1 3
Topics in Current Chemistry (2018) 376:44
Interestingly, the controlled PDI can still be obtained (PDI < 3) with high molecular weight (Mn > 1.1 × 10
5
g·mol
−1
) for produced polymers (i.e., poly(acrylamide))
even the value of Bo is rather low during the polymerization process in the capillary
microreactor (Fig. 2b). However, tiny hot spots inside the capillary microreactor and
the decrease of the molecular diffusion due to the formation of hydrogels might contribute to a relatively large PDI (about 4.5) for some rare cases at a high temperature
(i.e., 90 °C).
Furthermore, the mixing of polymer solutions in microreactors can be investigated
with the aid of a biazo-coupling reaction system (consecutive-competitive reaction system) and a high-speed camera. Su et al. found that a smaller inner diameter, a higher
Dean number, and a lower Torsion number could promote the micromixing performance in microreactors with helical coil form for the mixing of polymer solutions [74].
Dean number (De) can be used to depict the flow characteristics in a curved flow [75].
where D i is the helical diameter (curvature radium). In case of helical coil form, a
modified Dean number ( De
′ ) is proposed [76–79]:
(19)
De = Re
d i
D i
0.5
(20)
De
� = Re
d i
D
�
i
0.5
(21)
D
�
i = D i
1 +
p
D i
2
Fig. 2 The variation of Bo with the residence time (a), the variation of PDI with Bo (b), in the capillary
microreactor for the polymerization of acrylamide at different temperatures. Reprinted with permission
from [55]. Copyright (2018) American Chemical Society
155
Reprinted from the journal
Topics in Current Chemistry (2018) 376:44
Interestingly, the controlled PDI can still be obtained (PDI < 3) with high molecular weight (Mn > 1.1 × 10
5
g·mol
−1
) for produced polymers (i.e., poly(acrylamide))
even the value of Bo is rather low during the polymerization process in the capillary
microreactor (Fig. 2b). However, tiny hot spots inside the capillary microreactor and
the decrease of the molecular diffusion due to the formation of hydrogels might contribute to a relatively large PDI (about 4.5) for some rare cases at a high temperature
(i.e., 90 °C).
Furthermore, the mixing of polymer solutions in microreactors can be investigated
with the aid of a biazo-coupling reaction system (consecutive-competitive reaction system) and a high-speed camera. Su et al. found that a smaller inner diameter, a higher
Dean number, and a lower Torsion number could promote the micromixing performance in microreactors with helical coil form for the mixing of polymer solutions [74].
Dean number (De) can be used to depict the flow characteristics in a curved flow [75].
where D i is the helical diameter (curvature radium). In case of helical coil form, a
modified Dean number ( De
′ ) is proposed [76–79]:
(19)
De = Re
d i
D i
0.5
(20)
De
� = Re
d i
D
�
i
0.5
(21)
D
�
i = D i
1 +
p
D i
2
Fig. 2 The variation of Bo with the residence time (a), the variation of PDI with Bo (b), in the capillary
microreactor for the polymerization of acrylamide at different temperatures. Reprinted with permission
from [55]. Copyright (2018) American Chemical Society
155
Reprinted from the journal