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.