Polythioethers

The tiiermal properties of the para-, meta-, and ort/jo-substituted polyphenylene sulfides (8a-c, 9a-c) were examined using thermogravimetric analysis. Although all of these polymers exhibited good thermal stability, TGA results indicated that the thermal stabfiity of tiiese polymers decreased in the order p- m- o-. For example, the onsets for weight loss in polymers 9a-c were 512,491, and 448°C, respectively. 

The solubilities of polymers 12a-d were also highly dependent on the number of methylene units in their backbones. It was found that polymers 12c and 12d were soluble in organic solvents such as THF and chloroform in hght of the 6- and 8-carbon ahphatic chains in their backbones. These polymers were determined to have weight average molecular weights of 13,500 and 21,400, respectively. Because of the short aliphatic spacers in polymers 12a and 12b, these polymers were found to be insoluble. 

DSC of the organic polythioethers provided the glass transition temperatures of these polymers. The values of these polymers were approximately 100°C lower than those observed for the polyaromatic ethers and about 50°C lower than those of the polyaromatic thioethers. This is due to both the flexible aliphatic spacers in the polymer backbones and the presence of thioether rather than ether bridges. The Tg values of polymers 12b-d were 33, 34, and 37°C, respectively. It can be concluded that increasing the length of the aliphatic spacers decreased the glass transition temperatures of these materials slightly. 

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Heat-SensitiZingProcess. Another process used to make latex mbber articles of thicker section involves sensitizing the compound so that it coagulates when heated to a given temperature, then using heated molds to build the article to the desired thickness. Ammonia-preserved latex is used in this process, and polyether, polythioether, or poly(vinyl methyl ether) (PVME) can be used as heat-sensitizing agents. 

Two of the more recendy developed polysulftde polymers are the mercaptan-terminated polyoxypropylene urethane polymer and the polythioether polymer. The urethane-backbone-based polymer is used in many sealant formulations for insulating glass appHcations. The thioether backbone contains sulfur, but no S—S bonds, which are the weakest part of the conventional polysulftde polymer. This polymer improves the thermal stabiHty and reduces the gas—Hquid permeabiHty. 

Various polymers, such as polythiourethanes, polythioethers, and polythioacrylates, are used to produce resins which are transparent, colorless and have a high refractive index and good mechanical properties, useful for the production of optical lenses. Higher refractive indices are promoted by sulfur compounds and especially by esters of mercaptocarboxyhc acids and polyols such as pentaerythritol (41) (see Polymers containing sulfur). 

Of the many other aliphatic polyethers, polythioethers and polysulphides prepared in the laboratory, some have become commercially available. Those of interest to the plastics industry are dealt with later in this chapter. 

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

Condensation of dicesium 2-thioxo-l,3-dithiole-4,5-diselenolate with fo/s-alkylating polythioethers under high dilution conditions afforded the TTF-containing macrocycles possessing soft donor sites and 12-, 15-, and 18-membered rings <%JCS(P1)1995>. 

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... 

M. J. Incorvia. Polythioether corrosion inhibition system. Patent US 4759908, 1988. 

The acyclic and macromonocyclic polythioethers were well illustrated in CCC (1987 Section 47.8.3.2).1 Only a few recent examples will be given of this chemistry here. 

A range of functionalized polythioethers have been developed as carriers for radio-isotopes such as "mTc, 105Rh and 188Re for diagnostic and therapeutic applications.168,169... 

Dehydrocoupling of polyhydrosiloxane 44 with thiol 45 proceeds smoothly in the presence of Wilkinson s catalyst to furnish polythioether 46 in high yield <00TL1127>. 

Macrocyclic lattice hosts, 14 111 Macrocyclic mercuracarboranes, 4 216-217 Macrocyclic oligoesters, 25 125 Macrocyclic polymers, 14 252 Macrocyclic polythioethers, 23 707 Macrocylic ligands, 7 576 Macroemulsions, 10 113 16 433-434 Macrofouling organisms, in industrial water treatment, 26 149-150 Macrolide antibiotics, 15 271-320. See also Macrolides... 

Poly(monosulfide)s, 23 702-711 aliphatic, 23 702-704 aromatic, 23 706 conjugated polymers, 23 709 macrocyclic polythioethers, 23 707 poly(arylene sulfide)s, 23 704-706 poly(monosulfide ketone)s, 23 709-711 polythiophenes, 23 708 tetrathiafulvalene polymers,... 

Polythiocarbamates, 23 735-738 Polythiocarbonates, 23 626, 725-729 thermal stability of, 23 726-727 Polythioesters, 23 729-732 preparation of, 23 730-731 Polythioether-based urethane sealants, 22 36... 

Polythioether polymer, 22 40-41 Polythioethers, 23 704 Polythionic acids, 23 641 Polythiophene(s), 22 207t 23 708 conducting, 7 517-520 7 523, 527 electrochromic material, 6 572t, 575, 581t... 

The systems with which we have been working involve aquo-copper(II) ion reacting with a series of cyclic and open-chain polythioether ligands, each with four or more donor atoms. We first noticed that, as one increases the concentration of "inert" anions, such as CIO, BF, and CF SO, the stability of the... 

A similar linear relationship between Cu(II/I) potential values and logarithmic Cu" L stabiKty constants may exist in non-aqueous solvents, but such a relationship has not been adequately established. Measurements conducted in our laboratories on a variety of polythioether complexes have shown that the Cu"L stability constants tend to increase by approximately 10 on going from water to acetonitrile, whereas the Cu L stability constants tend to decrease by a similar order of magnitude [54]. These values obviously reflect the preference of Cu (I I) to be solvated by water and the corresponding preference of Cu(I) to be coordinated to acetonitrile [111]. 

E. M. Fettes and F. O. Davis, in N. G. Gaylord, ed., Polyethers, III, Polyalkylene Sulfides and Other Polythioethers, Interscience Publishers, New York,... 

Although polyethers are the main building blocks of the prepolymer, other materials such as polyesters, polythioethers, and polybutadienes are also used. Most urethanes use blends of polymers to achieve desired properties. Urethane sealants have pood inherent adhesion to most substrates, but silane adhesion promoters are often used to unprove this adhesion,... 

C. Copper Polymers Assembled by Aliphatic Dithioether and Polythioether Ligands... 

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