Synthesis, characterization, and self-assembly of comb-dendronized amphiphilic block copolymers Part A Polymer chemistry

Novel amphiphilic comb-dendronized diblock copolymers composed of hydrophobic Percec-type dendronized polystyrene block and hydrophilic comb-like poly(ethylene oxide) grafted polymethacrylate P(PEOMA) block were designed and synthesized via two steps of atom transfer radical polymerization (ATRP). The comb-like P(PEOMA) prepared by ATRP of macromonomers (PEOMA) with two different molecular weights (Mn = 300 and 475) were used to initiate the sequent ATRP of dendritic styrene macromonomer (DS). The molecular weights and compositions of the obtained block copolymers were determined by ¹H NMR analysis. The copolymers with relatively narrow polydispersities (1.27-1.38) were thus obtained. The bulk properties of comb-dendronized block copolymers were studied by using differential scanning calorimetry, polarized optical microscopy and wide-angle X-ray diffraction (WAXD). Similar to dendronized homopolymers, the block copolymers exhibited hexagonal columnar liquid-crystalline phase structure. By using such amphiphilic comb-dendronized block copolymers as building blocks, the rich self-assembly morphologies, such as twisted string, vesicle, and large compound micelle (LCM), were obtained in a mixture of CH₃OH and THF.