Poly regiorandom

T.A. Chen and R.D. Rieke, The first regioregular head-to-tail poly(3-hexylthiophene-2,5-diyl) and a regiorandom isopolymer nickel versus palladium catalysis of 2(5)-bromo-5(2)- (bromozincio)-3-hexylthiophene polymerization, J. Am. Chem. Soc., 114 10087-10088, 1992. 

The quest for regioregularity is not restricted to PTE 16a but occurs as well in the alternating copolymerization of HIT with />diethynylbenzene and poly(phenyleneethynylenethienyleneethynylene) (PPETE, 6 Charts 1 and 2). Yamamoto reported the regiorandom 6a in 1993 (Table 6, entries 1 and 3), and Pang later prepared the regiorandom 6a with... 

A regiorandom copolymer of 3-methylthiophene and 3-butylthiophene possessed a conductivity of 50 S/cm, while a more regioregular copolymer with a 2 1 ratio of HT to HH couplings had a higher conductivity of 140 S/cm. Films of regioregular poly[3-(4-octylphenyl)thiophene] (POPT) with greater than 94% HT content possessed conductivities of 4 S/cm compared to 0.4 S/cm for regioirregular POPT. 

Excitation Dynamics in Pristine and C o-Doped MEH-PPV Photoexcitations in Regiorandom and Regioregular Poly-3 Alkyl Thiophenes Photoexcitations in Poly(diphenyl-acetylene)... 

Figure 16.35 Chemical structures of regioregular head-to-tail (HT) poly(3-hexylthiophene) and regiorandom (or regioirregular) poly(3-hexylthiophene)...

Recently, a systematically regiocontrolled synthesis of poIy(3-alkylthiophene)s mediated by Rieke zinc has been proposed [187] and a series of poly(3-alkylthiophene)s with different regioregularities has been obtained starting from the same compounds. Thus it was possible to prepare a completely regioregular HT polymer and a totally regiorandom one. 

Regioregular and regiorandom poly-3-alkylfurans have also been reported (154). Conductivity was found to be highly dependent on degree of regioregularity, reaching 10 S/cm in the 95% head-to-tail (H-T) polymer but only 10 S/cm in the 75% H-T polymer. 

General Preparation of Regiorandom Poly(3-Alkylthiophenes) from... 

Reversible piezochromism has been observed in regioregular and regiorandom poly(3-alkylthiophene)s (32-35). Optical absorption spectra of solutions of poly(3-hexylthiophene) (P3HT) in toluene were observed to exhibit large bathochromic shifts with increasing hydrostatic pressure, compared to ambient pressure. The optical band gap of P3HT in toluene solution was 2.4 eV under ambient pressure but was reduced to 1.7 eV at 8 kbar (0.8 GPa) (32). 

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