Layer-by-Layer Assembly of a pH-Responsive and Electrochromic Thin Film

This article summarizes an experiment on thin-film fabrication with layer-by-layer assembly that is appropriate for undergraduate laboratory courses. The purpose of this experiment is to teach students about self-assembly in the context of thin films and to expose students to the concepts of functional polymeric coatings. Students dip coat microscope slides and conductive glass with films containing polyaniline (PANi), a conducting polymer, and sulfonated polystyrene. Assembly of the film is characterized by visual inspection, UV−vis spectroscopy, and conductance measurements with a hand-held multimeter. Green-colored films with measurable conductance are apparent after two PANi layers. Subsequently, the students observe the pH-dependent optical properties of the films and also determine the electrochromic performance of the films using spectroelectrochemistry. The feasibility of this experiment has been tested by inclusion into an undergraduate-level polymer science laboratory with third- and fourth-year students.National Science Foundation (U.S.) (MRSEC Program award number No. DMR-0819762