Effects of catalyst loading amount on the synthesis of poly(3-hexylthiophene) via externally initiated Kumada catalyst-transfer polycondensation

Abstract

A series of model polymerization are carried out via the one-pot externally initiated Kumada catalyst-transfer polycondensation (KCTP) of 2-bromo-5-chloromagnesium thiophene monomers, and the excess amount of initiators or catalysts are found no need to be isolated during the polycondensation process. Especially, the impacts of the nickel catalyst loading variation on regioregularity (rr), yield, molecular weight (M_n), polydispersity (PDI) and initiation efficiency of poly(3-hexylthiophene) (P3HT) are systematically investigated. The ¹H NMR, size-exclusion chromatography (SEC), and MALDI-TOF mass spectroscopy results indicated that an excess amount of catalyst does not influence yield, rr, M_n, and PDI of P3HT, nor the initiation efficiency. However, the PDI of the product is broad, and the M_n and rr values decreased in the absence of 1,3-bis(diphenylphosphino)propane (dppp). It can be concluded that the in-situ KCTP polymerization of P3HT is a practical and effective process. These results are especially valuable for the synthesis of all-conjugated block copolymers where macroinitiators are used.

Keywords

Kumada catalyst-transfer polycondensation (KCTP) / poly(3-hexylthiophene) (P3HT) / regioregularity (rr)

References

[1] Sheina E E, Liu J, Iovu M C, . Chain growth mechanism for regioregular nickel-initiated cross-coupling polymerizations. Macromolecules, 2004, 37(10): 3526–3528

[2] Iovu M C, Sheina E E, Gil R R, . Experimental evidence for the quasi-“living” nature of the grignard metathesis method for the synthesis of regioregular poly(3-alkylthiophenes). Macromolecules, 2005, 38(21): 8649–8656

[3] Yokoyama A, Miyakoshi R, Yokozawa T. Chain-growth polymerization for poly(3-hexylthiophene) with a defined molecular weight and a low polydispersity. Macromolecules, 2004, 37(4): 1169–1171

[4] Miyakoshi R, Yokoyama A, Yokozawa T. Catalyst-transfer polycondensation. mechanism of Ni-catalyzed chain-growth polymerization leading to well-defined poly(3-hexylthiophene). Journal of the American Chemical Society, 2005, 127(49): 17542–17547

[5] Osaka I, McCullough R D. Advances in molecular design and synthesis of regioregular polythiophenes. Accounts of Chemical Research, 2008, 41(9): 1202–1214

[6] Kiriy A, Senkovskyy V, Sommer M. Kumada catalyst-transfer polycondensation: mechanism, opportunities, and challenges. Macromolecular Rapid Communications, 2011, 32(19): 1503–1517

[7] Liu J, Sheina E, Kowalewski T, . Tuning the electrical conductivity and self-assembly of regioregular polythiophene by block copolymerization: nanowire morphologies in new di- and triblock copolymers. Angewandte Chemie International Edition, 2002, 41(2): 329–332

[8] Miyakoshi R, Yokoyama A, Yokozawa T. Synthesis of poly(3-hexylthiophene) with a narrower polydispersity. Macromolecular Rapid Communications, 2004, 25(19): 1663–1666

[9] Liu J, McCullough R D. End group modification of regioregular polythiophene through postpolymerization functionalization. Macromolecules, 2002, 35(27): 9882–9889

[10] Javier A E, Varshney S R, McCullough R D. Chain-growth synthesis of polyfluorenes with low polydispersities, block copolymers of fluorene, and end-capped polyfluorenes: toward new optoelectronic materials. Macromolecules, 2010, 43(7): 3233–3237

[11] Huang L, Wu S, Qu Y, . Grignard metathesis chain-growth polymerization for polyfluorenes. Macromolecules, 2008, 41(22): 8944–8947

[12] Miyakoshi R, Shimono K, Yokoyama A, . Catalyst-transfer polycondensation for the synthesis of poly(p-phenylene) with controlled molecular weight and low polydispersity. Journal of the American Chemical Society, 2006, 128(50): 16012–16013

[13] Yokoyama A, Kato A, Miyakoshi R, . Precision synthesis of poly(N-hexylpyrrole) and its diblock copolymer with poly(p-phenylene) via catalyst-transfer polycondensation. Macromolecules, 2008, 41(20): 7271–7273

[14] Senkovskyy V, Tkachov R, Komber H, . Chain-growth polymerization of unusual anion-radical monomers based on naphthalene diimide: a new route to well-defined n-type conjugated copolymers. Journal of the American Chemical Society, 2011, 133(49): 19966–19970

