Atom Transfer Radical Polymerization Driven by Near-Infrared Light with Recyclable Upconversion Nanoparticles

Abstract

Near-infrared (NIR) photoinduced chemical processes are highly attractive for specific applications owing to the deep penetration of NIR into the nontransparent materials including biological and synthetic materials. Robust NIR photoinduced atom transfer radical polymerization (photoATRP) was achieved using upconversion nanoparticles (UCNPs) as an internal light converter to turn a 980 nm NIR light to the wavelength of UV/vislight. This NIR photoATRP was capable of polymerizing both hydrophobic and hydrophilic monomers at a low loading of ppm concentrations of the CuBr2/tris­(2-pyridylmethyl)­amine catalyst under the irradiation of a 980 nm NIR light (4 W/cm2) and UCNPs with reusable performance, providing well-defined polymers with predetermined molecular weight, low dispersity, and excellent chain-end fidelity. The switching of light “on/off” showed an excellent temporal control of the polymerization. The NIR photoATRP exhibited excellent penetrations through several visible light-proof barriers using NIR light, and it may provide future directions of photopolymerization in nontransparent systems, especially biological systems containing photosensitive moieties.

Mediated Generation of Conjugate Acid by UV and Blue Sensitizers with Upconversion Nanoparticles at 980 nm

“…Assisted photoreactions via upconversion nanoparticles ( UCNP ) gained increased attention in the last years [1–10] . They convert longwave radiation into shortwave emission, namely NIR light into UV and blue light.…”

“…They convert longwave radiation into shortwave emission, namely NIR light into UV and blue light. This led to several developments in biomedicine, [11] bioimaging, [12] security inks against counterfeiting, [1, 13, 14] dentistry, [15] photopolymerization, [2, 10, 16–18] controlled polymer synthesis following an ATRP protocol, [9, 10] 3D printing [3] —just to name some important fields where these fascinating materials have received remarkable attention. Their application combines the benefits of two radiation sensitive technologies; that is the use of highly reactive photosenistizers with absorption either in the UV or blue part while NIR radiation triggers this event by upconversion.…”

Catalytic Halogen Exchange in Supplementary Activator and Reducing Agent Atom Transfer Radical Polymerization for the Synthesis of Block Copolymers

“…To reduce the amount of catalyst to ppm levels, while maintaining control over the polymerization, different ATRP variations have been developed. These include activators regenerated by electron transfer (ARGET) ATRP, [ 8–10 ] initiators for continuous activator regeneration (ICAR) ATRP, [ 11,12 ] supplemental activator and reducing agent (SARA) ATRP, [ 13–16 ] photochemically mediated ATRP (photoATRP), [ 17–21 ] mechanoATRP, [ 22–24 ] and electrochemically mediated ATRP ( e ATRP) ( Scheme a). [ 25–31 ] SARA ATRP exploits the comproportionation of Cu II and Cu 0 to (re)generate active Cu I catalyst species (Scheme 1b).…”

Heterogeneous photocatalytic reversible deactivation radical polymerization

“…Recently, Pan et al 105 reported a UCNP-assisted NIR photoinduced ATRP. Under irradiation at 980 nm, the emission of UCNPs (β-NaYF 4 :30% Yb 3+ , 1% Tm 3+ ) at 365 nm matched well with the absorption of the ATRP system, which contained ethyl α-bromoisobutyrate (EBiB) as the initiator and tris(2-pyridylmethyl)amine (TPMA) as the ligand (Fig.…”

“…Fig.10The proposed mechanism for photoATRP under NIR irradiation assisted by UCNPs. Reproduced from ref 105. with permission from the American Chemical Society, copyright 2020.…”