One‐ and two‐photon activity of cross‐conjugated photoinitiators with bathochromic shift

Abstract

Intrigued by the good performance of 1,5‐diphenylpenta‐1,4‐diyn‐3‐one (DPD) as photoinitiator for radical polymerization we prepared and investigated several donor substituted derivatives. UV‐Vis spectroscopy revealed a gradual red‐shift of λmax and higher extinction in the order of the donor capability. A methoxy‐substituted derivative (O‐DPD) exhibited significant photoinitiation activity in photo‐DSC experiments. Steady state photolysis experiments showed decreased decomposition rates with increasing donor capability. A dimethylamino derivative N‐DPD was even photostable under these conditions. Because of to the D‐π‐A‐π‐D system of these compounds two‐photon induced 3D photopolymerization experiments were performed and N‐DPD showed outstanding performance compared to often applied single photon initiators. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3280–3291, 2007

Synthesis and structure‐activity relationship of several aromatic ketone‐based two‐photon initiators

“…A 1:1 mixture of Trimethylolpropane triacrylate (TTA) and ethoxylated (20/3)-trimethylolpropane triacrylate (ETA) as an acrylate-based test resin with the same molar PI concentration of 6.3 Â 10 À6 mol PI/g resin was used, since good results had been previously achieved under these conditions. 40 The different color of the bars and their corresponding numbers in Figure 4 indicate the quality of the structures. At write speeds beyond the ideal processing window, the initiation threshold is not reached and incompletely connected structures are obtained after the standard post processing procedure.…”

Functional polymers by two-photon 3D lithography

“…Only 0.025 wt% of photoinitiator were necessary to successfully fabricate parts with a wall thickness down to 300 nm (Fig. 4) [8].…”

“…After laser writing, the unexposed material was removed by development of the structure in methanol (rinsing). The detailed procedure is described elsewhere [8].…”

Rapid prototyping of micro-optics on organic light emitting diodes and organic photo cells by means of two-photon 3D lithography and nano-imprint lithography

“…2-Phenoxyethyl acrylate (PEA), acrylic acid isobornyl ester (AIB), divinylbenzene (DVB) and 2-hydroxyethyl acrylate (HEA) were tested for their suitability. The triple bond containing N-DPD [6] was used as suitable two-photon-initiator.…”

“…Such materials offer unique properties for new integration concepts [5] or efficient photo chemistry in terms of two photon triggered polymerization [6], which is a great benefit for 2P3DL.…”