Synthesis of Cylindrical Polymer Brushes with Umbrella-Like Side Chains via a Combination of Grafting-from and Grafting-onto Methods

Cylindrical polymer brushes with umbrella-like side chains have been synthesized by a combination of grafting-from and grafting-onto methods. First, the polymer brushes with azido end-functionalized poly( tert -butyl acrylate) (P t BA-N 3 ) side chains, PBIEM- g -(P t BA-N 3 ), were prepared by atom transfer radical polymerization (ATRP) of t BA monomers using polyinitiator PBIEM followed by a substitution of bromo-side terminals with sodium azide. Subsequently, polyamidoamino dendrons of three generations with a propargyl focal point (G n ) were introduced onto the brush-shaped P t BA-N 3 by copper-catalyzed azide–alkyne cycloaddition (CuAAC) coupling reaction. The efficiency of CuAAC between P t BA-N 3 side chains and G n has showed a dependence on generation number n of the dendrons. At the feed ratio of [G n ]:[N 3 ] = 1:1, the grafting efficiency of the first generation dendron (G1) reached above 95%, whereas that of G2 and G3 was at least 84% and 73%, respectively. AFM images indicated that diameter of the brushes hybridized with G3 increased obviously than that of the brushes without dendrons.