C2v symmetrical two-photon polymerization initiators with anthracene core: synthesis, optical and initiating properties

Abstract

A series of C(2v) symmetrical two-photon absorption compounds with anthracene core, 2,7-bis[2-(4-substituted phenyl)-vinyl]-9,10-dipentyloxyanthracenes designated as I, II and III (the substituted groups at the 4-position of phenyl of I, II and III were dimethylamino, methyl and cyano, respectively) were designed and synthesized as initiators in two-photon induced polymerization (TPIP). The anthracene ring was modified by linking vinylphenyl groups to the 2,7-position to extend conjugation system length and two pentyloxy groups to the 9,10-position to serve as electronic donors. Two-photon absorption cross section of I was around 300 GM, which was much larger than the 10 GM of II and 29 GM of III at 800 nm. I of 0.18% molar ratio in resin composed of methacrylic acid and dipentaerythritol hexaacrylate exhibited a dramatically low threshold of 0.64 mW compared with commercial photoinitiator benzil at a scanning speed 10 μm s(-1). Moreover, the threshold of photoinitiator I was only increased to 2.53 mW at a scanning speed of 1000 μm s(-1). The dependency of threshold on the concentration and exposure time was in accordance with theoretical calculation. Finally, a reasonable mechanism of the two-photon initiating process was proposed. This study provides good prospects for developing low threshold photoinitiator in TPIP.

Sensitive Photoresists for Rapid Multiphoton 3D Laser Micro‐ and Nanoprinting

“…Indeed, substantial efforts have been dedicated to designing, synthesizing, and characterizing photoinitiator molecules exhibiting large two‐photon‐absorption cross sections at certain wavelengths. [ 23–35 ] However, it has become evident from recent detailed one‐photon‐absorption experiments [ 36 ] that the absorption spectrum versus wavelength may peak at a completely different wavelength than the spectrum of the corresponding light‐induced polymerization rate. [ 36,37 ] Importantly, this surprising and not‐well‐understood finding refers to optically thin samples.…”

Two-photon polymerization microfabrication of hydrogels: an advanced 3D printing technology for tissue engineering and drug delivery

“…Moreover, the threshold of BPDPA was only increased to 2.53 mW at a scanning speed of 1000 µm s -1 . 41 High TPP initiating sensitivity of our designed photoinitiators results from their large δ TPA and low fluorescence yield. Our proposed concept of molecular design provides good prospects for developing TPP initiators with high initiating efficiency.…”

“…Our works focused on design and synthesis of TPP initiators(Fig. 3a, 3b and 3c) with C 2v symmetrical structure that have large δ TPA and low fluorescence quantum efficiency [37][38][39][40][41]. Not only large δ TPA but also low fluorescence quantum efficiency contributed to the excellent property of TPP initiators.…”

Polymerization Photoinitiators with Near-Resonance Enhanced Two-Photon Absorption Cross-Section: Towards High-Resolution Photoresists with Improved Sensitivity

“…35 While a lot of recent researches have focused on the use of PIs with optimized radical generation quantum efficiency, 34,[36][37][38][39][40][41] the improvement of σTPA has exclusively been addressed through a relatively classical chromophore engineering. [42][43][44][45][46][47][48][49][50] This followed the Equation 1 that approximates in the so-called "three-level model" the imaginary part of the third-order hyperpolarizability γ, responsible for the two-photon absorption phenomenon, where P denotes a permutation operator over the optical frequencies;…”