Thiadiazole polymers

PCS of the II type are the most interesting as modifiers. Many types of polymers belong to this type. Their chains contain heteroatoms N, O, S with non-distributed -electrons. Among them are polybenzimidazoles, thiazoles, thiadiazoles, polymers of hydrocyanic acid PCS with end heteroatoms - polymethynes, cyan dyes and their analogs, PCS with repeated heteroatoms in conjugated chains - polyazines, polyschiff bases, polymeric azo- and diazocompounds and so on. 

Colella S, Melcarne G, Mazzeo M, Gigli G, Grisorio R, Suranna GP, et al. Synthesis, characterization and photovoltaic properties of random poly(arylene-vinylene)s containing benzo-thiadiazole. Polymer 2011 52(13) 2740-6. 

Other Accelerators. Amine isophthalate and thiazolidine thione, which are used as alternatives to thioureas for cross-linking polychloroprene (Neoprene) and other chlorine-containing polymers, are also used as accelerators. A few free amines are used as accelerators of sulfur vulcanization these have high molecular weight to minimize volatility and workplace exposure. Several amines and amine salts are used to speed up the dimercapto thiadiazole cure of chlorinated polyethylene and polyacrylates. Phosphonium salts are used as accelerators for the bisphenol cure of fluorocarbon mbbers. 

Dimercapto-l,3,4-thiadiazole derivatives, accelerated by amines, are used to cross-link chlorinated polyethylene. Polyisobutylene containing brominated i ra-methylstyrene cure functionahty can be cross-linked in polymer blends with dimercapto-1,3,4-thiadiazole derivatives accelerated with thiuram disulfides. Trithiocyanuric acid is suggested for use in polyacrylates containing a chlorine cure site and in epichlorohydrin mbbers. 

A parallel synthesis of 1,2,3-thiadiazoles employing a catch-and-release strategy has been reported using the Hurd-Mori reaction. A polymer-bound tosyl hydrazide resin reacted with a-methylene ketones to afford a range of sulfonyl hydrazones. Treatment of these sulfonyl hydrazones with thionyl chloride causes 1,2,3-thiadiazole formation and cleavage of the resin in one step <1999JOC1049>. 

Chemists have found numerous industrial applications for 1,2,3-thiadiazole derivatives. In particular, 1,2,3-thiadiazole derivatives have been used as insecticide synergists, herbicides, and polymer compounds. They have also been shown to have sedative, antibacterial, and antibiotic activity. Examples of these compounds were discussed in CHEC(1984) and CHEC-II(1996). 

The photochemical reactivity of 1,2,3-thiadiazoles has been utilized in the formation of cross-linked polymers <1996CHEC-II(4)289>. No new developments in this area have been reported since the publication of CHEC-II(1996). 

Another example of a polymer formation is the oxidation of l,3,4-thiadiazole-2,5-dithiol [27] including the formation of an intermediate disulfide (5). As the latter is... 

The 1,2,5-thiadiazoles have found value across pharmaceutical, agricultural, industrial, and polymer chemistry. These uses have been well documented <84CHEC-I(6)513>. 

The stability and relatively ready accessibility of thiadiazole diazonium salts has encouraged their use in the production of numerous monoazo-dyes that have proved particularly suitable for dyeing polymers.192,196... 

The photolysis of 1,2,3-thiadiazoles also leads to the evolution of nitrogen, but the unstable thiirene is not obtained. 1,2,3-Thiadiazole itself yields nitrogen, acetylene, and polymer.96 In the presence of perfluorobut-2-yne, however, 2,3-bis(trifluoromethyl)thiophene is... 

Di(2-thienyl)thieno[3,4-c][l,2,5]thiadiazole (178) has been polymerized to give a narrow band gap heterocyclic polymer with interesting optical and electrochemical properties <93SM1251>. Stable dithiazolyl radicals, such as (18) and (19), are useful as inhibitors and stabilizers for radical reactions <82EGP156366>. 

The polymer-templated OMSs such as SBA-1545 possess pores about 8-12 nm, which are more spacious and can be decorated with more complex ligands. The SBA-15 sample studied exhibited ordered mesopores about 10 nm, and irregular micropores in the mesopore walls as shown in Figure 1. Initially chloropropyl-SBA-15 material was obtained and subsequently grafted with 2,5-dimercapto-l,3,4-thiadiazole ligand16 (OMM-3 material in Figure 1). These... 

Thiadiazoles readily undergo photochemical reactions (see Section 4.24.3.1) which have been utilized in polymer chemistry. For instance, polymers of type (46), formed by condensation of bisphenol epichlorohydrin copolymers and a l,2,3-thiadiazole-4-carboxylic acid, undergo photochemically induced crosslinking (70SST(1)444). This type of process is useful in the printing and electronic industries. 

The photochemistry of 1,2,3-thiadiazoles promises to also be interesting. The parent compound photolyses to yield N2, C2H2, CS2 and polymer, initiated by... 

These tellurium-containing polymers were checked for their catalytic activity in the ep-oxidation of olefins and as oxidizing agents. The polymeric 4-methoxyphenyl tellurium oxide did not react with amines, amides, alcohols, or phenols, but oxidized hydroquin-ones to quinones, thiols to disulfides, thioketones to ketones, thioesters to esters, and thiobenzamides in organic solvents to cyanobenzenes and in acetic acid to 2,5-diaryl-4,l, 3-thiadiazoles. ... 

In the first step, the cadmium ion binds to one group (either SH or N, SH) and the second step could be a polymerisation step to give a polymer in which the cadmium bridges 2 thiadiazole groups. An additional step is possible... 

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