Amphiphilic cylindrical brushes with poly(acrylic acid) core and poly(n-butyl acrylate) shell and narrow length distribution

Abstract

Core–shell cylindrical polymer brushes with poly(t-butyl acrylate)-b-poly(n-butyl acrylate) (PtBA-b-PnBA) diblock copolymer side chains were synthesized via 'grafting from’ technique using atom transfer radical polymerization (ATRP). The formation of well-defined brushes was confirmed by GPC and 1H NMR. Multi-angle light scattering (MALS) measurements on brushes with 240 arms show that the radius of gyration scales with the degree of polymerization of the side chains with an exponent of 0.57±0.05. The hydrolysis of the PtBA block of the side chains resulted amphiphilic cylindrical core–shell nanoparticles. In order to obtain a narrow length distribution of the brushes, the backbone, poly(2-hydroxyethyl methacrylate), was synthesized by anionic polymerization in addition to ATRP. The characteristic core–shell cylindrical structure of the brush was directly visualized on mica by scanning force microscopy (SFM). Brushes with 1500 block copolymer side chains and a length distribution of lw/ln=1.04 at a total length ln=179nm were obtained. By choosing the proper solvent in the dip-coating process on mica, the core and the shell can be visualized independently by SFM.