Conjugated polymers-based sensors for detection of water pollutants

One of the most serious issues facing life on earth is the severe extent of contamination of water bodies around the globe. Water, by virtue of being a universal solvent, suffers from contamination by an extremely wide variety and nature of compounds, including heavy metal ions, pesticides, fertilizers, pharmaceutical products, organic solvents, etc. These contaminants are harmful, and often carcinogenic if consumed above a certain concentration. As a result, several decontamination technologies have been developed over the years to provide clean water to humans, especially for drinking and daily household purposes. It should be remembered here that no single decontamination technology can perform the removal of all contaminating compounds from water. Therefore, a mix of technologies is often employed to achieve clean water. Also, the nature of contaminants present in water varies depending on a number of factors, including the nature of water bodies, their geographical location, their surrounding environment, etc. Therefore, it is always advisable to detect the pollutants present in a certain water source before performing the decontamination steps. This will ensure proper and to-the-point involvement of often costly water treatment technologies. In addition, the performance of sensing after decontamination, to make sure proper removal of pollutants, is also critical from the aspect of quality control and to ensure safety to the consumers. Keeping these points in mind, researchers have so far developed many sensing materials—the functioning of most of which depend on the conducting attribute of the material itself. In this regard, conjugated polymers (CPs), especially conducting CPs, offer one of the best property attributes among all the materials tested and reported so far. This is because, these polymers are highly unique as their conductivity can be tailor-made and fine-tuned to suit a specific sensing application, by alteration of the polymeric chain length, attached functional groups, oxidation states, pH of the solution, etc. This chapter will report and discuss conducting CPs-based sensing materials for water contaminants, which have been reported in the last 5-year period (i.e., 2015-20), and will analyze their suitability in the said application.