Nahinfrarot‐sensibilisierte photoinduzierte ATRP mit einer Kupfer(II)‐Katalysatorkonzentration im ppm‐Bereich

Abstract

Eine NIR-sensibilisierte photoinduzierte radikalische Atomtransferpolymerisation (ATRP) gelingt mit [Cu II -(Tri(2-pyridylmethyl)amin)]Br 2 als Katalysator in ppm-Konzentrationen, einem Polymethin als Photosensibilisator und a-Bromphenylacetat als Alkylhalogenid-Initiator.U nter den untersuchten Polymethinen mit einer kationischen (1), zwitterionischen (2, 3)und anionischen (4)Struktur war lediglich 2 als Sensibilisator mit NIR-Licht bei Raumtemperatur geeignet, um Polymere mit kontrollierten Molekulargewichten und Funktionalitäten zu erhalten. Die Barbituratgruppe von 2 trägt maßgeblichz ur Aktivitäti nd ieser ATRP bei. Die Funktionsfähigkeit der Endgruppe des erhaltenen Polymers wurde mittels Kettenverlängerungs-und Blockcopolymerisationsexperimenten nachgewiesen. Das System ist sehr photostabil bei Bestrahlung mit NIR-Licht. Die Abhängigkeit von der verwendeten Strahlung wurde durch periodische Ein/Aus-Phasen während der Polymerisation gezeigt.

Carbon Dots as a Promising Green Photocatalyst for Free Radical and ATRP‐Based Radical Photopolymerization with Blue LEDs

“…reacts with bromide in the photocatalytic cycle, resulting in regeneration of the CD. This is similar to the mechanism previously discussed for photo‐ATRP initiated by NIR exposure …”

“…Regarding the latter, the in situ photolytic generation of Cu I complexes from Cu II under irradiation as an initiator for controlled polymerization facilitates CRP with a copper concentration in the ppm range . This has been successfully demonstrated with systems requiring UV, visible, or NIR light.…”

“…In the context of this contribution we extended our studies to living radical photopolymerizations based on ATRP. Protocols obtained for NIR irradiation were transferred to blue‐emitting LEDs . Scheme proposes a possible reaction mechanism.…”

Photoinduced Controlled/Living Polymerizations

“…A further interesting photosensitizer, polymethine, with a zwitterionic nature was used as a near-infrared (NIR) light active catalytic system for realizing the polymerization of MMA using ppm levels of Cu II Br 2 /TPMA. [55] Later, a similar NIR photoATRP process was conducted by using recyclable up-conversion nanoparticles (UCNPs). [56] The UCNPs functioned as an internal light source to convert NIR light of λ = 980 nm into UV/Vis light to commence polymerization.…”

Photoinduced step‐growth polymerization of thieno[3,4‐b] thiophene derivatives. The substitution effect on the reactivity and electrochemical properties

“…[ 21 ] Extensive research into main polymerization methods demonstrates that free‐radical, [ 22–24 ] cationic [ 25–30 ] and anionic chain polymerizations, [ 31,32 ] and step‐growth polymerizations [ 33–35 ] can be performed under wavelength irradiation covering UV, visible, and near‐infrared (IR) region. [ 36–39 ] Recent examples of photoinduced controlled/living polymerization, [ 40–44 ] and ligation techniques [ 45 ] demonstrate their ability to synthesize wide range of complex macromolecules with diverse topologies, well‐defined structures and desired functionalities. Despite extensive usage of photoinduced processes in synthetic polymer chemistry, their application in the preparation of the conjugated polymers has been scarcely investigated.…”