Polymers regioregularity

H. Liang, J. Yan, and J. Lu, Synthesis and optical characterization of a novel blue luminescent polymer regioregular poly(l-alkoxy-2,4 -m-phenylene vinylene), Synth. Met., 142 143-145, 2004. 

K. Sivula, C. K. Luscombe, B. C. Thompson, J. M. J. Fr6chet, Enhancing the thermal stability of polythiophene fullerene solar cells by decreasing effective polymer regioregularity, J. Am. Chem. Soc., 128, 13988-13989 (2006). 

Mauer R, Kastler M, Laquai F (2010) The impact of polymer regioregularity on charge transport and efficiency of P3HT PCBM photovoltaic devices. Adv Funct Mater 20 2085-2092... 

Optically active polymers are potentially very useful in areas such as asymmetric catalysis, nonlinear optics, polarized photo and electroluminescence, and enantioselective separation and sensing.26 Transition metal coupling polymerization has also been applied to the synthesis of these polymers.27 For example, from the Ni(II)-catalyzed polymerization, a regioregular head-to-tail polymer 32 was obtained (Scheme 9.17).28 This polymer is optically active because of the optically active chiral side chains. 

The microstructure and architecture of polymers can also gready influence die properties of die polymers. For example, poly(3-substituted thiophene)s could have three microstructure joints s-trans (head to tail), s-trans (head to head), and s-cis (head to tail) (Fig. 9.3). The regioregular head-to-tail poly(3-substituted thiophene)s exhibit higher electrical conductivity values and higher... 

The monomer 19 can also be polymerized using analogous methods of initiation to those employed in organic polymer science. Radical initiators afford regioirregular polymers, whereas anionic initiators add selectively to the phosphorus atom of the P=C bond and thus yield a regioregular polymer [85]. The product of the initial addition of MeLi across the P=C bond, Mes(Me)P-CPh2Li, was identified spectroscopically. The polymers obtained from anionic initiation are spectroscopically identical to those obtained from the thermolysis. Reasonable molecular weights (ca. 5000-10,000 g mol 0 are obtained when methyllithium is used as an initiator. 

Pomerantz et al. [493] prepared regioregular polymers HHTT-400 and HHTT-401 (Scheme 2.66) and compared them with previously synthesized irregular polymers 400 and 401 (Scheme 2.63) [485]. Regioregular polymers showed blue shifts in absorption for solution and films (23-30 nm and 57-79 nm, respectively Table 2.4), interpreted in terms of shorter conjugation length. Blue shifts in PL and EL were much less-pronounced (10-15 nm) and the PLED showed 2-4 times lower 4>el (Table 2.4) [493]. 

S. Amou, O. Haba, K. Shirato, T. Hayakawa, M. Ueda, K. Takeuchi, and M. Asai, Head-to-tail regioregularity of poly(3-hexylthiophene) in oxidative coupling polymerization with FeCl3, J. Polym. Sci., Part A Polym. Chem., 37 1943-1948, 1999. 

A. Bolognesi, W. Porzio, G. Bajo, G. Zannoni, and L. Fanning, Highly regioregular poly (3-alkylthiophenes) a new synthetic route and characterization of the resulting polymers, Acta Polym., 50 151-155, 1999. 

Y. Zhu, M.M. Alam, and S.A. Jenekhe, Regioregular head-to-tail poly(4-alkylquinoline)s synthesis, characterization, self-organization, photophysics, and electroluminescence of new n-type conjugated polymers, Macromolecules, 36 8958-8968, 2003. 

Fig. 2 (top) Planar regioregular polymer with directly overlapping pi orbitals vs. twisted backbone with 7i orbitals out-of-plane [1]... 

A convenient direct route has recently been described for obtaining regioregular polyalkylthiophenes using a tandem iridium-catalyzed borylation to produce the monomer, and a palladium-mediated coupling to produce the polymer [68]. The treatment of substituted thiophenes with B2pin2 in the presence of [lrCl2(COD)]2/ 4,4 -di-tert-butyl-2,2 -bipyridine (DTBPY) provided the expected monomer in 97% yield (Scheme 7.35). 

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