A versatile flash cyclization technique assisted by microreactor†
Abstract
Cyclic polymers have been confirmed to possess unique properties and have potential in different applications due to the absence of free end groups. However, efficient synthesis of cyclic polymers remains a significant challenge. In this context, a versatile flash cyclization technique assisted by a microreactor (or micromixer) is presented. Unlike the conventional batch system procedure, the cyclization of linear poly(ethylene oxide) (l-PEO) can be instantly and completely realized in a micromixer. Successful cyclization can also be accomplished with an elevated flow rate of l-PEO and/or catalyst solution. Based on the flash character of the microreaction system, an upgraded setup is also constructed by introducing a circulation loop to recycle the catalyst solution. The cyclization time is therefore considerably shortened and the consumption of solvent is greatly reduced, which provides a significant improvement in cyclization efficiency.