Summary and perspective
Due to the advantages of 5E (efficiency, enabling, economical, energy
saving and environmental-friendly), photopolymerization technology has
been applied in many fields, such as coatings, inks, adhesives, printing
materials, microelectronic products, 3D printing, biological materials,
etc., and plays an increasingly important role in our daily life. With
the continuous development of technology and enhancement of
environmental protection consciousness, photopolymerization will attract
new development opportunities, simultaneously, it also faces new
requirements. Firstly, it is a trend that LED photopolymerization
replaces traditional UV photopolymerization. A large number of
scientists are committed to the development of LED photopolymerization.
So there are a lot of research results on LED photopolymerization in
recent years. However, the color problem stemmed from the PIs also
limits the application of LED photopolymerization in colorless and deep
layer polymerization systems. In addition, the cost of producing LED
source is relatively expensive, and further improvement of the
manufacturing technology is needed. Secondly, the greenization of
production process for photopolymerization raw material is also worth
noting even though it as a green technology has been deeply rooted in
people’s concepts. Furthermore, the toxicity of PIs has attracted much
attention, and many countries have introduced regulations or licensing
lists to restrict the use of it. Therefore, it is very important to
design PIs with low toxicity and high migration stability, or based on
natural materials. Thirdly, radical photopolymerization will encounter
some limitations in practical application due to its obviously
shortcomings such as serious volume shrinkage and oxygen inhibition. For
example, 3D printing based on radical photopolymerization system leads
to the decrease of dimensional accuracy of products, while cationic
photopolymerization can overcome the problem of volume shrinkage due to
epoxy ring-opening. At present, the research of cationic
photopolymerization needs further development to meet the application
requirements. Last but not least, the development of new applications
for photopolymerization technology is extremely necessary thing for its
continuous progress, as well as the key factor that keeps it from being
eliminated. For the moment, 3D printing, electronic information
industry, biomaterials field, aviation field, etc. are the focus and
research hotspots of the whole world scientific community. Researchers
on photopolymerization technology should develop new applications to
make photopolymerization continue to prosper.