Novel brush-type copolymers bearing thiophene backbone and side chain quinoline blocks. Synthesis and their use as a compatibilizer in thiophene-quinoline polymer blends

New copolymers bearing different degree of grafted polyquinoline segments onto a polythiophene backbone were obtained via atom transfer radical polymerization of a vinyl quinoline monomer using a properly modified polythiophene backbone as macroinitiator. The initiator preparation was based on the bromination to a certain extent of a commercially available poly(3-hexylthiophene-2,5-diyl) (P3HT) and subsequent conversion of the bromine groups to proper propionyl bromide units through a three-step process. Polymerization of the vinyl quinoline monomer, using typical ATRP conditions, resulted in the desired copolymers, which were effectively characterized using H-1 NMR, UV-vis, and luminescence spectroscopy, as well as cyclic voltammetry. These copolymers were used in order to study their compatibilization efficiency in an immiscible P3HT/polyquinoline blend, which has been tested previously with respect to its photovoltaic efficiency. A detailed morphology study using atomic force microscopy (AFM) has shown that nanophase separated systems were obtained and the domain size was dependent on the blend composition, as well as the copolymer grafting density.