Two-photon absorption initiation for polymerization with microlasers at 532 and 1064 nm

We report here the caracterization of efficient photoinitiators for radicalar polymerization by two-photon absorption (TPA). Symmetric molecules bearing tertiary amines as a donor group D and a biphenyl or a fluorene for the transmitting electron group π were proposed for the visible. For IR, the selected phoinitiator presents the general structure D-π-A-π-D, in which A is an acceptor group. The initiation efficiencies of these systems were evaluated by the determination of the threshold intensities for a given exposure duration. Molecules for the visible are more sensitive than those designed for IR. Comparing to the commercial resins for UV photopolymerization generally involved for TPA, these optimized intiators led to a significant increase of the sensitivity during fabrication. Weaker incident intensities and faster scanning speeds could be used. This approach led the fabrication of tridimensional micro-objects with a less onerous nanosecond pulses microlaser.