A group of UK chemists have developed a method that allows a family of insoluble polymers to be easily characterised for the first time. 

Aromatic poly(etherketone)s, such as the commercially available polymer PEEK, are very strong, thermally stable polymers. Due to their low density and resistance to corrosion, they are increasingly replacing metals in industrial applications such as aircraft construction. However, these polymers are insoluble in all organic solvents and are very difficult to characterise. 

By converting the aromatic ketone groups in PEEK to dithioacetals, Howard Colquhoun at the University of Reading, UK, and colleagues made a soluble derivative of the polymer, which can be characterised by conventional techniques such as NMR spectroscopy and especially gel permeation chromatography. The reaction is reversible and causes no degradation to the polymer. 

'This will provide a greatly enhanced understanding of this class of materials,' said Colquhoun. 'Our results should enable much improved product and process control in the rapidly expanding poly(etherketone)s industry.' 

The dithioacetalisation chemistry could potentially be used to introduce a wide variety of functional groups into the polymers, leading to polymers with novel physical and chemical properties. 

'Poly(etherketone)s are still some of the most expensive structural polymers in commercial production. The characterisation methodology described in our paper can only assist in the search for alternative, low-cost synthetic approaches to this type of polymer,' said Colquhoun. 

Joanne Thomson