Iodine-mediated photo-controlled atom transfer radical polymerization (photo-ATRP) and block polymerization combined with ring-opening polymerization (ROP) via a superbase†
Most organocatalysts for photo-controlled atom transfer radical polymerization (photo-ATRP) are metal complexes or synthetically elaborate organic dyes, which are toxic and expensive. Herein, we present a combination of 1,1,3,3-tetramethylguanidine (TMG) and sodium iodide (NaI) under white LED irradiation that could catalyze iodine-mediated photo-ATRP. Using a dual initiator and combining with ring-opening polymerization (ROP), well-defined poly(methacrylate)-b-polyester diblock copolymers can be successfully prepared in “one-pot” using a TMG/NaI photoredox catalytic system. Moreover, several superbases such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-diazabicyclo [5.4.0]-undec-7-ene (DBU) and a phosphazene superbase (t-Bu-P4) could also be employed with NaI to serve as photoredox catalysts for this polymerization system and block copolymers could be synthesized in “one-pot”.