Synthesis of Poly(3‐hexylthiophene) with a Narrower Polydispersity

Abstract

Summary: The polymerization of 2‐bromo‐3‐hexyl‐5‐iodothiophene (1) with isopropylmagnesium chloride and Ni(dppp)Cl2 was quenched with 5 M hydrochloric acid instead of water to yield head‐to‐tail poly(3‐hexylthiophene) (HT‐P3HT) with a very low polydispersity. The $\overline M _{\rm n}$ of the polymer was controlled by the feed ratio of 1 to Ni(dppp)Cl2. Quenching with 5 M hydrochloric acid seemed to promote protonolysis of HT‐P3HT‐Ni complexes before the coupling reaction between HT‐P3HT.GPC profiles of HT‐P3HT obtained after quenching with water and 5 M hydrochloric acid, respectively.imageGPC profiles of HT‐P3HT obtained after quenching with water and 5 M hydrochloric acid, respectively.

End-group stannylation of regioregular poly(3-hexylthiophene)s

“…15 Ni(dppp)Cl 2 catalyst was added in one portion, and the reaction mixture was quenched with 5 M HCl aq in order to attain a small PDI and to avoid the dimerization of living P3HT chains, 16 respectively. The number averaged M n of P3HT determined by GPC was 5600 with a PDI of 1.08 when the amount of Ni(dppp)Cl 2 was 0.05 equiv.…”

Development of catalyst‐transfer condensation polymerization. Synthesis of π‐conjugated polymers with controlled molecular weight and low polydispersity

“…The GPC profile of the polymer obtained by quenching with water was shown to be bimodal (M n ¼ 20,500, M w / M n ¼ 1.28), whereas the polymers obtained by quenching with hydrochloric acid showed unimodal, narrower molecular weight distribution (M n ¼ 17,200, M w /M n ¼ 1.10). 25 In addition, the 1 H NMR spectra of the HT-PHT obtained showed more than 98% head-to-tail coupling, irrespective of quenching with water or hydrochloric acid. The polymer corresponding to the shoulder peak of the GPC elution curve would be formed by disproportionation of PHT-Ni-Br complex, followed by reductive elimination of PHT-PHT after quenching with water, because the molecular weight of the shoulder peak was double that of the main peak.…”

Kumada Catalyst‐Transfer Polycondensation: Mechanism, Opportunities, and Challenges

“…Much more clear is the role of several factors that can cause unintentional termination via negligent polymerization conditions. Yokozawa and coworkers [88] reported that a shoulder in GPC of P3HT occurred at approximately doubled MW when quenching active P3HT chains with water, while quenching with hydrochloric acid resulted in monomodal GPC profiles.…”

“…While it was already known that P3HT obtained via this method exhibits narrow polydispersities [26] and well-defined chain ends, [12,27] the discovery of the chain-growth mechanism marked a clear cut by providing new insight into the mechanism of the KCTP/GRIM method. Since then, many other welldefined CPs, including thiophene-, [25] fluorene-, [28,29] phenylene-, [30] and pyrrole-based [31] conjugated homopolymers, low bandgap homopolymers, [32,33] all-conjugated block copolymers, [28,31,34,[35][36][37][38][39][40][41] gradient copolymers, [42] and polymer brushes, [43][44][45][46][47][48][49][50] have been synthesized using KCTP.…”