Photocontrolled Organocatalyzed Living Radical Polymerization Feasible over a Wide Range of Wavelengths

Abstract

Photocontrolled organocatalyzed living radical polymerization was conducted over a wide range of irradiation wavelengths (350-750 nm). The polymerization was induced and controlled at the desired wavelengths by exploiting suitable organic catalysts. This system was finely responsive to the irradiation wavelength; the polymerization was instantly switched on and off, and the polymerization rate was sensitively modulated by altering the irradiation wavelength. The polymer molecular weight and its distribution (M(w)/M(n) = 1.1-1.4) were well controlled for methacrylate monomers up to fairly high conversions in many cases. The monomer scope encompassed various functional methacrylates, and their block copolymers were obtained. The feasibility of such a wide range of wavelengths and the fine response to the wavelength are unprecedented features. As a unique application of the wavelength-responsive nature of this system, we demonstrated "one-pot" selective regulation of living radical polymerization and another type of polymerization (ring opening polymerization), where the regulation was achieved by simply altering the irradiation wavelength. Facile operation and applicability to a wide range of polymer designs are advantages of this polymerization.

Exploiting Metalloporphyrins for Selective Living Radical Polymerization Tunable over Visible Wavelengths

“…This is the first example, showing that a polymerization can be tuned by the wavelength using a single unique catalyst. In a previous work, 45 Goto, Kaji and coworkers have reported the polymerization of MMA under different wavelengths by using various photoredox catalysts. In our work, using a single photoredox catalyst, we were able to control the polymerization as demonstrated by the excellent control of the molecular weights in combination with the low polydispersity index (PDI < 1.10) ( Figure 2C,D).…”

Tertiary amine catalyzed photo-induced controlled radical polymerization of methacrylates

“…30,31 Mechanistically, RCMP is based on the reversible activation of a dormant species (P n -iodine) to a propagating radical species using organic amines as complexing agents to drive the radical-forming step (Scheme 2b). 30,31 Mechanistically, RCMP is based on the reversible activation of a dormant species (P n -iodine) to a propagating radical species using organic amines as complexing agents to drive the radical-forming step (Scheme 2b).…”

Photo-Induced Living Radical Polymerization via Organic Catalysis

“…We recently developed a new family of LRP, reversible complexation-mediated polymerization (RCMP) [20][21][22][23]. RCMP uses iodine as X (capping agent) and organic amines and organic salts as catalysts to drive the reversible activation (Scheme 1b).…”

“…The catalysts are inexpensive, relatively non-toxic, easy to handle, and amenable to a variety of functional groups and monomers. Another useful feature is that RCMP can be controlled photochemically [22,23] as well as thermally [20,21].…”

“…In this review, we briefly summarize the concept, polymerization performance, and applications of this photo-controlled RCMP (photo RCMP) [22,23]. This system is an ideal on-off switchable system by an external photo stimulus and that the polymerization rate (R p ) is also finely tunable by the photo irradiation power.…”