The Synthesis of Water-Soluble PHEMA via ARGET ATRP in Protic Media

Abstract

2-Hydroxyethyl methacrylate has been polymerized in methanol using activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP), to produce water-soluble poly(2-hydroxyethyl methacrylate) (PHEMA). The various parameters that determine control ofthe living polymerization have been explored. Using the Cu(II)/TPMA catalyst system (TPMA tris(2-pyridylmethyl) -amine), controlled polymerization was achieved with Cu concentrations as low as 50 ppm relative to HEMA, with a [TPMA]/[Cu(II)] ratio of 5. Use of hydrazine as the reducing agent generally gave better control of polymerization than use of ascorbic acid. The polymerization conditions were tolerant of small amounts of air, and colorless polymers were easily isolated by simple precipitation and washing steps.