Polymer regioregular

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]. 

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

In the highly regioregular polymer 522, in its pristine amorphous form, the absorption maximum of spin-cast films is 493 nm (2.86 eV) (94MM6503 01JPC(B)7624). On treating the films with chloroform vapor, the maximum was shifted to 602 nm (2.06 eV), and the spectrum showed a fine vibronic structure with AE = 0.19 eV, typical of a more-planar ordered conformation. 

A regioregular polymer, 129, having chiral monomeric units has been synthesized. This polymer does not show CD absorption in chloroform, a good solvent. 

Ng, S.C., J.M. Xu, and H.S.O. Chan. 2000. Synthesis and characterization of regioregular polymers containing substituted thienylene/bithienylene and phenylene repeating units. Macromolecules 33 (20) 7349-7358. 

A regioregular polymer 212 having chiral monomeric units has been synthesized. This polymer does not show CD absorption in chloroform, a good solvent. However, on addition of Cu(OTf)2 to the solution, the resulting suspension showed strong CD bands. Because no gelling effect... 

The NMR spectrum provides additional connectivity information. The HT-regioregular polymers have only four resonances in the aromatic region, whereas regioirregular samples contain varying proportions of up to 12. Low nuclear receptivity and low concentrations of the non-HT isomers often preclude direct detection of defects. Mucci and Schenetti bypassed this limitation with a inverse detection... 

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