Facile Synthesis of Unimodal Polymethacrylates with Narrow Dispersity via NIR LED Light‐Controlled Bromine–Iodine Transformation Reversible‐Deactivation Radical Polymerization

Abstract

A facile and clean strategy for synthesizing unimodal polymethacrylates with narrow dispersity (Đ < 1.10) is successfully developed by a near‐infrared (NIR) light‐emitting diode (LED) light (λmax = 740 nm)‐controlled in situ bromine–iodine transformation reversible‐deactivation radical polymerization system without the use of NIR dyes and expensive catalysts. In this system, alkyl iodide ethyl α‐iodophenylacetate (EIPA) initiator is generated in situ by the nucleophilic substitution reaction between an alkyl bromide compound ethyl α‐bromophenylacetate and sodium iodide (NaI). At the same time, excessive NaI is also acted as a highly active catalyst by forming halogen bonds with terminal iodine of the polymer chains in this system to make it capable of precisely synthesizing polymethacrylates with narrow dispersities (Đ = 1.03–1.10). In addition, the strong penetration ability of NIR LED light is illustrated by the successful polymerization even through 11 pieces of A4 paper.

An aqueous photo-controlled polymerization under NIR wavelengths: synthesis of polymeric nanoparticles through thick barriers

“…Taking advantage of the enhanced penetration of NIR light, photopolymerizations were performed with non-transparent barriers between the light source and the reaction vessel, resulting in high polymerization rates (0.21-0.34 hour À1 ) and well-dened polymers (dispersity (Đ) < 1.15). Although photopolymerization through barriers has been demonstrated in previous NIR light mediated RDRP systems, [21][22][23][44][45][46]51 this is the rst aqueous system which displays fast polymerization in the presence of thick barriers and does not require deoxygenation. Aqueous media and excellent oxygen tolerance facilitate the potential application of this NIR system in materials engineering and biomedicine.…”

“…[48][49][50][51][52] Although photo-RDRP systems that use visible light (l ¼ 400-700 nm) are well-established, systems regulated by near-infrared light (NIR, l ¼ 700-2500 nm) are still rare. [20][21][22][23][24][25][26][43][44][45][46][47] This is mainly due to the difficulty in using long wavelength, low energy (E ¼ h/l) irradiation to drive photochemical reactions. 59 While PCs with NIR light absorption exist, they commonly possess lower redox potentials of excited state (S 1 and T 1 ), resulting in limited catalytic performance and inability to mediate photoinduced electron/energy transfer (PET) processes.…”

“…Photoinduced reversible deactivation radical polymerization (photo-RDRP) 1–58 techniques enable the production of polymers with low dispersity and defined architectures and provide a high degree of spatio–temporal reaction control. As a useful photo-RDRP variant, photoinduced reversible addition–fragmentation chain transfer polymerization (photo-RAFT) polymerization process 26–58 often uses ppm range photocatalysts (PCs) to activate RAFT agents under visible light without the need for deoxygenation.…”

Continuous synthesis of grafted polyesters through successive photocontrolled BIT-RDRP and ROP strategies in flow tube reactors

“…Currently, BIT-RDRP has become a facile and promising RDRP method in metalfree catalyzed polymer synthesis. [25][26][27][28][29][30][31][32] So far, the synthesis of copolymers is usually conducted under batch conditions, which might need multi-step reactions and intermediate purifications that are time-consuming and tedious. 33 Besides, the light intensity decreased significantly in the deep of the reaction system, causing uneven irradiation distribution and therefore poor polymerization control in the case of light mediated polymerization, unfavorable for scale-up preparation.…”

RAFT Polymerization of Semifluorinated Monomers Mediated by a NIR Fluorinated Photocatalyst

“…Boyer et al reported the use of phthalocyanine compounds, [40,41] and bacteriochlorophyll 𝛼 [42] as a photoinitiation system for RAFT polymerization under NIR wavelengths. Cheng et al [43,44] reported the bromine-iodine transformation reversible-deactivation radical polymerization of methacrylates under the irradiation of NIR LED light. Although the NIR light-induced RAFT polymerization has been applied to construct well-defined polymers, to our best knowledge, there is no report on the synthesis of PFs through one step of semifluorinated monomers mediated by a NIR photocatalyst with good photostability.…”