2.2.4. Determination of Polymers Size

The DLS method was used to determine the durability and stability of polymer particles in 0.155 M sodium chloride at pH = 7.4 at 25 ◦C. The polymer particles suspended in the electrolyte were illuminated with a helium-neon (He–Ne) laser with a wavelength of 633 nm. Measurements were performed with a Zetasizer Nano ZS apparatus (Malvern Instruments, Malvern, UK). Using the Stokes–Einstein equation, the apparatus converted the particle velocity caused by Brownian motion into particle distribution. When determining the particle size, the Non-Invasive Back Scatter method was used, in which the detector is positioned at an angle of 173 degrees. The measured value is the hydrodynamic diameter. Size distributions by numbers were obtained. The resulting values were burdened with an error expressed as a standard deviation. All PS had a polydispersity index (called PDI, used to describe the variation in size) lower than 0.3. Additionally, analysis using the ELS technique was carried out that allowed for determining the zeta potential values of the tested systems.
