SOLUBILITY AND PROCESSING OF CPs

1 Note on Commonality with Material in Other Chapters. . . 208 

4 LONG CHAIN ALKYL SUBSTITUTED POLY(THIOPHENES). .. 215 

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Solubility and processing of CPs have much in common with the related subjects of CP composites and template-based polymerizations, and some elements in common with self-doped CPs. These subjects are however excluded from this chapter and dealt with in Chapters 5, 9 and 10, to which reference is made. 

The processibility of CPs is of course related to their solubility, and many applications involve processing of solutions. 

Another sulfonated P(PV) derivative, which has an [0(CH2)3S03(Na/H)] group at both meta positions of every other phenylene ring in P(PV), has been described by the Reynolds group [254]. This was synthesized via a complex route using 1,4-phenyl bisboronic acid and Pd catalysts. As is characteristic for many of the sulfonated CPs, however, it is again highly soluble and processible only in its metal salt form. 

Why is the term "soluble and processible CPs" frequently a misnomer in describing many such CP systems What do you think are the features of doped CPs that prevent their ready solubility and processibility List all the methods gleaned from this chapter that circumvent these problems indirectly (such as in-situ polymerization) and directly (such as solution in unusual solvents). 

Molecular weight (MWt) of CPs can be determined by a number of direct and indirect methods, most direct methods unfortunately requiring some maimer of solubility or processibility of the polymer. The three types of MWt applicable to... 

Typically, solvents are screened to identify one that gives optimal results. Assuming that the substrate and catalyst are soluble, solvent polarities varying from alkanes, aromatics, halogenated, ethers, acetonitrile, esters, alcohols, dipolar aprotic to water have been used. An example of this, using a ketone and the rhodium cp TsDPEN catalyst, is shown in Table 35.3. Further optimization of this reaction improved the enantiomeric excess to 98%. A second example involved the reduction of 4-fluoroacetophenone in this case the enantioselectivity was largely unaffected but the rate of reduction changed markedly with solvent. Development of this process improved the optical purity to 98.5% e.e. 

The d group 3 and lanthanide complexes Cp MR are isoelectronic with the [Cp2MR]+ catalysts discussed in the previous section. These nonionic complexes are soluble in most hydrocarbons and as one-component systems make ideal models for many of the fundamental processes in polymerization catalysis. For example, an alkyl-alkene complex can be observed by NMR when Cp 2 YH is allowed to react with an o , )-diene (equation 13). ... 

It is suggested that the redox process prevents the corrosion (i.e., formation of rust or hydrated iron oxides) by catalyzing the formation of passivating coating of Fe Oj via chemical reactions shown in Figure 1.55. However, above mechanism remained doubtful and represent chemical unbalance. Therefore, more systematic studies are required to probe exact anti-corrosion mechanism. The efforts have been made to form CP-based copolymers (to improve solubility) and blends (to provide both... 

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