Topics in Current Chemistry (2018) 376:44
1 3
Boyer et al. investigated the polymerization of N,N’-dimethylacrylamide
(DMAm) and N,N’-diethylacrylamide (DEAm) in a microreactor under the green
light irradiation provided by a LED stripe [177]. As shown in Fig. 14, the flow reactor device consisted of a low-energy LED stripe (600 LED pillars) attached to the
inside of a 15-cm i.d. poly(vinyl chloride) (PVC) pipe, with the polytetrafluoroethylene (PTFE) tubing coiled around the outside of a 10 cm o.d. PVC pipe, allowing the
reaction mixture flowing through the PTFE tubing. The zinc tetraphenylporphyrin
was used as the photoredox catalyst in the PET-RAFT process. Such a continuousflow setup ensured the large illuminated area for the polymerization. With the use of
this photomicroreactor setup, the PDEAm-co-PDMAm copolymer was successfully
prepared with a high molecular weight of 22,500 g mol
−1
and a low PDI value of
1.06 without prior deoxidation.
Wenn and Junkers studied the reversible addition–fragmentation radical chaintransfer polymerization of n-butyl acrylate, methyl acrylate, or their combination using conventional photoinitiators in a glass chip microreactor (i.e., Labtrix Start R2.2 (Chemtrix BV) system) [178]. In this process, the RAFT agent
was 2-([(dodecylsulfanyl)thiosulfanyl]sulfanyl)propionic acid (DoPAT), and an
OmniCure S1000 system with a 100-W high-pressure mercury vapor short arc
lamp (spectral emission: 320–500 nm; peak at 365 nm) was applied as a UV light
source. The type of initiator, the light intensity, the RAFT agent-to-initiator concentration ratio, and the reaction temperature were found to be important for this
photoRAFT reaction. Optimal polymerization performance was obtained when
the initiator benzoin was used in a ratio of 0.25 to the initial RAFT agent at 60 °C
reaction temperature and 30-mW cm
−2
light intensity (365 nm). It should be
noted that decomposition rates of the photoinitiators were very high under flow
conditions, and the polymerization proceeded to completion with the effective
Fig. 14 ‘‘On’’/‘‘off’’ experiments of photo-controlled living radical polymerization in a continuous-flow
microreactor. Reprinted with permission from [171]. Copyright (2015) Royal Society of Chemistry
182
Reprinted from the journal
1 3
Boyer et al. investigated the polymerization of N,N’-dimethylacrylamide
(DMAm) and N,N’-diethylacrylamide (DEAm) in a microreactor under the green
light irradiation provided by a LED stripe [177]. As shown in Fig. 14, the flow reactor device consisted of a low-energy LED stripe (600 LED pillars) attached to the
inside of a 15-cm i.d. poly(vinyl chloride) (PVC) pipe, with the polytetrafluoroethylene (PTFE) tubing coiled around the outside of a 10 cm o.d. PVC pipe, allowing the
reaction mixture flowing through the PTFE tubing. The zinc tetraphenylporphyrin
was used as the photoredox catalyst in the PET-RAFT process. Such a continuousflow setup ensured the large illuminated area for the polymerization. With the use of
this photomicroreactor setup, the PDEAm-co-PDMAm copolymer was successfully
prepared with a high molecular weight of 22,500 g mol
−1
and a low PDI value of
1.06 without prior deoxidation.
Wenn and Junkers studied the reversible addition–fragmentation radical chaintransfer polymerization of n-butyl acrylate, methyl acrylate, or their combination using conventional photoinitiators in a glass chip microreactor (i.e., Labtrix Start R2.2 (Chemtrix BV) system) [178]. In this process, the RAFT agent
was 2-([(dodecylsulfanyl)thiosulfanyl]sulfanyl)propionic acid (DoPAT), and an
OmniCure S1000 system with a 100-W high-pressure mercury vapor short arc
lamp (spectral emission: 320–500 nm; peak at 365 nm) was applied as a UV light
source. The type of initiator, the light intensity, the RAFT agent-to-initiator concentration ratio, and the reaction temperature were found to be important for this
photoRAFT reaction. Optimal polymerization performance was obtained when
the initiator benzoin was used in a ratio of 0.25 to the initial RAFT agent at 60 °C
reaction temperature and 30-mW cm
−2
light intensity (365 nm). It should be
noted that decomposition rates of the photoinitiators were very high under flow
conditions, and the polymerization proceeded to completion with the effective
Fig. 14 ‘‘On’’/‘‘off’’ experiments of photo-controlled living radical polymerization in a continuous-flow
microreactor. Reprinted with permission from [171]. Copyright (2015) Royal Society of Chemistry
182
Reprinted from the journal