Surface indentation arrays for high-throughput analysis of viscoelastic material properties

Viscoelastic relaxation processes factor into polymer performance and stability throughout an application lifetime, controlled by the polymer network structure and dynamics which occur over a wide spectrum of time scales. In this work, we detail the design and operation of an independent array of surface indenters which can measure the creep response at multiple points on a polymer substrate. Samples with composition and temperature gradients are used to exhibit the ability to measure viscoelastic properties under unique conditions for each indentation. Methacrylate photopolymer systems are measured at different compositions and crosslink densities simultaneously within an indenter array to increase the measurement throughput, with a measured creep compliance ranging from $10−9Pa−1$ to $10−5Pa−1$⁠. The application of temperature gradients allows for the viscoelastic measurements to be assembled onto a master curve using time-temperature superposition.