OSTE+ for in-situ SAXS Analysis with Droplet Microfluidic Devices

International audience; In recent years, microfluidic-based sample preparation techniques have emerged as a powerful tool for measurements at large scale X-ray facilities. Most often the microfluidic device was a form of hybrid system, i.e. an assembly of different materials, because a simple, versatile and inexpensive microfabrication method, on the one hand, and X-ray compatibility, on the other hand, cannot generally be achieved by the same material. The arrival of a new polymer family based on Off-Stoichiometric Thiol-Ene-epoxy (OSTE+) has recently redistributed the cards. In this context, we studied the relevance and the compatibility of OSTE+ for small-angle X-ray scattering (SAXS) studies. The material was characterized regarding its X-ray properties (transmission coefficient, attenuation coefficient, scattering pattern and polymer aging under X-ray light) and their comparison with those of the usual polymers used in microfluidics and/or for synchrotron radiation experiments. We show that OSTE+ has a better SAXS signal than polyimide, the polymer of reference in the SAXS community. Then a detailed protocol to manufacture a suitably thin full OSTE+ chip (total thickness