Optical sensor based on ultrathin films of δ-form syndiotactic polystyrene for fast and high resolution detection of chloroform

In this work are analyzed the performances of an optoelectronic sensor based on a sensitive nanoscale film of semicrystalline syndiotactic polystyrene (sPS) with a nanoporous crystalline phase developed for fast and high resolution detection of chloroform. In particular, the change of the polymer refractive index due to chloroform sorption into the polymer layer when the sensor is exposed to ${\mathrm{C}\mathrm{H}\mathrm{Cl}}_3$ has been used as transduction property. Reflectance measurements have been performed using a fiber optic refractometer, coated with nanometric sPS film at very low pressure of chloroform, demonstrating high sensitivity and fast-time response combined with excellent reversibility. Mass sorption experiments have also been performed on the same polymeric material with an electronic microbalance at the same conditions at which the optical sensor has been characterized. This allowed a quantitative correlation between the mass of the analyte sorbed within the polymer layer and the refractive index variation, which has been found to be essentially independent of the temperature.