Successful ATRP Syntheses of Amphiphilic Block Copolymers Poly(styrene-block-N,N-dimethylacrylamide) and Their Self-assembly

Amphiphilic AB-type block copolymers of poly(styrene-block-N,N-dimethylacrylamide) (PSt-b-PDMAA) were successfully synthesized by atom transfer radical polymerization (ATRP) of DMAA initiated by bromide end-capped PSt (polydispersity = 1.08), PSt-Br, under an appropriate catalyst/ligand system of CuCl/N,N,N′,N′,N″-pentamethyldiethylenetriamine, where PSt-Br was pre-synthesized by ATRP of St using ethyl-α-bromopropionate as an initiator under CuCl/2,2-bipyridine. We investigated the self-assembly behavior of PSt-b-PDMAA with different polymerization degree (DP) of hydrophilic PDMAA block and a constant DP of PSt block in various aqueous milieus. The dynamic laser light scattering (DLLS) studies demonstrated that every PSt-b-PDMAA formed the self-assembled matters whose radii depended on both polymer and salt concentrations. Transmission electron microscope (TEM) and the chain length of PSt-b-PDMAA suggested that the present polymers formed vesicular assembly with a size-controllable hollow structure.