A millistructured reactor and spectroscopic setup for contactless kinetic measurements in oscillating droplets is presented in this work. The polymerization of acrylic acid serves as a model reaction. Design and construction of the reactor focus on the optical access for Raman measurement, the nearly isothermal behavior, and the preservation of droplets during long‐term reactions with a high increase of viscosity. Another key aspect is the possibility of full automation at a later stage.

This work discusses a new measurement concept that uses contactless Raman spectrometry of free radical polymerization (FRP) in a milliscale reactor. The setup is based on a multiphase system with unsteady operation due to a change in the flow direction. The objective is to develop a quasi-isothermal measurement method for the determination of reaction kinetics with high automation capability. The FRP of acrylic acid with 2,2′-azobis(2methylpropionamidine) dihydrochloride as the initiator serves as the model reaction. The reaction order for the initiator and monomer concentrations as well as the temperature dependence is determined. On the basis of the measured rates, an estimation of the thermal behavior of the reactor can be made. The pendular slug reactor is an extension of the known measurement methods for FRP and requires only a few grams of material.

In this work we present a new concept of a millistructured capillary reactor setup for contactless kinetic measurements via in-line Raman spectroscopy for three phase reactions in single slugs.