Polythioether synthesis

Polythioethers, synthesis, 506 Poly(thiophene-alt-MA), 660 Poly(tributyltin methacrylate-alt-MA), 383 Poly(trichloroethylene-alt-MA), 380 ... 

The Use of Phthalimide Photochemistry in Macrocyclec Polyamide, Polyether, and Polythioether Synthesis... 

Recently, the scope of these preparations has also been extended to the synthesis of polythioethers and copo-lythioethers. 

The chemical and physical properties of the polymers obtained by these alternate methods are identical, except insofar as they are affected by differences in molecular weight. In order to avoid the confusion which would result if classification of the products were to be based on the method of synthesis actually employed in each case, it has been proposed that the substance be referred to as a condensation polymer in such instances, irrespective of whether a condensation or an addition polymerization process was used in its preparation. The cyclic compound is after all a condensation product of one or more bifunctional compounds, and in this sense the linear polymer obtained from the cyclic intermediate can be regarded as the polymeric derivative of the bifunctional monomer(s). Furthermore, each of the polymers listed in Table III may be degraded to bifunctional monomers differing in composition from the structural unit, although such degradation of polyethylene oxide and the polythioether may be difficult. Apart from the demands of any particular definition, it is clearly desirable to include all of these substances among the condensation... 

Various types of bis-Mannich bases (Table 32), ranging from kctonic to phenolic and amidic, are suitable for condensation with bis-amines and bis-thiols. As far as bis-amines are eoncemed, besides the compounds 379-381 of Table 31, methylpiperazine 404 is used. An even larger number of bis-thiols (405-409) arc employed in the synthesis of polythioethers. 

The variation in the complexation properties by this substitution (polyether to polythioether) was used by Cram for ion complexation and by Inouye for the synthesis of macrocycles for sugar recognition (Scheme 35) [71,88]. 

A wide variety of group 4 (Ti, Zr, Hf) metallocene-containing polyethers, polythioethers, polyesters, polyamines, polyoximes, and polyamidoximes has also been reported. Their synthesis, which is based on the polycondensation (with HCl elimination) of CP2MGI2 with difunctional organic species such as diols, dithiols, etc. (Scheme 14), was carried out either in aqueous solution or using interfacial condensation techniques, based upon the... 

The majority of the structures is prepared from AB2 monomers by polycondensation, to result in hb polyesters, polyamides, polyethers, poly(ester amide)s, polysulfones, poly(ether ketone)s, polyphenylenes (among others), and increasingly also by polyaddition leading to, for example, poly(carbosilane)s, poly(urea urethane)s, polyarylenes, poly(ether amide)s or polythioethers, and many others [6-11, 13, 17, 21]. In particular, cycloaddition reactions offer the advantage of an often very selective and clean, high-yield reaction that is not influenced by special functionalities [33]. The relatively easy synthesis of the hb polyphenylenes described by Mullen et al. [34]. is an excellent example of this. In addition, certain cycloaddition reactions form as Hnear units nonstable intermediates, which allows the preparation of hb polymers without any linear units, which therefore exhibit formally a DB of 100% [35]. 

There have been few recent studies on the synthesis of polyethers and polythioethers derived from vegetable oils, and all arise from castor oil-based monomers. They are, therefore, discussed in the next section devoted to this very special renewable resource. The same applies to polyanhydrides. 

In 1973, the synthesis of titanium, zirconium, and hafiiium polyesters via reaction of the dicyclopentadienylmetal dichloride complexes with disodium dicarboxylates in either aqueous or organic solvents was reported (31). Aroimdthe same time the synthesis of polyethers and amines of titanocene and polythioethers of zirconocene was also reported using similar methodologies (32,33). 

A novel one-pot synthesis of sulfur-containing polymers including poly(monosulfide)s (polythioethers), poly(disulfide)s, polythioesters, and poly-thiourethanes from a five-membered cyclic dithiocarbonate (5-phenoxjunethyl-l,3-oxathiolane-2-thione) and diamines has been examined. Polythioethers with Mn = 2600-17,700 were obtained by condensation of in situ forming dithiol with o ,a -dibromo-p-xylene [623-24-5] (25). A synthesis by using a bifimctional five-membered cyclic dicarbonate and benzylamine [100-46-9] has also been reported (26). 

Scheme 15.20. Synthesis of polythioether dendrons on solid support.

In addition to polysubstitution, the polyaddition reaction can be used for synthesis of LC polymers. It is an alternative method for obtaining simple LC polyethers and their analogs—polythioethers and polyimines. Easily soluble LC polymers with a low molecular weight were obtained with the Michael reaction between mesogenic diacrylates and diamines or dithiols (in solution, at a temperature under 60 C) [21] ... 

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