Living Anionic Polymerization Using a Microfluidic Reactor
Thomas Q. Chastek, Kazunori Iida, Eric J. Amis, Michael J. Fasolka, Kathryn L. Beers, Jae H. Chun
Living anionic polymerizations were conducted within aluminum-polyimide microfluidic devices. Polymerizations of styrene in cyclohexane were carried out at various conditions, including elevated temperature (60 °C) and high monomer concentration (42 %, by volume). The transparent polyimide allowed for visual verification that the reactions remained below the boiling point of cyclohexane (81 °C) at all points in the reactor. Conducting these reactions in a batch reactor results in uncontrolled heat generation with potentially dangerous rises in pressure. Moreover, the microfluidic nature of these devices allows for flexible 2D designing of the flow channel. Four flow designs were examined. It was found that a zigzag pattern with acute bending angles performed the best in terms of lowering the PDI of a sample found to have a relatively broad molecular weight within a straight sample. We attribute this enhancement to mixing resulting from either laminar recirculations or elastic turbulence caused by the highly curved flow streams associated with the zigzag pattern. These sources of mixing are not expected to be exhibited in a straight channel.