Synthesis of conjugated-ionic block copolymers by controlled radical polymerization

Abstract

A novel series of well-defined amphiphilic block copolymers containing conjugated poly-(fluorene) (PF) block and coillike poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) were successfully synthesized through atom transfer radical polymerization (ATRP) initialized by a 2-bromoisobutyrate end-capped PF macroinitiator using CuCl/HMTETA (1,1,4,7,10,10-hexamethyltriethylenetetramine) as the catalyst. The first-order kinetics plot indicated a constant number of active species present in the polymerization. The molecular weight and molecular weight distribution were well controlled, implying well-defined block structure of the prepared block copolymers. The chemical structures of the copolymers were confirmed by 1H NMR studies. The copolymers could be successfully quanternized, and the final conjugated-ionic block copolymers were found to form PF aggregates in water as confirmed by 1H NMR, UV-vis, and photoluminescence (PL) spectra. PL spectra and quantum efficiency measurement also suggested the formation of excimers within the PF aggregates.