[15] Sontag S K, Marshall N, Locklin J. Formation of conjugated polymer brushes by surface-initiated catalyst-transfer polycondensation. Chemical Communications, 2009, 45(23): 3354–3356

[16] Senkovskyy V, Khanduyeva N, Komber H, . Conductive polymer brushes of regioregular head-to-tail poly(3-alkylthiophenes) via catalyst-transfer surface-initiated polycondensation. Journal of the American Chemical Society, 2007, 129(20): 6626–6632

[17] Khanduyeva N, Senkovskyy V, Beryozkina T, . Grafting of poly(3-hexylthiophene) from poly(4-bromostyrene) films by Kumada catalyst-transfer polycondensation: revealing of the composite films structure. Macromolecules, 2008, 41(20): 7383–7389

[18] Khanduyeva N, Senkovskyy V, Beryozkina T, . Surface engineering using Kumada catalyst-transfer polycondensation (KCTP): preparation and structuring of poly(3-hexylthiophene)-based graft copolymer brushes. Journal of the American Chemical Society, 2009, 131(1): 153–161

[19] Doubina N, Jenkins J L, Paniagua S A, . Surface-initiated synthesis of poly(3-methylthiophene) from indium tin oxide and its electrochemical properties. Langmuir, 2012, 28(3): 1900–1908

[20] Senkovskyy V, Beryozkina T, Bocharova V, . A core-first preparation of poly(3-alkylthiophene) stars. Macromolecular Symposia, 2010, 291–292(1): 17–25

[21] Bronstein H A, Luscombe C K. Externally initiated regioregular P3HT with controlled molecular weight and narrow polydispersity. Journal of the American Chemical Society, 2009, 131(36): 12894–12895

[22] Smeets A, Van den Bergh K, De Winter J, . Incorporation of different end groups in conjugated polymers using functional nickel initiators. Macromolecules, 2009, 42(20): 7638–7641

[23] Okamoto K, Luscombe C K. Controlled polymerizations for the synthesis of semiconducting conjugated polymers. Polymer Chemistry, 2011, 2(11): 2424–2434

[24] Yuan M, Okamoto K, Bronstein H A, . Constructing regioregular star poly(3-hexylthiophene) via externally initiated Kumada catalyst-transfer polycondensation. ACS Macro Letters, 2012, 1(3): 392–395

[25] Wang J, Lu C, Mizobe T, . Synthesis and characterization of all-conjugated graft copolymers comprised of n-type or p-type backbones and poly(3-hexylthiophene) side chains. Macromolecules, 2013, 46(5): 1783–1793

[26] Wang J, Ueda M, Higashihara T. Synthesis of all-conjugated donor–acceptor–donor ABA-type triblock copolymers via Kumada catalyst-transfer polycondensation. ACS Macro Letters, 2013, 2(6): 506–510

[27] Wang J, Higashihara T. Synthesis of all-conjugated donor–acceptor block copolymers and their application in all-polymer solar cells. Polymer Chemistry, 2013, 4(22): 5518–5526

[28] Doubina N, Ho A, Jen A K, . Effect of initiators on the Kumada catalyst-transfer polycondensation reaction. Macromolecules, 2009, 42(20): 7670–7677

[29] Senkovskyy V, Sommer M, Tkachov R, . Convenient route to initiate Kumada catalyst-transfer polycondensation using Ni(dppe)Cl₂ or Ni(dppp)Cl₂ and sterically hindered grignard compounds. Macromolecules, 2010, 43(23): 10157–10161

[30] Doubina N, Stoddard M, Bronstein H A, . The effects of binding ligand variation on the nickel catalyzed externally initiated polymerization of 2-bromo-3-hexyl-5-iodothiophene. Macromolecular Chemistry and Physics, 2009, 210(22): 1966–1972

[31] Bilbrey J A, Sontag S K, Huddleston N E, . On the role of disproportionation energy in Kumada catalyst-transfer polycondensation. ACS Macro Letters, 2012, 1(8): 995–1000

[32] Wong M, Hollinger J, Kozycz L M, . An apparent size-exclusion quantification limit reveals a molecular weight limit in the synthesis of externally initiated polythiophenes. ACS Macro Letters, 2012, 1(11): 1266–1269

[33] Koch F P V, Smith P, Heeney M. “Fibonacci’s route” to regioregular oligo(3-hexylthiophene)s. Journal of the American Chemical Society, 2013, 135(37): 13695–13698

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