Regioregular properties

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... 

Kobashi, M. Takeuchi, H. 1998. Inhomogeneity of spin-coated and cast non-regioregular poly(3-hexylthiophene) films. Structures and electrical and photophysical properties. Macromolecules 31 7273-7278. 

Poly(l,4-benzamide) (PBA), 13 371 Poly(1-butene) (PB), 4 429. See also Blown PB film Isotactic PB resins Isotactic poly(l- butene) (PB) PB entries Pipe-grade PB resin Syndiotactic poly(1-butene) (PB) mechanical properties of, 20 418 polymerization processes for, 20 424-425 uses of, 20 430-431 commercial manufacture of, 20 429 Poly-1-olefins, regioregular, 26 513 Poly(l,4-butylene terephthalate) (PBT), 10 188... 

Regioregular polythiophenes with various side chains containing ether, ester, and thiol units had been synthesized, and showed interesting properties [330]. However, the polydispersity of these polymers was not con-... 

Regioregular poly(3-alkylthiophene)s have received a lot of attention, especially because of their high electrical conductivities in the doped state, and because of their unusual solvatochromic and thermochromic behavior . Hence, a lot of research has been focused on clarifying the structure of these materials, both in the solid state and in solution. Today, it is agreed that supramolecular aggregation of polythiophene chains plays an important role in their physical properties. 

A crucial property of a polyolefin is its regioregularity. It is governed by the catalyst used for its production, i.e. by the regioselectivity with which it controls the direction of olefin insertion into a metal-alkyl bond. For example, propylene can insert either with its CFI2 or its CHMe end toward the metal. The first... 

The thermal and mechanical properties of polypropylene and other polymers produced from a-olefins depend - just as much as on their regioregularity - on the stereoregularity of consecutive olefin insertions, i.e. on the relative configuration of the tertiary C atoms which occupy every other position in the polymer backbone. Some of the diastereomeric structures are represented as Fischer-type projections in Figure 2. 

The primary structure of polymers is the most basic information for estimating physical properties. Table 11.1 summarizes the lists of papers in which NMR is used to characterize the tacticity, regioregularity, end group, branch, degradation and so on. 

The synthesis of alternating copolymers from carbon monoxide (CO) and olefins using palladium catalysts is currently an area of intense research. In cases where a-olefins are used, the regiochemistry (head/tail orientations) and stereochemistry (tacticity) of olefin insertion have a strong influence on the physical and mechanical properties of the polymers. Unlike regioregular a-olefins homopolymers, these copolymers have a directionality along the polymer backbone due to the incorporation of CO. Therefore isotactic, regioregular CO/a-olefin polymers are chiral by virtue of their main-chain stereochemistry (Scheme 11). 

Reitzel, N. et al.. Self-assembly of conjugated polymers at the air/water interface. Structure and properties of Langmuir and Langmuir-Blodgett films of amphiphilic regioregular polythiophenes, J. Am. Chem. Soc. 122, 5788-5800, 2000. de Boer, B. et al.. Amphiphilic, regioregular polythiophenes. Macromolecules 35, 6883-6892, 2002. 

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