Sulfur‐Containing Polymers
Authors: Kultys Anna 
Published: October 2003

This review describes methods of synthesis and some more interesting properties of the various new sulfur‐containing polymers, with particular regard for their potential application possibilities. Also, some new or improved methods of synthesizing already known polymers are discussed.

Polysulfides, including poly(monosulfide)s and poly(disulfide)s are the subject of many detailed studies. In the last decade, extensive efforts have been devoted to the synthesis of cyclic oligomers (macrocyclic aromatic sulfides and disulfides) as precursors for the preparation of high molecular weight poly(thioarylene)s by ring‐opening polymerization. The coordination chemistry of macrocyclic polysulfides has also received considerable attention. The thiacrown ether polymer ligands can be used as ion‐exchange resins, metal ion adsorbents, and polymeric phase‐transfer catalysts. Molecular systems in which tetrathiafulvalene is incorporated into macrocycles with supplementary donor atoms are potential electroactive cation sensors. Perfluoro‐ and polyfluorothiophenes have been studied as precursors to novel electrically conductive polymers.

Polysulfoxides are used as functional polymers. Polymers with sulfoxide group in the main chain can be used as novel polymeric oxidizing reagents, compatibilizers, and polymer solvents, and those with chiral sulfonyl groups as stationary phases of chiral hplc column or as polymeric reagents.

Polysulfonium salts can be used as ion‐exchange resins, polymer supports in peptide synthesis, polymeric reagents, or conducting and photochemical polymeric materials. There have been reports of examples of polymers with sulfonium salt moieties applied as a catalyst to organic reactions and precursors of such polymers as PPS, perfluorinated PPS, PPV, and PPSA. Poly(thiophenium salt)s were found to act as a new type of polymeric alkylation reagents.

Polymers substituted by sulfo groups have a wide range of applications. Water‐soluble polymers are used as emulsifiers, flocculants, thickeners, tanning agents, conductive polymers, etc. Sulfonated polyelectrolyte block copolymers are effective stabilizers in emulsion polymerization. Insoluble polymers are used as ion‐exchange resins and they find application as membrane materials. A great demand for chemically stable ion‐exchange membranes for electromembrane processes (such as electrodialysis, polymer electrolyte membrane electrolysis, and polymer electrolyte fuel cells) has, in the past years, stimulated investigations dealing with the developing of the sulfonation process of thermally and chemically stable engineering plastics. Sulfopolymers are employed in biomedical systems. Much effort has been expended to improve blood‐contacting biomaterials, eg, segmented polyurethanes, and develop various polysulfates and polysulfonates as antithrombotic or antiviral agents.

Polysulfates also have potential biomedical applications, eg, as antithrombotic agents. Polysulfates in general, and sulfated polysaccharides in particular, are active against a wide variety of enveloped viruses. A major commercial sulfated polysaccharide is carrageenan, used in ice cream and other food products.

Polythioesters, polythiocarbonates, as well as polythiourethanes are interesting thermoplastics. Thus, biphenyl‐based polythioesters are high thermal stability polymers. Polythiocarbonates showing a high refractive index are potentially interesting for optical applications. Polymers bearing five‐membered cyclic dithiocarbonate groups in the side chain are potentially the most versatile reactive polymers. Thiopolyurethanes bearing the thiol groups may be used as reactive polymers to produce optical materials.

Segmented thiopolyurethanes based on simple thiodiols as chain extenders with poly(tetramethylene oxide) soft segment are high elasticity thermoplastic elastomers. Polymers containing diphenylmethane units with active methylene groups are new, potentially peroxide‐curable, HDI‐based thiopolyurethanes, whereas polymers containing benzophenone units may find use as interesting modifiers of photosensitive polyurethanes.

Studies on polysulfoximines, the new potentially high performance engineering plastics, have recently been undertaken.