polyethersulfones

Polyethersulfones are a family of high-temperature thermoplastic polymers characterized by repeating ether linkages (-O-) and sulfone groups (-SO2-) in their backbone. The class includes polyethersulfone (PESU) and related copolymers, which are typically transparent, amorphous, and known for a favorable combination of thermal stability, chemical resistance, and processability. These properties make PESU useful in demanding applications such as filtration membranes, medical devices, and fluid handling components.

Structure and synthesis

The polymer backbone consists of aryl rings connected through sulfone and ether linkages. The ether-to-sulfone ratio and the choice of dihydroxy or difunctional monomers influence properties and processing. PESU is usually prepared by nucleophilic aromatic substitution polycondensation between difunctional difluorinated sulfone monomers and bisphenols (for example hydroquinone or bisphenol A derivatives) in high-temperature polar aprotic solvents with a base, forming long chains with alternating ether and sulfone linkages.

Properties

PESU exhibits high thermal stability with a high glass transition temperature and retains mechanical strength at elevated temperatures. It is generally amorphous and transparent, offering good dimensional stability and chemical resistance to many acids, bases, and organic solvents. It is resistant to steam sterilization and is compatible with a range of solvents used in pharmaceutical and industrial processes.

Processing and applications

PESU can be melt processed via extrusion or molding at elevated temperatures, or processed from solution by casting. Common solvents for solution processing include DMF, DMAc, and NMP. A major application area is membrane technology, where PESU is used for ultrafiltration and microfiltration membranes, as well as for sterilizable medical devices, pharmaceutical filtration, and certain industrial components.