Conjugated Ketocarbazoles as Efficient Photoinitiators: From Facile Synthesis to Efficient Two-photon Polymerization

Exploration of straightforward synthetic strategies to construct efficient two-photon initiators (2PIs) containing a long conjugate length is essential to promote the development of two-photon photopolymerization (2PP). This paper described a series of ketocarbazoles with C=C bonds as π bridges, cyc...

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Bibliographic Details
Published in:Journal of Photopolymer Science and Technology 2019/06/24, Vol.32(2), pp.257-264
Main Authors: Hu, Peng, Zhu, Junzhe, Liu, Ren, Li, Zhiquan
Format: Article
Language:English
Subjects:
Absorption cross sections
Aldehydes
Aldol condensation reaction
Carbazoles
Chemical synthesis
Initiators
Ketocarbazole
Ketones
Microfabrication
Photoinitiators
Photon absorption
Photons
Photopolymerization
Two-photon initiator
Two-photon polymerization
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Summary:Exploration of straightforward synthetic strategies to construct efficient two-photon initiators (2PIs) containing a long conjugate length is essential to promote the development of two-photon photopolymerization (2PP). This paper described a series of ketocarbazoles with C=C bonds as π bridges, cyclic ketones as electron acceptors, and 9-alkyl substituted carbazoles as electron donors. The conjugated 2PIs were prepared straightforwardly via classical aldol condensation reaction and the impact of the central ring size on the photoactivity was systematically studied. The maximum absorption of the 2PIs was located at ~440 nm and good photobleaching behaviors were observed. The initiator with cyclopentanone held the largest two-photon absorption cross section of 377 GM. All the conjugated ketocarbazoles can be used as efficient 2PIs to induced 2PP and exhibited lower threshold energy compared to the widely used commercial photoinitiator TPO and the two- photon resists IP-L.
ISSN:0914-9244
1349-6336
DOI:10.2494/photopolymer.32.257