3.2. 3D Printing
Different from traditional manufacturing methods, the three-dimensional
(3D) printing techniques were introduced during the 1980s with the aim
to fabricate customized/complex objects without the need for molds or
machining, also known as additive manufacturing (AM)
technology.[80-82] 3D printing method based on the
photopolymerization techniques has been a hot topic in recent years due
to many advantages such as highest accuracy, high production efficiency,
material utilization rate of nearly 100 % and mild
facilities.[83-84] Therefore, photopolymerization
3D printing have received revitalized attentions in a variety of 3D
printing such as stereolithography (SLA),[85]direct laser writing (DLW),[86] digital light
processing (DLP),[87] ink
jetting,[88] and real-time curing of
DIW.[63, 89]
Several commercial UV-light-sensitive PIS such as TPO, BAPO, Irgacure
184, and Irgacure 369 were used for the 3D printing processes of
photopolymerization under irradiation at UV
light.[35] Whereas, as explained in section 2.2,
visible light source has obvious advantages over traditional UV light
source, hence the development for novel PIs or PISs for
photopolymerization 3D printing induced by visible light is essential.
Xiao et al.[35] investigated a series of
disubstituted aminoanthraquinone derivatives which are capable of
initiating the radical photopolymerization under irradiation at blue to
red LEDs. The chemical structures of the studied disubstituted
aminoanthraquinone derivatives (AHAQ, 14-DAAQ, and 15-DAAQ) and
additives (Iod, NVK, TEAOH, and R-Br) are shown in Figure
21.15-DAAQ/TEAOH/R-Br PISs was used for the 3D printing due to the
highest capacity to initiate the radical polymerization of acrylates and
the 3D resin. It took less than 8 min to print the keyring when
using15-DAAQ/TEAOH/R-Br system under irradiation at polychromatic
visible light (400–730) nm with light intensity 3.6 mW
cm-2, as a contrast, TPO took 35 min. Markedly, the
printing speed was significantly enhanced when using the
15-DAAQ/TEAOH/R-Br as the PISs, which indicates that 15-DAAQ/TEAOH/R-Br
system can be used as a promising PIS for fast 3D printing. The
experimental 3D printing product using 15-DAAQ/TEAOH/R-Br PISs is shown
in the Figure 22.
Figure 21 Chemical structures of the studied disubstituted
aminoanthraquinone derivatives and additives.[35]