A new synthetic method for controlled polymerization using a microfluidic system.

While many parallel synthesis methods developed by the pharmaceutical and life science communities are being applied to polymer synthesis, there remains a need to construct "libraries" of polymeric materials that explore a wider range of polymer structures with accuracy, flexibility, and rapid, often small, changes. We report the use of microfluidics to create an environment for continuous controlled radical polymerization. Varying either the flow rate or the relative concentrations of reactants (i.e., stoichiometry) controls the molecular properties of the products. Molecular variables, here molecular weight, can then be varied continuously. Well-defined materials with narrow molecular weight distributions are produced inside the microfluidic reactor and are available for processing, such as further mixing, deposition, or coating on surfaces. Preliminary kinetic data appear to agree well with literature values reported for larger-scale reactions.