ABSTRACT
Polysulfones (PSUs) are a family of aromatic, amorphous, transparent, high temperature engineering thermoplastics that are characterized by the sulfone group (–C6H5-SO2-).
The first PSU was invented [1,2] by Imperial Chemical Industries (ICI) in 1965. There are five major types of PSU made by three companies (Table 22.1):
• Union Carbide-polyaryl sulfones (Udel, Radel trade names) • ICI-polyether sulfones (Vitrex trade name) • 3M-polyarylether sulfones (Astrel trade name)
Other companies that manufacture and/or supply PSUs are
• Solvay Advanced Polymers • BASF (“Baden Aniline and Soda Factory”) • HOS-Technik • PolyOne Corporation
PSUs [3-6] are made via two main routes:
1. Polysulfonylation 2. Polyetherification
Figure 22.1 is a schematic of the polyetherification process for the making of Udel-type PSU. In this process, bisphenol-A is reacted with 4,4′-dichlorodiphenylsulfone. The polycondensation reaction takes place in a highly polar solvent such as dimethysulfoxide or sulfolane. The process differs from that of making polyetherether ketone (PEEK) because a dichloro version of the phenylsulfone is used instead of the more expensive and more reactive fluorine version. The reaction takes place at about 130°C-140°C. The produced PSU structure and other sulfone resins consist of benzene rings or phenylene
units linked by at least two different chemical groups, a sulfone group and an ether linkage. The three most commercially important PSUs are bisphenolA based PSU, 4,4′-dihydroxydiphenylsulfone-based polyethersulfone (PES), and 4,4′-dihydroxydiphenyl-based polyphenylsulfone (PPSU).
