Alternating Amphiphilic Multiblock Copolymers: Controlled Synthesis via RAFT Polymerization and Aqueous Solution Characterization

Abstract

Four linear amphiphilic multiblock copolymers based on 2-(dimethylamino)ethyl methacrylate (DMAEMA, hydrophilic) and methyl methacrylate (MMA, hydrophobic), bearing from two to five blocks, were synthesized using reversible addition−fragmentation chain transfer polymerization and stepwise monomer additions. The degree of polymerization of each hydrophilic polyDMAEMA block was ∼50, while that of the hydrophobic polyMMA blocks was ca. 20. The stepwise monomer addition procedure secured that each higher multiblock was composed of its immediately lower homologue plus exactly one extra block. The molecular weights (MW) of the synthesized (co)polymers, as measured by gel permeation chromatography (GPC), were close to the theoretically expected. GPC also indicated rather narrow molecular weight distributions which, however, broadened with the number of blocks. The compositions of the copolymers, as determined by proton nuclear magnetic resonance spectroscopy, were also close to the expected values. The cloud poi...