Ultrafast, high-resolution and large-size three-dimensional structure manufacturing through high-efficiency two-photon polymerization initiators

In this article, we report the synthesis of a series of π-expanded benzophenone-based photoinitiators for additive manufacturing based on two-photon polymerization, and detailed analysis of the initiators' theoretical simulation, optical properties and the relationship between structure and property. Three kinds of acrylate resins were used to add 10 μmol/g of these initiators to the photonic polymerization system to make 3D woodpile structures, and their quality were checked to determine the efficiency of initiators. The results showed that, compared with the commercial initiator bis(4-(diethylamino)-phenyl)methanone, the benzophenone-based photoinitiators exhibited excellent performance, with higher writing speed (up to 100,000 µm/s) and broader applicable processing windows. The relationship between line width and power and writing speed was studied, and it was concluded that the line width was proportional to the square root of the writing speed. At a speed of 100,000 µm/s, a complex three-dimensional structure with a size of 1.2 mm × 0.9 mm × 0.9 mm was quickly manufactured in one hour. It showed that the benzophenone-based photoinitiators can potentially improve the manufacturing efficiency and thus become promising initiators for two-photon polymerization. A series of two-photon polymerization initiators centered on benzophenone were synthesized with great polymerization effect. It was found that the initiators can still initiate polymerization to obtain a fine three-dimensional structure at a high writing speed of 100,000 µm/s. And a fine and complete three-dimensional structure with a size of 1.2 mm × 0.9 mm × 0.9 mm was quickly manufactured in one hour with designed initiator. • A series of D-π-A-π-D conjugated molecules with the π-extended structure as a new type of photoinitiator. • Produce good three-dimensional structures in the range of 100 μm/s to as high as 100,000 μm/s. • Analyzed the size of the line width, the line width is proportional to the square root of the writing speed. • A structure with a size of 1.2 mm × 0.9 mm × 0.9 mm was quickly manufactured in one hour.