Photo‐Induced atom transfer radical polymerization with nanosized α‐Fe₂O₃ as photoinitiator

Abstract

Photo-induced atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was achieved in poly(ethylene glycol)-400 with nanosized a-Fe 2 O 3 as photoinitiator. Well-defined poly(methyl methacrylate) (PMMA) was synthesized in conjunction with ethyl 2-bromoisobutyrate (EBiB) as ATRP initiator and FeCl 3 Á6H 2 O/Triphenylphosphine (PPh 3 ) as complex catalyst. The photo-induced polymerization of MMA proceeded in a controlled/living fashion. The polymerization followed first-order kinetics. The obtained PMMA had moderately controlled number-average molecular weights in accordance with the theoretical number-average molecular weights, as well as narrow molecular weight distributions (M w /M n ). In addition, the polymerization could be well controlled by periodic light-on-off processes. The resulting PMMA was characterized by 1 H nuclear magnetic resonance and gel permeation chromatography. The brominated PMMA was used further as macroinitiator in the chain-extension with MMA to verify the living nature of photo-induced ATRP of MMA.

Calcium bridging drives polysaccharide co-adsorption to a proxy sea surface microlayer

“…Alginate hydrolysis kinetics are also enhanced in acidic solution, thereby changing the alginate molecular weight distribution in solution over time. 97,98 Deprotonated palmitate molecules are slightly more soluble in water, 60,61 so IRRAS spectra were maintained and collected at constant surface pressure to minimize any interpretation impacts from dissolution. The surface pressure values of 5 mN/m and 25 mN/m were chosen to represent the tilted condensed (TC) and untilted condensed (UC) two-dimensional monolayer phases, respectively.…”

Photoinduced Electron Transfer Reactions for Macromolecular Syntheses

“…Several other studies have also reported the same strategy using Ir-based photoredox systems for carrying out photoinitiated ATRP reactions. ,− A dinuclear gold­(I) complex has been shown to catalyze the ATRP process in a similar manner to the Ir photoredox system under visible light irradiation . Analogous to Ir photoredox, the iron-based photocatalytic systems have been recently developed. − Matyjaszewski and co-workers obtained a well-controlled photoinduced process utilizing an iron­(III) catalyst under irradiation . A photoinitiation mechanism concerning the reduction of Fe III species which required the presence of MMA was proposed.…”

Role of External Field in Polymerization: Mechanism and Kinetics

“…It is worth mentioning that Cu-based photoATRP has also been widely investigated in diverse areas, such as ionic liquid promoted polymerization, new Cu-based catalyst complex design, − aqueous polymerization, , automated polymer synthesis, continuous flow synthesis, preparation of semifluorinated (meth)­acrylate-based copolymers, − and polymer dispersity tuning based on the dispersity equation (Table ). In addition, additives such as Mn 2 (CO) 10 , heterogeneous compounds (e.g., ZnO, mpg-C 3 N 4 , α-Fe 2 O 3 , Cu-MOF), − and photosensitizer (e.g., polymethines) can also participate in promoting the Cu-based photoATRP. Well-defined polymers were produced in these systems.…”