Visible-light-mediated, additive-free, and open-to-air controlled radical polymerization of acrylates and acrylamides

Abstract

Oxygen tolerance in controlled radical polymerizations has been an active field of study in recent years. Herein, we report a photocontrolled, additive-free iniferter polymerization that operates in completely open vials utilizing the "polymerizing through oxygen" mechanism. Trithiocarbonates are directly activated with high intensity 450 nm light to produce narrowly dispersed (Mw/Mn = 1.1-1.6) polyacrylates and polyacrylamides. Living behavior is demonstrated through chain extension, block copolymer synthesis, and control over molecular weight through varying the monomer:iniferter ratio. A slight increase in induction period is observed for the open vial polymerization compared to the air-free reaction, but polymers with similar Mn and Mw/Mn values are produced after 30-60 minutes of irradiation. This system will provide a convenient platform for living additive manufacturing because of its fast reaction time, air tolerance, wide monomer scope, and lack of any additives beyond the monomer, iniferter, and DMSO solvent.