Light‐induced controlled free radical polymerization of methacrylates using iron‐based photocatalyst in visible light

Abstract

A novel visible light mediated catalytic system based on low cost iron complex, that is, Fe(bpy)3(PF)6 photocatalyst that initiates and control the free radical polymerization of methacrylates using ethyl α‐bromoisobutyrate (EBriB) as an initiator and 20 watt LED as light source is developed. The polymerization is initiated with turning the light on and immediately terminated by turning the light off. In addition, the molecular weight of polymer can be varied by changing the ratio of monomer and initiator. The merits of the present methodology lie in the use of low cost less precious, highly abundant iron‐based photocatalyst, avoidance of sacrificial donor and need of lower catalyst amount under visible light. The optimum amount of catalyst and initiator were established and successful polymerization of various methacrylates was achieved under the optimized polymerization conditions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2739–2746

Photocatalysts in Polymerization Reactions

“…Copper complexes bearing a bis(2‐(diphenylphosphino)phenyl)ether chelate (Figure ) to enhance their excited‐state lifetimes presented unprecedented photocatalytic activities in the photopolymerization of acrylate and epoxide monomers by using visible‐light LEDs . Even with their low excited‐state lifetimes, iron complexes bearing iminopyridyl ligands (Figure ) acted as efficient redox photocatalysts in FRP, in particular when photosensitive functionalities such as pyrene were linked to the ligands (Figure ) . More interestingly, in the presence of a sacrificial electron donor, such as an amine (Scheme ), a living character was observed for the acrylates and methacrylates radical polymerization by using iron‐based PCs (see below) …”

“…Recent articles reported the CRP of methacrylates by using catalytic amounts of iron(II) complexes under visible‐light irradiation. For instance, iron complexes bearing bipyridine or iminopyridine ligands (see Figure ) induced a CRP process with methacrylate monomers and allowed the synthesis of PMMA‐ b ‐P(benzyl methacrylate) or PMMA‐ b ‐P(butyl acrylate) block co‐polymers, respectively. Moreover, controlled surface patterning has been made possible by using Fe II –iminopyridine complexes as CRP photocatalysts …”

ChemInform Abstract: Photocatalysts in Polymerization Reactions

“…[47b, 51] Copper complexes bearing ab is(2-(diphenylphosphino)phenyl)ether chelate ( Figure 3) to enhancet heir excited-state lifetimes [52] presented unprecedented photocatalytic activities in the photopolymerizationo fa crylate ande poxide monomers by using visible-light LEDs. [53] Even with their low excited-state lifetimes, [54] iron complexes bearing iminopyridyl ligands ( Figure 3) acted as efficient redox photocatalysts in FRP, [55] in particularw hen photosensitive functionalities such as pyrene were linked to the ligands ( Figure 3). [20a] More interestingly,i n the presence of as acrificial electron donor,s uch as an amine (Scheme 4), al iving character was observed for the acrylates and methacrylates radicalp olymerization by using iron-based PCs (see below).…”

“…[102] Recent articles reported the CRP of methacrylates by using catalytic amountso fi ron(II) complexes under visiblelight irradiation. For instance, iron complexes bearing bipyridine [55] or iminopyridine ligands( see Figure 3) [20a] induced aC RP process with methacrylatem onomers and allowed the synthesis of PMMA-b-P(benzyl methacrylate) or PMMA-b-P(butyla crylate) block co-polymers, respectively.M oreover, controlled surfacep atterningh as been made possible by using Fe II -iminopyridine complexes as CRP photocatalysts. [20a] Very recently,t he family of photoredox metal catalysts for ATRP was enlargedt oi nclude gold complexes.H avingalow redox potential in the excited state, ad inuclearg old complexesp roved to be av ersatile catalyst that was able to control the radicalp olymerization of various monomers including methacrylates, triacrylates, and fluorinated acrylates under UV or visible-light irradiation.…”

Assessment of kinetics of photoinduced Fe‐based atom transfer radical polymerization under conditions using modeling approach

“…It was, therefore, able to prepare various well‐defined polymers or even realize well‐controlled polymerization in aqueous media . Apart from the Cu‐based photoinduced ATRP, other metal catalyzed (e.g., Ru, Ir, Fe) or metal‐free (organic catalyst) mediated ATRP systems were well studied. Even so, a comprehensive knowledge of the reaction process of photoinduced ATRP (e.g., overall reaction kinetics, the contribution of photochemically mediated reactions, the effect of side reaction on overall reaction kinetics) is indispensable for its utilization.…”