The topology of polymer networks dictates key mechanical properties including stiffness, toughness, and self-assembly. In this talk, I will present recent work in our lab on leveraging differential kinetics of various ternary thiol-ene systems to control polymerization mechanism. Systematic monomer variations are used to span from a purely step-growth mechanism to a purely chain-growth mechanism. Polymerization kinetics and associated gelation kinetics are probed via complementary real-time Fourier Transform Infrared Spectroscopy (RT-FTIR) and small-angle oscillatory shear (SAOS) photorheology. Post-synthesis, dynamic mechanical analysis (DMA) is used to measure crosslink density. Comparisons to mean-field models reveal the likely presents of defects, even in step-growth networks that are typically considered more 'ideal'. These results are compared to coarse-grain molecular dynamics simulations (CG-MD), which reveal the formation of loops for all chemistries and are used to rationalize experimental results.
