Abstract

Continuous Flow Processing of RAFT Polymers

Christian Hornung, Director of FloWorks, CSIRO

The Reversible Addition-Fragmentation chain Transfer (RAFT) method is a convenient and versatile approach to control free radical polymerisations, compatible with a wide range of monomers and standard reaction conditions. It allows the synthesis of polymers with narrow molecular weight distributions and defined end groups, as well as complex architectures, such as blocks, stars and others. Recently, we demonstrated novel continuous flow processes for the synthesis and subsequent on-processing of RAFT polymers, using several different tubular reactor systems.  A variety of different monomers, such as acrylates, acrylamides and others, were polymerized to high conversions between 80 and 100% at temperatures between 60 and 120 °C and in comparatively short reaction times of 2h or less. The continuous flow approach provides a facile alternative scale-up route to conventional batch polymerisation, and at its maximum capacity the continuous reactor produced a total of more than 1.3 kg of RAFT polymer per day.  Due to the living character of the RAFT approach, the product can be polymerized further in a second continuous reactor to synthesise block co-polymers.  With the help of sequential processing, it is also possible to remove or modify the end group of the polymer continuously, directly after polymerisation.