Leveraging drainage mechanics to follow the UV-triggered solidification of polymer foams

Polymeric foams are widely used architected materials, owing to their great versatility exploited in a broad spectrum of applications. However, the lack of control over their morphology has led to the emergence of a new field of investigation, referred to as liquid foam templating , which aims at controlling finely the architectures of solid foams by controlling those of their liquid precursors. Here we focus specifically on the liquid/solid transition of monodisperse polyurethane foams, where the solidification is externally triggered via UV irradiation for a precise control of the foam morphology. We show that it is possible to take advantage of the mechanics of drainage of the matrix of the foam to quantify the efficiency of the external stimulus. To do so, monodisperse foams are prepared via millifluidics, and their morphology is analyzed via X-ray tomography as a function of the delay between generation and irradiation of the foam. The mechanism of solidification triggered by UV exposure includes here thermal effects, but the protocol developed to follow the influence of the external stimulus could be applied to a wide range of stimuli to assess – and exploit – the solidification of foams in a non-destructive manner.