Yuan-Hong Sun

Synthesis and nonlinear optical properties of novel multi-branched two-photon polymerization initiators

Efficient Witting and Pd-catalyzed Heck coupling methodology are employed to synthesize three multi-branched two-photon photopolymerization initiators diphenyl-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (abbreviated to DPVPA), phenyl-bis-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (abbreviated to BPVPA) and tris-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (abbreviated to TPVPA). The experimental results confirm that all these compounds are good two-photon absorbing chromophores and operative two-photon photopolymerization initiators. The calculated two-photon absorption cross sections of DPVPA, BPVPA and TPVPA for the lowest excited state are 59.3, 30.2 and 42.4 × 10−50 cm4 s photon−1, respectively. A microstructure using BPVPA as initiator has been fabricated under irradiation of 200 fs, from a 76 MHz Ti∶sapphire femtosecond laser at 820 nm. The possible photopolymerization mechanism is discussed.

Structures and nonlinear optical properties of new symmetrical two-photon photopolymerization initiators

Four new symmetrical, two-photon photopolymerization initiators, 9-(4-{(1E,11E)-4-[(E)-4-(9H-carbazol-9-yl)styryl]-2,5-dimethoxystyryl}phenyl)-9H-carbazole (1), N-(4-{(1E,8E)-4-[(E)-4-(diphenylamino)styryl]-2,5-dimethoxystyryl}phenyl)-N-phenylbenzeneamine (2), 1,4-bis{2-[4-(2-pyridin-4-ylvinyl)phenyl]vinyl}-2,5-bisdimethoxybenzene (3) and 1,4-bis{2-[4-(2-pyridin-4-ylvinyl)phenyl]vinyl}-2,5-bisdodecyloxybenzene (4), have been synthesized and characterized. One-photon fluorescence, one-photon fluorescence quantum yields, one-photon fluorescence lifetimes, and two-photon fluorescence have been investigated. The results show that they are all good two-photon absorbing chromophores and effective two-photon photopolymerization initiators. The two-photon absorption cross-sections of these molecules have been evaluated by theoretical calculations. Microfabrication via two-photon-initiated polymerization has been studied and the possible photopolymerization mechanism is discussed.

Synthesis, Characterization, and Non-Linear Optical Properties of Two New Symmetrical Two-Photon Photopolymerization Initiators

Two new symmetrical two-photon free-radical photopolymerization initiators, 1,4-bis-{2-[4-(2-pyridin-4-ylvinyl)phenyl]vinyl}-2,5-bisdimethoxybenzene 6 and 1,4-bis-{2-[4-(2-pyridin-4-ylvinyl)phenyl]vinyl}-2,5-bisdodecyloxybenzene 7, were synthesized using an efficient Wittig and Pd-catalyzed Heck coupling methodology. One-photon fluorescence, one-photon fluorescence quantum yields, one-photon fluorescence lifetimes, and two-photon fluorescence have been investigated. Experimental results show that both compounds were good two-photon absorbing chromophores and effective two-photon photopolymerization initiators. Two-photon polymerization microfabrication experiments have been studied and the possible photopolymerization mechanism is discussed.