Facile Synthesis of ABC and CBABC Multiblock Copolymers of Styrene, tert-Butyl Acrylate, and Methyl Methacrylate via Room Temperature ATRP of MMA

A detailed investigation of the atom transfer radical polymerization of methyl methacrylate (MMA) with the ethyl 2-bromoisobutyrate (2-EiBBr)/CuBr/N,N,N‘,N‘,N‘ ‘-pentamethyldiethylenetriamine (PMDETA) catalyst system in anisole was performed at 30 °C. The number-average molecular weight of the PMMA was observed to increase gradually and linearly while the polydispersity index (PDI) remained narrow throughout the reaction time. The summary of these studies showed that PMMA with molecular weight up to 10⁵ g/mol could be synthesized in a controlled fashion at room temperature. The new route developed was utilized to demonstrate the facile synthesis of ABC and CBABC multiblock copolymers of styrene, tert-butyl acrylate (tBA), and MMA. For this, the starting blocks of AB and BAB were synthesized by coupling different ATRP methods reported. The end-block consisting of PMMA was synthesized by the ATRP of MMA using the CuCl/PMDETA catalyst system (halogen exchange) with anisole as the solvent at room temperature. Gel permeation chromatography (GPC) was used to determine the M_n, M_w, and PDI of the polymers synthesized. The PDI of all the block copolymers is found to be low (1.1−1.4). ¹H NMR spectroscopy was used to determine the chemical composition of the block copolymers. Additional evidence for the blocky nature was also gained from FT-IR and thermal analysis.