Characterization of amphiphilic block-copolymers constituted of a low band gap rigid segment (PCPDTBT) and P4VP based coil block synthesized by two different strategies

Abstract

Two homologous series of rod-coil block-copolymers, composed by a low band gap rod moiety (poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3.4-b’]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)], PCPDTBT) and a flexible poly(4-vinylpyridine) based polar block, were synthesized by two different approaches. Step Growth-like procedure provided copolymers with longer coil, whilst copolymers with longer rod arise from Chain Growth-like process. Both the series were deeply investigated with different analytical techniques (1H NMR, SEC-DV, and MALDI-TOF MS) in order to prove the coupling process and elucidate the composition of the obtained materials. Chemical composition was evaluated by 1H NMR analysis. DSC heating traces of rod-coil copolymers synthesized by Step Growth-like route present two well resolved glass transition temperatures corresponding to the rod and coil blocks. The low band-gap rod-coil block copolymers especially these with short coil can find application in hybrid solar cells.