microreactor system consisting of a polydimethylsiloxane-based multilamination
mixer and a PTFE microtube leads to narrower molecular weight distribution
(M w /M n of about 1.2 for the flow reactor and 1.5 for the batch reactor), although
molecular weights are similar (flow M n of about 20,000 for the flow reactor and
about 18,000 for the batch reactor) [228]. The use of a simple T-shaped connector
as a mixer leads to broader molecular weight distribution, indicating the importance
of fast micromixing. This flow microreactor system can be applied to the polymerization and copolymerization of other amino acid NCAs to obtain poly(Glu), copoly
(Lys-Ala) and copoly(Lys-Leu) of narrower molecular weight distribution than
those obtained from the batch reactor (Table 8).
A silicon-glass-based flow microreactor system that is suitable for long periods
of use has been developed and applied to the polymerization of amino acid NCAs
[229]. The flow microreactor exhibits excellent controllability of the molecular
weight distribution. Moreover, a single flow microreactor can produce 100 mg/min
of copoly(Lys-Leu). This means that more than 200 g of copoly(Lys-Leu) acids can
be produced in 2 months.
Hyperbranched polymers have attracted much attention because these polymers
exhibit different characteristic features, such as a lower viscosity, higher solubility,
and higher amount of terminal groups, compared with those of the corresponding
linear polymers. Such polymers can be prepared by ring-opening multibranching
polymerization. Hyperbranched polyglycerols are popular because they have a large
number of hydroxyl groups and exhibit excellent biocompatibility [230].
A continuous micromixer-assisted flow process for the synthesis of hyperbranched
polyglycerol by ring-opening multibranching polymerization of glycidol was
Table 8 Comparison of polymer properties
Polymer
System
M n
M w /M n
Poly(Glu)
Batch
40,200
1.56
Microreactor
40,000
1.17
Copoly(Lys-Ala)
Batch
17,700
2.56
Microreactor
18,800
1.64
Copoly(Lys-Leu)
Batch
18,100
2.13
Microreactor
19,200
1.54
Fig. 32 Flow microreactor system consisting of a polydimethylsiloxane (PDMS) multilayered
laminar micromixer and PTFE microtubes for polymerization of amino acid N-carboxyanhydride
(NCA) initiated by triethylamine
30
A. Nagaki and J.-i. Yoshida
mixer and a PTFE microtube leads to narrower molecular weight distribution
(M w /M n of about 1.2 for the flow reactor and 1.5 for the batch reactor), although
molecular weights are similar (flow M n of about 20,000 for the flow reactor and
about 18,000 for the batch reactor) [228]. The use of a simple T-shaped connector
as a mixer leads to broader molecular weight distribution, indicating the importance
of fast micromixing. This flow microreactor system can be applied to the polymerization and copolymerization of other amino acid NCAs to obtain poly(Glu), copoly
(Lys-Ala) and copoly(Lys-Leu) of narrower molecular weight distribution than
those obtained from the batch reactor (Table 8).
A silicon-glass-based flow microreactor system that is suitable for long periods
of use has been developed and applied to the polymerization of amino acid NCAs
[229]. The flow microreactor exhibits excellent controllability of the molecular
weight distribution. Moreover, a single flow microreactor can produce 100 mg/min
of copoly(Lys-Leu). This means that more than 200 g of copoly(Lys-Leu) acids can
be produced in 2 months.
Hyperbranched polymers have attracted much attention because these polymers
exhibit different characteristic features, such as a lower viscosity, higher solubility,
and higher amount of terminal groups, compared with those of the corresponding
linear polymers. Such polymers can be prepared by ring-opening multibranching
polymerization. Hyperbranched polyglycerols are popular because they have a large
number of hydroxyl groups and exhibit excellent biocompatibility [230].
A continuous micromixer-assisted flow process for the synthesis of hyperbranched
polyglycerol by ring-opening multibranching polymerization of glycidol was
Table 8 Comparison of polymer properties
Polymer
System
M n
M w /M n
Poly(Glu)
Batch
40,200
1.56
Microreactor
40,000
1.17
Copoly(Lys-Ala)
Batch
17,700
2.56
Microreactor
18,800
1.64
Copoly(Lys-Leu)
Batch
18,100
2.13
Microreactor
19,200
1.54
Fig. 32 Flow microreactor system consisting of a polydimethylsiloxane (PDMS) multilayered
laminar micromixer and PTFE microtubes for polymerization of amino acid N-carboxyanhydride
(NCA) initiated by triethylamine
30
A. Nagaki and J.-i. Yoshida