High-efficiency two-photon polymerization initiators based on coumarin derivatives for additive manufacturing with sub-wavelength resolution

Abstract

Efficient photoinitiators are very important for two-photon polymerization additive manufacturing. In this paper, a series of new initiators based on coumarin groups have been designed and synthesized, and their optical properties and two-photon polymerization properties have been studied and discussed in detail, and the relationship between their structures and properties has been analyzed. The synthesized initiators can realize a two-photon polymerization process with a speed of 100,000 μm/s under a laser power of 35–50 mW, and successfully obtain a series of clear three-dimensional structures with sub-wavelength resolution. Starting from the principle of two-photon polymerization, the relationship between laser power and writing speed and resolution was discussed, two simple mathematical models were established, and a fitting formula with physical meaning was obtained, which provides a way for the prediction and control of resolution. Finally, under the conditions of 100,000 μm/s and 50 mW laser power, a low-density ring with an outer diameter of 2.4 mm and an inner diameter of 2.0 mm with sub-wavelength resolution was manufactured in just over 10 min for the fusion target experiment. This proves the possibility of using the resulting initiator to manufacture precision micro-nano devices.