All-Conjugated, All-Crystalline Donor–Acceptor Block Copolymers P3HT‑<i>b</i>‑PNDIT2 via Direct Arylation Polycondensation

The synthesis and characterization of all-conjugated, all-crystalline donor–acceptor block copolymers (BCPs) containing poly­(3-hexyl­thiophene) (P3HT) and poly­{[<i>N</i>,<i>N</i>′-bis­(2-octyl­dodecyl)­naphthalene-1,4,5,8-bis­(dicarboximide)-2,6-diyl]-<i>alt</i>-5,5′-(2,2′-bithiophene)} (PNDIT2) is presented. Direct arylation polycondensation (DAP) of dibromo­naphthalene­diimide and bithiophene is carried out in the presence of P3HT end-cappers to allow the in situ formation of BCPs P3HT-<i>b</i>-PNDIT2. As-prepared, well-defined H-P3HT-Br with hydrogen and bromine chain termini shows nonoptimal reactivity under the DAP conditions used. Therefore, H-P3HT-Br is converted into either H-P3HT-Th (thiophene) or H-P3HT-Mes (mesitylene), giving α,ω-hetero-C–H functionalized P3HT with modulated C–H reactivity. The influence of the different C–H chain termini of P3HT on the ability to act as end-capper and the resulting block structures is investigated in detail using wavelength-dependent size exclusion chromatography (SEC) and NMR spectroscopy. Different C–H reactivities of α,ω-hetero-C–H functionalized P3HT cause different contents of multiblocks, which in turn lead to varied degrees of crystallinity. These results show that careful tuning of C–H reactivity is a promising way to obtain well-defined, all-conjugated block copolymers via DAP