Synthesis of amphiphilic diblock copolymers poly[2-(N, N-dimethylamino)ethyl methacrylate]-b-poly(stearyl methacrylate) and their self-assembly in mixed solvent

Amphiphilic diblock copolymers consisting of 2-(N, N-dimethylamino)ethyl methacrylate (DMAEMA, abbreviated as DMA) and stearyl methacrylate (SMA) with different degrees of polymerization and compositions were prepared by reversible addition-fragmentation chain transfer (RAFT) copolymerization. The composition and chemical structures of (co)polymers were confirmed by the measurements of H-1 NMR spectroscopy and gel permeation chromatography (GPC). The self-aggregating structures of amphiphilic diblock copolymers with the concentration of 0.1 similar to 0.3 wt.% in THF/water mixed solvent was investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). It was found that both the morphologies and aggregating particle size resulted from the amphiphilic diblock copolymers depended on the variation of pH values, the lengths of the hydrophobic PSMA chains, and the weight ratio of THF/water mixed solvent.