Poly regioirregular

Stereo- and Regioirregular High Molecular Weight Poly (Higher (XrOlefin)s... 

Fig. 1 NMR spectra in the carbonate region in CDCI3 of poly(propylene carbonate) A regioselective 94% head-to-tail selective copolymer prepared using a (salan)CrCl catalyst B regioirregular random polymer commercially available from Aldrich Chemicals...

Catalysts based on the Hf pyridyl amine complexes 126-128 have been used for the preparation of ethylene/ propylene co-polymers as well as of ethylene/propylene/l-octene terpolymers. These co-polymers are characterized by having at least 60 wt% propylene units, Mw around 300000, and Mw/Mn in the range 2.0-2.4. The NMR analysis of these co-polymers showed that the propylene sequences are remarkably isotactic mm > 90%) and showed the presence of regioirregularly inserted propylene units(<0.5% mol). The most interesting property of catalysts based on 126-128 is their high thermal stability.1119 Using modifications of isospecific bis(phenoxy-amine)-based catalysts, such as complex 164, the controlled synthesis of iPP- /orjf-poly/E-co-P) diblock co-poly-mers has been achieved. This is a remarkable result since iPP and PE are both polymeric materials of extreme industrial relevance.1206... 

Microstructures of Poly(chlorofluoroethylene)s The carbon-13 NMR spectrum of PVCF consists of a —CH2— resonance at 54.1 ppm and a —CFC1— resonance at 108.8 ppm. There is no splitting of these lines due to tacticity, nor are there any other resonances to indicate the presence of regioirregular monomer sequences. However the polymer is stereoirregular, as shown by the fluorine-19 NMR spectrum in Figure 1. There are three principal resonances spread by 3 ppm owing to triad stereosequences, with some pentad fine structure which is barely resolved. 

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. 

It was stated earlier that A max was to some extent a function of concentration. Thus it can be said that Amax is a function of film thickness for solid-state spectroscopy. As films thicken, the morphological disorder of the polymer can increase. The evidence for these phenomena is studies on film thickness showing different spectra for thick vs. thin films. Roncali demonstrated that regioirregular poly(3-methylthiophene) (ir-PMT) exhibited thickness dependent spectra that correlated with the conjugation lengths and the conductivity of the films [191-193]. It was found that the A ax for thick films (0.2 pim) was 510 nm, while for thin films (0.006 xm) it was 552 nm. By comparison, relatively thick films (1-3 pim) of rr-PAT show similar results to the thin films of ir-PMT. This indicates that... 

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

Example 9.6 Heck Crosscoupling of Regioirregular Poly(3-dodecylthienylene vinylenes) ... 

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