Polymerization McCullough method

Poly[(i )-2-bromo-5-(tributylstannyl)-3-l4-(4-ethyl-2-oxazolin-2-yl)-phenyl]thiophene [Polymerization of (i )-2-bromo-5-(tributylstannyl)-3-[4-(4-ethyl-2-oxazolin-2-yl)phenyl]thiophene (EOPT-Br,Sn) with Pd2(dba)3 as a catalyst, the CuO-modified Stille-McCullough method] [74]. 

Scheme 6 One-pot synthesis of P3HT-MI macroinitiators for NMRP using the McCullough method followed by in situ endcapping with the Grignard derivative of a common alkoxyamine initiator. Starting from these macroinitiators, the acceptor monomer PerAcr is polymerized to give fully functionalized, double-crystalline block copolymers P3HT-/ -PPerAcr...

Soon after the report of the McCullough method, the Rieke method (Scheme 2.2B) was published (Chen and Rieke, 1992). In this method, the stcuting material is changed to 2,5-dibromo-3-alkylthiophenes 34, which reacts with Rieke zinc at low temperature to yield a mixture of two isomeric organozinc intermediates 35 and 36 in a ratio of 90 10 directly. The intermediates are polymerized in the presence of Ni(dppe)Cl2. The yield of P3ATs 33 is increased to 75%, and the polymer parameters (Mn = 24,000-34,000, PDI = 1.4) are maintained in a comparison to McCullough method. 

The first synthesis of HT rr-P3AT (Scheme 9.1), known as the McCullough method was reported in 1992 (Scheme 9.1, Table 9.1, entry 1) [25,26]. The key to this method is the regiospecific generation of 2-bromo-5-bromomagnesio-3-alkylthiophene 3 from 2-bromo-3-alkylthiophene, which is then polymerized by Kumada and coworkers [27-29] cross-coupling methods using catalytic amounts of... 

Figure 2.2 Conversion (filled symbols) and logarithm of monomer concentration (open symbols) vs time plots for 2-bromo-3-hexylthiophenepolymerization at different concentration ofNi(dppp)Cl2 initiator (23-25°C) [M]o = 0.075 mol L (M, [M]o [Ni(dppp)Cl2] = 136 1 ( , o) [M]o [Ni(dppp)Cl2] = 57 1 (A, A) [M]o [Ni(dppp)Cl2] = 49 1. The McCullough method was used for polymerization of2-bromo-3-hexylthiophene. Reprinted with permission from E. E. Sheina, J. Liu, M. C. lovu, D. W. Laird and R. D. McCullough. Chain growth mechanism for regioregular nickel-initiated cross-coupling polymerizations. Macromolecules 37(10), 3526-3528 (2004). Copyright 2004 American Chemical Society...

Table 9.4 Polymerization of P3ATs using the McCullough method.

Shortly after Yokozawa s initial report, McCullough s group also reported evidence for a chain-growth mechanism for the McCullough method [110] as well as for the GRIM polymerization [111]. Their mechanism (Scheme 8) predicted that both polymerizations go through the two following steps (1) transmetallation... 

PATs XVIII have received attention due to their solubility in organic solvents induced by hydrocarbon side-chains, as the first works in 1986 [213-215]. Polymerization of 3-substituted thiophenes may result in three different configurations, that is, head-to-tail (HT), head-to-head (HH), and tail-to-tail (TT) (Fig. 9.23. Different synthetic methods have been carried out that have been extensively reviewed in particular by Roncali [204] and McCullough [205]. 

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