Development of pH sensing colloidal nanoparticles and oil/water separating electrospun membranes containing oxazolidine from functional polymers

Abstract

Photoresponsive polymer nanoparticles have attracted a large attention in the field of chemical sensors due to their capability of sensing polarity, ions, and pH. Incorporation of oxazolidine into polymer nanoparticles resulted in fluorescence chemosensors with fast responsivity and high sensitivity of polarity and pH. Photoresponsive polymeric nanofibers have also become interesting owing to their unique applications in design of smart membranes to separate oil in water mixtures. Surface wettability of these nanofibers could reversibly be tuned by visible light or UV irradiation. Smart polymer nanoparticles and nanofibers containing oxazolidine were prepared by nanoprecipitation and electrospinning methods, respectively. The molecular weight and chemical structure of the prepared polymers by reverse atom transfer radical polymerization were evaluated by proton nuclear magnetic resonance. According to the dynamic light scattering data, the photoresponsive nanoparticles showed size in the range of 60–80 nm with a narrow distribution. Furthermore, polymer nanoparticles and nanofibers had spherical and uniform morphology, respectively. Optical characterization of the nanoparticles at different pHs displayed their potential application in the pH chemical sensors field by coloration and fluorescence emission mechanisms. Evaluation of the optical properties of the nanofibers showed a remarkable hydrophobicity/hydrophilicity photoswitching (variation of surface water contact angle from 135 to 58° upon UV/visible light irradiation cycles), which was used for the preparation of oil/water separating nanofibrous membranes.