Synthesis of molecular brushes with block copolymer side chains using atomtransfer radical polymerization

Brush macromolecules having poly(n-butyl acrylate-block-styrene) and poly(s tyrene-block-n-butyl acrylate) side chains have been synthesized by the "gr afting from" approach using atom transfer radical polymerization (ATRP). Th e molecular weights of the resulting polymers were characterized by gel per meation chromatography (GPC) using refractive index and multiangle light sc attering detection. The block copolymer side chains were cleaved from the b ackbone and analyzed by GPC, confirming the synthesis of well-defined copol ymer brushes. Visualization of individual molecules by atomic force microsc opy (AFM) enabled analysis of the conformation and microstructure of the br ush macromolecules on mica surface. The brushes with the pnBuA core were al most fully stretched, while the inverted structure with the pS core exhibit ed longitudinal contraction compared to the contour length of the main chai n. In addition, the poly(n-butyl acrylate-block-styrene) brushes demonstrat ed a characteristic necklace morphology which was attributed to the interpl ay between the extension of the pnBuA core and microphase segregation of th e pS tails.