Two Photon Activable Photacid Generators for 3D Microfabrication – 2PAGmicroFab

1) synthesis of new photo-acids with two-photon antenna and photo-acid genrators.
2) photophysics study
3) time-resolved spectrocopy of primary chemical reactions
4) optimisation of two-photon polymerisation, and demonstration of 3D microfabrication with microlasers

T0+18 months results:
synthesis of Et-O-PS and Et-O-Ms, spectrocopy and 3D fabrication published in CHEMISTRY OF MATERIALS 24 (2) 237-244 , JAN 24 (2012)
time resolved spectrocopy of breaking of C-S leading to photoacid.
demo of 3D microfabrication with sub-mw power of microlasers

on-going project

Malval, Jean-Pierre; Jin, Ming; Morlet-Savary, Fabrice; Chaumeil, Helene; Defoin, Albert; Soppera, Olivier; Scheul, Teodora; Bouriau, Michel; Baldeck, Patrice L.
Enhancement of the Two-Photon Initiating Efficiency of a Thioxanthone Derivative through a Chevron-Shaped Architecture
CHEMISTRY OF MATERIALS 23 (15) 3411-3420, AUG 9 2011

Xia, Rongjie; Malval, Jean-Pierre; Jin, Ming; Spangenberg, Arnaud; Wan, Decheng; Pu, Hongting; Vergote, Thomas; Morlet-Savary, Fabrice; Chaumeil, Helene; Baldeck, Patrice; Poizat, Olivier; Soppera, Olivier
Enhancement of Acid Photogeneration Through a Para-to-Meta Substitution Strategy in a Sulfonium-Based Alkoxystilbene Designed for Two-Photon Polymerization
CHEMISTRY OF MATERIALS 24 (2) 237-244 , JAN 24 (2012)
Baldeck, Patrice L.; Scheul, Teodora; Bouriau, Michel; Stephan, Olivier; Malval, Jean-Pierre; Lin, Chih-Lang; Lin, Chin-Te; Tseng, Chang-Li; Huang, Cheng; Chung, Tien-Tung
Nonlinear photochemistry and 3D microfabrication with Q-switched Nd:YAG microchip lasers LINEAR AND NONLINEAR OPTICS OF ORGANIC MATERIALS XI
Proceedings of SPIE 8113 Article Number: 811309 2011 (conférence invitée)
Chin-Te Lin, Hsu Fan, Michel Bouriau, Chao-Yaug Liao, Chih-Lang Lin, Cédric Masclet, Jean-Claude Léon, Tien-Tung Chung and Patrice L. Baldeck
Simulation and Correction of Angular Defects in Two-Photon Lithography
Journal of Photopolymer Science and TechnologyVol. 24, No. 6, 651-655 Dec. 2011

Photoacid generators (PAGs) constitute an essential class of cationic photoinitiators in the field of photosensitive resins which are used for many applications all related to microfabrication (microelectronics, microfluidics, micromechanics…). The majority of photoacids that are commercialized are excited with wavelengths from UV to DUV which enables to reach a sub-micrometer spatial resolution. Multiphoton absorption photopolymerization constitutes a technological alternative quite as promising in term of spatial resolution. Moreover this technique enables to produce objects with more complex tri-dimensional geometries. However the large scale development of this technique is mainly hampered by the requirement of expensive femtosecond pulsed laser sources. In addition, main photoacids used for two photon polymerization are bi-component systems. In this case, a photosensitizing process between a two-photon excited chromophore and the photoacid leads to the generation of acid. However, such a primary sequence constitutes a limiting step which considerably increases the two-photon polymerization energy threshold. To our knowledge, very few examples relative to a direct two-photon activation of highly reactive photoacid are reported in litterature. Indeed the photophysical criteria necessary to increase the biphotonic absorption cross section are often antagonistic with those required to enhance photoacidity. Therefore overcoming this effect should lead to a drastic reduction of the biphotonic polymerization threshold. As a consequence, the use of more flexible and less expensive excitation sources such as sub-nanosecond microlasers would be allowed. Hence, the present project has two clearly distinctive objectives : (i) The development a new generation of photoacids that can be directly two-photon activated and which exhibits weak biphotonic photopolymerization thresholds. (ii) The development of microfabrication techniques with sub-nanosecond microlasers with a concomitant integration of these new photoacids associated with a large set of commercial resins. Such an approach aims to demonstrate the pratical impact of this complete solution for a large range of applications. This pluridisciplinary project which deals with fundamental and applied issues related with two-photon polymerization gathers competences of researchers from organic chemistry for macromolecular synthesis, from photochemistry for the molecular engineering, the study of primary mechanisms and the photoreactivity upon linear and non-linear excitation, from physics for instrumentation and microfabrication by multiphotonic absorption.