Two‐in‐One: λ‐Orthogonal Photochemistry on a Radical Photoinitiating System. Issue 13 (29th November 2016)

• Record Type: Journal Article
• Authors: Hurrle, Silvana; Lauer, Andrea; Gliemann, Hartmut; Mutlu, Hatice; Wöll, Christof; Goldmann, Anja S.; Barner‐Kowollik, Christopher
• Other Names: Boyer C. A. guestEditor.; Miyake G. M. guestEditor.
• Is Part Of: Macromolecular rapid communications. Volume 38:Issue 13(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2016-11-29
• Subjects: λ‐orthogonality -- copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) -- functional radical initiator -- light induced chemistry -- pulsed laser polymerization; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.201600598
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract : An alkyne functional radical photoinitiator, 2‐(4‐(2‐hydroxy‐2‐methylpropanoyl)phenoxy)ethyl hex‐5‐ynoate, and evidence that both reactive moieties – the alkyne and the photoinitiator terminus – can be independently addressed with light of disparate wavelength (λ‐orthogonality) are introduced. The alkyne functionality is subjected to a visible light (420 nm) induced copper‐catalyzed Huisgen reaction, which is employed for the selective functionalization of the initiator with a poly(ethylene glycol) (PEG) chain. This reaction proceeds completely λ‐orthogonal in the presence of the UV‐reactive photoinitiating moiety. Conversely, it is demonstrated that the alkyne functionality of the photoinitiator is quantitatively orthogonal to UV irradiation emitted by the pulsing action of an excimer laser (351 nm, pulsed‐laser polymerization, PLP) and the generated radical species. In turn, the PEGylated initiator can readily be employed as a macrophotoinitiator during PLP. The introduced λ‐orthogonally addressable dual functional initiator can be used in a wide range of applications, including surface lithography and post‐synthetic modification of photocured materials. Abstract : A bifunctional photoinitiator is introduced that can undergo copper‐catalyzed azide‐alkyne cycloadditions (CuAAC) and free radical polymerization λ‐orthogonally. The CuAAC reaction is initiated by visible light, whereas the polymerization proceeds under UV light. These two reactions can be performed sequence‐independent due to the stability of each functionality toward the other wavelength.