Chemists from Poland and France have made hybrid polymers that not only have electrical properties, but also electrochromic and pH-dependent electrochemical properties.

The family of polymers has potential as components in pH sensors with optical or electrochemical processes. Such sensors are used in laboratories and hospitals across the world.

Malgorzata Zagorska from the Warsaw University of Technology and her team have engineered aniline side chains to sit at regular intervals along a soluble conducting polymer backbone. Zagorska first produced the polyalkylthiophene chain and attached the short aniline side-arms at a later stage. 

The use of functionalisation steps after the polymerisation has the advantage of allowing greater control over the regularity of the substituents on the backbone of the polymer, thereby giving more reliable properties in the polymer.

Peter Wright of the Department of Engineering Materials in Sheffield commented that 'the control of electrochemical function by imparting sensitivity to an appropriate applied stimulus is clearly one of the important ways in which conjugated polymers can contribute to sensor technology.'

Zagorska said that the polymer 'can easily be generalised to grafting functional substituents other than oligoanilines'. 

She also said that future projects may focus on introducing complexing sites for use in ion-selective electrodes, catalytically active sites, groups with non-linear optical properties, and also groups that can promote the self-organisation of macromolecular systems which may have tunable properties. 

Emma C D Lawrence