On gelation and form: linear & nonlinear rheology of gelling networks during fluid-mediated shape formation

Soft materials can obtain their shape and form through fluid-mediated fabrication processes. Interfacial flows, hydrodynamic instabilities, or flow kinematics during stretching flows can all generate transient patterns in a liquid precursor. These patterns gradually evolve towards their final state as the underlying network ultimately cures into a viscoelastic solid via gelation. By performing a series of experiments on different curing elastomeric networks and combining linear & nonlinear rheological measurements we capture the essential features of such complex mutating systems as they approach the critical gel point. We magnify our probing window through time-connectivity superposition principle, and develop appropriate constitutive models that form a quantitate universal framework for predicting both the behavior of curing networks in strong flows and the ultimate shapes & patterns that form in soft assemblies: a rheologist’s almanac for gelling systems.