Monitoring the structural transformation of polymers via spectroscopic ellipsometry

We have used spectroscopic ellipsometry to map the dielectric function of Poly(Disperse Red 1 methacrylate, PDRM), a thermo-responsive polymer, during its structural transformation. The polymer films were fabricated by dissolving PDRM in tetrahydrofuran, and were spin coated on silicon substrates. Series of films, with varying concentration and thickness were fabricated and analyzed using ellipsometry; spectra were obtained at multiple angles of incidence, and between 200 nm and 1700 nm. The ellipsometry spectra were modelled to obtain the dielectric function and thickness of each film. Subsequently, we coupled a heating stage into the ellipsometer, and obtained temperature-dependent spectra. Analyzing the dielectric function and mapping the corresponding oscillators that represent the dielectric function of PDRM with temperature, allow us to gather information on how the electronic transitions effect the structural transformation.