Nanostructured Spherical-Shaped Sc(III) Polyacrylate for Monitoring the Moisture Level

This paper reports the investigation of transmitted power through the nanostructured scandium polyacrylate (Sc(III) PAcr) deposited on flat borosilicate substrates to examine the adsorption/desorption of humidity at room temperature. For this purpose, the precursor of Sc(CH₂ = CH-COO)₃ was prepared and used for film deposition. The film was then investigated using scanning electron microscope (SEM) and UV-Visible (Vis) absorption techniques. SEM showed the spherical-shaped clusters of the material. Energy band gap of the film was estimated as 3.887 eV by UV-Vis spectrophotometer. Transmission electron microscope revealed the minimum grain diameter of ~21 nm and selected-area electron diffraction showed its polycrystalline nature. From Zeta nanosizer, minimum particle size was found as 18 nm. Fourier transforms infra-red spectroscopy confirmed the bond formation in the material. The surface area analysis shows that the pore volume of Sc(III) PAcr is 0.15 cm³/g, which is quite small, whereas the surface area and mean pore radius of the spherical structure are 60.1 m²/g and 41.2 Å, respectively. The film was employed as transmission-based optoelectronic humidity sensor. Maximum sensitivity was found as 2.1 μW/%RH with 89% reproducibility. Response and recovery times of the sensor were found as 25 and 155 s, respectively.