Atom transfer radical block copolymerization of 2-(N,N-dimethylamino)ethyl methacrylate and 2-hydroxyethyl methacrylate

Block copolymerization of 2-(N,N-dimethyl-amino)ethyl methacrylate (DMAEMA) with 2-hydroxyethyl methacrylate (HEMA) via atom transfer radical polymerization (ATRP) was studied in methanol using a macroinitator method and a "one-pot" sequential addition method. The polymerization sequence of the two monomers strongly affected the block copolymer formation. When DMAEMA was used as the first monomer, both methods produced block copolymer samples containing significant amounts of DMAEMA homopolymer chains, because of the elimination of active halogen chain-ends during the preparation of polyDMAEMA. Well-controlled block copolymers with various block lengths were obtained via the macroinitator method when poly-HEMA was used as macrointitiator to initiate the polymerization of DMAEMA. The sequential addition method, in which HEMA was polymerizee first with 90% conversion and DMAEMA a subsequently added, also yielded controlled block copolymers when the polymerization was carried out at room temperature with the DMAEMA conversion was carried out at room temperature with the DMAEMA conversion below 60%. Increasing the temperature to 60degreesC promoted the copolymerization rate but the reaction suffered from gel formation. The addition of water to the system accelerated the polymerization rate, but led to the loss of the system livingness.