Influence of the Coil Block on the Properties of Rod−Coil Diblock Copolymers with Oligofluorene as the Rigid Segment

Abstract

Rod−coil diblock copolymers of 2-hydroxyethyl methacrylate (HEMA) with well-defined oligofluorene initiator were synthesized using the atom transfer radical polymerization (ATRP) technique. The resulting copolymers were characterized using spectroscopic (1H NMR, GPC), optical (UV, photoluminesence), and thermal (DSC) techniques. The incorporation of the initiator into the polymeric chain was confirmed by spectroscopic methods, while strong evidence for microphase separation was obtained both from DSC and AFM. A detailed AFM study of the surface morphology in thin films was performed using rod−coil diblock copolymers having different flexible blocks, namely HEMA and polystyrene. Common solvents for both rod and coil blocks were used as a function of the solutions concentration of the diblock copolymers. By increasing the concentration of a selective solvent, formation of either islands, a stringlike morphology, and honeycomblike structures was observed. The optical properties of the HEMA copolymers from TH...