties of Silicone/Methacrylate Hybrid Elastomers

Hybrid silicone-organic materials offer an alternative formulation for tough, silicone based elastomers. While such systems can be synthesized using a simple UV-copolymerization scheme between end-functional polydimethylsiloxane (PDMS) and methacrylate monomers, the unique morphologies of the resulting materials complicate the establishment of clear structure-property relationships. In this work, we study the effects of composition and cure parameters on the mechanical and optical properties of PDMS/polymethacrylate hybrid elastomers. We observed that differences in the mixing thermodynamics between methacrylate and silicone components lead to hybrid materials with substantially different properties. Based on the observed trends, we further argue that both increases in UV curing intensity and PDMS chain length reduce the graft density in these hybrids, leading to shared changes in stiffness, extensibility, and transparency. Lastly, we characterize the linear and nonlinear viscoelasticity of these networks to relate the presence of mechanical dissipation to improved toughness.