Preparation of Forced Gradient Copolymers Using Tube‐in‐Tube Continuous Flow Reactors

Abstract

The preparation of forced gradient polymers has received considerable attention using batch reactors, while the preparation of usable quantities of forced gradient copolymers using continuous flow reactors has been hampered by the need to vary the composition of the monomer feedstock continuously during the reaction. A reactor that allows for addition of a monomer feedstock continuously at all points along the length of the reactor tubing allows for the preparation of forced gradient copolymers in continuous flow reactors, allowing for the scale‐up and bulk preparation of these polymers. This study reports here the initial investigation of preparing forced gradient copolymers using the reversible addition–fragmentation chain transfer methodology in tube‐in‐tube continuous flow reactors.

Asymmetric Copolymers: Synthesis, Properties, and Applications of Gradient and Other Partially Segregated Copolymers

“…However, drawbacks include not only complex experimental setup, low repeatability and reproducibility, but also lower polymerization rate, broader molar mass distribution, and higher fraction of dead chains compared to batch copolymerization. [3] Forced gradient copolymers prepared by different reaction mechanisms, such as NMP, [73,74,[106][107][108][109][110][111][112][113][114][115] Ni-catalyzed chain-growth polycondensation, [116][117][118][119] ATRP, [120,121] RAFT, [122][123][124] and living cationic polymerization [125][126][127][128] have been extensively described in the literature. Routinely, a syringe pump is used during the synthesis to control the monomer feed and tailor the gradient profile of the materials (Figure 8).…”

“…This problem has recently been overcome by the use of a tube-in-tube continuous flow reactor which allows a wide variety of gradient copolymers to be synthesized by varying the flow rates and monomer ratios through the reactor (Figure 9). [124] Macromol. Rapid Commun.…”

“…Forced gradient copolymers prepared by different reaction mechanisms, such as NMP, Ni‐catalyzed chain‐growth polycondensation, ATRP, RAFT, and living cationic polymerization have been extensively described in the literature. Routinely, a syringe pump is used during the synthesis to control the monomer feed and tailor the gradient profile of the materials ( Figure ).…”

“…However, their use in the synthesis of forced gradient copolymers has been restricted by the need to continuously vary the monomer feed. This problem has recently been overcome by the use of a tube‐in‐tube continuous flow reactor which allows a wide variety of gradient copolymers to be synthesized by varying the flow rates and monomer ratios through the reactor ( Figure ) …”

“…Diagram showing “forward” flow in the reactor with the two reagent streams mixing before the heated zone. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”