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

• Published in: Macromolecules Vol. 50; no. 5; pp. 1909 - 1918
• Main Authors: Nübling, Fritz, Komber, Hartmut, Sommer, Michael
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.03.2017
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.7b00251

The synthesis and characterization of all-conjugated, all-crystalline donor–acceptor block copolymers (BCPs) containing poly­(3-hexyl­thiophene) (P3HT) and poly­{[N,N′-bis­(2-octyl­dodecyl)­naphthalene-1,4,5,8-bis­(dicarboximide)-2,6-diyl]-alt-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-b-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.