Continuous Kinetic Sampling of Flow Polymerizations via Inline UV-Vis Spectroscopy.

Gapless monitoring of polymerization reactions is of paramount interest for academia and the polymer industry, allowing for efficient reaction screening and precise tailoring of the polymeric products. Herein, UV-visible spectroscopy (UV-vis) is employed as an operando measurement technique in continuous flow polymerization with ex situ calibration, to calculate monomer conversions with unprecedented resolution of only 10 s. A mathematical model based on volume contraction is provided for the first time, which yields monomer conversions from the absorption in the visible region for theoretically any homopolymerization. This model is validated for different monomers, solvents, and concentrations in a photoiniferter reversible addition-fragmentation chain transfer polymerization, proving the versatility of the presented setup. Notably, an ultralow measurement volume of merely a few hundred nanoliters is enough to ensure high accuracy.