Today’s polymer manufacturing is under pressure to provide tailor-made properties at low production costs. The continuous production of functional block copolymers might fulfill these demands. In addition to the advantages inherent to flow chemistry (high control of reaction parameters, fast heat-exchange and high reaction efficiencies), the use of reactor cascades also allows sequential addition of monomers, making them an ideal engineering tool to develop and synthesize functional multiblock copolymers with high end group fidelities. In a first example, poly(2-oxazoline) block copolymers were targeted. Poly(2-oxazoline)s (PAOx) are an emerging class of biocompatible and non-toxic polymers, making them an interesting alternative for poly(ethylene glycol). Here, two types of PAOx triblock copolymers were synthesized via a living cationic ring-opening polymerization, carried out in a microfluidic reactor cascade (Figure 1). First, the homopolymerization of 2-ethyl-2-oxazoline (EtOx) was investigated on a simple lab-on-chip microreactor. Later, a more specialized microreactor with an additional inlet halfway in the reactor was employed to synthesize diblock copolymers of EtOx and 2-n-propyl-2-oxazoline (nPropOx). By coupling this reactor to a second set-up, a microreactor cascade was formed to target EtOx-b-nPropOx-b-EtOx and nPropOx-b-EtOx-b-nPropOx triblock copolymers. Next, poly(acrylate) block copolymers were targeted via a continuous reversible addition-fragmentation chain transfer (RAFT) polymerization in a home-made tubular reactor cascade (Figure 2). Here, systematic studies have been carried out on di- and triblock copolymers with well-defined sequences and different monomer ratios. At a later stage, the employed procedure was extended to synthesize a PnBuA-b-PMA-b-PEA-b-PtBuA tetrablock copolymer in large quantities (± 150 g) in 26 h, illustrating the high applicability of multistep flow processes.

Continuous reactor cascades for block copolymer synthesis

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.