Polymer Probes and Sensors

Solvatochromic probes have found applications in polymer characterisation, where they can be used to look for localised polar features at the molecular level. Two distinct approaches can be adopted  

In the first case, the environment is fixed and so the probe is unable to choose a preferred site for its colour change, but can give information of chain orientation etc. In the second, the probe is mobile and will seek out the most favourable site over a period of time, enabling areas of differing polarity within the polymer to be 

These two methods can be adapted for use in the commercially attractive area of polymer bound sensors. These offer, especially when coupled with fibre optics, a safe way of examining flammable solvents for their composition and levels of liquid impurities. 

For example, dissolving the betaine (1.98) or another negative solvatochromic dye in PMM and spin coating the solution to give a film on a sensor tip provides a product suitable for the analysis, in visible absorption or transmission mode, of alcohols and ethers in gasoline. 

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